本文通过对焊接过程热应力的分析并借助试验设计，提出了凿岩钎头裂纹形成和扩展机理。即裂纹源产生于快速加热过程并在随后的快速冷却中得以扩展。 Based on the analysis of thermal stress in welding process and the experimental design, the mechanism of crack formation and propagation in rock drill bit is proposed. That is, the source of the crack is generated during the rapid heating process and is expanded in the subsequent rapid cooling.