淬火转移时间对A357 铝合金力学性能与微观组织的影响

樊振中; 郑卫东; 张显峰; 李红; 王少华

doi:10.3981/j.issn.1000-7857.2014.32.003

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科技导报 ›› 2014, Vol. 32 ›› Issue (32) : 22-27. DOI: 10.3981/j.issn.1000-7857.2014.32.003

研究论文

淬火转移时间对A357 铝合金力学性能与微观组织的影响

作者信息 -

1. 中国航空工业集团公司北京航空材料研究院, 北京 100095;
2. 北京理工大学材料学院, 北京 100081

作者简介:

樊振中,博士研究生,研究方向为薄壁复杂整体铝合金铸件凝固成形控制与新型合金开发,电子信箱:fanzhenzhong2010@163.com

Influence of Quenching Transfer Time on the Mechanical Properties and Microstructure of A357 Aluminum Alloys

Author information -

1. Beijing Institute of Aeronautical Materials, China Aviation Industry Corporation, Beijing 100095, China;
2. Schol of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China

摘要

采用OM、DSC、SEM 与TEM,结合力学性能测试研究淬火转移时间对A357 铝合金力学性能与微观组织的影响。结果表明:随着淬火转移时间由3 s 延长至49 s,A357 铝合金经T6 热处理后的抗拉强度、屈服强度与延伸率分别由351 MPa、275MPa 与12.4%降低至320 MPa、254 MPa 与6.5%,合金材料的抗拉强度连续下降,屈服强度变化较小,延伸率呈现出先上升后下降的变化趋势。初生与共晶Si 相逐渐由细长的针状或片层状转变为椭圆球状或棒状,平均长度为10~25 μm,平均宽度为5~10 μm,当淬火转移时间超过35 s 后,初生与共晶Si 相则仍以细长的针状或片层状形貌为主。拉伸断口形貌以韧窝断裂为主,附带部分沿晶断裂,随着淬火转移时间的增加,断口表面韧窝数量随之减少,沿晶断裂裂纹数量不断增加;Mg 与Si 元素集中分布于晶粒边界处的二元与三元共晶组织中,Al 元素广泛分布于晶粒内部及晶粒边界处;人工时效过程析出的Mg₂Si 强化相长度约为0.2~1 μm,宽度为0.02~0.08 μm,且随着淬火转移时间的延长,Mg₂Si 强化相的析出数大量减少,长径比不断下降,合金材料的强度与塑性随之降低。

Abstract

In the present work, the effects of quenching transfer time on the mechanical properties and microstructure of A357 aluminum alloys are investigated by using optical microscopy (OM), scanning electron microscope (SEM), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), as well as tensile mechanical properties testing methods. The results show that with the increase of quenching transfer time from 3 s to 49 s, the tensile strength, yield strength and elongation of A357 aluminum alloys are reduced from 351 MPa, 275 MPa, and 12.4% to 320 MPa, 254 MPa, and 6.5% , respectively after T6 heat treatment, together with a continuous declining of tensile strength, tiny variation of yield strength and a continuous variation of elongation. The average length and width size of silicon particles are 10~25 μm and 5~10 μm, respectively, and the morphologies of neonatal and eutectic silicon particles evolve from needle and lamellar structures to spheroidal and rod structures after the T6 heat treatment process. Silicon particles are shown as needle and lamellar mostly when the quenching transfer time exceeds 35 s. The tensile fracture morphology is observed as dimple and intergranular fracture, and the intergranular fracture is increased with the prolonged quenching transfer time. Magnesium and silicon elements are distributed nearby the grain boundaries and the binary and ternary eutectic structures, whereas the aluminium elements are concentrated in the grain and grain boundaries. The length and width size of Mg₂Si phase are 0.2~1 μm and 0.02~0.08 μm, respectively, the precipitation amount and size ratio of Mg₂Si phase are declined, together with the decreases of strength and ductility of A357 aluminum alloy with the prolonged quenching transfer time.

导出引用

樊振中, 郑卫东, 张显峰, 李红, 王少华. 淬火转移时间对A357 铝合金力学性能与微观组织的影响[J]. 科技导报, 2014, 32(32): 22-27 https://doi.org/10.3981/j.issn.1000-7857.2014.32.003

FAN Zhenzhong, ZHENG Weidong, ZHANG Xianfeng, LI Hong, WANG Shaohua. Influence of Quenching Transfer Time on the Mechanical Properties and Microstructure of A357 Aluminum Alloys[J]. Science & Technology Review, 2014, 32(32): 22-27 https://doi.org/10.3981/j.issn.1000-7857.2014.32.003

中图分类号： TG166.3

参考文献

[1] Gall K, Horstemeyer M. Finite element analysis of the stress distributions near damaged Si particle clusters in cast Al-Si alloys[J]. Mechanics of Materials, 2000, 32(4): 277-301.
[2] Fisher J C, Hollomon J H. Precipitation from solid solution[J]. Industrial and Engineering Chemistry, 2002, 44(6): 1324-1327.
[3] Wang Q G, Davidson C J. Solidification and precipitation behavior of Al-Si-Mg casting alloys[J]. Journal of Material Science, 2001, 36(8): 739-750.
[4] Dorward R C. A dynamic quench model for strength predictions in heattreatable aluminum alloys[J]. Journal of Materials Processing Technology, 1997, 66(4): 25-29.
[5] 熊艳才, 刘伯操. 铸造铝合金现状及未来发展[J]. 特种铸造及有色合金, 1998, 4(1): 1-5. Xiong Yancai, Liu Bocao. Review and prospect of cast aluminum alloy[J]. Special Casting and Nonferrous Alloy, 1998, 4(1): 1-5.
[6] 陈振中, 解传浩, 朱成香. A357铸造铝合金疲劳特性及热处理的影响[J]. 轻金属, 2010(7): 58-61. Chen Zhenzhong, Xie Chuanhao, Zhu Chengxiang. The effects of heat treatment on fatigue properties of A357 casting aluminium alloy[J]. Light Metals, 2010(7): 58-61.
[7] Embury J D, Sargent C M. The effect of quench deformation on the defect structure of quenched metals and alloys[J]. Acta Metallurgica, 1962, 10 (2): 1118-1121.
[8] Myung G K, Sang G K. Thermally induced stress analysis of composite/ aluminum ring specimens at cryogenic temperature[J]. Composities Science and Technology, 2008, 68(4): 1080-1087.
[9] Anjabin N, Karimi A. Physically based material model for evolution of stress-strain behavior of heat treatable aluminum alloys during solution heat treatment[J]. Materials and Design, 2010, 31(1): 433-437.
[10] Francis J A, Delphine C G M. The role of defects in the fracture of an Al-Si-Mg cast alloy[J]. Materials Science and Engineering A, 2005, 407(1-2): 322-329.
[11] Li X L,Hao Q T, Jie W Q. Development of pressure control system in counter gravity casting for large thin- walled A357 aluminum alloy components[J]. Transactions of Nonferrous Metals Society of China, 2008, 18(4): 847-851.
[12] Tan L J, Zabaras N. A thermo-mechanical study of the effects of mold topography on the solidification of aluminum alloys[J]. Materials Science and Engineering A, 2005, 404(1-2): 197-207.
[13] Eskin D G. Recent trends in the science and technology of crystallization of aluminum alloys[J]. Metal Science and Heat Treatment, 2012, 53(9- 10): 408-413.
[14] Wyatt J E, Berry J T, Williams A R. Residual stresses in aluminum castings[J]. Journal of Materials Processing Technology, 2007, 191(1- 3): 170-173.
[15] Carrera E, Rodriguez A, Talamantes J, et al. Measurement of residual stresses in cast aluminium engine blocks[J]. Journal of Materials Processing Technology, 2007, 189(1-3): 206-210.
[16] Jiang L T, Wu G H, Yang W S, et al. Effect of heat treatment on microstructure and dimensional stability of ZL114A aluminum alloy[J]. Transactions of Nonferrous Metals Society of China, 2010, 20(11): 2124-2128.