6061铝合金搅拌摩擦焊曲线接头的组织与性能  

Microstructure and properties of 6061 aluminum alloy friction stir welding curved joints

作　　者：曲来鹏 马宁[1] 肖笑[1] 张柯柯[1,2] QU Lai-peng;MA Ning;XIAO Xiao;ZHANG Ke-ke(School of Materials Science and Engineering,Henan University of Science and Technology,Luoyang 471023,China;Collaborative Innovation Center for New Materials and Advanced Processing Technology of Non-ferrous Metals,Luoyang 471023,China)

机构地区：[1]河南科技大学材料科学与工程学院,河南洛阳471023 [2]有色金属新材料与先进加工技术省部共建协同创新中心,河南洛阳471023

出　　处：《材料热处理学报》2023年第12期176-184,共9页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(U1604132);中原基础研究领军人才(ZYYCYU202012130);河南省科学院科研开发专项(220910009)。

摘　　要：采用光学显微镜(OM)、扫描电镜(SEM)、电子背散射衍射(EBSD)技术及显微硬度仪等研究了6061-T6铝合金搅拌摩擦焊曲线搭接接头的显微组织和性能,重点研究了半径R对接头成形和力学性能的影响。结果表明:对于小半径(R<7 mm)的6061-T6铝合金搭接搅拌摩擦焊,会出现严重的焊接材料堆积。当半径R超过7 mm时,可以形成良好的宏观接头。接头拐角处的不同区域均由α-Al和金属间析出相β组成。热影响区(HAZ)的显微组织相对粗糙,焊核区(WNZ)颗粒最细,溶解了部分的β相。在拐角的中央WNZ处,晶粒尺寸比两端大,拐角内侧晶粒尺寸较外侧更大。接头的硬度分布呈现出“W”形,内侧HAZ区域的硬度最低。当R≤7 mm时,随着R的增加,接头的抗剪强度增加,R>7 mm时,接头抗剪强度的变化变得相对较小。在R=7 mm时,接头的抗剪强度最大,为(101.32±6.89)MPa,断裂机制主要是韧性断裂主导的混合断裂。Microstructure and properties of 6061-T6 aluminum alloy friction stir welded curve overlap joints were studied by means of optical microscope(OM),scanning electron microscopy(SEM),electron backscatter diffraction(EBSD)technique and microhardness tester,with a focus on the influence of radius R on the formation and mechanical properties of the joints.The results show that for the 6061-T6 aluminum alloy overlap friction stir welding with small radii(R<7 mm),serious welding material accumulation will occur.When the radius R exceeds 7 mm,well-formed macroscopic joints can be achieved.The different areas at the corners of the joints are composed ofα-Al and intermetallic precipitatesβ.The microstructure of the heat affected zone(HAZ)is relatively rough,while the particles in the weld nugget zone(WNZ)are the finest and contain dissolvedβphase.At the center WNZ of the corner,the grain size is larger than the two ends,and the grain size on the inner side of the corner is larger than on the outer side.The hardness distribution of the joints presents a“W”shape,with the hardness in the inner HAZ area being the lowest.When R≤7 mm,the shear strength of the joints increases with the increase of R.When R>7 mm,the change in shear strength of the joints becomes relatively small.When R=7 mm,the maximum shear strength of the joint is(101.32±6.89)MPa,and the fracture mechanism is mainly a mixed fracture dominated by ductile fracture.

关 键 词：铝合金 曲线 搅拌摩擦焊 微观结构 力学性能 

分 类 号：TG453[金属学及工艺—焊接]