AZ31镁合金双面对称搅拌摩擦焊接头疲劳性能  

Fatigue properties of AZ31 magnesium alloy welded joint by double-sided friction stir welding

作　　者：闫志峰[1] 王卓然 王树邦 张红霞[1] 贺秀丽 董鹏[1] YAN Zhifeng;WANG Zhuoran;WANG Shubang;ZHANG Hongxia;HE Xiuli;DONG Peng(Taiyuan University of Technology,Taiyuan,030024,China;Department of Mechanical Engineering,Taiyuan Institute of Technology,Taiyuan,030008,China)

机构地区：[1]太原理工大学,太原030024 [2]太原工业学院,太原030008

出　　处：《焊接学报》2022年第6期61-68,I0006,I0007,共10页Transactions of The China Welding Institution

基　　金：山西省应用基础研究计划项目(201801D221137,201601D202028)。

摘　　要：针对搅拌摩擦单面焊两侧热输入不均匀性导致疲劳强度低的问题,采用双面对称搅拌摩擦焊方法对10 mm厚的AZ31镁合金板材进行焊接,并研究其疲劳性能.结果表明,双面对称搅拌摩擦焊接头的屈服强度为130 MPa,与单面焊的屈服强度123 MPa相比提高了5%;其疲劳极限为88 MPa,比单面焊接头的50 MPa提高了76%;双面对称接头疲劳裂纹萌生在上/下侧的前进侧位置,并跨越上/下侧焊缝交界面,最终在下/上侧焊缝的后退侧RS区域瞬断,其疲劳断口均为以解理特征为主的脆性断裂.双面对称焊接头其中一面应变范围与单面搅拌摩擦焊的应变较高的后退侧接近.通过双面搅拌摩擦焊接的镁合金接头疲劳强度得到了大幅度提升,疲劳寿命得到了延长.In order to solve the problem of the low fatigue strength of single-sided welding(SSFSW) caused by the uneven heat input, double-sided friction stir welding(DSFSW)was used to weld AZ31 magnesium alloy with a thickness of10 mm. The results show that the yield strength of DSFSW joint is 130 MPa, which is 5% higher than that of the SSFSW joint. The fatigue limit of the DSFSW joint is 88 MPa, which is 76% higher than that of the SSFSW joint. The fatigue crack of DSFSW joint starts at the advancing side of the upper/lower side, crossing the interface of the upper/lower weld seam and breaking in the retreating side(RS) of the one weld seam finally. The fatigue fracture surface of DSFSW is brittle fracture mainly composed of cleavage. The strain range of one side of DSFSW joint is close to the RS strain of SSFSW. The fatigue strength and life of magnesium alloy joint welded by DSFSW have been greatly increased.

关 键 词：AZ31B镁合金 双面对称搅拌摩擦焊 疲劳极限 疲劳断裂 疲劳变形 

分 类 号：TG405[金属学及工艺—焊接]