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I-i

I

REPORT ON

THE MECHANICAL AND THERMAL PROPERTIES OFTUNGSTEN AND TZM SHEET PRODUCED IN THE

REFRACTORY METAL SHEET ROLLING PROGRAM

Part 1

to

Bureau of Naval WeaponsContract No. N600(19)-59530

Southern Research Institute

2000 Ninth Avenue South

Birmingham, Alabama 35205August 31, 1966

7563-1479-XII

ABSTRACT

This report describes an evaluation program that was performedto obtain preliminary design data for tungsten and TZM sheet produced inthe Refractory Metal Sheet Rolling Program. Tungsten sheet 0. 060- and0. 10-in. thick, and TZM sheet 0.020-, 0.040-, and 0.060-in. thick, wereinvestigated. Both materials were studied in the optimum (warm workedand stress relieved) and recrystallized conditions, Me.chanical propertiesevaluated included tensile, notched- tensile, compression, bearing, shear,creep, thermal-stability, weld joint efficiency. The recrystallization andbend-transition temperatures were also determined. Physical propertiesthat were evaluated included density, thermal expansion, thermal conduc-tivity and specific heat. Tensile and bend evaluations were performed onthe TZM sheet after application of two commercial coatings, PFR-6 andW-3.

SOUTHERN RESEARCH INITITUTE

AI

TABLE OF CONTENTS

Pa ge_

INTRODUCTION . . . 1

SCOPE . ... . . . . . . . . 2

MATERIALSRS.... . . . . . . . 4

Tungsten Sheet . . . . . . . . . . . .. 4TZM Sheet . . . . . . . . . . . . . . . 7

PREPARATION OF SPECIMENS . . . . . . . . 8

EQUIPMENT . . . . . . . . . 11

TEST PROCEDURES . . . . . . . . . . . . 14

Recrystallization . . . . . . . . . . . . . 14Tens ile. . . . . . . . . 17Notched Tensile . . . . . . . . . . . . . 19Bend-Transition Temperature . . . . . . . . . . 20Compression . . . 24Bearing . . . . . . . . . . . . . . . . 28Shear . . . . . . . . . . . . . . . . . 28Creep ........................ . 28Thermal Stability ............... 31Weld-Joint Efficiency . 31Density .. . . . .... . . . . . . . . . . . 34Thermal Conductivity . . . . . . . . . . . . 34Heat Capacity. . . 36Thermal Expansion . 38

L DISCUSSION AND RESULTS . . . . . . . . . . . . 39Proper tics of T.1un.gstenr Sheet3

Recrystallization Temperature . . . . . . . . 39Tensile . . . 39

Notch-Tensile Properties . . . . . . . .59Bend Properties . . . . . . . . . . . . . 65Compressive Strength 78Shear and Bearing ....... ........ . . . . . 83Creep . . . . . . .... . . .... 86Thermal Stability . . . . . . . . . . . . 86Density . . . . ... 90Thermal Expansion . . . . . . . . . . . . 90Thermal Conductivity 92Ileat Capacity . ............... ... 92

-UTHEN RESEARCH INSTITUTE

TABLE OF CONTENTS (Cont'd)

Page

Properties of the TZM Sheet . . . . . . . .. 95

Recrystallization Temperature . . . . . . . . . 95Tensile -Uncoated Sheet . . . . . . . . . . . 105Tenzile -Coated Sheet . . . . . . . . . . . 119Notched Tensile Properties . . . . . . . .. . 119Bend Properties . . . . . . . . . . . . . . 130Compressive Strength . . . . . . . . . . . . 144Shear and Bearing . .. . . . ... . 144Creep ... . . . . .............. 144Thermal Stability . . .............. 151Fusion Weld Joint Efficiency . . . . . . . . . . 153Density . . . . . . . ... . . . 153Thermal Expansion ........................ 153Thermal Conductivity ..... . ........ . . . . . 156Heat Capacity . . . . . . . . . . .. . 156

BIBLIOGRAPHY . . . . . . . . . . . . . . . . . 160

APPENDIX A - Composition and Release Properties of TZM Sheet . 163

APPENDLX B - Tabulated Data for Thermal Property Evaluations . 172

DISTRIBUTION LIST ............. 185

i iii

LIST OF TABLES

Number Page

I Summary of Property Evaluations. . . . . . . . . 3

II Identification and Size of the Tungsten Sheets ..... 4

III Approximate Composition of Tungsten Powder in Percentby Weight . . . . . . . . . . . . 5

IV Identification and Size of the TZM Sheets .. . . . . 7

V Composition of TZM Materials Received for PropertyEvaluation. . . . . . . . . . . . . . 9

VI Summary of Welding Conditions for Tungstenand TZM Sheet . . . . . . . . . . . . . . 33

VII The Hardness and Percent Recrystallization of Three0. 060-In. -Thick Tungsten Sheets After Holding at Dif-ferent Temperatures for Five and Sixty Minutes . . 40

ViII The Hardness and Percent Recrystallization of 0. 100-In. -Thick Tungsten Sheet After Holding at Different Tempera-tures for Five and Sixty Minutes . . . . . . . . . 42

IX Tensile Properties of 0. 060-In. -Thick Tungsten Sheet inthe Optimum Condition at Different Temperatures . . . 49

X Tensile Properties of 0. 060-In. -Tungsten Sheet in theRecrystallized Condition at Different Temperatures . 50

XI Tensile Properties of 0. 100-In. -Thick Tungsten Sheetin the Optimum Condition at Different Temperatures . 51

XII Tensile Properties of 0. 100-In. -Thick Tungsten Sheetin the Recrystallized Condition at Different Temperatures 52

XIII Notched-Tensile and Unnotched-Tensile Data for 0. 060-In. Tungsten Sheet in the Optimum Condition at Moderately-Elevated Temperatures. . . . . . . . . . . . 60

XIV Notched-Tensile and Unnotched-Tensile Data for 0. 060-In.Tungsten Sheet in the Recrystallized Condition at Moderately-Elevated Temperatures . .. ... . .... 61

iv

-OUT14F -R&ARC NTTT

LIST OF TABLES (Cont'd)

Number Page

XV Notched-Tensile Transition Temperature for Tungsten Sheet . 62

XVI Data for Determination of the Bend-Transition Temperaturein the Longitudinal Dire ction for 0. 060-In. -Thick TungstenSheet in the Optimum Condition - 1. 5t Punch Radius. . . . 66

XVII Data for Determination of the Bend-Transition Temperaturein the Transverse Direction for 0. 060-In. -Thick TungstenSheet in the Optimum Condition - 1. 5t Punch Radius .... 68

XVIII Data for Determination of the Bend-Transition Temperaturein the Longitudinal Direction for 0. 060-In. -Thick TungstenSheet in the Optimum Condition - 8t Punch Radius . . . . 72

XIX Data for Determination of the Berid-Transition Temperaturein the Longit-dinal Direction for 0. 060-In. -Thick TungstenSheet in the Optimum Condition - 4t Punch Radius . . . 74

XX Data for Determination of the Bend-Transition Temperaturein the Transverse Direction for 0. 060-In. -Thick TungstenSheet in the Optimum Condition - 4t Punch Radius .... 75

XXI Data for Determination of the Bend-Transition Temperaturein the Longitudinal Direction for 0. 060-In. -Thick TungstenSheet in the Recrystallized Condition - 4t Punch Radius . . 76

XXII Data for Determination of the Bend-Transition Temperaturein the Transverse Direction for 0. 060-In. -Thick TungstenSheet in the Recrystallized Condition - 4t Punch Radius . . 77

%IXXIJ Suiiary of IDoiiU- Li JIIl "• - ....r-o, f or 0-n0,M _Thick Tungsten Sheet. . . . . . . . . . . . . 81

XXIV Longitudinal and Transverse Compression Properties atRoom Temperature of 0. 060-In. -Thick Tungsten Sheet in theOptimum and Recrystallized Conditions . . . . . . . 82

XXV Compression Properties of Tungsten Sheet at ElevatedTemperature . . . . . . . . . . . . . . 84

XXVI Sliear Strength of 0. 0 6 0-In. Tungsten Sheet . . . . . . 85

XXVII Bearing Strength of 0. 060-In. Tungsten Sheet ..... 85

V

LIST OF TABLES (Cont'd)

Number 1'ape

XXVIII Time for 1% Creep Deformation of 0.060-In. TungstenSheet at 2500' F and Different Stress Levels . ... 86

XXIX Tensile Properties of the Tungsten Sheet After CreepExposure to 1% Deformation at 25000 F . . . . . 89

XXX Density of Tungsten Sheet . . . . . . . . . . 90

XXXI Hardness and Percent Recrystallization of 0. 020-In. TZMSheet after Iloiding for Five and Sixty Minutes at DifferentTemperatures . . . . . . . 96

XXXII Hardness and Percent Recrystallization of 0. 040-In.TZM Sheets after Holding for Five and Sixty Minutesat Different Temperatures . . . . . . . . . 97

XXXIII Hardness and Percent Recrystallization of 0. 060-In.TZM Sheet after Holding for Five and Sixty Minutesat Different Temperatures . . . .o. . . . 98

XXXIV Recrystallization Temperature of the TZM Sheet . . . 95

ZI1 V A .1 -Io e lc e sl e~J I L LJt Lt V . ~J UA lk . ~J.L" 1~IVI '.S LLI b1L%Optimum Condition at Different Temperatures . . 106

XXXVI Tensile Properties of 0. 020-1n. TZM Sheet at DifferentTemperatures in the Recrystallized Condition . . . . 107

XXXVII Tensile Properties of 0. 040-1n. TZM Sheet in theOptimum Condition at Different Temperatures . . . . 108

XXXVIII Tensile Properties of 0. 040-In. TZM Sheet in theRecrystallized Condition at Different Temperatures . . 109

XXXIX Tensile Properties of 0. 060-In. TZM Sheet in theOptimum Condition at Different Temperatures , 110

XL Tensile Properties of 0. 060-In. TZM Shoet in theRecrystallized Condition at Different Temperatures , . 111

XLI Comparison of Tensile Data for TZM Sheet in the OptimumCcndition from Universal Cyclops and Southern ResearchInstitute . . . . . . . . . . . . . . . 120

vi

LIST OF TABLES (Cont'd)

Number Page

XLII Tensile Properties of W-3 Coated 0. 040-In. TZM Sheetin the Optimum Condition at Different Temperatures . 121

XLIII Tensile Properties of PFR-6 Coated 0. 040-In. TZM Sheetin the Optimum Condition at Different Temperatures. . . 122

XLIV Notched-Tensile and Unnotched-Tensile Data for 0. 040-In.TZM Sheet in the Optimum Condition at Low Temperatures. 126

X!LV Notched-Tensile and Unnotched-Tensile Data for 0. 040-In.TZM Sheet in the Recrystallized Condition at Low Tempera-tures . . . .......... . . . . . . . 127

XLVI Notched-Tensile Transition Temperature of TZM Sheet. . 130

XLVII Data for Determination of the Bend-Transition Temperaturein the Longitudinal Direction of 0. 040-In. TZM Sheet in theOptimum Condit.on, 4t Punch Radius . . . . . . . 131

XLVIII Data for Determination of the Bend-Transition Temperaturein the Transverse Direction of 0. 040-In. TZM Sheet in theOptimum Condition, 4t Punch Radius . . . . . . . 132

IL Data for Determination of the Bend-Transition Termperaturein the Longitudinal Direction of 0. 0 4 0-In. TZM Sheet inthe Recrystallized Condition, 4t Punch Radius .... 133

L Data for Determination of the Bend-Transition Temperaturein the Transverse Direction of 0.040-In. TZM Sheet in theRecrystallized Condition, 4t Punch Radius . . . . . 134

LI Data for Determination of the Bend-Transition Temperaturein the Longitudinal Direction of 0. 040-In. TZM Sheet in th7eCoated-Optimum Condition, 4t Punch Radius . . . . . 135

LII Data for Determination of the Bend-Transition Temperatbrein the Thansverse Direction of 0. 040-In. TZM Sheet in theCoated-Optimum Condition, 4t Punch Radius . . . .. 136

LIII Data for Determination of the Bend-Transition Temperaturein the Longitudinal Direction of 0. 040-In, TZM Sheet in theCoated-Optimum Condition, 4t Punch Radi.us ..... 137

vii

LIST OF TABLES (Con+'d)

Number Page

LIV Data for Determination of the Bend-Transition Tempera-ture in the Transverse Direction of 0. 040-In. TZM Sheetin the Coated-Optimum Condition, 4t Punch Radius . . . 138

LV Bend-Transition Temperatures of Uncoated and CoatedTZM Sheet, 4t Punch Radius . . .. . . 143

LVI Compression Properties of 0. 040-In. TZM Sheet atRoom Temperature in the Optimum and RecrystallizedConditions. . . . . . . . . . . . . . . 145

LVII Shear Strength at Room Temperature of 0. 040-In. TZMSheet ............ ................ 146

LVIII Bearing Strength at Room Temperature of 0. 040-1n. TZMSheet . . . . . . . . . . . . . . . . 146

LLNI Summary of Time to 1% Creep Deformation for 0o 040-In.TZM Sheet in the Optimum Condition . . . . . . . 151

1.X Tensile Properties at Room Temperature of TZM SheetAfter Creep-Exposure to 1% Deformation at 20000 F or2500 F . . . . . . . . . . . . . . . 152

LXII Density of TZM Sheet . . . .. . .. .. 153

LXI Room-Tempeiature Tensile Properties of Fusion-Welded0. 040-In. TZM Sheet in the As-Welded and Heat-TreatedConditions . . . . . . ........ 154

APPENDIX B

i-b The Thermal Expansion of Tungsten Sheet Using theQuartz Tube Dilatometer ........ 173

ii-b The Thermal Expansion of Tungsten Sheet Using theGraphite Dilatometer. . . . . . . . . . . . 174

iii-b The Thermal Conductivity of Tungsten Sheet Using theComparative Rod Apparatus with Armco Iron References 176

viii

LIST OF TABLES (Cont'd)

Number Page

iv-b The Thern ial Conductivity of Tungsten Sheet Using the RadialInflow Apparatus .. . . . . . . . 177

v-b The Enthalpy of Tungsten Sheet ......... 178

vi-b The Enthalpies and Heat Capacities of Sheet Tungsten andTZM Calculated from the Equations Fitted to the ExperimentalData and From the Graphical Solutions ....... 179

vii-b The Thermal Expansion of TZM Sheet Using the QuartsTube Dilatometer ..... .... . 180

viii-b The Thermal Expansion of TZM Sheet Using the GraphiteDilatometer . . . . . . . . . . ... . . 181

ix-b The Thermal Conductivity of TZM Sheet Using the Compara-tive Rod Apparatus with Armco Iron References 0 . . . 182

x-b The Thermal Conductivity of TZM Sheet Using the RadialInflow Apparatus . . . .. ....... . 183

xi-b The Enthalpy of TZM Sheet . . . 184

ix

LIST OF FIGURES

Number Page

I The microstructure in longitudinal and transverse orien-tations of the 0. 060-in. thick tungsten sheet in the opti-mum condition . .... . . . . . . . . 6

2 Special tensile apparatus capable of wide range of strainrates, heating rates, and evaluation temperatures . . . 12

3 Vacuum furnace system and universal testing machine fortensile evaluations up to 4000° F. . . . . . . . . 13

4 Vacuum chamber and pumping system for use in recrystal-lization, heat treatment, and creep-rupture evaluation ofrefractory metal alloys . . . . . . . . . . . 15

5 Recrystallization specimen . . . . . . . . . . 16

6 Specimens for tensile and creep tests . . . . . . . 18

7 Notched tensile specimen with a stress concentration factor,Kt. of 4.2 ............. . . .. . 21

8 Bend-test fixture . . . . . . . . . . . . . 22

9 Bend specimen ........ .......... . . .. 23

10 Compression fixture showing cross-section of thesupport blocks with specimen in place . . . . . . . 25

11 Compression specimen . . . . . . . . . . . 26

12 Compression speci fren f use at elevated temp.r7tr.. . 27

13 Bearing specimen. . . . . . . . . . . . . 29

14 Shear specimen . . . . o . . . . . . . . 30

15 Typical welded test panel from which tensile specimenswere machined. . . . . . . . . . . . . . 32

16 Laminated thermal conductivity specimen configuration forsheet metal materials, and photograph of broken TZM spe-cimen showing depth of heat affected zone ..... 35

x

rMLI rRN 9FAAC N4T1P

LIST OF FIGURES (Cont'd)

Number Page

17 Stacked disc cyiindrical thermal conductivity specimenconfiguration for the radial inflow apparatus .... 37

18 The Re hardness o- 0. 030- and 0. 100-in. -thick tungstensheet after holding :i anid 60 min at different temperatures . 43

19 The DPH at the mid thickness on longitudinal sections ofdifferent 0. 060-in. -tthick tungsten sheet after holding 5and 60 min at different temperatures ... . . . 44

20 The DPH at mid-thickness on longitudinal sections of0. 10 0 -in. -thick tungsten sheet after holding 5 and 60min at different temperatures . . ...... 45

21 Effect of temperature and time at temperature on therecrystallization of 0. 060-in. -thick tungsten sheet . . . 46

22 Effect of temperature and time at temperature on therecrystallization of 0. 100-in. -thick tungsten sheet . . . 47

23 Comparison of the longitudinal microstructure of thethree 0. 060-in. -thick tungsten sheets after recrystalli--zaton at 27000 F for A0 nm . . . . . . . . . . 48

24 The ultimate-tensile and 0. 2%o offset-yield strengths at dif-ferent temperatures of 0. 060-in. tungsten sheet in the opti-mum and recrystallized conditirons . . . . . . . . 53

25 The elongation and reduction of a•rea of 0. 060-in. tungstensheet in the optimum and recrsvtailized conditions at dif-ferent temperatures . . . . . . . . . . 54

26 The ultimate-tensile and 0. 21-offset-yield strengths at dif-ferent temperatures of 0. 100-in. tungsten sheet in the opti-mum and recrystallized conrittions . . . . . . . . 55

27 The elongation and reduction ot area of 0. 100-in. -tungstensheet in the optimum and recrystallized conditions at dif-ferent temperatures . . . . . . . . . . . . 56

xi

LIST OF FIGURES (Cont'd)

Number Page

28 The modulus of elasticity at different temperatures of0. 060-in. and 0. 100-in. tungsten sheet in the optimumand recrystallized conditions . . . . . . . . .. 57

29 Notched and unnotched tensile strength and notched/un-notched tensile strenga ratio at different temperaturesfor 0. 060-in. tungsten sheet in the optimum condition . . . 63

30 Notched and unnotched tensile strength and notched/unnotched tensile strength ratio at different temperaturesfor 0. 060-in. tungsten sheet in the recrystallized condi-tion . . . . . . . . . . . . . . . . . . 64

31 Bend-transition-temperature curves based on bend angleunder load for the longitudinal orientation of three 0. 060-in. -thick tungsten Eheets in the optimum condition usinga punch with a radius of 1. St, a span of 1. 5 in., and aram-rate of 1. 0 in. /rin ............... . . 70

32 Bend-transition-temperature curves based on bend angleunder load for the transverse orientation of three 0. 060-in. -thick tungsten sheets in the optimum condition using apunch with a radius of 1. St, a span of 1. 5 in., and a ram-rate of 1. 0 in. /mn n . . . . . . . . . . . . 71

33 Bend-transition-tempez'ature curves based on bend angleunder load for the longiludinal orientation of two 0. 060-in. -thick tungsten sheets in the optimum condition using a punchwith a radius of 8t, a span of 1. 5 in., and a ram-rate of1. 0 in. /min . . . . . . . . . . . . .. . 73

34 Bend-transition-temperature curves based on bend angleunder load for the longitudinal and transverse orientationof three 0. 060-in. -thick tungsten sheets in the optimumcondition using a punch with a radius of 4t, a span of 1. 5 in. ,and a ram rate of 1. 0 in. /in. /min. . . . . . . . . 79

35 Bend- iransition-temperature curves based on bend angleunder load for the longitudinal and transverse orientationof three 0. 060-in. -thick tungsten sheets in the recrystal-lized condition using a punch with a radius of 4t, a span of1.5 in., and a ram rate of 1.0 in. /in. /rin . . . . . . 80

xii

LIST OF FIGURES (Cont'd)

N'umber Page

36 Time-deformation curves for 0. 060-in. -thick tungsten

sheet at 2500° F and ditferent stresses . . . . . . . 87

37 Effect of stress on time to 1% creep deformation at2500" F for 0. 060-in. tungsten sheet ..... 88

38 Thermal expansion of tungsten sheet parallel to the planeof the sheet . . . . . . . . . . . . . 91

39 Thermal conductivity of tungsten sheet parallel to the planeof the sheet . .* . . . . . . . . . . . . . 93

40 The heat capacity and enthalpy of tungsten sheet . . . . 94

41 The effect of temperature and time at temperature on thesurface hardness and cross-section hardness of 0. 020-in.

TZM sheet. Each data point shown represents the average

of five readings. . . . . . .. # . . , 99

42 The effect of temperature and time at temperature on

the surface hardness and the cross-section hardness of0. 040-in. TZM sheet .*. . . . . . . . . . . 100

43 The effect of temperature and time at temperature on thesurface hardness and cross-section hardness of 0. 060-in.

TZM sheet . . . . . . . . . . . . . . . 101

44 The effect of temperature and time at temperature on therecrystallization of 0. 020-in. TZM Sheet . . . . . . 102

45 The effect of temperature and time at temperature on therecrystallization of 0. 040-in. TZM Sheet . . . . . . 103

46 The effect of temperature and time at temperature on therecrystallization of 0. 060-in. TZM Sheet ...... 104

47 The ultimate-tensile and 0. 2%-offset-yield strengths of

0. 020-in. TZM sheet in the optimum and recrystallizedconditions at different temperatures . . . . . 112

48 The percent elongation and reduction of area of 0. 020-in.TZM sheet in the optimum and recrystallized conditionsat different temperatures . . . . . . . . . . . 113

xiii

0

LIST OF FIGURES (Cont'd)

Number Page

49 The ultimate-tensile and 0, 2%-offset-yield strengths of0.040-in. TZM sheet in the optimum and recrystallizedconditions at different temperatures . . . . . . . 114

50 The percent elongation and reduction of area of 0. 040-in.YZM sheet in the optimum and recrystallized conditions atdiii'erent temperatures . . . . . . . . . . . . 115

51 The ultImate tensile and 0. 2%-offset-yield strengths of0. 060-in. TZM sheet in the optimum and recrystallizedconditions at different temperatures . 0 . . . . . . 116

52 Percent elongation and reduction of area of 0. 060-in. TZMsheet in the optimum and recrystallized conditions at dif-ferent temperatures . . . . . . . . . . . 117

53 Modulus of elasticity of TZM sheet in the optimum and re-crystallized conditions at differerA temperatures . . . . 118

54 The ultimate-tensile and 0. 2%-offset-yield strengths ofcoated 0. 040-in. TZM sheet in the optimum condition atdifferent temperatures . . . . . . . . . . . . 123

55 The present elongation and reduction of area of coated0. 040-in. TZM sheet in the optimum condition at differenttemperatures. . .*. . . . . . . . . . . . 124

56 The modulus of elasticity of coated 0. 040-in. TZM sheetin the optimum condition at different temperatures . . 125

57 Notched and unnotched tensile strength and notched/unnotched tensile strength ratio at different temperaturesfor 0. 040-in. TZM sheet in the optimum condition . . . 128

58 Notched and unnotched tensile strength and notched/unnotched tensile strength ratio at different temperaturesfor 0. 040-in. TZM sheet in the recrystallized condition . 129

59 Bend-transition temperature curves based on bend angleunder load for the longitudinal orientation of 0. 040-in. TZMsheets in the optimum and recrystallized conditions. Punchradius 4t . . . . . . . . . . . . . . 139

xiv

t

LIST OF FIGURES (Cont'd)

Number Page

60 Bend-transition-temperature curves based on bend angleunder load for the transverse orientation of 0. 040-in. TZMsheets in the optimum and recrystallized conditions. Punchradius 4t . . . . . . . . . . . . . . . . 140

61 Bend-transition-temperature curves based on bend angleunder load for the longitudinal and transverse orientationof 0. 040-in. TZM sheets with W3 coating in the optimumcondition. Punch radius 4t . . . . . . . . . 141

62 Bend-transition-temperature curves based on bend angleunder load for the longitudinal and ransverse orientation of0. 040-in. TZM sheets with PFR-6 coating in the optimumcondition. Punch radius 4t . . . . . . . . . 142

63 Time-deformation curves for 0. 040-in. TZM sheet at2000' F and different stresses .... . . . . 147

64 Effect of stress on time to 1% creep deformation at20000 F for 0.040-in. TZM sheet . . . . . . . . 148

65 Time-deformation curves of 0. 040-in. TZM sheet at25)00°D F and UiJ. et : sr se . . . . . . ... 149

66 Effect of stress on time to 1% creep deformation at 25000 Ffor 0. 040-in. TZM sheet. . . . . . . . . . . 150

67 The thermal expansion of TZM sheet parallel to the planeof the sheet . . . . . . . . . . . . . . . 155

68 The thermal conductivity of TZM sheet parallel to theplane of the sheet . . . . . . . . . . . . . 157

69 The enthalpy and heat capacity of TZM sheet . . . . . 158

xv

REPORT ON

THE MECHANICAL AND THERMAL PROPERTIES OFTUNGSTEN AND TZM SHEET PRODUCED IN THE

REFRACTORY METAL SHEET ROLLING PROGRAM

Part 1

INTRODUCTION

The increasing need for materials capable of withstanding high operatingtemperatures in advanced aircraft and space vehicles has created increasing con-sideration of refractory metals and their alloys for engineering applications. Inview of the increasing demand for new and better materials for present and futureaerospace requirements, the Bureau of Naval Weapons (BuWeps) initiated a Re-fractory Metal Sheet Rolling Program (RMSPR) to develop information necessary

to provide sheet materials worthy of the classification of "aerospace quality."The work was programmed into three Phases:

I, determination of the material and process parameters and the pro-duction of plate and sheet by the optimum procedures developed;

TT, investigation of the mechanical and physical properties to assessthe materials for aerospace applications;

III, establishment of plate and sheet product applicability and fabrica-tion techniques.

This report covers an investigation of the mechanical and thermal proper-ties of two refractory-metal sheet materials that were produced in the RMSRP:

(1) tungsten sheet, which was produced from powder compacts by theFansteel Metallurgical Corp. and

(2) TZM molybdenum alloy sheet, which was produced from arc-meltedingots by Refractomet Division of Universal-Cyclops Steel Corp.

The objective of the program was to provide preliminary design data sufficient toallow consideration of the materials for applications at various temperatures.

2

SCOPE

The two sheet materials evaluated were furnished by BuWeps. Both thetungsten and TZM sheet were supplied in the optimum condition (warm-workedand stress-relieved) developed in Phase I of the RMSRP. In addition to t.his con-dition, specimens from both sheet materials were evaluated in the recrystallizedcondition, and the TZM sheet was evaluated in the optimum-coated condition.Part of the experimental work included determination of the recrystallization

temperatures, which information was then used in treating the as-received ma-terials to obtain the recrystallized specimens. The coatings for the TZM alloywere selected in collaboration with personnel at BuWeps, University of DaytonResearch Institute, and the Air Force Materials Laboratory. Evaluation ofcoated tungsten sheet was deleted from the program upon the recommendation ofthe Refractory Metal Sheet Rolling Panel because suitable coatings for tungstenwere not available. Instead of evaluating both the tungsten and TZM sheet in theoptimum-coated condition, as originally scheduled, we evaluated the TZM sheetwith two selected coating systems. The coatings selected for the TZM sheetwere W-3 (Chromalloy) and PFR-6 (Pfaudler). The static oxidation tests oncoated TZM, which were originally scheduled in the program, were conductedby the University of Dayton Research Institute because they have an apparatus forthese evaluations that meets the requirements of MAB-189-M, "Evaluation Pro-cedures for Screening Coated Refractory Metal Sheet." This arrangement wasmade in an effort to coordinate the evaluation of the nxidation resistance of coated

TZM sheet with similar work that was performed by the University of Dayton Re-search Institute for the Air Force Materials Laboratory. The results of the oxi-dation tests on the TZM are summarized in the final report on A.F33(615)1312.

A summary of the various types of evaluations in the program, the testtemperatures, and the material conditions are show:, in Table I. To the extent

possible, the procedures described in Materials Advisory Board Report aMAB-192-M, "Evaluation Test Methods for Refractory Metal Sheet Materials, "i)were used. Originally, all the properties listed in Table I were to be determinedfrom only one gage of each material. However, upon a recommendation by theRefractory Metal Sheet Rolling Panel and after approval by BuWeps, the tensileevaluations were extended to three gages for the TZM and two gages for the tung-sten sheet as a practical means to develop some information on the influence ofsheet thickness on the mechanical properties. For the tungsten sheet, all of thedifferent types of evaluations were conducted on 0. 060-in. -thick sheet with addi-tional tensile evaluations at selected temperatures on 0. 100-in. -thick sheet. Forthe TZM sheet, all of the different types of evaluations were conducted on 0. 040-in. -thick sheet with additional tensile evaluations on 0. 020- and 0. 060-in-thick

a Numbers in parentheses relate to references in the Bibliography.

3

Table I

Summary of Property Evaluations

Material ..

Proprty Material Condition' Temperatures, F

Tensile TZM 0., R. , C. RVT, 1200, 2000, 2200. 2500, 3000W 0., n. RT2, 1200, 2000, 2500, 3000, 3500, 4000, 4500

Compression TZM 0., R. RTW 0., R.3 R'1, 600, 750, 900. 1200, 1500, 18•C

Tensile Notch TZM 0., R. RT and to above the transition temperatureSensitivity W 0., R. RT and to above the transition temperature,

Shear Strength TZM 0. RTW 0. RT

Bearing Strength TZM 0. RTW 0. RT

Tensile Creep TZM 0. 2000, 2500W 0. 2500

Thermal Stability TZM 0. RTW 0. RT

Bend Transition Temperature TZM 0., R., C As necessary to establish bend transition temp.W 0,1 R. As necessary to establish bend transition .emp.

Fusion Weld Joint Efficiency TZM A.W., H.T. RT, 2500

Density TZM 0. RTW 0. RT

Thermal Expansion TZM 0. Obtain curve RIT to 2500W 0. Obtain curve RT to 2500

Thermal Conductivity TZM 0. 500, 1200, 1800, 2500W 0. 500, 120u, 1800, 2500, 3000

Heat Capacity TZM 0. 500, 1200, 1800, 2500W O. 500, 1200, 1800, 2500, 3000

.. . ., . A5 s ii- .ay to ustab-inh recrystaiiization temp.W 0. As necessary to establish recrystallization temp.

Oxidation4 TZM C. 2500, 2800

0. - optimum, R. - recrystallized, C. - coated, AW. - as-welded, I. T. - heat treated.J Evaluations made in both transverse and longitodinal orientations; all others in longitudinal orientation only.s Recrystallized specimens evaluated at room temperature only.4 Tests performed by the University of Dayton Research Institute and reported in the final report on

AF33(615)1312.

V. • - - '--'-w-~-"---"-

4

sheet. As the program progressed, a number of :-evisions of the original scopewere made, with the approval of BuWeps, to obtain additional data for some pro-perties and to eliminate other evaluations that were not appropriate after prelim-inary data and other informatior. from this and related programs became available.Besides these relatively minor revisions, the scope of the program was extendedto obtain data on the tensile and notched-tensile properties of TZM sheet in -optimum and recrystallized conditions for a statistical analysis of the variatiol ofthese properties at different temperatures for different locations within sheets,different sheets, different heats, and different sheet thicknesses. The work per-formed in the extension is summarized in a separate volume (Part 2) of the finalreport. (2)

MATERIALS

Tungsten Sheei

The tungsten sheet materials were produced in Phase I of the RMSRP byFansteel Metcllurgical Corporation on BuWeps Contract No. NOw-60-0621-c.The size and identification of each sheet supplied to SRI for determination of themechanical and thermal properties is shown in Table II.

Table II

Identification and Size of the Tungsten Sheets

Sheet Fansteel Thickness, Length Width, Area,No. Lot No. In. In. In. Sq. Ft.

6 A5467 0.055-0.058 46-47.5 21.0 6.715 A5467 0.057-0.062 51-53 21.5 7.817 A5467 0.059-0.063 53 51.0 7.7

112 A5467 0.099-0.105 32-32.5 19.0 4.2

The available processing information for the tungsten sheet is given inthe final report on BuWeps Contract No. NOw-60-0621-c (3). Briefly, thesheets were hot-rolled from sintered sheet-bars that were produced from re-duced ammonium paratungstate. The tungsten-powder particle size rangedfrom about 1. 5 to 15 microns in diameter, with a mean diameter between 4and 5 microns. Table III shows the approximate chemistry of the tungsten

5

powder used for the sheets.

Table III

Approximate Compo.•ition of TungstenPowder in Percent by Weight (3)

.A._ N ti Mn Mg Mo Fe Al Si Cu Ag Ca

0.026 0.0005

6

Longitudinal TransverseSheet No. 6

TLon. g t 11d in a1 TransverseSheet No. 15

Longitudinal She o 7 Transverse

Figure 1. The microstructure in longitudinal and transverseorientations of the 0. 060- in, thick tungsten sheetin the optimum condition.

Magnification: lOOX E tchant: K3 Fe (CN),

7

Specimen blanks were cut from different locations in the three 0.060-in. -and the one 0. 100-in. -thick tungsten sheets to systematically sample each sheet,insofar as practical, for the different evaluations.

TZM Sheet

The TZM sheet materials were produced by the Refractomet Division ofUniversal-Cyclops Steel Corporation on BuWeps Contract No. NOas 59-6142-c.The size and identificaticn of each sheet is shown in Table IV.

Table IV

Identification and Size of the TZM Sheets

Universal-Sheet Cyclops Thickness, Length, Width, Area,

No. Lot. No. 1 In. In. In. Sq. Ft.

55 10 0.037-0.V03 64 24 10.6856-1 10 0.037-0.043 15-1 24 2.6756-2 10 0.037-0A043 48 24 8.0074 13 0.018-0.022 12j 23 - 2.0723 05. 057-0.063 12-1 24 2.08

SAll of the different lots were from Heat No. KDTZM 1196.

A summary of the composition, manufacturing processes, and releaseproperties for all the TZM sheets used in the program is shown in Appendix A.The TZM sheet was produced from an 8-in. diameter arc-melted ingot, whichwas extruded to a 4. 5-in. -diameter round at 21000 F. The rgsulting round

slab was annealed for 1 hour at 28000 F and forged in "Infab" at 34000 F to1. 5-in. -thick sheet bars. The sheet bars were annealed at 28000 F for onehour and longitudinally rolled at 22000 F in two intermediate reductions andfinally cross-rolled at 18000 F to within 0. 004 to 0. 008 in. of the final thick-ness. The sheets were annealed at 27000 F and 21500 F respectively after thefirst and second longitudinal rolling operations. Each gage was stress-relieved

b "Infab" is a facility for processing metals in an inert atmosphere. Thefacility was built and is operated by Universal Cyclops Steel Corporationunder a Navy contract.

. . .

8

at 23000 F after cross-rolling and finished to the final thickness by belt grindingand pickling. Table V shows thle chemistry of each sheet furnished for evaluation.

The TZM sheet materials, as received at SRI, appeared to be in excellentcondition, and no serious surface defects were found by visual examination. Themicrostructure on longitudinal and transverse sections from the different gagesof the as-received TZM sheets are shown in Figures 44, 45 and 46.

The two 0.040-in. -thick TZM sheets, No. 55 and 56, were sampledequally for the different types of mechanical-property evaluations.

PREPARATION OF SPECIMENS

The specific specimen designs used for the different types of evaluationswill be discussed and shown in a later section of the report on the testing pro-cedures. Where possible, the specimen&.; conformed to those recommended inMaterials Advisory Board Report MAB-192-M (0).

The preparation of all specimens was accomplished by SRI with conven-tional machining and grinding equipment, The gage section of specimens for themechanical-property evaluations were ground with a surface grinder and fin-ished by hand polishing with "00" abrasive paper.

Pin-type gripping was used, where possible, for the tensile, bearing,shear, and creep specimens. Loading holes (3/8-in. dia) were drilled in thesespecimens with carbide drills and a special holding fixture in which the speci-men blanks were clamped. The drilling process involved three steps, (a) roughdrilling with an undersize drill; (b) finish drilling; (c) deburring wilth fineabrasive. Shoulded-loaded specimens were used in evaluation of the tungstenm.ateria.s under conditionS where pin-loaded spenimrns failed at the loadingholes rather than in the gage section.

Ipsenlab of Rockford, Inc., recrystallized the tungsten and TZM speci-mens required for the tensile, notched-tensile, compression and bend-transitionevaiuations in the recrystallized condition). The specimens were recrystallizedin a vacuum of 5 x i0- torr or better at time-temperature conditions selectedby SRI from data developed in the present investigation. The recrystallizationtreatments for the two materials investigated were:

Material Temp, ° F Time at temp, hr

Tungsten 2550 1TZM 2475 1

C4 In

Cd ~ 000w-D Cz 6 C 0' C

Cd v 6]

m- -4mm

ddd

ot

V VV

-qCI--I N

0

Jul

4 -- 4c ~ ~

000

to

0

N6 6

or Lo to mit-MoO0

V).4

tb

10

TZM specimens for determination of the bend-transition temperature andthe tensile properties in the optimum-coated condition were prepared for coatingby SRI and submitted to the University of Dayton Research Institute for coating ap-plication by the coating vendors. The University of Dayton Research Institute co-ordinated the application of the coatings for the bend and tensile specimens, forevaluation by SRI, with the coating of the specimens for the oxidation tests thatthey performed relative to Contract No. AF 33(615)1312. The coating systemsselected for evaluation were PFR-6 and W-3, which are proprietary pack-cementationprocesses of The Pfaudler Company and Chromalioy Corp. respectively. The proce-dure used by SRI to prepare the tensile and bend specimens for coating by bothsystems was as follows:

a. Long edges of bend specimens and edges of the gage section of thetensile specimens were draw-filed and polished with 240 grit paperto a full radius.

b. Etched in an aqueous solution of 50% HNOQ and cleaned in a solutionof 4.2 gms of chromic acid in 88 ml of water and 12 ml H2SO4.

c. Inspected and additionally polished with 240 grit paper if necessary toremove any flat areas or other imperfections on the edges of the speci-mens.

d. Re-etch and clean conditioned specimens as outlined in Step b.

Since the purpose of the tests of the coated materials was to determine theeffect of the coating on the room- and elevated-temperature properties (in vacuum)and not to determine the protective capability of the coatings, no attempt was madeto prepare the ends of the bend specimens or the shoulders of the tensile specimensto remove sharp edges or other surface defects which would normally cause failurecf thi enoaintgs Application of the PFR-6 coating caused the specimen thickness

to increase 0. 0074 in. (0. 0037 in. on each side) while the W-3 coating resulted inan increase of 0. 0022 in. in thickness of the specimen,

Westinghouse Electric Company, Astronuclear Laboratory, made TIGwelds on the 0.060-in. tungsten sheet and the 0.040-in. TZM sheet and electron-beam welds on the TZM sheet for evaluation of the weld joint efficiency. TheTIG welding was accomplished in a high-purity helium atmosphere while theelectron-beam welding was done in a vacuum of 10-5 torr. The specimens weremachined after welding.

11

EQUIPMENT

Most of the facilities that were used for the mechanical- and thermal-property evaluations have been described in detail in numerous publications andreports crn similar work for various governmental agencies and industrial con-cerns (4-20).

Two unive.'sal testing machines, with different full-scale load capacitiesfroin 3,000 to 120,000 1b, equipped with X-Y and autographic load-deformationrecorders plus strain-rate control instrumentation, were used to evaluate thetensile, compression and bend properties. A special screw-driven tensilemachine, developed at SRI, was used in the bearing, shear and notch-tensile work.This machine is capable of straining specimens to failure at rates from5 x 10' to 60 in. /in. /min over a temperature range of -320 to 6000' F. Thedesign features of the machine have been described in detail in WADC TR57-649Part I and other reports and publications (4, 6). A photograph of this machineis shown in Figure 2. Vacuum chambers, inert atmosphere devices, coldchambers, controlled- rate heating units, and high-temperature extensometerswere available for use, as needed, with the machines described above. Specialfixtures, which are discussed later in the report, were used in conjunction withthe testing machines as required to conduct the mechanical-property evaluations.

A Satec creep-rupture machine, equipped with a vacuum chamber and ap-propriate instrumentation for automatically recording temprat,,rp Pr time-deformation curves, was used for the creep tests. With this machine specimenswere loaded by weights, which act through a lever arm (20:1 ratio).

Two vacuum systems were used in the determination of the different pro-perties at high temperatures. A "High Vacuum Equipment Corp." unit was usedin conjunction with the universal testing machine and the creep machine to de-termine the elevated-temperature tensile and creep properties. This system iscapable of maintaining a chamber pressure of 10- torr at temperatures up to3500° F. Specimens were heated in the split-type vacuum furnace by radiation

from tantalum-sheet heating elements. The furnace has a sighting port and

thermocouple inlets for monitoring and controlling the temperature. A photo-graph of this system as used with the universal testing machine is shown inFigure 3. A second vacuum system, built by the Kinney Division of the New YorkAir Brake Company, was used for the determination of the recrystallizationtemperatures. This system is capable of maintaining a chamber pressure in therange of 10' torr. Specimens can be heated in this system by radiation to approxi-mately 35000 F or to their melting temperatures by self-resistance. In thedetermination of the recrystallization temperatures, the specimens were heate dby self-resistance. This chamber, like the other unit, has a sighting port and anumber of thermocouple inlets. The system is shown mounted on the special

VILL'

194

-4

0)

wcu

En WC-'-

4) 5-4

ncd

QC )

b-C

4-'-

Cd

wh)Cd

W-M4

fl;

14

tensile machine in Figure 2 and as used in determination of the recrystallizationtemperatures in Figure 4.

A Bausch and Lomb Research Metallograph was used for the metallographicexaminations and to obtain the photomicrographs.

DPH hardness tests were conducted with a Tukon Tester with a load of3 kg for the tungsten sheet and 1 kg for the TZM sheet. Other standard Rockwellhardness testers were used for the measurement of surface hardness.

The determination of thermal conductivity up to 15000 F was made with acomparative rod apparatus in which Armco Ingot Iron was used as a conductivityreference. This apparatus has been described in detail in the final report (15)for the program on Air Force Contract AF33(657)-8594. A radial inflow apparatuswas used to determine thermal conductivity from 15000 F to 25000 F for the TZMsheet or to 3000° F for the tungsten sheet. The radial-inflow equipment has beendescribed in the final report (16) on Contract No. AF33(657)-11298.

The heat capacities were determined to 10000 F with an adiabaticcalorimeter and from 10000 F to 25000 F, for the TZM sheet, or to 30000 F forthe tungsten sheet, with an ice calorimeter. Both apparatuses are described inreferences 15 and 16 in the Bibliography.

The thermal expansions of the tungsten and TZM sheet were determinedfrom 70 to 10000 F with a quartz-tube dilatometer and from 1000 to 25000 F witha graphite dilatometer. Expansions were measured with mechanical dial gageswhich could be read to 0. 0001 in. (0. 00004 in. /in.).

TEST PROCEDURES

Recrystallization

For determination of the recrystallization temperatures, tungsten andTZM strip specimens, 3/8 in. wide x 7 in. long as shown in Figure 5, wereresistance heated in a vacuum of 1. 5 x 10-4 torr to temperatures between 1800and 32000 F and held at temperature for 5 or 60 minutes, The heating time tothe different holding temperatures was approximately 5 min. Specimentemperatures up to 21000 F were measured by chromel-alumel thermocouples,and above 21000 F the temperatures were measured with an optical pyrometer.Corrections were made in the optical pyrometer readings for the emissivity oftungsten or molybdenum and for adsorption by the glass viewing port of thevacuum chamber. These corrections were rechecked and verified after the testswere completed by simultaneously measuring the temperature of the specimen

15

AY

Figure 4. Vacuum chamber and pumping system f or use in recrystallization,hat treatment, and creep-rupture evaluation of refractory mectal

16

0. 37.5in.

7 in.

Figure 5. Recrystallization specimen.

17

with the optical pyrometer and with W-5%Re vs W-26%Re thermocouples. Amanually controlled high-current heating unit was the source of power.

The Re hardness of the 0.060- and 0. 100-in. tungsten sheet was measuredon the surface of the specimens. In addition, the DPH at the mid-thickness of thesheet and metallographic estimates of the percentage of recrystallized structurewere determined to establish the recrystallization characteristics of the differentsheets. 'ITo observers independently estimated the percentage of recrystalliza-tion, and the results of these independent observations were averaged to determinethe reported values. Determination of the recrystallization characteristics of the0.060-in. -thick sheet was based mainly on results from Sheet No. 15; however,the recrystallization behavior of Sheet Nos. 6 and 7 were checked with that ofSheet No. 15 at five different time-temperature combinations.

The Ra hardness of the 0.040-in. and 0.060-in. TZM sheet and theRockwell 15- T hardness for the 0.020-in. TZM sheet were measured on thesurface of the specimens. The procedures for determining the DPH andmetallographic estimates of the percentage of recrystallization were thesame as those described for the tungsten sheet. Determination of the 5-ecrystal-lization parameters for the 0. 020-in., 0. 040-in. and 0. 060-in. TZM sheet werebased primarily on the results from Sheet Nos. 74, 55, and 23 respectively;however, the recrystallization behavior of the 0.040-in. Sheet No. 56 waschecked with that of Sheet No. 55 at different temperatures.

In general, the recrystallization temperature of the tungsten and TZMsheet were determined by metallographic and hardness measurements, as out-lined in MAB-192 (1).

Tensile

Tensile evaluations were conducted on both tungsten and TZM materialsto (a) determine the tensile properties at room- and elevated-temperatures, (b)determine the notched-tensile strength at room temperature, (c) evaluate thethermal stability of creep-strained materials, and (d) evaluate fusion-weldedjoint efficiencies (TZM only). The effect of temperature on the tensile propertiesof the two materials in the optimum, recrystallized, and optimum-coated (TZMonly) conditions was determined principally with the equipment described earlier.Duplicate, or triplicate, tensile specimens were evaluated at each temperatureshown in Table I according to the specifications of MAB-192-M (1). Sketchesof the unnotched specimen configurations for the room-temperature and elevated-temperature evaluations are shown in Figure 6. The shoulder-loaded specimenwas used for the room- and moderately elevated-temperature tensile evaluationswhere the pin-loaded specimens fractured across the shoulders. Specimens

18

0.

C) i I ) d

Cý 00

tn

oc

0D 0

oo 41LO 0, cd )

Vn4

19

were heated to temperature in approximately 30 minutes in a vacuum of 5 x 10-4

torr or better by radiation from tantalum elements, held 15 minutes at tempera-ture, and then strained to failure at controlled rates. At room temperature and12000 F the strain rates were 0.005 min-1 to 0.6% offset and 0.05 min- 1 tofracture. For evaluations at 20000 F and higher, the strain rate was approximately0.05 min` throughout the tests. Temperatures were measured with chromel-alumel thermocouples, attached to the specimen, up to 20000 F and by an opticalpyrometer or W-5%Re vs W-26%Re thermocouples at higher temperatures. Theheating unit was manually controlled. Corrections for the emissivity of tungstenor molybdenum and for absorption by the glass viewing port of the vacuum fur-nace were made in the optical temperature measurements.

Strain during the elevated-temperature evaluations was detected by strain-gage extensometers clipped onto the water-cooled pull-rods of the furnace chamber.Stress was sensed by a strain-gage load cell. Excitation was supplied to theextensometer and load cell bridges from a stable 5000 cps AC source. Theoutputs from the two bridges, which were proportional to strain and stress,was amplified, demodulated, filtered, and fed as a DC signal into the X (strain)and Y (stress) axis of an X-Y recorder. Application of the extensometer atthe pull-rods, rather than at the specimen gage points, for evaluations atelevated temperatures introduced a slight error into the strain measurements.This error necessitated correcting the modulus-of-elasticity values, but did notsignificantly affect the determination of other tensile properties. The requiredcorrection factors for the moduli of the two materials were determined from room-temperature modulus values obtained with a conventional differential-transformerextensometer (Class B-1 per ASTM E 83-57T) over a 1.0-in. gage length. Thecorrection as applied to the reported moduli was the ratio of apparent elasticmodulus, obtained with the extensometer attached to the pull-rods, to theelastic modulus obtained with the conventional extensometer attached at the gagepoints of the specimens.

The 0. 2%-offset yield strength, ultimate tensile strength, and modulusof elasticity was determined from the recorded stress-strain curves. The totalelongation and reduction of area, where possible, were measured from thefractured tensile specimens.

Notched Tensile

Notched-tensile evaluations were conducted at different temperatures onthe tungsten and TZM sheet in the optimum and recrystallized conditions to es-tablish the brittle -to-ductile transition temperature. The notched specimenshad a major width of 0. 500-in., 600 notches with 0.010-in. radii, and a notch-to-notch width of 0. 2 50-in., which produced a stress concentration- factor, Kt,

20

of 4. 2. The notched specimen is shown in Figure 7. Unnotched tensile speci-mens were tested at each temperature where notchcd specimens were testedin order to determine the notched-strength ratio. For the tungsten sheet, thetemperature range over which the notched tensile tests were performed wasfrom 200' F through 9000 F; for the TZM, the temperatures at which notchedspecimens were tested were from -2000 F through room-temperature. Thetungsten notched-tensile specimens were heated to temperature in approximately15 minutes, held 5 minutes at temperature, and strained to fracture at a cross-head rate of approximately 0. 005-in. min-. The TZM specimens were cooledby metering low-temperature nitrogen gas, by means of a manually operatedvalve, into a cryostat that surrounded the specimen. The nitrogen gas wascooled by passing it through a copper coil immersed in liquid nitrogen in avacuum flask. Approximately 5 min were required to cool the specimens tothe desired temperature, after which they were strained to fracture at a cross-head rate of approximately 0.005 in. min-'. For both the elevated- and low-temperature tests the temperature of the specimens was measured by thermo-couples, held in contact with the surface of the specimen, and a nul-balancepotentiometer.

Bend- Transition Temperature

Evaluations of the bend properties for both the longitudinal and transverseLIeciu _ n. 30in tungsten shect4 and 4-1- 0 _A;". 'P7 M she in thedirect-ions of *"Ut 0. nOPVV_ Ln. E"•n• LI•^- ,•c"' LI and "he 0.4 -•,. AO, h~÷. •.

optimum, recrystallized and coated (TZM only) conditions were conducted inaccordance with the recommendations of MAB-192-M (1). A bend fixture, shownin Figure 8, was used in conjunction with a universal testing machine for theseevaluations. Punches with radii of 1. 5, 4, and 8 times the sheet thickness(1. 5t, 4t, 8t) were used to evaluate the tungsten specimens, and a punch radiusof 4t was used to evaluate th-e TZM specimens. The distance between the anvilswas 1.50-in. for the 0.060-in. tungsten and 1. 25-in. for the TZM sheet.Figure 9 shows the dimensions of the bend specimens. The criterion for thedefinition of the bend-transition temperature range was the minimum temperatureat which a 900 bend could be made without cracking, at a given punch diameter,and highest temperature at which a 90' bend could not be made without cracking.The test temperature range was 300° F to 700' F for the tungsten sheet and -2200 Fto 2000 F for the TZM sheet. The elevated-temperature-bend specimens wereheated by tungsten-element radiation lamps, which were controlled by smallchromel-alumel thermocouples in contact with the bottom surface of the speci-men. A thermocouple attached to the punch was used to measure and controlthe temperature of the punch tip. For evaluations below room temperature,gaseous nitrogen, which was cooled in a coppei coil immersed in liquid nitro-gen, was usea to cool the specimen and fixture to the desired temperature.The flow of nitrogen gas into an insulated chamber that surrounded the specimen

21

h_ 1.00-1i 0.75

1.75

0.250 +0. 50 45

3.00 600 0 1.00 4.50

0.500 0.500. 50R

1.75

0.'753 dia

Figure 7. Notched tensile specimen with astress concentration factor, K,of 4. 2.

22

Punch baseattached to

stationery crosshcadof Universal tensile machine

___Replaceable Pinch

•• |Pulnch-RIoll

|Radius (it - lot)

Anvil

(adjustable fori spans,lw /1/of 1/2 in. - 2 1 /2 in.)

Anvil Radius 0 - 5

S/ /

pan Anvil base

movable ct.oss-head of Universal

tensile machil'e.

Figure 8. Bend-test fixture.

23

mtLW TZM:W - 1/2 in., t 0.040 in.Tungsten: W - 3/4 in., t - 0.060 in.

Edges slightly roundedby polishing with120 grit abrasivein longitudinal direction

3-1/4 in.

Figure 9. Bend specimen.

24

and fixture was controlled by a solenoid valve, which was actuated by a chromel-alumel thermocouple attached to the specimen, and a temperature controller.All 6pecimens were held at temperature approximately 10 minutes before bendingat a deflection rate of 1. 0 in. /min. A mirror, which was positioned under thespecimen between the anvils of the fixture, was used to observe the surface ofthe specimen during the tests. The surface of the specimens that were bent 90°without apparent fractures were examined with a magnifying glass to determineif fine cracks existed. The bend angle at the first indication of fracture wascalculated from the geometry of the fixture and the displacement of the punch.

ComprC 3sion

Compression evaluations were conducted at room temperature fromboth longitudinal and transverse orientations for the 0.060-in. tungsten and0.040-in. TZM sheet in the optimum and recrystallized conditions. A sub-press was used with the universal testing machine to provide bending restraintand to axially load the specimens. Sketches of the fixture and specimen con-figuration used in the compression determinations are shown in Figures 10 and11 respectively. Support blocks, which were polished and lubricated to mini-mize friction, were used to prevent buckling of the specimens. Strain was mea-sured at the gage-point lugs with a strain-gage extensometer, and load wasmeasured with the weighing systems of the universal testing machine. A stress-strain curve was recorded, up to 0. 67% offset, with an X-Y recorder. Tlie strainrate for these tests was approximately 0.005 min-'. In general, the procedureand apparatus used for these evaluations meet the requirements of ASTM Speci-fications E9-52T and E209-63T.

A few elevated-temperature-compression evaluations were conductedto obtain data needed by Solar in the performance of contract No. NOw 63-0786d,which is nart nf Phase I!! of the RMSRP. A total of sixteen compression testspecimens, five each from the 0.020- and 0.060-in. and six from the 0. 100- in.RMSRP tungsten material were fabricated by Solar as shown in Figure 12. Thisspecimen configuration was designed to stand without lateral support betweenthe platens of the compression fixture. Although there are some disadvantageswith this particular specimen geometry, it permits the evaluation of tungstensheet at elevated temperatures without prohibitive, elaborate heating andlateral-support apparatus. The compression specimens were evaluated at tem-peratures of 600' F and 750° F, 9000 F and 15000 F, and 12000 F and 18000 F forthe 0.020-in., 0.060-in., and 0. 100-in. tungsten sheet respectively. Specimenswere heated to t~emperature in approximately 20 minutes in an argon atmosphereby a split-muffle type radiation furnace, held 10 minutes at temperature, andthen strained t6 0.6% offset at a controlled rate of approximately 0. 005 min-.

25

Pushrod

II liS II II - -

il ItII IIil II

r' 'i

r-n (0Compression9ub-Press

SLup)port Blocks

CompressionSpec imen

T ool-SteelPush Spade

S I i

L-.J

Figure 10. Compression fixture showing cross-section of the supportblocks with specimen in place.

- Z..

26

t TZM: t = 0.040 in.Tungsten: t - 0.060 in.

3 /32"1 /1 ,6"

Extensometer 1/32 it

Lugs 2"

2 5/8"

F e 5 1 8"-2-

Figure 11. Compression specimen.

27

Approx.

Figure 12. Compression specimen for use atelevated temperatures.

28

Bearing

Bearing evaluations were conducted on longitudinally oriented specimensof the 0.060-in. tungsten and 0.040-in. TZM sheet in the optimum condition todetermine the bearing ultimate Ftrength and yield strength at 2% deformation ofthe bearing hole. The area on which these strengths are based is the product ofthe bearing hole diameter and the sheet thickness. A specimen with an e/D ratioof 1.5, as shown in Figure 13, was used for the evaluations. The tungsten speci-mens were evaluated at 300' F and 400" F and the TZM specimens at room tem-perature. For the elevated-temperature evaluations the specimens were heatedwith radiation lamps, which were automatically controlled by a potentiometer con-troller actuated by a signal from a chrornel-alumel thermocouple attached to thespecimen. Load versus bearing-hole deformation was recorded with an X-Yrecorder as sensed by a strain-gage load cell and extensometer. Specimenswere loaded to failure at a crosshead speed of 0.005 in. min-1 .

Shear

Evaluations to determine the ultimate shear strength were conducted atroom temperature on the 0. 040-in. TZM and at 4000 F on the 0. 060-in. tungstenin the optimum condition. All specimens were machined so that the shear planewas in the longitudinal direction. The specimen design used for both materialsis show..n in Figure 14. Th shear test section was 3/16-in- lonn defined by two1/16-in. -diameter holes spaced 1/4 in. apart on the axis with two offset slotsat 450 to the axis. For the tests at 400" F the specimens were heated by radia-tion lamps and the temperature was messiiwed and controlled by thermocouplesthat were flash welded to the surface near the shear plane. The specimens wereloaded to fracture at a crosshead speed of 0. 005 in. min-.

Creep

Creep evaluations at 25000 F for the tungsten sheet and at 20000 F and25000 F for the TZM sheet were conducted on longitudinally orientated speci-mens of the materials in the optimum condition. The specimen design was thesame as that used for the tensile tests as shown in Figure 6 (a). All tests wereperformed in a vacuum furnace at a pressure of approximately 1 x 10-4 torr.Specimens were heated to temperature in approximately 20 minutes by radiationfrom tantalum heating elements, held 10 minutes, and then loaded to differentstress levels selected to F-roduce 1% total deformation in approximately 100hours. A constant load was maintained on the specimens through the lever-arm system of the creep machine. Temperature was automatically controlledand recorded by a temperature-control instrument actuated by a signal from a

IL - -

29

4.) i.'

(0. 469)e __

Figure 13. Bear~ing spe'rimer1

20

11/2

314--o

3/8 D

IL-

a

Figure 14. Shear specimen

31

W-5%Re vs W-267oRe thermocouple attached to the specimen, which in turncontrolled the current to the furnace elements by a saturable reactor. Strainwas continuously recorded against time by means of a differential-transformerextensometer, attached to the pull rod of the local train, and a strip-chart re-corder. The creep tests were discontinued after 1% deformation so that thermal-stability tests could be performed with the creep-strained specimens.

Thermal Stability

Thermal stability was determined by means of room-tempers ture ten-sile evaluations on the tungsten and TZM creep specimens after straining to 1%total creep at selected elevated temperatures. Stress-strain curves were re-corded using the equipment described earlier for obtaining room-temperaturetensile data. Tensile properties were determined from these curves and are re-ported along with the tensile elongation and permanent creep elongation.

Weld-Joint Efficiency

The TIG welds of tungsten and TIG and electrrn-beam (EB) welds ofTZM sheet, for evaluation at room temperature and one elevated temperaturein the as-welded and welded-and-heat- treated conditions, were aecomplishedby Westinghouse. The welded materials were subsequently machined into ten-sile s pecimens for evaluations to determine the weld-joint efficiency.

Figure 15 shows a typic-a welded test panel for tungsten or TZM sheetand the location of the tensile specimerisin the welded panels. The weldingparameters, supplied by Westinghouse, hat, were followed in the preparationof these panels are given in the summary sh:own in Table VI.

32

41

Rolling Direction

TZM: t - 0.040 in.

Tungsten: t =0. 060 in.

- Weld

t

Figure 15. Typical welded test panel from whichtensile specimens were machined.

- -

33

Table VI

Summary of Welding Conditions for Tungsten and TZM Sheet

Clamping Weld Atmos. PurityPreheat Current, Space, Speed, ppm

Material Identity 0 F P nps In. IPM 09H

TIG Welds on TZMSamples 55-112A

to 55-112B None 100 3/8 7.5 9 3

Samples 56-112A56-112B 600 95 3/8 7.5 4 3

TIG Welds onTungsten

Samples 17A to 17B 600 210 3/8 7.5 6 3Samples 6A to 6B 600 210 3/8 7.5 7 5

EB Welds on TZMSamples 55-110A

to 55-110B None 5.8 1/2 25 10-5 torr

Samples 56-1I1A 5to 56-I1OB None 5.8 1/2 25 10- torr

All specimens wei'e longitudinally orientated, with the weld perpendicular to therolling direction of the sheet.

Even though special precautions were used to prevent breakage duringpreparation, specimens could not be successfully obtained from the weldedtungsten panels due to the extreme brittleness of the welds. Because of this,the weld-joint efficiency of the TIG-welded tungsten could not be evaluated.Specimens were successfully machined from the TIG- and EB-welded TZMpanels without extraordinary difficulty.

The equipment and procedures used in the tensile tests to determine theweld-joint efficiency were the same as those discussed earlier for room- andelevated-temperature tensile evaluations of the TZM sheet, The strength pro-perties were obtained fiom the recorded stress-strain curves.

34

Dens ity

The density of the various sheets of tungsten and TZM alloy was determinedby weighing samples in air and in water at 26. 30 C (79. 3 F). A sample calculationfor a tungsten specimen is shown below:

Density Weight Weight Weight in airVolume Volume . Weight in air - Weight in HO

Density of H2 0

Weight in air x Density of H20 - 32. 522 ± 1 x 0. 99681Density - Weight in air - Weight in H20 32.522 ± 1 30.8360 ;72

- 19. 226 1 0.0004 gms /cc at 26.30 C (79.30 F)

Thermal Conductivity

The specimen configuration used for determination of the thermal con-ductivity up to 10000 F in the comparative rod apparatus is shown in Figure 16.To make the laminated sheet specimens, squares cut from the sheets were tightlyclamped together to form small cubes. Single welds, perpendicular to the sheets,were made at opposite ends of the cubes with an inert-gas arc welder. The speci-mens were then machined as shown in Figure 16. Most of the weld area was re-moved in maching and the thermocouple holes were placed outside the heat-affected zones of the welds. A picture of a broken TZM specimen in Figure 16shows the depth of weld penetration. To prevent oxidation of the samples at thehigher temperature, the comparative rod apparatus was partially evacuatedseveral times and purged with helium during the runs. Thermatoinic carbon,sifted zirconia, and diatomaceous earth powder were used at different times asinsulation for the 6pecimen aiiud £.efeie ce cou m... ^-G -- LL-7 LA;L" .. .11J.1LGLIUof thermal conductivity was accomplished by measuring both the heat flux density,flowing axially through the cylindrical specimen, and the temperature gradientalong a known axial gage length. The heat flux density was determined with twoheat meters or references of known conductivity placed coaxially at the top andbottom of the specimen. The temperature gradient was measured by thermocouplesinstalled in the specimens. Radial losses were carefully controlled with guardheaters. The uncertainty for this equipment is about - 5%.

In the radial inflow apparatus, which was used to determine thermal con-ductivity to 25000 F and 30000 F, a cylindrical specimen consisting of stackeddiscs was radiantly heated, and the radial heat inflow measured by a watercalorimeter placed axially through the center of the specimen. Temperaturemeasurements were made at two different radii in the specimens, permitting a

35

111

TZM Spec imen I after exposure, Note weldpenetration at each end and path of weld on tcp sijifare

Specimens of lamninated metal made 00 eachend nr asWliOby pressing pieces of sheet together,weldin~g, and then machining to lfinal dimensions

2 HI-tes

0. 750' 1 . OOIY (TZM)1 250' (W)

Weld

Figure 16. Laminated thermal conductivity specimen configuration for sheetL metal materials, and photograph of broken TZM specimen show-

I ing depth of heat affected zone.

36

direct calculation of the conductivity. A helium atmosphere was maintained inthis apparatus during the determinations. The probable error for this apparatushas been established at - 7%. The specimens for this apparatus consisted offrom 32 to 34 one-inch di ý . ter discs with one-quarter inch holes in their cen-ters. Temperatures were -.casured at the bottom of small holes drilled axiallyin the specimen on two different radii, see Figure 17. A one-sixteenth inchdiameter tungsten pin was placed through the discs near their outer edge to aidin alignment.

Heat Capacity

For determination of the heat capacity up to 10000 F in the adiabaticcalorimeter, the heated (or cooled) specimen, consisting of several smallsquares of the sheet, was dropped into a thermally guarded c .librated cup,and the specimen enthalpy mas measured as a function of the increase in tem-perature of the cup. In the drop type ice calorimeter, which was used above10000 F, the heated specimen was dropped into the ice calorimeter, which wassurrounded by an ice mantle. The enthalpy of the specimen was determinedfrom measurements of the volume of ice melted as the specimen cooled fromits drop temperature to 320 F.

The Ieat capacities were determmined frnm the slnpes of the enthalpyversus temperature curves. Heat capacity was determined graphically and alsoby using the derivative of an equation for enthalpy obtained using the leastsquares method. The enthalpy data were first fitted to an equation of the form

h 32 = aT + bT 2 + cT 1 + d. (a)

The derivative of this equation was adjusted to agree with the graphically de-termined heat capacity at a selected temperature to obtain an equation forheat capacity of the form

HC = a + 2bT - c* T-2 (b)

Temperatures (T) are in degrees Rankine. Values determined from the equa-tion are generally valid over a range extending from about 1000 F from eachend point and cannot be used to extrapolate the data.

II

37/

TT Drill in 0. 400 Rall pieces

. 103 109 )ia Hole"'.093

0.788Top Guard 28 Discs

4062 .2187 .080 Dia HoleSpeci.0n7L3- .071

FI / I I

2 ,. ./• 1822

,Specimen • .1-• " ;16I Discs- -

r,, /Z/ Fractional Dimensions:

Bottom Guard---&. 2+ 328 Discs Other Dimensions: + 0.001"

1/4

Figure 17. Stacked disc cylindrical thermal conductivity specimenconfiguration for the radial inflow apparatus.

38

Thermal Expansion

For determination of thermal expansion, the tungsten specimen was about3" x 0.50" x 0. 10" with each end ground to a 3-inch radius. A graphite sleevepositioned the specimen in the dilatometers. The TZM specimen was made bylaminating about six strips of the metalwith three welds on each side using aninert gas arc welder. The procedure was similar to that for making the com*-parative rod conductivity specimens discussed earlier. The laminated specimenwas three inches long, about 3/8 inches square, with a three-inch sphericalradius on each end. A split graphite sleeve was used to insure good alignmentin the dilatometers. All determinations were made in a helium environment.The uncertainty of the thermal expansions determined using the dilatometers hasbeen established at ± 5 percent. Corrections were made for the expansions ofthe quartz and graphite dilatometers which were reflected in the gagereadings. Specimen temperatures below 1000' F in the quartz dilatometerwere measured with several thermocouples attached to the specimen. In thegraphite dilatometer, a thermocouple near the specimen surface was used tomeasure specimen temperature from 10000 F to 15000 F. At 15000 F boththe thermocouple and an optical pyrometer were used, and above 15000 Foptical measurements were used. The thermal expansion data were fitted toan equation similar to equation(a), using the same procedure as used for theheat capacity data. The derivative of this equation was adjusted to agree

empe rature o cta erquaincA Coefficient of thermal expansion at .etemperature to obtain an equation for the coefficient of thermal expansion.

*1

39

DISCUSSION AND RESULTS

Properties of Tungsten Sheet

Recrystallization Temperature

Materials Advisory Board Specification MAB-192-M defines the recrystal-lization temperature as the minimum temperature at which in one hour the structureof a material is 50 percent recrystallized and the decrease in hardness is 2/3 ofthe total decrease from the initial worked condition to the fully recrystallized con-dition. On this basis, 24000 F was determined as the recrystallization tempera-ture of both the 0.060- and 0.100-in. -thick tungsten sheet.

The Rc and DPH hardness measurements plus estimated percent of re-crystallization for the 0. 060- and 0. 100-in. tungsten sheets are tabulated inTables VII and VIII and plotted as functions of temperature in Figures 18 through22. The plots of data for the three 0.060-in. sheets, Figures 18, 19 and 20, showthat the decrease in hardness and increase in percentage of recrystallizedstructure for the sheets are comparable for the so-ne conditions of temperatureand time. However, the recrystallized structure of Sheet No. 6 was found to bedifferent from that of Sheets Nos. 15 and 17 as shown in Figure 23. The recrystal-lized structures of Sheets Nos. 15 and 17 were uniform and had a grain size ofabout ASTM No. 8, whereas the structure of Sheet No. 6 was irregular and thegrain size ranged from ASTM No. 6 to 2, with some subgrains of about ASTM No.6 visible within the large grains. The structure of Sheet No. 6 in the as-receivedcondition, Figure 1, was coarser than that of Sheets Nos. 15 and 17 and appearedto have had a larger grain size than the other sheets before working.

The recrystallization characteristics of the 0. 100-in. tungsten sheet,as shown in Figures 18, 20 and 22 are approximately the same as for the0.060-in. sheets.

Tensile

The tensile properties from room temperature through 4500° F for the0. 060- and 0. 100-in. tungsten sheet in the optimum and recrystallized condi-tions are summarized in Tables IX through XII and plotted in Figures 24 through28. In addition to data obtained at the scheduled evaluation temperatures, thesefigures also show results from unnotched specimens that were tested to definethe notched-unnotched strength ratio, which will be discussed subsequently.

40

Table VII

The Hardness and Percent Recrystallization of Three0. 060 In. Thick Tungsten Sheets After Holding at 2

Different Temperatures for Five and Sixty Minutes

Time at EstimatedSpecimen Temp. Temp. Rc 3 Recrystallization

No. Min. F Hardness DPHý _

Sheet No. 15

C-15 As-Received 42.8 443 -A-15 5 1800 42.8 - -

B-15 5 2000 43.1 - -D-15 5 2200 42.7 - -E-15 5 2400 42.6 440 1U-15 5 2425 43.8 - -P-15 5 2500 42.4 438 10V-15 5 2525 41.1 427 15S-i5 5 2550 39.7 413 30X-15 5 2575 37.5 388 75F-15 5 2600 36.7 372 90G-15 5 2800 35.6 362 100H-15 5 3000 34.6 359 -1-15 60 1800 44.4 458 -J-15 60 2000 43.7 443. -K-15 60 2200 42.6 439 2L-15 60 2400 41.6 422 40T-15 60 2425 38.6 389 80R-15 60 2450 36.1 367 100

•Q-15 60 2500 36.3 364 -M-15 60 2600 36.1 -N-15 60 2800 36.1 363 -0-15 60 3000 35.3 - -

Sheet No. 17

G-17 As-Received 43:4 - -A-17 5 2500 44.7 439 8B-17 5 2575 41.6 362 75

SOUTHERN RESEARCH INSTITUTE

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Table VII (Continued)

The Hardness and Percent Recrystallization of Three0, 060 In. Thick Tungsten Sheets' After Holding at

Different Temperatures for Five and Sixty Minutes2

Time at Estim,- edSpecimen Temp. Temp. Rc Recr'ystallizaton

No. Min. F Hardness3 DPW_ %

Sheet No. 17 (Continued)

C-17 60 2200 43.4 438 3D-17 60 2400 36.9 463 77E-17 60 2425 38.1 356 90F-17 60 2700 36.5 352 100

Sheet No. 6

G- As-Received 42.7 - -A-6 5 2500 41.6 434 10B3-6 5 2575 39.6 414 60C- 6 60 2200 42.3 437. 3D-6 60 2400 38.7 373 60E-6 60 2425 40.6 361. 65F- 6 60 2700 32.7 350 100

1 Sheet numbers 6, 15, and 17 from Fansteel Lot No. A5467.Specimen number suffix denotes sheet number.

2.Specimens in optimum condition were resistance heated in avacuum of I x 10` torr.

""Re hardness measured on surface of the sheet.

4 DPH at mid-thickness on a longitudinal sectioi with a 3 Kg load,

,6

42

Table VIII

The Ilardness and Percent Recrystallization of0. 100 In. Thick Tungsten SheetI After Holding at

Different Temperatures for Five and Sixty Minutes

Time at EstirimatedSpecimen Temp. Temp, Rc Recrystallization

No. Min. F Hardness 3 DPIJ4 _ _0

K As-Received 41.7 438 1B 5 1800 43.9 485 1C 5 2000 43.9 466 1D 5 2200 43.8 462 1Y 5 2300 42.0 -E 5 2400 41.8 458 5L 5 2500 40.2 433 20F 5 2600 37.4 378 95z 5 2700 35.0 361 100G 5 2800 35.0 359 -N 5 2900 33.7 -I1 5 3000 33.8 -

I 5 3200 33.6 359 -0 60 1900 41.9 449 5P 60 2100 41.0 445 5Q 60 2300 40.9 441 10U 60 2400 38.3 388 60R 60 2500 34.6 347 100V 60 2600 34.3 344S 60 2700 33.7 346W 60 2800 33,2 346T 60 2900 33.6 349X 60 3000 33.0 344

'Sheet No. i12 from F'ansteel Lot No. A 5467.

2Specimens in optimum condition were resistance heated in avacuum of 1 x 10-5 torr.

3 Rc hardness measured nn surface of the sheet.

4DPH at mid-thickness on a longitudinal section with a 3 Kg load.

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43

455

40*6 I.

1•:• 60m I: i• • •::. :1: ::1j 1 • i• :

44

460 ~1* 1 1 ~ iT ~ 7 r ~ IK!il .V!L I440 _ - - 1!.- I . . .. . , .. .420 -5 m ill_4

.o .-. .. ..-7I .

m •.. x- I .... [flI6 , i I n

....................... --- --- --

360 .........

3660

- 0Sheet 15 - 5 min

9 'i Sheet 15 - (30 in... w. . • . .. •

340 I 0 Sheet 17- 5o in, i.. 360 0 Sheet 1 7 -60 min10S ee 5- 5m I .. - -. .. ...

E Sheet 1 , -,0 'Y _ 1 • : s_ i ! IASheet 67 - 5 mmi

A Sheet 6 - 50 mm in

320100 2000 2200 2400 2600 2800 3000

Temperature, 0 ],

Figure 19. The DPI! at the mid-thickness on longitudinal sectionsof different 0. 060-in.--thic;, tungsten sheet afterholding 5 and 60 min at different temperatures.

SOUTHERN RESEARCH INSTITUTE

IL-

45

I L

od 420 ~ 4 -

m~KI TFI IVM400 771.V

S 380

.. .. ... . .

0 .. . . . . ..

.~360 -- --

34 800 2000 2200 2400 2600 2800 3000Temperature, F

Figure 20. The DPH at mnid-thickness on longitudinal sectionsof 0. 100-in.- thick tungsten sheet after holding5 and 60 muin at different temperatures.

46

C 03

4(D

1 '~ ,-

It I

cl

E•

'C) C

E u_

•rr

I -4

C~,-

/ I oI I I

47

-1, 4-

L-,

iti

VS~

1~jJ4~ ;.,4 A~J~ ~ I COn-ý4'4 ,v

48

Q 44

41-

~ ~Ž!cu)

'' L.

49

Table IX

Tensile Prope. tics of 0.060-in. -Thick Tungsten Sheetin the Optimum Condition at Different Temperatures'

0. 2%-Offset Ultimate Mod. of Elong. ReductioiiSpecimen Temp., Yld. Str., Ten, Str., Elasticity, in 1.25 in. , of Area,

No. Orientation oF ksi ksi 0I psi Vi% _ /1___

6-150 Long. 70 IM8.0 190.5 46 0.5 _2

17-295 Long. 70 200.0 208.0 48 0.8 -

15-2 Long. 70 196.0 200.5 55 0.8 -2

Average 194.7 199.7 50 0.7

15-136 Trans. 70 216. 1 218. 53 52 0.5 2

17-438 Trans. 70 - 150.0 52 0 2

Average 216. 1 218.5 52 0.2

15-4 Long. 1200 77,4 87.2 43 7 616-141 Long. 1200 77.0 82.2 42 7 51Average 77.2 84.7 43 7 56

17-284 Long. 2000 62.7 66.0 38 8 686-142 Long. 2000 59.0 62.2 43 8 70Average 60.8 64.3 41 8 69

5-15 Long. 2500 45.7 54.9 48 9 >9517-285 Long. 2500 48.6 57.1 35 10 >95Average 47.6 56.0 42 10 >95

6-15 Long, 3000 7.6 17.4 44 60 >956-143 Long. 3000 6.7 18.7 42 71 >95Average 7.1 18.0 43 64 >95

6-144 Long. 3500 5.8 12.6 43 59 6917-286 Long. 3500 6.5 13.2 33 50 70Average 6.1 12.9 38 54 70

17-287 Long 4000 _ 6.7 17 24 6015-7 Long 4000 4.0 7.5 15 22 69Average 4.0 7.1 is 23 64

15-8 Long 4500 1.4 2.3 12 21 596-145 Long 4500 2.0 3.1 II 10 32Average 1.7 2.7 11 16 45

. Specimens were heated by radiation in a vacuum of approximately 1 x 10-4 torr andheld at temperature 15 min before straining. At 70 and 1200' F the strain rateto 0.6 %offset was 0.005 mrinand from .6, o.ffset to frae. . .. 0.05 mi-!At 20000 F and above, the strain rate was 0.05 min-' to fracture.

Too small to be measured.

3 Specimen fractured before 0.2% offset.

4 Extensometer slipped before 0.2% offset.

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50

'Fable X

"Tcnsilc Properties of 0. 060-In. -Tungsten Sheet in theRecrystallized Condition at Different Temperatures"'

2

0. 2%-Offset Ultimate Mod. of Elong. ReductionSpecimen Orien- Temp Yld. Str. Tens. Str. Elasticity in 1 in, of AreaNumber tation * F ksi ksi 10 psi % Q/_

15-12 Long 75 -3 56.8 56 0 017-294 Long 75 -_ 55.8 68 0 0Average 56.3 62 0 0

15-137 Trans 75 -3 47.8 68 0 017-439 Trans 75 _3 67.7 64 0 06-269 Trans 75 - 44.3 66 0 0Average 53.3 66 0 0

6-156 Long 1200 11.1 44.1 47 53 746-151 Long 1200 9.0 41.0 47 52 7517-2XG Long 1200 13.8 55.0 34 55 72Average 11.3 46.7 43 53 74

15-13 Long 2000 10.0 34.4 52 31 >9517-297 Long 2000 12.1 40.0 40 47 >95Average 11.0 37.2 46 39 >95

6-152 Long 2500 7.3 27.5 38 51 >9517-298 Long 2500 8.6 26.7 43 52 >95Average 8.0 27.1 41 52 >95

6-153 Long 3000 8.6 19.3 44 71 8615-14 Long 3000 8.0 18.7 42 44 >95Average 8.3 19.0 43 58 >90

15-15 Long 3500 6.1 11.8 45 50 6017-299 Long 3500 5.8 11.1 31 48 50Average 6.0 11,5 38 49 55

17-300 Long 4000 4.3 8.4 16 24 5917-301 Long 4000 4.7 9.0 16 23 64Average 4.5 8.7 16 24 62

6-154 Long 4500 2.0 4.5 10 18 546-155 Long 4500 2.3 4.3 9 17 46Average 2.2 4.4 10 18 50

' Specimens were recrystallized at 2550' F in 1 hour.

2 Specimens were heated by radiation in a vacuum of approximately 10" torr and held at

temperature 15 rmin before straining. At 75 and 1200° F the strait, rate to 0.61/ offsetwas 0. 005 min- and from 0.6% offset to fracture was 0.05 mrin. At 20000 r andabove the strain rate was 0.05 min-' to fracture.

3 Specimen fractured before yielding.

51

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0)~4 0-~ 000 Cl000 to Lh U' Lo LOLO $

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53

iTrans -

20 Long g,

175 _4I

125'

*d Optimum 44 4150

25 ..

Trans. Recrystallized KI0 ; : . I 1 -0 1000 2000 3000 4000 5000

Temperature, F

J¶ITrans.

200 1

175 Ki1III:t

w125 '4 4 I

ZOptimum i00100

50 5

0 1000 2000 3000 4000 5000Temperature, 0F

Figure 24. The ultimate- tensile and 0. 2%.-offset-yieidstrengths at different temperatures of 0. 060-in. tungsten sheet in the optimum and re-crystallized conditions.

SOUTHERN RESEARCH INSTITUTE

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70

160 tallaliz d ize

40l}

20

0 1000 2000 300 4000 5000

Temperature, F

Rcytallizedcodtosadifrntmprtrs

200&--og :21:

175 T

Ii~~ ~ ~ optimnum]t !'100 20 . 2

75 Long. \ 2 : :

S 50 Trans.-i2 ~ ~ : 10

Recrystallize,'-. T

0 1000 2000 3000 4000 5000Temperature, F

225 TT717:r~Tran's. '

175 1~~

En 125 ~iIOptimnum

50 '125 Rerystali zed-I .1

0 1000 2000 3000 4000 5000Tlemperature, 0F

Figure 26. The ultimate -tensile and 0. 2% offset-yieldstrengths at different temperatures of 0. 100in. tungsten sheet in the optimum and re-crystallized conditions.

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80- - I

701

*~*

60i~t

Recrystallized

20 t1Z. I7L

10 *..

Optimum0 _ _ K

0 1000 2000 3000 4000 5000Temperature, F

100 t -

80 ~ Rer'rys alized' '

u 60 LI. ,-optimum *

V 40 'I -2JitI IH n tfl~

20 j 4 /.i-v +H4+i#< i.1~

20

0 1000 2000 3000 4000 5000Temperature, 0F

Figure 27. The elongation and reduction of area of 0. 100-in. tungSte n sheet ira the optimum and recrys-tallized conditions at different temperatures.

57

60

.:.T .............V oig 7j ...:: . ...

0

4~4

00 1000 2000 3000 4000 5000

Tenmperature, F

J ans. fILog 0. 100-1n. Sheet

-460 _ýRecrys allized~-

VIVo 00

Telmpeaure,0Fiue2.Temdlso0lsict tdfeettmeaue

of0,2-nad020-itnse0seti h

opiuInjersalie odtos

SOTtR tEERHITTT

58

The room-temperature tensile properties were comparable for both gagesof the tungsten sheet in the optimum condition. The tensile, strength propertieswere, however, about 3 to 5 ksi higher for the transverse direction than theywere for the longitudinal direction. As shown in Figures 24 and 26, for the 0. 060-in. and 0. 100-in. sheet respectively, the strength properties of the recrystallizedsheet were much lower than those of the optimum sheet, Brittle fracture of therecrystallized sheet limited the tensile strength at room temperature to lowervalues than were obtained at moderately elevated temperatures (up to 10000 F).There was not a significant difference in the tensile strengths of the recrystal-lized sheet in the longitudinal and transverse directions.

As the testing temperature was increased from room temperature to about"10030 F, the strength of the tungsten sheet in the optimum condition (warm worked;.rd ýtress relieved) decreased from about 200 ksi to about 100 ksi, as may beseen in Figures 24 and 26, with a corresponding decrease in yield strength.This rapid decrease in strength with a rather slight increase in temperature isnormal for tungsten and some other body-centered cubic metals such as molybde-num. The decrease in strength between 1000 and 2500' F was gradual, about25 psi *F-1 . A large decrease in strength occurred between 2500 and 30000 F,which is attributable to recrystallization. Above the recrystallization tempera-ture the strength decreased as a linear function of the testing temperature toabout 15 ksi at 4500° F.

The yield and tensile strength of the recrystallized tungsten sheet waslower than for the sheet in the optimum condition at all temperatures up to therecrystallization temperature. Above the recrystallization temperature the pro-perties of the originally ova'mum-condition sheet, which recrystallized duringtesting, and the previously recrystallized sheet were con.parable.

At room temperature the elongation of the optimum-condition sheet wasless than one percent and the reduction in area was too small to be measured.At room temperature and up to about 7000 F the .. : •...zed structure frac-tured in a brittle manner, consequently the elongation and reduction in are-awere zero. As Figures 25 and 27 show, the elongati ii W %he sheet in the opti-mum condition was between 5 and 10% at 10000 F up to 25C.f v., slightly below,the recrystallization temperature. Over this ,%ne temperature range theelongation of the recrystallized sheet was significantly higher at 40 to 55%. At30000 F and higher, at which temperatures the "optimum-condition" sheet wasrecrystallized during testing, both sheet materials had practically the sameelongation at comparable testing temperatures. The elongation decreased fromits maximum value of about 60/% at 30000 F to about 16% at 45000 F. The reduc