基于超声波C扫描的SUS304不锈钢板点焊接头质量分析

Analyses on Joint Quality of Spot Welds on SUS304 Stainless Steel Based on Ultrasonic C-Scan

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C扫描成像检测;研究了不同焊接工艺参数下获得点焊接头的超声波C扫描图像特征,据此分析了接头的焊核直径,并与焊核切口端面尺寸进行了比较;对点焊接头进行了拉伸—剪切试验,测试了接头的力学性能。结果表明:超声波水浸聚焦入射法能够观测出点焊焊核直径,并能有效地观测出焊核内部形貌特征。当焊接电流为定值(4k A),供给压力为0.15 MPa时,接头出现飞溅、焊穿等缺陷,并且在超声波C扫描图像中能够清晰地反映出来;当供给压力为0.45 MPa时,虽然点焊焊核直径增大,且未出现焊接缺陷,但是过大的供给压力导致接头厚度变小,影响了接头抗拉强度。当供给压力为定值(0.4 MPa),焊接电流为9 k A时,在C扫描图像上同样反映出飞溅、焊穿等典型的焊接缺陷,此时接头的失效载荷及能量吸收值急剧下降。

The quality of spot welds in 1mm SUS304 austenitic stainless steel sheet metal was evaluated by using ultrasonic water immersion focusing method. The specifics of nugget diameters and the ultrasonic C-scan image were analyzed under different welding process parameters. Furthermore,the tensile-shear tests were carried out to examine the mechanical behavior of sport welds. Results show that the C-scan image can get nugget diameter and effective information from the inner pattern of the spot weld based on ultrasonic water immersion focusing method. When the welding current is 4 k A and the supply pressure is 0. 15 MPa,it can get the information which included splash,solder to wear and other weld defects from the ultrasonic C-scan image. When the supply pressure is 0. 45 MPa,the nugget diameter is increasing. But the excessive supply pressure leads to the joint thickness decreasing and the joint quality is failing. When the supply pressure is 0. 4 MPa and the welding current is 9 k A,the failure strength and energy absorption value decrease rapidly,it can get the information which includes splash,solder to wear and other weld defects from the ultrasonic C-scan image.