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702 florent lefevre-schlick_november_2005

Mukhlis Adam
Mukhlis Adam

This document discusses recrystallization in metals and methods to investigate the nucleation stage of recrystallization. It summarizes different techniques to induce or inhibit recrystallization including deformation, annealing, and rapid/ultrafast heating methods. Instrumented indentation and electron backscatter diffraction are identified as tools to characterize local microstructure changes during the initial nucleation events. Future work should focus on controlling nucleation sites and integrating experimental data on local misorientation into recrystallization models.

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1 RECRYSTALLIZATION IN METALS FLORENT LEFEVRE-SCHLICK and DAVID EMBURY Department of Materials Science and Engineering McMaster University, Hamilton, ON, Canada
2 OUTLINE Recrystallization What is it? How is it usually treated? Importance of local misorientation/strain gradients on nucleation First stages of recrystallization; how can we investigate the nucleation? Rapid heat treatments What are they? What can we expect from them? Recrystallization in metals Modeling Conclusions-Future work
3 What is it? Fe E =Estored=~100J/mol Deformation Heat Recovery (rearrangement of dislocations in sub grains) Recrystallization (development of new strain free grains) Recrystallization
4 Recrystallization HOW DOES RECRYSTALLIZATION START? nucleation Strain Induced Boundary Migration 1 2 3 4 1 3 4 1 2 1 2 2 E 1 E 2> Coalescence and growth of subgrains Migration of a boundary In simple systems: small number of nuclei lead to recrystallized grains
5 Improving the mechanical properties of materials How does recrystallization proceed? How to control recrystallization? How to achieve an important grain refinement? Can we control more than just the scale? 0 1000 2000 3000 4000 5000 6000 7000 0 2 4 6 8 10 d -1/2 (袖m -1/2 ) Y(MPa) Cu Fe Al Recrystallization Grain refinement strengthening
6 Johnson, Mehl, Avrami, Kolmogorov approach 1 exp( )n X Bt= 0 1 recrystallizedfractionX time Random distribution of nucleation sites Constant rate of nucleation and growth n=4 Site saturation n=3 Recrystallization
7 Johnson, Mehl, Avrami, Kolmogorov approach Recrystallization Is n misleading? <1Fe-Mn-C 1.7Aluminium+ small amount of copper, 40% cold rolled 4Fined grained Aluminium, low strain 4/3/2Constant nucleation rate 3d/2d/1d 3/2/1Site saturation 3d/2d/1d
8 NUCLEATION OF RECRYSTALLIZATION Recrystallization Hu et al. (1966) Adcock et al. (1922) Large orientation gradient (transition bands) Strain heterogeneities (shear bands) Fe-Si system Cu
9 Particle Stimulated Nucleation Leslie et al. (1963) Humphreys et al. (1977) Oxide inclusions in Fe Al-Si system Cluster of SiO2 in Ni Recrystallization originates at pre-existing subgrains within the deformation zone Nucleation is affected by particle size and particle distribution NUCLEATION OF RECRYSTALLIZATION Recrystallization
10 INVESTIGATING THE NUCLEATION EVENT Injecting nucleation sites to increase N: Local misorientation (twins) Local strain gradient (high deformation) Recrystallization o Impeding growth of recrystallized grains Rapid heat treatments
11 What are rapid heat treatments? T time ≒Slow heat treatment (salt bath) ≒Rapid heat treatment (spot welding machine) ≒Ultra-fast heat treatment (pulsed laser) T time T time seconds mseconds nano/pico/femtoseconds Rapid heat treatments
12 Slow heat treatment: Salt bath Time/Temperature profile during salt bath heat treatment 0 100 200 300 400 500 600 700 0 5 10 15 Time (sec) Temperature(C) Duration of the heat treatment: 5 seconds. Temperature range: 500o C to 650o C. Heating rate ~300C/sec Cooling rate ~1000C/sec Salt bath
13 NUCLEATION IN IRON Fe deformed by impact at 77K 50 袖m B=[011] 01-1 -21-1 -200 21-1 -2-11 2-22 (-2-11) (1-11) grain twin Twinning plane {112} Shear direction 111 Production of deformation twins to promote a variety of potential nucleation sites for recrystallization, either at twin/grain boundary or twin/twin intersections 4 袖m Salt bath
14 ZA=[011] ZA=[113] ZA=[113] ZA=[113] 200 0-11 22-2 21-1 ZA=[133] -110 0-31 12-1 -301 21-1 -110 0-31 12-1 -301 21-1 -110 0-31 12-1 -301 21-1 Kikuchi patterns of the parent grain, a twin and a cell of dislocations. Shift of about 0.5 deg in the ZA between the grain (green circle) and the cell (red circle). -301 -310 5 seconds at 500o C BF images of a nuclei along a deformed twin. Salt bath NUCLEATION IN IRON
15 NUCLEATION IN COPPER 50 袖m 1 袖m 4 袖m 25 袖m Cu 60% cold rolled Cu ~ 2% recrystallized 5 seconds at 250o C No noticeable effect of annealing twins on nucleation Salt bath
16 45% cold rolled @ 77K 100袖m Stainless steel 316L Cooperation with X. Wang Salt bath NUCLEATION IN STAINLESS STEEL
17 2 min @ 950C 25袖m Stainless steel 316L Average grain size: 7袖m Salt bath NUCLEATION IN STAINLESS STEEL
18 25袖m 2 min @ 900C Stainless steel 316L Average grain size: 5袖m Salt bath NUCLEATION IN STAINLESS STEEL
19 Stainless steel 316L 25袖m 2 min @ 850C Average grain size: 3袖m Salt bath NUCLEATION IN STAINLESS STEEL
20 1 min @ 800C 10袖m Role of annealing, deformation twins and phases on nucleation and growth? Stainless steel 316L Salt bath NUCLEATION IN STAINLESS STEEL
21 DF image (austenite) DF image (austenite + martensite) DF image (Twin) BF image Salt bath 1 min @ 800C Stainless steel 316L Fine and complex deformed microstructure Over a range of possible growing grains, only a few seem to grow NUCLEATION IN STAINLESS STEEL
22 Salt bath Stainless steel 316L, 2 min @ 850C 25袖m RECRYSTALLIZATION AS A WAY TO CONTROL THE NATURE OF GRAIN BOUNDARIES? 10o 20o 30o 40o 50o 60o 0% 30% ~30% of 裡3 boundaries (rotation 60o , axis <111>)
23 RAPID HEAT TREATMENT: SPOT WELDING MACHINE 3mm 250 袖m Fe annealed (thickness = 500 袖m) Fe 60% cold rolled (thickness = 200 袖m) Electrode of Cu Pulse discharge width: 1 msec Energy output: 100 J to 1 J Estimated heating rate ~105 K/sec Spot welding machine
24 PHASE TRANSITION IN IRON 50 袖m 50 袖m 40 J 20 J Melted zone Heated zone Refinement of the microstructure via phase transitions Distribution in grain size from 40 袖m down to less than 1 袖m Spot welding machine
25 RECRYSTALLIZATION AND PHASE TRANSITION IN IRON 40 J 50 袖m100 袖m Refinement of the microstructure via phase transitions and recrystallization Distribution in grain size from 100 袖m down to less than 1 袖m Spot welding machine Fe 60% cold rolled
26 20 J 50 袖m Localized event along specific grain boundaries Spot welding machine RECRYSTALLIZATION AND PHASE TRANSITION IN IRON Fe 60% cold rolled
27 Laser pulse: Energy (nJ to 袖J) Time (fsec to nsec) Beam size (袖m to mm) Small volume on the surface Rapid heating and cooling (104 to 1012 K/sec) Increase in pressure (up to TPa) Shock wave. ULTRA FAST HEAT TREATMENT: PULSE LASER IRRADIATION (nano/pico/femtosecond) Cooperation with Preston/Haugen group ~100 nm to mm Pulse lasers
28 了 = 800 nm The beam has a Gaussian profile with a radius 0 E0: full energy pulse (~10 袖J) p: duration of the pulse (~ 10 nsec/ 100psec/ 150 fsec) : fluence or energy per unit area (J/cm2 ) th: threshold fluence (J/cm2 ) fluence required to transform the surface Pulse lasers ULTRA FAST HEAT TREATMENT: PULSE LASER IRRADIATION (nano/pico/femtosecond)
29 WHY PULSED LASERS? Pulse lasers
30 SINGLE PULSE ABLATION OF FE E = 9.2 袖J 10 袖m 5 袖m E = 1.0 袖J 10 袖m E = 3.2 袖J 5 袖m E = 0.2 袖J What is the temperature profile? How to characterise the irradiated volume? Pulse lasers
31 Si substrate SiO2 isolant layer Platinum 2 mm 2 mm 100 袖m 25 nm2 袖m resistor connector TEMPERATURE MEASUREMENT DEVICE Summer work of B. Iqbar Measuring the changes in resistivity of Pt estimating the temperature Pulse lasers
32 Fe annealed, 1 grain Corrected harmonic contact stiffness: 1.106 N/m 0 10 20 30 200 400 600 800 1000 1200 Load On Sample (mN) Displacement Into Surface (nm) 1 2 3 4 5 [6] U HD I E M HN L 0 100 200 300 400 200 400 600 800 1000 1200 Reduced Modulus (GPa) Displacement Into Surface (nm) IM H N 0 2 4 6 8 10 12 14 16 0 200 400 600 800 1000 Hardness (GPa) Displacement Into Surface (nm) 1 2 3 4 5 [6] I M HN INSTRUMENTED INDENTATION Pulse lasers 0 10 20 30 40 200 400 600 800 1000 1200 Load On Sample (mN) Displacement Into Surface (nm) [2] 3 4 U HD I E M HN L Fe annealed, 3 different grains 0 100 200 300 400 200 400 600 800 1000 1200 Reduced Modulus (GPa) Displacement Into Surface (nm) I MH N 0 2 4 6 8 10 12 14 16 200 400 600 800 1000 1200 Hardness (GPa) Displacement Into Surface (nm) [2] 3 4 IM HN
33 1 2 3 12 11 10 -1 0 1 2 3 4 5 6 7 100 200 300 400 Load On Sample (mN) Displacement Into Surface (nm) 1 2 3 4 5 6 7 8 [9] 10 11 12S U HDI EM H N L -2 0 2 4 6 8 10 12 14 16 18 20 100 200 300 400 Hardness (GPa) Displacement Into Surface (nm) 1 2 3 4 5 6 7 8 [9] 10 11 12 IM HN INSTRUMENTED INDENTATION Pulse lasers Softening of the deformed material? Is there local melting/solidification or local heating?
34 SGGrain I Grain II nucleus Grain I Grain II )( 2 )( tr tG 粒 > Modeling ZUROBS MODEL FOR RECRYSTALLIZATION Needs input on local misorientations
35 CONCLUSIONS FUTURE WORK Investigation of the first stage of recrystallization by: o Designing microstructures to promote N o Using rapid heat treatments to allow nucleation but not G o o Characterize the heat treatment in terms of time/temperature profile Characterize the nucleation event in terms of local misorientation, local strain gradient (EBSD) Introduce the data on misorientation into Zurobs model

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702 florent lefevre-schlick_november_2005

  • 1. 1 RECRYSTALLIZATION IN METALS FLORENT LEFEVRE-SCHLICK and DAVID EMBURY Department of Materials Science and Engineering McMaster University, Hamilton, ON, Canada
  • 2. 2 OUTLINE Recrystallization What is it? How is it usually treated? Importance of local misorientation/strain gradients on nucleation First stages of recrystallization; how can we investigate the nucleation? Rapid heat treatments What are they? What can we expect from them? Recrystallization in metals Modeling Conclusions-Future work
  • 3. 3 What is it? Fe E =Estored=~100J/mol Deformation Heat Recovery (rearrangement of dislocations in sub grains) Recrystallization (development of new strain free grains) Recrystallization
  • 4. 4 Recrystallization HOW DOES RECRYSTALLIZATION START? nucleation Strain Induced Boundary Migration 1 2 3 4 1 3 4 1 2 1 2 2 E 1 E 2> Coalescence and growth of subgrains Migration of a boundary In simple systems: small number of nuclei lead to recrystallized grains
  • 5. 5 Improving the mechanical properties of materials How does recrystallization proceed? How to control recrystallization? How to achieve an important grain refinement? Can we control more than just the scale? 0 1000 2000 3000 4000 5000 6000 7000 0 2 4 6 8 10 d -1/2 (袖m -1/2 ) Y(MPa) Cu Fe Al Recrystallization Grain refinement strengthening
  • 6. 6 Johnson, Mehl, Avrami, Kolmogorov approach 1 exp( )n X Bt= 0 1 recrystallizedfractionX time Random distribution of nucleation sites Constant rate of nucleation and growth n=4 Site saturation n=3 Recrystallization
  • 7. 7 Johnson, Mehl, Avrami, Kolmogorov approach Recrystallization Is n misleading? <1Fe-Mn-C 1.7Aluminium+ small amount of copper, 40% cold rolled 4Fined grained Aluminium, low strain 4/3/2Constant nucleation rate 3d/2d/1d 3/2/1Site saturation 3d/2d/1d
  • 8. 8 NUCLEATION OF RECRYSTALLIZATION Recrystallization Hu et al. (1966) Adcock et al. (1922) Large orientation gradient (transition bands) Strain heterogeneities (shear bands) Fe-Si system Cu
  • 9. 9 Particle Stimulated Nucleation Leslie et al. (1963) Humphreys et al. (1977) Oxide inclusions in Fe Al-Si system Cluster of SiO2 in Ni Recrystallization originates at pre-existing subgrains within the deformation zone Nucleation is affected by particle size and particle distribution NUCLEATION OF RECRYSTALLIZATION Recrystallization
  • 10. 10 INVESTIGATING THE NUCLEATION EVENT Injecting nucleation sites to increase N: Local misorientation (twins) Local strain gradient (high deformation) Recrystallization o Impeding growth of recrystallized grains Rapid heat treatments
  • 11. 11 What are rapid heat treatments? T time ≒Slow heat treatment (salt bath) ≒Rapid heat treatment (spot welding machine) ≒Ultra-fast heat treatment (pulsed laser) T time T time seconds mseconds nano/pico/femtoseconds Rapid heat treatments
  • 12. 12 Slow heat treatment: Salt bath Time/Temperature profile during salt bath heat treatment 0 100 200 300 400 500 600 700 0 5 10 15 Time (sec) Temperature(C) Duration of the heat treatment: 5 seconds. Temperature range: 500o C to 650o C. Heating rate ~300C/sec Cooling rate ~1000C/sec Salt bath
  • 13. 13 NUCLEATION IN IRON Fe deformed by impact at 77K 50 袖m B=[011] 01-1 -21-1 -200 21-1 -2-11 2-22 (-2-11) (1-11) grain twin Twinning plane {112} Shear direction 111 Production of deformation twins to promote a variety of potential nucleation sites for recrystallization, either at twin/grain boundary or twin/twin intersections 4 袖m Salt bath
  • 14. 14 ZA=[011] ZA=[113] ZA=[113] ZA=[113] 200 0-11 22-2 21-1 ZA=[133] -110 0-31 12-1 -301 21-1 -110 0-31 12-1 -301 21-1 -110 0-31 12-1 -301 21-1 Kikuchi patterns of the parent grain, a twin and a cell of dislocations. Shift of about 0.5 deg in the ZA between the grain (green circle) and the cell (red circle). -301 -310 5 seconds at 500o C BF images of a nuclei along a deformed twin. Salt bath NUCLEATION IN IRON
  • 15. 15 NUCLEATION IN COPPER 50 袖m 1 袖m 4 袖m 25 袖m Cu 60% cold rolled Cu ~ 2% recrystallized 5 seconds at 250o C No noticeable effect of annealing twins on nucleation Salt bath
  • 16. 16 45% cold rolled @ 77K 100袖m Stainless steel 316L Cooperation with X. Wang Salt bath NUCLEATION IN STAINLESS STEEL
  • 17. 17 2 min @ 950C 25袖m Stainless steel 316L Average grain size: 7袖m Salt bath NUCLEATION IN STAINLESS STEEL
  • 18. 18 25袖m 2 min @ 900C Stainless steel 316L Average grain size: 5袖m Salt bath NUCLEATION IN STAINLESS STEEL
  • 19. 19 Stainless steel 316L 25袖m 2 min @ 850C Average grain size: 3袖m Salt bath NUCLEATION IN STAINLESS STEEL
  • 20. 20 1 min @ 800C 10袖m Role of annealing, deformation twins and phases on nucleation and growth? Stainless steel 316L Salt bath NUCLEATION IN STAINLESS STEEL
  • 21. 21 DF image (austenite) DF image (austenite + martensite) DF image (Twin) BF image Salt bath 1 min @ 800C Stainless steel 316L Fine and complex deformed microstructure Over a range of possible growing grains, only a few seem to grow NUCLEATION IN STAINLESS STEEL
  • 22. 22 Salt bath Stainless steel 316L, 2 min @ 850C 25袖m RECRYSTALLIZATION AS A WAY TO CONTROL THE NATURE OF GRAIN BOUNDARIES? 10o 20o 30o 40o 50o 60o 0% 30% ~30% of 裡3 boundaries (rotation 60o , axis <111>)
  • 23. 23 RAPID HEAT TREATMENT: SPOT WELDING MACHINE 3mm 250 袖m Fe annealed (thickness = 500 袖m) Fe 60% cold rolled (thickness = 200 袖m) Electrode of Cu Pulse discharge width: 1 msec Energy output: 100 J to 1 J Estimated heating rate ~105 K/sec Spot welding machine
  • 24. 24 PHASE TRANSITION IN IRON 50 袖m 50 袖m 40 J 20 J Melted zone Heated zone Refinement of the microstructure via phase transitions Distribution in grain size from 40 袖m down to less than 1 袖m Spot welding machine
  • 25. 25 RECRYSTALLIZATION AND PHASE TRANSITION IN IRON 40 J 50 袖m100 袖m Refinement of the microstructure via phase transitions and recrystallization Distribution in grain size from 100 袖m down to less than 1 袖m Spot welding machine Fe 60% cold rolled
  • 26. 26 20 J 50 袖m Localized event along specific grain boundaries Spot welding machine RECRYSTALLIZATION AND PHASE TRANSITION IN IRON Fe 60% cold rolled
  • 27. 27 Laser pulse: Energy (nJ to 袖J) Time (fsec to nsec) Beam size (袖m to mm) Small volume on the surface Rapid heating and cooling (104 to 1012 K/sec) Increase in pressure (up to TPa) Shock wave. ULTRA FAST HEAT TREATMENT: PULSE LASER IRRADIATION (nano/pico/femtosecond) Cooperation with Preston/Haugen group ~100 nm to mm Pulse lasers
  • 28. 28 了 = 800 nm The beam has a Gaussian profile with a radius 0 E0: full energy pulse (~10 袖J) p: duration of the pulse (~ 10 nsec/ 100psec/ 150 fsec) : fluence or energy per unit area (J/cm2 ) th: threshold fluence (J/cm2 ) fluence required to transform the surface Pulse lasers ULTRA FAST HEAT TREATMENT: PULSE LASER IRRADIATION (nano/pico/femtosecond)
  • 30. 30 SINGLE PULSE ABLATION OF FE E = 9.2 袖J 10 袖m 5 袖m E = 1.0 袖J 10 袖m E = 3.2 袖J 5 袖m E = 0.2 袖J What is the temperature profile? How to characterise the irradiated volume? Pulse lasers
  • 31. 31 Si substrate SiO2 isolant layer Platinum 2 mm 2 mm 100 袖m 25 nm2 袖m resistor connector TEMPERATURE MEASUREMENT DEVICE Summer work of B. Iqbar Measuring the changes in resistivity of Pt estimating the temperature Pulse lasers
  • 32. 32 Fe annealed, 1 grain Corrected harmonic contact stiffness: 1.106 N/m 0 10 20 30 200 400 600 800 1000 1200 Load On Sample (mN) Displacement Into Surface (nm) 1 2 3 4 5 [6] U HD I E M HN L 0 100 200 300 400 200 400 600 800 1000 1200 Reduced Modulus (GPa) Displacement Into Surface (nm) IM H N 0 2 4 6 8 10 12 14 16 0 200 400 600 800 1000 Hardness (GPa) Displacement Into Surface (nm) 1 2 3 4 5 [6] I M HN INSTRUMENTED INDENTATION Pulse lasers 0 10 20 30 40 200 400 600 800 1000 1200 Load On Sample (mN) Displacement Into Surface (nm) [2] 3 4 U HD I E M HN L Fe annealed, 3 different grains 0 100 200 300 400 200 400 600 800 1000 1200 Reduced Modulus (GPa) Displacement Into Surface (nm) I MH N 0 2 4 6 8 10 12 14 16 200 400 600 800 1000 1200 Hardness (GPa) Displacement Into Surface (nm) [2] 3 4 IM HN
  • 33. 33 1 2 3 12 11 10 -1 0 1 2 3 4 5 6 7 100 200 300 400 Load On Sample (mN) Displacement Into Surface (nm) 1 2 3 4 5 6 7 8 [9] 10 11 12S U HDI EM H N L -2 0 2 4 6 8 10 12 14 16 18 20 100 200 300 400 Hardness (GPa) Displacement Into Surface (nm) 1 2 3 4 5 6 7 8 [9] 10 11 12 IM HN INSTRUMENTED INDENTATION Pulse lasers Softening of the deformed material? Is there local melting/solidification or local heating?
  • 34. 34 SGGrain I Grain II nucleus Grain I Grain II )( 2 )( tr tG 粒 > Modeling ZUROBS MODEL FOR RECRYSTALLIZATION Needs input on local misorientations
  • 35. 35 CONCLUSIONS FUTURE WORK Investigation of the first stage of recrystallization by: o Designing microstructures to promote N o Using rapid heat treatments to allow nucleation but not G o o Characterize the heat treatment in terms of time/temperature profile Characterize the nucleation event in terms of local misorientation, local strain gradient (EBSD) Introduce the data on misorientation into Zurobs model
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