5A06铝合金焊接接头在超长寿命区间的疲劳性能  

Super-long life fatigue property of 5A06 aluminum alloy welded joint

作　　者：李想[1] 邓彩艳[1] 龚宝明[1] 王东坡[1] 

机构地区：[1]天津大学材料科学与工程学院,天津300072

出　　处：《焊接学报》2016年第2期59-62,131-132,共4页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(51375331)

摘　　要：采用自行研制的TJU-HJ-I型超声疲劳试验系统对5A06铝合金TIG焊焊接接头在超长寿命区间的疲劳性能进行研究.疲劳试验结果表明,圆柱状母材试件、圆柱状焊接接头试件和薄板状焊接接头试件,在经历107循环周次后,S-N曲线仍呈下降趋势,没有发现明显转折,传统意义上的疲劳极限并不存在.焊接接头试件在107周次和109周次下的疲劳强度仅为母材的50%~70%.通过扫描电子显微镜进行断口形貌观察发现：母材疲劳扩展区断口较焊接接头断口平整,瞬断区呈韧窝状,而无余高焊接接头试件存在气孔、夹杂等焊接缺陷,导致疲劳性能明显降低.The super-long life fatigue properties of 5A06 aluminum alloy TIG welded joint were investigated with a selfmade TJU-HJ-I ultrasonic fatigue test device. The results show that the S-N curve descended continuously for the cylindricalshape base material specimens,cylindrical-shape welded joint specimens and thin plate welded joint specimens after 107 cycles. No obvious turning was found in the S-N curve. The fatigue strength of welded joint in 107 and 107cycles was just 50%-70%of that of base material. The ultrasonic fatigue fracture morphology of specimens,observed with scanning electron microscope,reveals that the fracture surface in fatigue crack propagation area of base material was flatter than that of welded joint. Dimples existed in the transient rupture zone. However,welding defects like pores and inclusions were found in the welded joint without reinforcement,which significantly degraded the fatigue properties of the welded joint.

关 键 词：超长寿命区间 焊接接头 超声疲劳试验 疲劳曲线 

分 类 号：TG405[金属学及工艺—焊接]