摘要
在焊后热处理过程中,搅拌摩擦焊接头焊核区细小的再结晶晶粒在高温下极不稳定,很容易发生晶粒异常长大降低接头性能。研究2024铝合金和7075-2024异质铝合金搅拌摩擦焊接头组织热稳定性,结果发现:增大搅拌头转速、降低焊速有利于提高接头组织热稳定性,接头焊核区晶粒尺寸差异越小,第二相粒子尺寸越小,密度越大,接头组织热稳定性越好;降低固溶温度或缩短固溶时间可以降低晶粒异常长大程度,但接头力学性能将发生下降。对于3 mm厚2024铝合金搅拌摩擦焊接头,在ω=2 500 r/min,v=20 mm/min的焊接参数下,495℃-30 min固溶处理后接头无明显晶粒异常长大现象。对于1.5 mm厚7075-2024异质铝合金搅拌摩擦焊接头,在ω=2 500 r/min,v=50 mm/min的焊接参数下,450℃-20 min固溶处理后接头晶粒异常长大基本得到控制,接头强度达到母材的90%。研究结果表明优化焊接工艺参数和焊后热处理工艺参数能获得较好的晶粒异常长大抑制效果,为铝合金搅拌摩擦焊接头组织性能调控提供参考。
In the post-weld heat treatment process,the fine recrystallized grains in the weld nugget area of the friction stir welded joints are extremely unstable at high temperatures,and abnormal grain growth is prone to reduce joint performance.Research on the microstructural thermal stability of 2024 aluminum alloy and 7075-2024 aluminum alloy friction stir welded joints,the results found that:increasing the rotational rate and reducing the welding speed are beneficial to improve the microstructural thermal stability of the joint,and the smaller the difference in grain size in the weld nugget,the smaller the particle size of the second phase,the greater the density,and the better the thermal stability of the joint structure;lowering the solution temperature or shortening the solution time can reduce the abnormal grain growth,but the mechanical properties of the joint are decreased.For the 3 mm thick 2024 aluminum alloy friction stir welded joint,with the welding parameters of ω=2 500 r/min,v=20 mm/min,there is no obvious abnormal grain growth of the joint after solution treatment at 495 ℃-30 min.For the 1.5 mm thick 7075-2024 aluminum alloy friction stir welded joint,with the welding parameters of ω=2 500 r/min,v=50 mm/min,the abnormal grain growth of joint after the solution treatment at 450 ℃-20min is basically controlled.The joint strength reaches 90% of the base material.The research results obtain a good effect of inhibiting abnormal grain growth,which provides a reference for the control of the structure and performance of aluminum alloy friction stir welded joints.
作者
张嘉恒
胡志力
ZHANG Jiaheng;HU Zhili(Hubei Key Laboratory of Advanced Technology for Automotive Components,Wuhan University of Technology,Wuhan 430070;Hubei Collaborative Innovation Center for Automotive Components Technology,Wuhan University of Technology,Wuhan 430070;Hubei Engineering Research Center for Green&Precision Material Forming,Wuhan University of Technology,Wuhan 430070)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2022年第6期73-80,共8页
Journal of Mechanical Engineering
基金
国家自然科学基金(51775397)
中国汽车产业创新发展联合基金(U1564202)
湖北省技术创新专项重大(2019AAA007)资助项目。
关键词
铝合金
搅拌摩擦焊
组织热稳定性
晶粒异常长大
aluminum alloy
friction stir welding
microstructural thermal stability
abnormal grain growth
