Properties and Performance of a

High Chromium Nickel Alloy

Filler Metal: 52iFiller Metal: 52iDouglas G. Baldrey1, Catherine M. Brown2, James B. Burns1, Thomas E.

Capobianco1, Heather M. Mohr1, David S. Morton1, Tyler E. Moss1, John V. Mullen1, Larry Paul3, Elaine West1, and

George A. Young1

1Bechtel Marine Propulsion Corporation, Knolls Atomic Power Laboratory, Niskayuna, NY 123092Bechtel Marine Propulsion Corporation Bettis Atomic Power Laboratory, West Mifflin, PA 15122

3Outokumpu VDM USA LLC, Richburg, SC 29706

Scope of Work

• Physical and Thermal Properties

• Elastic and Mechanical Properties

• Weldability

• Environmentally Assisted Cracking• Environmentally Assisted Cracking

– Low Temperature Crack Propagation

– Corrosion Fatigue in Primary Water

– Primary Water Stress Corrosion

• Metallurgical Stability

2

Materials and Welding Processes• 3 Heats of material assessed

• Property data primarily on A-GTAW

– Weld pads and v-grooves

• Limited testing of shielded-metal-arc welds

• Weldability testing also on M-GTAW and GMAW• Weldability testing also on M-GTAW and GMAWTable I. Comparison of the Composition of Each Heat of Material in wt.%

Heat Cr Fe Nb Mn Ti S P C N

MLTS-2 26.83 3.05 2.51 3.19 0.17 0.0014 0.003 0.032 0.009

187775 26.98 2.55 2.58 3.04 0.37 0.0010 0.002 0.040 0.039

126373 26.97 2.55 2.29 2.97 0.30 0.0010 0.003 0.043 0.017

Specification* 26.0

28.0

2.0

3.0

2.2

2.4

2.5

3.5

0.2

0.4 <0.002 <0.008

0.03

0.05

0.015

0.040

*Most recent values based on current testing

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Physical PropertiesDensity, CTE, specific heat, conductivity are typical of Ni-Cr alloys

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Elastic Properties<100> weld texture influences modulus

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Mechanical Properties (1)• Typical tensile

properties given

from multiple

heats and tests

• Room T YS~65

ksi, UTS ~95 ksi,

80

90

100

70

80

90

100

110

% E

lon

ga

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nd

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Str

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gth

(k

si)

Typical Tensile PropertiesEffect of Stress Relief: 'L' GTAW

UTS

30 hrs / 1050°F

As Welded

ksi, UTS ~95 ksi,

>50% RA and

~40% EL

• No detrimental

effect of PWHT

(1050°F / 30

hours)6

30

40

50

60

70

0

10

20

30

40

50

60

70

0 100 200 300 400 500 600 700 800 900

% E

lon

ga

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Str

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gth

(k

si)

Temperature (oF)

YS

%RA

%El

30 hrs / 1050°F

Mechanical Properties (2)GTAW and SMAW properties comparable. Little effect

of orientation with exception of lower ‘T’ %Elongation

80

90

100

80

90

100

110

% E

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As-Welded 'L' Tensile PropertiesEffect of Process: GTAW vs. SMAW

UTS

SMAW

GTAW80

90

100

80

90

100

110

% E

lon

ga

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Typical Tensile PropertiesEffect of Orientation: GTAW

UTS

T

30

40

50

60

70

0

10

20

30

40

50

60

70

0 100 200 300 400 500 600 700 800 900

% E

lon

ga

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nd

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rea

Str

en

gth

(k

si)

Temperature (oF)

YS

%RA

%El

GTAW

7

20

30

40

50

60

70

0

10

20

30

40

50

60

70

0 100 200 300 400 500 600 700 800 900

% E

lon

ga

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(k

si)

Temperature (oF)

YSYS

%RA

%El

T

L

Weldability (1)Good resistance to solidification cracking, Spec limit on

Nb changed to improve on Heat 187775

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Weldability (2)

EN52i data (red bars)show good resistance toDDC and solidificationcracking relative to otherNi-Cr filler metals

# of

cracks

# of

cracks# of

9

# of

cracks

# of

cracks

Weldability (3)Vendor experience consistently good. Comparable to ‘good

welding’ EN82H. GTAW, SMAW, GMAW.

Table III. Summary of Industrial Experience with EN52i

User Process Comments

B&W (Barberton)

Automatic GMAW and manual

GTAW cladding and groove EN52i can directly replace

EN82H B&W (Barberton) GTAW cladding and groove

welds EN82H

B&W (Mount Vernon) Automatic GTAW cladding

EN52i has similar weldability,

bead texture, bead tie-in, and

puddle control as EN82H

Hamill Manufacturing Manual GTAW for dissimilar

metal weld joints

EN52i has the same welding

characteristics as EN82H

Electric Boat GTAW pipe welds with Alloys

600 and 690

Excellent flow and tie-in with

EN52i

Newport News Shipyard GTAW pipe welds with Alloys

600 and 690

Excellent flow and tie-in with

EN52i

Arc Applications GTAW steam generator tube

plug development

No significant difference

between EN52i and EN82H

10

LTCP ResistanceVery high toughness in air. LTCP resistance ≥ EN82H

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Corrosion Fatigue in Primary WaterComparable to A690 & EN82H, benefit relative to 304L SS

12

Primary Water SCC (1)At Least 50X Benefit Relative to EN82H

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Primary Water SCC (2)Samples only show pockets of SCC & cracks do not extend more

than 1 grain. Methodology to report CGR as 100% engagement

with no consideration of grain to grain incubation bias EN52i

rates high � 50X benefit is conservative. See paper by Moss et

al., these Proceedings

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Primary Water SCC (3)Composite material testing confirms >50X benefit, no increase in

growth after 24 months(!), cracks slow/arrest in 1st 52i bead

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680°F

KI=30 ksi√in

Metallurgical StabilitySeveral Ni-Cr Alloys could be susceptible to long range

ordering. Testing on 52i to date (3000 hours) shows no

evidence of LRO.

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Conclusions (1)• Physical properties consistent with other nickel-chromium

weld filler metals.

• Typical of most FCC ‘austenitic’ weld filler metals, EN52i welds display significant <100> type texture. Consequently Young’s modulus can display anisotropy.

• The tensile strength of EN52i is moderate (~65 ksi) and ductility is high (%Elongation and %RA ≥ 30%).ductility is high (%Elongation and %RA ≥ 30%).– The tensile properties are insensitive to typical post weld heat

treatments (~1050°F / 30 hours)

– Tensile properties are comparable between GTAW and SMAW

– Little effect of L vs. T orientation

• Both in-house and vendor experience with EN52i indicates very good weldability. Vendor experience confirms that welding parameters developed for EN82H can be directly used for EN52i.

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Conclusions (2)• High fracture toughness in air and more resistant to Low

Temperature Crack Propagation (LTCP) than EN82H.

• Corrosion fatigue testing shows crack growth rates consistent with Alloy 690 & EN82H and superior to 304L stainless steel.

• The primary water SCC resistance of EN52i is far superior to EN82H. Aggressive testing, 680°F near Ni/NiO stability indicate ≥ 50X slower rates in EN52i relative to EN82H. – This benefit is likely conservative, based on adjusting the crack – This benefit is likely conservative, based on adjusting the crack

growth to 100% engagement and does not account for an incubation time for cracking to propagate into new grains.

– Composite specimen testing confirms this benefit as shown by SCC in the E-182 / EN52i samples markedly slowing their rate or possibly arresting in the first weld bead diluted with EN52i.

• Testing between 631-878°F (333-470°C) for times up to 3,000 hours indicated good metallurgical stability with no hardening that would suggest susceptibility to long range ordering.

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