高频感应加热处理对2219铝合金FS W焊接接头残余应力的影响

Effect of high frequency induction heating on residual stress of 2219 alloy FSW welded joints

采用搅拌摩擦焊接工艺焊接8mm厚2219铝合金板材,自行研制设计了高频感应加热装置,对2219铝合金搅拌摩擦焊接接头进行了应力表征与高频感应加热去应力研究,试验温度分别为90℃、140℃、190℃,利用X射线衍射法测试了焊缝热处理前、后纵向和横向残余应力,分析了搅拌摩擦焊接头微观组织和力学性能。结果表明,经高频感应加热处理后,焊接纵向残余应力峰值显著降低,经190℃感应加热处理后纵向残余应力峰值下降51.3%,残余拉应力区间变窄,随着高频感应加热温度的降低,去应力效果减弱。热处理前、后焊接接头微观组织和力学性能变化不明显,显微硬度分布趋势相同,说明高频感应加热技术在有效降低焊接残余应力的同时不改变焊接接头的力学性能。

8 mm thick 2219 aluminum alloy plates are welded by friction stir welding technology. The stress characterization and stressrelieving of 2219 aluminum alloy friction stir welded joint is studied by using a self-developed high frequency induction heating device, the test temperature is set as 90 ℃,140 ℃ and 190 ℃ respectively. Through measuring the longitudinal and transverse residual stress of weld before and after heat treatment by using X ray diffraction method,the microstructure and mechanical properties of welded joints are analyzed. The results show that peak value of longitudinal residual stress reduces significantly after high frequency induction heat treatment,which declines by 51.3% at the temperature of 190 ℃ HT,and the range of residual tensile stress narrows. As temperature of high frequency induction heating drops,the effect of stress-relieving decreases. Microstructure,microhardness and mechanical properties of welded joints do not change obviously before and after heat treatment. The high frequency induction heating technology can reduce the welding residual stress effectively,at the same time does not change the mechanical properties of welded joint.