5A06/AZ31异质合金RFSSW接头组织及性能研究  

Study on Microstructure and Mechanical Properties of 5A06/AZ31 Dissimilar Alloy RFSSW Joint

作　　者：宋奎晶[1] 季雨凯 徐萌 韦勇 刘鑫泉 张铭雨 孔德浩 钟志宏[1] SONG Kuijing;JI Yukai;XU Meng;WEI Yong;LIU Xinquan;ZHANG Mingyu;KONG Dehao;ZHONG Zhihong(School of Materials Science and Engineering,Hefei University of Technology,Hefei 230009,China;Aerospace Engineering Equipment(Suzhou)Co.,Ltd.,Suzhou 215200,China)

机构地区：[1]合肥工业大学材料科学与工程学院,安徽合肥230009 [2]航天工程装备(苏州)有限公司,江苏苏州215200

出　　处：《热加工工艺》2024年第17期20-26,共7页Hot Working Technology

基　　金：国家自然科学基金项目(51905143)。

摘　　要：采用不同的焊具搅拌转速和扎入深度开展了5A06铝合金上板/AZ31镁合金下板的回填式搅拌摩擦点焊试验,观察了焊点的宏观形貌,采用显微硬度及拉剪性能测试手段获得了焊点横截面的硬度分布和拉剪承载性能,并对搅拌套下方界面的晶粒、金属间化合物(IMC)层进行了微观表征和成分分布定量分析。结果表明,焊点表面成形均较好,当搅拌速度、扎入深度过大时焊点表面出现较多飞边。当焊具搅拌速度为1900 r/min,扎入深度为1.6 mm时,拉剪强度最大,但也仅为57.65 MPa。在拉剪载荷下,焊点沿着界面水平方向断裂,断口呈现脆性断裂特征。随着焊接热输入增大,界面金属间化合物反应层变厚,反应产物为β-Al3Mg2和γ-Al12Mg17。因脆性相与合金基体之间存在热应力,界面位置出现微裂纹。搅拌套下方焊点界面两侧金属产生塑性变形并逐渐累积,促进动态再结晶形核,形成再结晶晶粒。Refilling friction stir spot welding(RFSSW)experiments of 5A06 aluminum alloy top plate/AZ31 magnesium alloy bottom plate were carried out by using different rotational speed and plunge depth.The macroscopic morphologies of the solder joints were observed,the cross-sectional hardness distribution and tensile shear load capacity of the RFSSW joints were tested by microhardness test and tensile shear test.The grains and IMC layer of the interface beneath the stirring sleeve were characterized and the composition distribution was quantitatively analyzed.The results show that surface forming of the solder joints is good,while the rotational speed and plunge depth are too big,there are lots of overlap on the surface of the solder joints.When the rotational speed is 1900 r/min,the plunge depth is 1.6 mm,the tensile shear strength is the maximum,which is only 57.65 MPa.Under the tensile shear load,it breaks along the horizontal direction of the interface,and the fracture exhibits brittle fracture characteristics.With the increase of welding heat input,the IMC reaction layer at the interface becomes thicker,and the reaction product consists ofβ-Al3Mg2 andγ-Al12Mg17.Due to thermal stress between the brittle phase and alloy matrix,microcracks appear at the interface.The plastic deformation is produced at the metals on both sides of the joint interface below the stirring sleeve produce and gradually accumulates,which promotes dynamic recrystallization cores and the recrystallization grains form.

关 键 词：回填式搅拌摩擦点焊 拉剪强度 脆性断裂 界面反应 

分 类 号：TG453.9[金属学及工艺—焊接]