STUDY ON QUALITY AND PERFORMANCE EVALUATION TECHNOLOGY OF SPOT WELDING JOINT BASED ON ULTRASONIC NONDESTRUCTIVE TESTING

As an important link to ensure the welding quality, the post-welding inspection of resistance spot welding joints has been paid much attention in the welding production of stainless steel metro vehicle body. At present, ultrasonic testing technology for spot welding joint quality is mostly qualitative testing, which cannot determine the quality information such as the geometric state of nugget and the size of internal defects. Therefore, the research on ultrasonic propagation characteristics and sound field distribution in resistance spot welding joints is carried out, and the visual image of internal connection state of spot welding joints is the key to realize quantitative nondestructive testing and quality evaluation of spot welding joints, which has important theoretical significance and practical value, and has broad application prospects in technical fields such as automobiles, rail passenger cars, aerospace and machinery.