SUS304不锈钢板点焊接头的超声成像及失效分析  

Analyses on Ultrasonic Imaging and Failure of Spot Welded Joints for SUS304 Stainless Steel

作　　者：张龙[1] 曾凯[1] 何晓聪[1] 邢保英[1] 孙鑫宇[1] 

机构地区：[1]昆明理工大学机电工程学院,云南昆明650500

出　　处：《热加工工艺》2016年第13期190-193,196,共5页Hot Working Technology

基　　金：国家自然科学基金资助项目(51565022;51565023)

摘　　要：利用超声波水浸聚焦入射法对1 mm厚的SUS304奥氏体不锈钢板点焊接头进行超声波C扫描成像检测,研究了不同工艺参数下获得接头的焊核直径与内部缺陷;借助于材料试验机及扫描电镜探究了接头力学性能与失效机理。结果表明超声波C扫描能够有效地观测出点焊焊核直径,并能够甄别出焊穿、飞溅等典型焊接缺陷;当焊接电流为8 kA时,接头的平均失效载荷最大（9707.1 N）,而当电流增加至9 kA时,接头的平均失效载荷急剧下降到6799.5 N;焊接电流在4~8 kA时,接头断口处出现大小不等的韧窝,呈现出韧性断裂过程,少数试件的接头出现韧性断裂与φ解理断裂过程;焊接电流为9 k A时,接头主要呈现出韧性断裂与过烧沿晶断口。The quality of spot welds in lmm SUS304 austenitic stainless steel sheet metal was evaluated by using ultrasonic water immersion focusing method. The specifics of nugget diameters and the internal defects were analyzed under different welding process parameters. The mechanical properties and failure mechanism of spot welds were studied by materials test machine and scanning electron microscope. Results show that the C-scan image can observe nugget diameter and effective information from the inner pattern of the spot weld based on ultrasonic C-scan, and splashing, weld penetration and other weld defects can be distinguished, too. When the welding current is 8 kA, the average maximum failure load of spot weld is 9707.1 N. When the welding current is 9 kA, the average failure load of spot weld is decreased to 6799.5 N. When the welding current is changed from 4 lea to 8 kA, there are many different size dimples on the fracture surface, which present ductile fracture process. Some joints appear a failure process of the ductile fracture and quasi cleavage fracture process. When the welding current is 9 kA, The joints appear mainly ductile fracture and the burnt intergranular fracture.

关 键 词：点焊 超声波 C 扫描 焊接缺陷 拉剪试验 断口分析 

分 类 号：TG453.9[金属学及工艺—焊接] TG115.28