Effect of isothermal compression and subsequent heat treatment on grain structures evolution of Al-Mg-Si alloy

Abstract

The constitutive relationships of Al-Mg-Si alloy deformed at various strain rates, temperatures and strains were studied. The microstructure evolution was quantitatively characterized and analyzed, including recrystallization fraction, grain sizes, local misorientation, geometrically necessary dislocation and stored strain energy during hot deformation and subsequent heat treatment. The results show that the dislocation density and energy storage are linear with lnZ during hot deformation and subsequent heat treatment, indicating continuous recrystallization occurring in both processes. With higher lnZ, the dislocation density declines more sharply during subsequent heat treatment. When lnZ is less than 28, dislocation density becomes more stable with less reduction during subsequent heat treatment after hot deformation. As these dislocations distribute along low angle grain boundaries, the subgrain has good stability during subsequent heat treatment. The main recrystallization mechanism during hot deformation is continuous dynamic recrystallization, accompanied by geometric dynamic recrystallization at higher lnZ.

Keywords

Al-Mg-Si alloy / Zener-Hollomon parameter / dislocation / recrystallization / grain boundaries

References

[1] BergsmaS C, KassnerM E, LiX, WallM A. Strengthening in the new aluminum alloy AA 6069 [J]. Materials Science and Engineering: A, 1998, 254(1): 112-118

[2] ChamanfarA, AlamoudiM T, NanningaN E, MisiolekW Z. Analysis of flow stress and microstructure during hot compression of 6099 aluminum alloy (AA6099) [J]. Materials Science and Engineering A, 2019, 743: 684-696

[3] PolettiC, Rodriguez-HortaláM, HauserM, SommitschC. Microstructure development in hot deformed AA6082 [J]. Materials Science and Engineering A, 2011, 528(6): 2423-2430

[4] RollettA D, KocksU F. A review of the stages of work hardening [J]. Solid State Phenomena, 1993, 35: 1-18 36

[5] McqueenH J. Development of dynamic recrystallization theory [J]. Materials Science and Engineering A, 2004, 387–389: 203-208

[6] LinY C, ChenX M. A critical review of experimental results and constitutive descriptions for metals and alloys in hot working [J]. Materials & Design, 2011, 32(4): 1733-1759

[7] ShiL, YangH, GuoL G, ZhangJ. Constitutive modeling of deformation in high temperature of a forging 6005A aluminum alloy [J]. Materials & Design, 2014, 54: 576-581

[8] KeB, YeL, TangJ, ZhangY, LiuS, LinH, DongY, LiuX. Hot deformation behavior and 3D processing maps of AA7020 aluminum alloy [J]. Journal of Alloys and Compounds, 2020, 845: 156113

[9] HuR, OguraT, TezukaH, SatoT, LiuQ. Dispersoid formation and recrystallization behavior in an Al-Mg-Si-Mn Alloy [J]. Journal of Materials Science & Technology, 2010, 26(3): 237-243

[10] RAKHMONOV J, LIU K, ROMETSCH P, PARSON N, CHEN X G. Effects of Al(MnFe)Si dispersoids with different sizes and number densities on microstructure and ambient/elevated-temperature mechanical properties of extruded Al — Mg — Si AA6082 alloys with varying Mn content [J]. Journal of Alloys and Compounds, 2020: 157937. DOI: https://doi.org/10.1016/j.jallcom.2020.157937.

[11] QianX, ParsonN, ChenX G. Effects of Mn content on recrystallization resistance of AA6082 aluminum alloys during post-deformation annealing [J]. Journal of Materials Science & Technology, 2020, 52189-197

[12] Mröwka-NowotnikG, SieniawskiJ. Influence of heat treatment on the microstructure and mechanical properties of 6005 and 6082 aluminium alloys [J]. Journal of Materials Processing Technology, 2005, 162–163: 367-372

[13] MukhopadhyayP. Alloy designation, processing, and use of AA6XXX series aluminium Alloys [J]. ISRN Metallurgy, 2012, 2012: 1-15

[14] ZenerC, HollomonJ H. Effect of strain rate upon plastic flow of steel [J]. Journal of Applied Physics, 1944, 15(1): 22-32

[15] HuangY, HumphreysF J. Transient dynamic recrystallizationin an aluminium alloy subjected to large reductions in strain rate [J]. Acta Metallurgica, 1997, 45(11): 4491-4503

[16] JiangW G, WangG C, LuS Q, LiJ W. Prediction of microstructure evolution of A1-1% Mg alloy during hot forming and sequential heat treatment [J]. Journal of Materials Processing Technology, 2006, 182(1–3): 274-280

[17] PariL D, MisiolekW Z. Theoretical predictions and experimental verification of surface grain structure evolution for AA6061 during hot rolling [J]. Acta Materialia, 2008, 56(20): 6174-6185

[18] SellarsC M, MctegartW J. On the mechanism of hot deformation [J]. Acta Metallurgica, 1966, 14(9): 1136-1138

[19] ZhaoJ H, DengY L, TangJ G, ZhangJ. Influence of strain rate on hot deformation behavior and recrystallization behavior under isothermal compression of Al-Zn-Mg-Cu alloy [J]. Journal of Alloys and Compounds, 2019, 809: 151788

[20] ZerilliF J, ArmstrongR W. Dislocation-mechanics-based constitutive relations for material dynamics calculations [J]. Journal of Applied Physics, 1987, 61(5): 1816-1825

[21] JazaeriH, HumphreysF J. The transition from discontinuous to continuous recrystallization in some aluminium alloys II — Annealing behaviour [J]. Acta Materialia, 2004, 52(11): 3251-3262

[22] HumphreysF J. A unified theory of recovery, recrystallization and grain growth, based on the stability and growth of cellular microstructures—I. The basic model [J]. Acta Materialia, 1997, 45(10): 4231-4240

[23] GholiniaA, HumphreysF J, PrangnellP B. Production of ultra-fine grain microstructures in Al — Mg alloys by coventional rolling [J]. Acta Materialia, 2002, 50(18): 4461-4476

[24] TakayamaY, SzpunarJ A. Stored energy and taylor factor relation in an Al-Mg-Mn alloy sheet worked by continuous cyclic bending [J]. Materials Transactions, 2004, 45(7): 2316-2325

[25] SCHWARTZ A J, KUMAR M, ADAMS B L. Electron backscatter diffraction in materials science [M]. Springer, 2010.

[26] LiuQ, JuulJ D, HansenN. Effect of grain orientation on deformation structure in cold-rolled polycrystalline aluminium [J]. Acta Materialia, 1998, 46(16): 5819-5838

[27] HuY, LiuH, FujiiH. Improving the mechanical properties of 2219-T6 aluminum alloy joints by ultrasonic vibrations during friction stir welding [J]. Journal of Materials Processing Technology, 2019, 27175-84

[28] KonijnenbergP J, ZaeffererS, RaabeD. Assessment of geometrically necessary dislocation levels derived by 3D EBSD [J]. Acta Materialia, 2015, 99: 402-414

[29] DohertyR D, HughesD A, HumphreysF J, JonasJ J, JensenD J, KassnerM E, KingW E, McnelleyT R, McqueenH J, RollettA D. Current issues in recrystallization: A review [J]. Materials Science and Engineering A, 1997, 238(2): 219-274