Abstract：In the peeling process of resistance spot welding samples using cross tensile equipment, it was found that the cracking position and fracture morphology of the solder joints were different. In order to study the factors that affect the cracking of the spotwelding joints during cross tensile test, the microstructure, hardness distribution and fracture condition after cross tension were observed and detected using the low carbon steel cold-rolled plates (H260LA, H340LA and DP780) as the samples. The factors affecting the cracking of welded joints were analyzed by comparing the microstructure and hardness distribution of different samples. The results showed that the content of martensite increased gradually in the nugget and the heat affected zone with increasing the contents of carbon and alloying elements in the base metal, which led to the increase of inter-structural stress and influenced the crack propagation. In addition, the local softening phenomenon of hardness was observed in each area of the welded joint, which had an important effect on the cracking of the solder joint in cross tensile tests.
2022, Vol. 40 
