铝合金搅拌摩擦焊接头的疲劳性能  

Fatigue properties of friction stir welds for aluminum alloys

作　　者：杨新岐[1] 秦红珊[2] 

机构地区：[1]天津大学材料科学与工程学院天津市现代连接技术重点实验室,天津300072 [2]天津大学理学院,天津300072

出　　处：《中国科技论文在线》2011年第2期109-114,共6页

基　　金：国家自然科学基金资助项目(50775159)

摘　　要：通过疲劳试验对LY12CZ（2A12-T4）、LD10CS（2A14-T6）、5A06-H112、7075-T6和LC4CS搅拌摩擦焊接头的疲劳性能进行了研究,采用光学显微镜和扫描电镜观察焊缝根部组织和疲劳断口形貌,讨论了根部焊接缺陷对疲劳性能的影响。结果表明：5A06-H112搅拌摩擦焊接头疲劳强度（50%存活率）是MIG焊接接头的1.64倍、LY12CZ、7075-T6及LC4CS搅拌摩擦焊接头疲劳强度（50%存活率）与母材比较分别为75%、89.5%和95%。当焊缝根部存在约为0.31~0.46 mm的＂弱连接＂缺陷时,对搅拌摩擦焊接头疲劳性能产生明显影响。搅拌摩擦焊接过程中搅拌工具的搅拌头顶端与支撑底板间隙控制不合适是产生＂弱连接＂缺陷的关键因素。The fatigue properties of friction stir welded （FSW） 5A06-H112, LY12CZ, 7075-T6 and LC4CS aluminum alloys were investigated based on the fatigue S-N curve experiments. The microstructure and fatigue fracture surface of friction stir welds were examined by using optical microscopy and scan electrical microscope （SEM） and the effects of root defects on the fatigue properties of FSW joints were discussed. It was found that the fatigue strength （50% of survival probability） of friction stir welds in 5A06-H112 alloys was 1.65 times that of MIG welded joints, and the fatigue strength （50% of survival probability） of LY12CZ, 7075-T6 and LC4CS alloys were 75%, 89.5% and 95% that of base materials respectively. Weak-bonding defects with sizes of 0.31-0.46 mm existed at the root site had obvious influence on the fatigue properties of friction stir welds. The inappropriate gap controlling between the pin tip and the supported platform surface should be the key factor to produce the weak-bonding defects.

关 键 词：搅拌摩擦焊 铝合金 接头 力学性能 显微组织 

分 类 号：TG453.9[金属学及工艺—焊接]