轴肩形貌对超薄铝合金μFSW接头力学性能及热力过程影响  

Effect of shaft shoulder morphology on mechanical properties and thermal processes for ultra-thin aluminum alloyμFSW joint

作　　者：刘晓 吕钊钊 董晟全[1] 刘博洋 周旭阳 LIU Xiao;LYU Zhaozhao;DONG Shengquan;LIU Boyang;ZHOU Xuyang(School of Materials Science and Chemical Engineering,Xi’an Technological University,Xi’an 710021,China;School of Defence Science and Technology,Xi’an Technological University,Xi’an 710021,China;Shaanxi Fast Auto Drive Group Co.,Ltd.,Xi’an 710119,China)

机构地区：[1]西安工业大学材料与化工学院,西安710021 [2]西安工业大学兵器科学与技术学院,西安710021 [3]陕西法士特汽车传动集团有限责任公司,西安710119

出　　处：《材料工程》2024年第11期141-149,共9页Journal of Materials Engineering

基　　金：陕西省自然科学基础研究计划(2023-JC-QN-0612)。

摘　　要：采用微连接搅拌摩擦焊技术焊接厚度为0.5 mm的6061-T6超薄铝合金,研究了3种不同轴肩形貌的搅拌头对6061-T6薄壁结构对接接头成形品质、微观组织、力学性能、焊接热循环及力的过程的影响差异,并逐一分析3种焊缝横截面塑性金属的流动特性。结果表明:焊缝表面成形效果受焊接热输入量的影响显著。3种轴肩形貌各异的搅拌头所形成接头横截面硬度分布趋势基本呈“W”形。无针的三渐开线导流槽轴肩焊接接头焊核区中心处最高硬度值及热机影响区最低硬度值均为三者中最高。三渐开线导流槽带针轴肩所形成接头力学性能表现突出,其拉伸强度、屈服强度和断后伸长率均高于其余两者,拉伸断口主要呈韧性断裂。热循环及力的过程参数能够精准反映焊接状态的变化趋势。维持焊缝金属软化所需热量来源于轴肩与工件的摩擦生热以及工件受轴肩轴向力和前进力所做之功。轴向力、前进力会随金属软化程度不同而波动,这种波动对塑性金属的迁移实现动态调节。轴肩表面对焊缝上部作用较强,驱动了前进侧与后退侧塑性金属迁移;搅拌头针部促进了塑性金属与垫板的作用,为焊缝金属上下部分流动提供了驱动力。实现最佳产热潜能是搅拌针与渐开线沟槽的综合结果,二者协同更易形成成形良好的焊缝。The 6061-T6 ultra-thin aluminum alloy with a thickness of 0.5 mm was welded using micro-joint friction stir welding technology.The effects of three kinds of stirring heads with different shaft shoulder morphology on the forming quality,microstructure,mechanical properties,welding thermal cycle,and force process of the 6061-T6 thin-wall butt joint were studied.The flow behavior characteristics of the plastic metal in the three welding cross-sections were analyzed in sequence.The results show that the forming effect of the weld surface is significantly affected by welding heat input.The hardness distribution trend of the joint cross-section formed by three kinds of stirring heads with different shaft shoulder morphology is a“W”shape.The highest hardness values in the center of the nucleation zone and the lowest hardness values in the thermo-mechanical affected zone of the needle-free three-involute diversion groove shaft shoulder welded joint are the highest among the three shaft shoulder welded joints.The mechanical properties of the joint formed by the three-involute guide groove with the needle shaft shoulder are outstanding,and the tensile strength,yield strength,and elongation after fracture are higher than those of the other two.The three tensile fracture forms are mainly ductile fractures.The process parameters of the thermal cycle and force can accurately reflect the changing trend of the welding state.The energy required to maintain the weld metal softening is from the heat generated by friction between the shaft shoulder and the workpiece and the work done by the axial and forward forces of the shaft shoulder.The axial force and forward force changed with the softening degree of the welded metal,playing a dynamic regulating role in the migration of plastic metal in the weld.The shoulder surface has a strong effect on the upper part of the weld,driving the plastic metal migration between the forward side and the backward side.The needle of the stirring head promotes the interaction between the plastic

关 键 词：轴肩形貌 微搅拌摩擦焊 超薄铝合金 工艺性能 过程分析 

分 类 号：TG453.9[金属学及工艺—焊接] TB31[一般工业技术—材料科学与工程]