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Texture of Metals
Typical Textures in Metals
Texture of Metals
1. Deformation Textures in fcc Metals2. Deformation Textures in bcc Metals3. Deformation Textures in hcp Metals4. Deformation Textures in Other Materials5. Composites6. Transformation Textures7. Texture Heterogeneities8. Solidification and Thin Film Textures
Contents
Texture of Metals
Deformation Textures in fcc Metals
Fiber textures (compression)
Rolling textures
Torsion texture (simple shear)
Texture of Metals
Fiber textures (Compression of Al, Cu, Ag, Brass)
Axisymmetric deformationTension compression
Only one direction to fully characterize the textures
Initial texture
simulated texture
experimental texture
Texture of Metals
Rolling textures (Variation with Strain)
Effect of strain on polycrystalline rolling textureSame texture Stronger and sharper texture
Fig. 111 pole figure (RD vertical)for rolled Cu
(a) 0 %, (b) 35%, (c) 58%, (d) 82%, (e) 90%, (f) 95%
Texture of Metals
Rolling textures (Variation with Material)
Fig. 111 pole figures for Cu-Zn alloys cold-rolledto 96% reduction with varying Zn content
Effect of alloying content on polycrystalline rolling texturecopper texture : pure metal type texture brass texture : alloy type texture
< 15% Zn
> 15% Zn
Texture of Metals
Rolling textures (Variation with Temperature)
Effect of temperature on polycrystalline rolling texturehigh temp. : pure metal type texture (copper)low temp. : alloy type texture (brass)
- 80oC - 150oC
- 196oCFig. 111 pole figures for Pu-9.6Ga rolled 95%
Texture of Metals
Rolling textures (Fiber and component analysis)
Two common approaches to analyzing rolling texture
1. Using texture component : to reduce the presentation of OD
into specific orientations
2. Using fibers: a single degree of freedom about a fixed axis: α- fiber : brass-Goss
β- fiber : copper-S-brass: not fixed in position
Texture of Metals
Rolling Textures (Fiber & Component Analysis)
Texture of Metals
Torsion textures (Simple Shear)
Usefulness of torsion test
: obtaining large plastic strains without friction
effect at interface btw specimen and platen
Specimen preparation
: surface layer separation + flattening
Texture of Metals
Texture of Metals
Shear Texture
• Shear strain means that displacements are tangential to the direction in which they increase.
• Shear direction=1, Shear Plane ⊥ 2-axis
ε12
1 = Shear Direction = <uvw>
2 =Torsion Axis= {hkl}
dε =0 +∆ 00 0 00 0 0
Texture of Metals
Torsion Textures :Twisting of a Hollow Cylinder Specimen
(a)
(b)(c)
Torsion Axis
Texture of Metals
{111}<uvw>
Torsion textures (ideal orientation)
{hkl}<110>
{001}<110>
Torsion axisShear plane
Shear direction
Texture of Metals
Shear Texture Components
• Why study shear textures? Shear strain near the surface of rolled parts
• Partial Fibers: A/D {111}<uvw>…<110>B {hkl} <110> … {112}
Components C {001}<110>D {112}<111>E {011}<111>F {110}<001>
Texture of Metals
{100} Pole figuresMontheillet et al.,
Acta metall., 33, 705, 1985
fcc bcc
Texture of Metals
fcc Torsion Textures
Plots of {111} and {200} pole figures (equal area projection; torsion axis vertical) for the following materials deformed in torsion; the shear direction points to the left in these figures.a) Nickel at γ=3.6b) Copper at γ=3.5c) Silver at γ=3.5d) Cu-30Zn at γ=3.5e) Ni-60Co at γ=3.2
Note that the partial "A" fiber is present in Ni and Cu, but is absent in the other materials. Silver, brass and Ni-60Co show instead a "D" fiber which is similar to the A fiber but rotated approximately 90° about the torsion axis. The B fiber is present to varying degrees in all the materials.
Texture of Metals
Torsion Textures (variation with material)
(a) Ni
(b) Cu
(c) Ag
(d) Cu-30Zn
(e) Ni-60Cu
γ = 3.2 ~ 3.6
Texture of Metals
Torsion Textures (Reversibility)
Assumption : single phase materialszero net strain (in reverse twist)
Irreversibility of work hardening :Accumulation of stored dislocation is sign-insensitive
Reversibility of texture evolution :
Texture development depends on accumulated changes in grain shapes
Expectation for reversion of texture evolution
Texture of Metals
Initial texture
γ = 3.5
Zero net strain
Irreversibility of Texture Evolution
111 and 200 pole figures for Al (99.99%)
Texture of Metals
Deformation Textures in bcc Metals
Comparing textures in fcc and bcc metals
Fiber textures (tension of Ta)
Rolling textures (Ta, steel)
Torsion texture (Fe)
Texture of Metals
Comparing textures in fcc and bcc metals
)()()()( ˆˆ sj
si
ssij nbL γ&=
( ))()()()()( ˆˆˆˆ si
sj
sj
si
sij nbnbm +=
21
( ))()()()()( ˆˆˆˆ si
sj
sj
si
sij nbnbq −=
21
( ) )()()()()()( ˆˆˆˆ sij
fccsi
sj
sj
si
sij
bcc mbnbnm =+=21
( ) )()()()()()( ˆˆˆˆ sij
fccsi
sj
sj
si
sij
bcc qbnbnq −=−=21
b̂n̂
L : velocity gradient
: slip direction
: slip plane normal
: symmetric part of distortion tensor
: skew part of distortion tensor
Texture of Metals
In Uniaxial deformationTexture developed in tension of fcc
= Texture developed in compression on bcc
In RollingInterchange of RD and ND for fcc and bcc
Comparing textures in fcc and bcc metals
Texture of Metals
: Rolled Copper (80%)
: Rolled Fe-3Si (80%)
Comparing Textures in fcc and bcc Metals
Texture of Metals
Fiber Textures (Tension of Ta)
: Rolled Ta (92%)
: in tension of 0.6 of (a)
Bcc metals under tensile deformation : <110> fiber(equivalent under wire drawing)
Texture of Metals
Rolling Textures (Ta, steel)
Position of ideal fibers for bcc materials
Texture of Metals
Peak intensity shift of fiber textures with strain
α-fiber : {001}<110> {112}<110>γ-fiber : {111}<112> {111}<110>
φ
ϕ1
ϕ2 =45ο
Rolling Textures
Texture of Metals
Rolling textures (Variation with Alloying Content)
: Hot rolled Fe-XSi
: Cold rolled Fe-XSi
Texture of Metals
Torsion texture (Fe, Ta)
Fewer publication than for fcc
Shear texture in bcc{112}<111>, {110}<001>
shear textures in fcc: {111}<uvw>, {hkl}<110>, {001}<110>
Texture of Metals
Deformation Textures in hcp Metals
Fiber textures( extrusion & compression)
Rolling textures
Tube textures
Texture of Metals
Twinning almost always provides significant deformation modes (texture)
slip: gradual lattice rotation with straintwinning: large scale lattice rotation
even for low strain
Zr alloy (Zircaloy)Ti alloys
Deformation Textures in hcp Metals
Texture of Metals
Fiber Textures ( Extruded Ti & Compressed Ti)
: extruded Ti
: compressed & cross rolled Ti
Extrusion axis
[1124]
ND
Texture of Metals
Rolling textures
Three groups according to c/a ratio
c/a > 1.633 : Zn, Cd
c/a = 1.633 : Mg, Co
c/a < 1.633 : Zr, Ti
Texture of Metals
Rolling textures
Mg
Zn
Ti
Fig. 0002 pole figures for rolled Mg, Zn, Ti.
Texture of Metals
Rolling textures
Roles of slip and twinning on rolling
Fig. 0002 pole figures for cold-rolled Ti(a) 20%, (b) 30%, (c) 55%, (d) 97%
low strain (<40%) major deformation mode : twining
high strain (>40%)major deformation mode : slip
Texture of Metals
Tube textures (Zircaloy)
Rw: reduction in wall thicknessRD: reduction in diameterεR: radial strainεT: tangential (or hoop) strain
Rw /RD >1: similar to rolling
Rw /RD =1: similar to wire drawing
Texture of Metals
Deformation Textures in intermetallics (NiAl)
Fig. Inverse pole figures for NiAl
Starting extruded at R.T extruded at 300oC
NiAl: low ductility at R.T, extensive g.b cracking Hydrostatic extrusion
Texture of Metals
1. Deformation Textures in fcc Metals2. Deformation Textures in bcc Metals3. Deformation Textures in hcp Metals4. Deformation Textures in Other Materials5. Composites6. Transformation Textures7. Texture Heterogeneities8. Solidification and Thin Film Textures
Part-2
Texture of Metals
Composites
Wire-drawn Cu-Nb composite
Extruded Al-SiC composites
Rolled Be-Al composites
Texture of Metals
Wire-drawn Cu-Nb composite
Expectationtexture in composite : “rule of mixtures” approach
Fig. Inverse pole figures for wire drawn Cu-Nb composite
Cu matrix(fcc)
Nb reinforcement(bcc)
Texture of Metals
Extruded Al-SiC(whisker) composites
Fig. Pole figures for extruded 8090 Al alloys with SiC whisker
0 %
15 %
30 %
Texture of Metals
Extruded Al-SiC(particle) composites
Fig. Pole figures for extruded 8090 Al alloys with 15% SiC particles
whisker : more effective at repressing texture development
Texture of Metals
Transformation Textures
Phase transformation
Recrystallization in rolled fcc metals
Texture of Metals
Phase transformation
Orientation relationship between parent phase and product phase :
Alignment of close-packed plane and direction
Kurdjumov-Sacks (KS) relationship
{111}fcc // {110}bcc <110>fcc // <111>bcc
Texture of Metals
at T>TR
Hot rolled steel :
{001}<100>
{001}<110>
{110}<001>
{110}<110>
Phase transformation (in steel)
In austenite (fcc) In ferrite (bcc)
Texture of Metals
Phase transformation (alloying effect)
Plain carbon steel Nb alloyed steel
Alloy addition : raising recrystallization temperature
ϕ2 =45o
Texture of Metals
Recrystallization in rolled fcc metals
Recrystallization texture : more complicate thanphase transformation texture
No texture change in recrystallization1. Large volume fraction of 2nd phase particles2. Axisymmetric deformation
Texture of Metals
Precipitation state
Recrystallization texture
Stacking fault energy Deformation state
Annealing temp.
Recrystallization texture
Texture of Metals
Fig. Recrystallization textures of cold rolled metals
Al Cu
Brass Al-Mn(A3103)
Recrystallization texture (material dependence)
BR: {236}<385>
Texture of Metals
Recrystallization texture (bcc)
coarse 2nd phase particle : weak recrystallization textureeffect of Mn in low carbon steel : decrease <111><111>//ND fiber , <110>//RD fiber [Raabe &Lucke, 1992]
Low carbon steel
Texture of Metals
Recrystallization texture (Cu)
Fig. 111 pole figures for recrystallized Cu
71 %
100 %91 %
45 %
11 %0 %
Texture of Metals
Recrystallization texture (Cu)
Fig. Volume fraction of major components in recrystallization of 90% rolled Cu
Effect of recrystallized fraction
Texture of Metals
Recrystallization texture (Cu)
Effect of prior strain
Fig. Volume fraction of cube component in recrystallized Cu
Texture of Metals
Texture Heterogeneities
Local heterogeneities in deformation
Texture gradient after deformation
Heterogeneities in recrystallization
Texture of Metals
Local heterogeneities in deformation
Grain-scale heterogeneities
Individual grains : subdivided into regions with a range of orientation
Deformation of polycrystalline
In cold-rolled polycrystalline Al [by Hansen, 1992]3o at 5 %, 15o at 20%, 20o at 30%
Texture of Metals
Multi-grain heterogeneities: local texture of shear band
Initiation at stress riser(corner or edge of rolled sheet)
Not significant contribution to global textureAffect subsequent recrystallization texture
Local heterogeneities in deformation
Texture of Metals
Most forming process : not uniform spatial distribution of texture
Surface-to-midplane gradient in rolled materials
Surface-to-core gradient in wire
Outer-to inner wall gradient in tube
Texture gradient after deformation
Texture of Metals
1. In rolling
Surface frictionRoll geometryRolling temperature
Texture gradient after deformation
Fig. 111 pole figures from rolled Fe-3%Si
Texture of Metals
Texture gradient after deformation
2. In wire drawing
Fig. 111 pole figures from drawn Al wire
R < 1mm R = 1.4mm
R = 1.8mm R = 1.95mm
Texture of Metals
3. In tube extrusion
Fig. Different types of texture gradient for zircaloy tubing
εR : radial strain
εT : tangential strain
OD: out diameter
ID : inner diameter
Texture gradient after deformation
Texture of Metals
Fe-3%Si sheet : used in transformer{110}<001> Goss texture
Hot rolling Cold rolling Recrystallization
Shear texture in bcc : {112}<111>, {110}<001>
Rolling texture in bcc : α+ γ fiber
Goss
α+ γ fiber
Goss
{111}<112>
α+ γ fiber
{111}<112>
Goss
α+ γ fiber
Goss
Heterogeneities in recrystallization
Texture of Metals
Grain growth of Fe-3%Si sheet (<1mm)
Heterogeneities in recrystallization
• Key factor : oxygen content
Low content (vacuum) : {110}<001> Gossγ110 < γ100
Presence of oxygen : {001}<100> Cubeγ110 > γ100
Texture of Metals
Solidification and Thin Film Textures
Solidification
Vapor deposition
Electrodeposition
Texture of Metals
Solidification (Cast Inconel)
Preferred Growth Direction of Dendrite in Cubic : <100>
Grain boundary map and 100 pole figures for cast Inconel X750
0~0.1mm 0.1~0.2mm 0.2~0.3mm
0.6~0.9mm 1.2~1.5mm 1.8~2.1mm
Texture of Metals
Solidification (Melt-Spun Pd-In Ribbon)
Bottom
Top
100 and 111 pole figures for melt-spun Pd-In
20o
20o
Texture of Metals
Vapor Deposition (CVD Ta)
Vapor Deposition : Strong fiber textureSelecting Plane to measure texture
100 pole figure CVDed Ta
Texture of Metals
Vapor deposition (sputtered Al)
sputtering : stronger texture than evaporation
electromigration in Al interconnectstrong <111> fiber : longer lifetimet <111> = 10 . t<110> [Joo & Thompson, 1994]
Texture of Metals
Electrodeposition
Texture of electrodeposits depend on1. Crystal structure of substrate and deposit 2. Bath conditions :
bath composition, current densityvoltage, temperature, pH
If difference btw asub and adepo > 15% : deposit texture depend on bath condition
If asub≒ adepo :initial layer : epitaxial growthintermediate layer : depend on bath condition
Texture of Metals
Summary
What materials ? What processing ?+
Metallurgical variables
Illustration of complexity and richness in texture development
Expectation of texture development