Evaluation of spot welding joints by ultrasonic method

Abstract

The basic connection used in the construction of vehicle bodies is the spot welded connection. On average, there are about 6,000 such connections on the car body. Despite the fact that this type connections have been used at the of vehicle manufacturing stage for many years, it is necessary to control the quality of spot welds in order to achieve high quality, stiffness and durability of the whole car body. There are two groups of methods for assessing the quality of spot welds, which include destructive and non-destructive methods, in particular ultrasonic methods. The article presents se-lected results of ultrasonic inspection of spot welds of vehicle body and verification-using destructive tests. Ultrasound transducer with a water delay line and a frequency of 20 MHz were used. The number of return echoes from the connection area and the RWS parameter were determined. Metallographic examinations of connection area were also made and shear force for connections of different quality (change in welding current intensity) was determined.