An ultrasonic non-destructive testing method for evaluating resistance spot welding quality

The resistance spot welding is a major method for joining sheet metals in high-speed train manufacturing industry. The accuracy and rapidity of evaluating the resistance spot welding quality is the key point of ensuring the manufacturing quality and running safety of the high-speed train. In this paper, a Nondestructive Testing (NDT) system is set up based on ultrasound pulse-echo method for detecting manufacturing defects and measuring the indentation depth and nugget diameter of resistance spot welding. In order to verify the accuracy of indentation depth and nugget diameter measured by the NDT system, the inspection results are compared with metallographic analysis. In addition, the resistance spot welding indentation depth of some resistance spot welding samples are analyzed before and after increasing the welding energy, the results show that increasing the welding energy can improve the welding quality