基于原位SEM的激光-MIG复合焊接7075-T6铝合金疲劳裂纹扩展行为  

In situ SEM based fatigue crack propagation behavior of hybrid laser welded 7075-T6

作　　者：常丽艳[1] 宋西平[1] 张敏[1] 吴圣川[2] 

机构地区：[1]北京科技大学新金属国家重点实验室,北京100083 [2]西南交通大学牵引动力国家重点实验室,成都610031

出　　处：《焊接学报》2016年第5期85-88,133,共4页Transactions of The China Welding Institution

基　　金：牵引动力国家重点实验室开放基金资助项目(2015TPL_T07;TPL1505);国家自然科学基金资助项目(11572267)

摘　　要：通过扫描电镜原位观察激光复合焊接头各区裂纹的扩展行为.结果表明,焊缝各区组织的不同使得疲劳裂纹扩展行为发生明显改变,疲劳裂纹位于焊缝中心时,裂纹总体沿着垂直于载荷主轴的方向扩展;疲劳裂纹位于热影响区时,裂纹大致成"Z"字型路径进行扩展;疲劳裂纹在焊缝中心和热影响区扩展时都存在二次裂纹;疲劳裂纹在母材区扩展时,呈现出单一和典型的裂纹扩展模式.此外,通过原位SEM观察获得不同循环周期下的裂纹扩展长度,进而推算得到7075-T6铝合金接头各区内疲劳裂纹扩展速率的Paris公式.The fatigue crack propagation behavior of welded 7075-T6 aluminium alloy was investigated by scanning electron microscope in-situ observation in room temperature. These results indicated that differences of fatigue crack propagation behavior among fusion zone,HAZ( heat affected zone) and base metal were attributed to microstructural feature. The crack propagated in fusion zone perpendicular to the stress axis; Zigzag crack propagation path was formed in HAZ; Many secondary cracks were observed at the surface of fusion zone and HAZ.'Single crack'mode was found in base metal. In addition,the Paris law of fusion zone,HAZ and base metal for welded 7075-T6 aluminium alloy was obtained by calculating through the lengths of fatigue crack and cycles.

关 键 词：7075-T6铝合金 焊接接头 疲劳裂纹 原位SEM观察 激光复合焊接 

分 类 号：TG405[金属学及工艺—焊接]