Effects of multi-axial forging and T852 heat treatment on microstructure and mechanical properties of Al-Cu-Li alloy

doi:10.13251/j.issn.0254-6051.2022.09.014

Abstract

Abstract: Effect of multi-axial forging with different passes and T852 heat treatment on microstructure and mechanical properties of Al-Cu-Li alloy was studied by means of SEM, EBSD, TEM and tensile test. The results show that the grain structure of the Al-Cu-Li alloy is significantly refined after multi-pass multi-axial forging, and the grain size is reduced from 450 μm in as-homogenized state to 5 μm in as-forged state with six passes. The grain refinement mechanism is mainly continuous dynamic recrystallization, accompanied by discontinuous dynamic recrystallization. After T852 heat treatment, the precipitates on grain boundary of the as-forged alloy with six passes present discontinuous distribution, and a large number of lath-shaped T₁ phases and a small amount of θ′ phases are precipitated in the grains. Compared with the coarsened T₁ phase in as-homogenized state, the T₁ phase in as-aged state is obviously refined. After 6 passes forging and T852 heat treatment, the tensile strength, yield strength and elongation of the alloy are 544 MPa, 462 MPa and 8.6%, respectively, which are 2.0, 2.4 and 4.1 times of those in as-homogenized state, and the corresponding fracture mode changes from brittle fracture to ductile fracture.

Key words: Al-Cu-Li alloy, multi-axial forging, heat treatment, microstructure, mechanical properties

CLC Number:

TG146.2

Zhong Liwei, Feng Zhaohui, Gao Wenli, Chen Junzhou, Lu Zheng. Effects of multi-axial forging and T852 heat treatment on microstructure and mechanical properties of Al-Cu-Li alloy[J]. Heat Treatment of Metals, 2022, 47(9): 79-86.

References

[1]Zhong Liwei, Gao Wenli, Feng Zhaohui, et al. Microstructure characteristics and constitutive modeling for elevated temperature flow behavior of Al-Cu-Li X2A66 alloy[J]. Journal of Materials Research, 2018, 33(8): 912-922.
[2]冯朝辉, 钟立伟, 高文理, 等. 时效制度对2050铝锂合金力学性能及断裂行为的影响[J]. 金属热处理, 2019, 44(9): 108-111.
Feng Zhaohui, Zhong Liwei, Gao Wenli, et al. Effect of aging on mechanical properties and fracture behavior of 2050 Al-Li alloy[J]. Heat Treatment of Metals, 2019, 44(9): 108-111.
[3]Zhong Liwei, Gao Wenli, Feng Zhaohui, et al. Hot deformation characterization of as-homogenized Al-Cu-Li X2A66 alloy through processing maps and microstructural evolution[J]. Journal of Materials Science and Technology, 2019, 35(10): 2409-2421.
[4]李天麒, 尹晨, 闫原原, 等. 退火工艺对搅拌摩擦加工镁合金微观组织和显微硬度的影响[J]. 金属热处理, 2020, 45(5): 141-146.
Li Tianqi, Yin Chen, Yan Yuanyuan, et al. Effect of annealing process on microstructure and microhardness of magnesium alloy fabrication by friction stir processing[J]. Heat Treatment of Metals, 2020, 45(5): 141-146.
[5]Martynenko N, Lukyanova E, Serebryany V, et al. Effect of equal channel angular pressing on structure, texture, mechanical and in-service properties of a biodegradable magnesium alloy[J]. Materials Letters, 2019, 238: 218-221.
[6]Toth L S, Gu C F. Ultrafine-grain metals by severe plastic deformation[J]. Materials Characterization, 2014, 92: 1-14.
[7]郭强, 严红革, 陈振华, 等. 多向锻造技术研究进展[J]. 材料导报, 2007, 21(2): 106-108.
Guo Qiang, Yan Hongge, Chen Zhenhua, et al. Research progress in multiple forging process[J]. Materials Review, 2007, 21(2): 106-108.
[8]Xia X S, Chen Q, Zhao Z D, et al. Microstructure, texture and mechanical properties of coarse-grained Mg-Gd-Y-Nd-Zr alloy processed by multidirectional forging[J]. Journal of Alloys and Compounds, 2015, 623: 62-68.
[9]Nie K B, Deng K K, Wang X J, et al. Multidirectional forging of AZ91 magnesium alloy and its effects on microstructures and mechanical properties[J]. Materials Science and Engineering A, 2015, 624: 157-168.
[10]Lu Z D, Zhang C J, Feng H, et al. Effect of heat treatment on microstructure and tensile properties of 2vol.%TiC_p/near-β Ti composite processed by isothermal multidirectional forging[J]. Materials Science and Engineering A, 2019, 761: 138064.
[11]Zhao J H, Deng Y L, Zhang J, et al. Effect of temperature and strain rate on the grain structure during the multidirectional forging of the Al-Zn-Mg-Cu alloy[J]. Materials Science and Engineering A, 2019, 756: 119-128.
[12]Rao P N, Singh D, Jayaganthan R. Mechanical properties and microstructural evolution of Al6061 alloy processed by multidirectional forging at liquid nitrogen temperature[J]. Materials and Design, 2014, 56: 97-104.
[13]Mahjoub R, Laws K J, Stanford N, et al. General trends between solute segregation tendency and grain boundary character in aluminum-An ab into study[J]. Acta Materialia, 2018, 158: 257-268.
[14]Wang Y X, Zhao G Q, Xu X, et al. Constitutive modeling, processing map establishment and microstructure analysis of spray deposited Al-Cu-Li alloy 2195[J]. Journal of Alloys and Compounds, 2019, 779: 735-751.
[15]Yu W C, Li H Y, Du R, et al. Characteristic constitution model and microstructure of an Al-3.5Cu-1.5Li alloy subjected to thermal deformation[J]. Materials Characterization, 2018, 145: 53-64.
[16]Yu Q Y, Yao Z H, Dong J X. Deformation and recrystallization behaviour of a coarse-grain, nickel-base superalloy Udimet720Li ingot material[J]. Materials Characterization, 2015, 107: 398-410.
[17]Sitdikov O, Garipova R, Avtokratova E, et al. Effect of temperature of isothermal multidirectional forging on microstructure development in the Al-Mg alloy with nano-size aluminides of Sc and Zr[J]. Journal of Alloys and Compounds, 2018, 746: 520-531.
[18]Lin Y, Zheng Z Q, Li S C, et al. Microstructures and properties of 2099 Al-Li alloy[J]. Materials Characterization, 2013, 84: 88-99.
[19]Deschamps A, Garcia M, Chevy J, et al. Influence of Mg and Li content on the microstructure evolution of Al-Cu-Li alloys during long-term ageing[J]. Acta Materialia, 2017, 122: 32-46.
[20]Jo H H, Hirano K I. Precipitation processes in Al-Cu-Li alloy studied by DSC[J]. Materials Science Forum, 1987, 13-14: 377-382.
[21]张显峰, 李国爱, 陆政, 等. 淬火后预拉伸对自然时效状态Al-Li合金组织和性能的影响[J]. 金属学报, 2016, 52(12): 1497-1502.
Zhang Xianfeng, Li Guoai, Lu Zheng, et al. Effect of preaged stretch after quenched on the properties and microstructure of a naturally aged Al-Li alloy[J]. Acta Metallurgica Sinica, 2016, 52(12): 1497-1502.
[22]Munoz M M A, Morris D G. Microstructure control during severe plastic deformation of Al-Cu-Li and the influence on strength and ductility[J]. Materials Science and Engineering A, 2011, 528(9): 3445-3454.
[23]Wang Y X, Zhao G Q, Xu X, et al. Microstructures and mechanical properties of spray deposited 2195 Al-Cu-Li alloy through thermo-mechanical processing[J]. Materials Science and Engineering A, 2018, 727: 78-89.
[24]Rao P N, Singh D, Brokmeier H G, et al. Effect of ageing on tensile behavior of ultrafine grained Al6061 alloy[J]. Materials Science and Engineering A, 2015, 641: 391-401.
[25]Seidman D N, Marquis E A, Dunand D C. Precipitation strengthening at ambient and elevated temperatures of heat-treatable Al(Sc) alloys[J]. Acta Materialia, 2002, 50(16): 4021-4035.