Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第25卷    第9期    总第198期    2015年9月

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文章编号:1004-0609(2015)-09-2342-08
焊后热处理对Al-Mg-Si-Cu合金激光焊接接头微观结构和力学性能的影响
朱东晖1,陈江华1,刘春辉1,孟立春2,郑 雄1,赖玉香1,陶冠辉1, 顾 媛1

(1. 湖南大学材料科学与工程学院,长沙 410082;2. 南车青岛四方机车车辆股份有限公司,青岛 266111)

摘 要: 采用电子显微学方法和力学性能测试,探究180℃下焊后时效处理工艺对Al-Mg-Si-Cu合金激光焊接接头微观结构和力学性能的影响。结果表明:经过焊后热处理的焊件焊接接头的力学性能得到一定程度的提升,但焊缝处由于在焊接过程中形成大量的第二相颗粒,消耗了大量的溶质原子,因此,焊接接头硬度最低。对于焊前处理为欠时效的焊件,热影响区硬度经过焊后热处理后完全恢复母材硬度水平;而对于焊前处理为峰值时效和过时效的焊件,热影响区硬度不能完全恢复,会出现一个硬度谷,即软化区。通过对软化区进行透射电镜表征后发现,该区域内析出相出现明显的粗化。

 

关键字: Al-Mg-Si-Cu合金;析出相;焊后热处理;微观结构;力学性能;热影响区;软化区

Effects of post-weld heat treatment on microstructure andmechanical properties of laser-beam welded Al-Mg-Si-Cu alloy
ZHU Dong-hui1, CHEN Jiang-hua1, LIU Chun-hui1, MENG Li-chun2, ZHENG Xiong1, LAI Yu-xiang1, TAO Guan-hui1, GU Yuan1

1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. CSR Qingdao Sifang Locomotive and Rolling Stock Co., Ltd., Qingdao 266111, China

Abstract:The effect of post-weld artificial aging at 180℃ on the microstructure and mechanical properties of laser-beam welded Al-Mg-Si-Cu alloy was investigated. The results show that the mechanical properties of the joint after post-weld heat treatment can be enhanced to some extent compared to the as-welded joint, while the hardness of the weld seam is still the lowest region because the formation of massive second particles during the welding process consumes many solute atoms needed to form strengthening precipitates. The hardness of heat-affected zone in the joint under-aged before welding can be fully recovered to that of base metal after post-weld heat treatment. While the hardness of heat-affected zones in the joint peak-aged and over-aged before welding can not be fully recovered after post-weld heat treatment, in these heat-affected zones, the hardness grooves, typical of softening zones, occur in the hardness profiles. The precipitates in the softening zone coarsen apparently as revealed by transmission electron microscopy (TEM).

 

Key words: Al-Mg-Si-Cu alloy; precipitate; post-weld heat treatment; microstructure; mechanical property; heat affected zone; softening zone

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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