Abstract: Leakage occurred to two soldered pipes at the position of soldered joint when test was carried out under alternating stress at about 400 ℃. In order to find out the failure cause, appearance observation, crack observation, fracture observation, EDS analysis, microstructure examination and microhardness testing were carried out. The results show that the occurrence of overheated intergranular cracks in soldered pipes is related to the small distance between the two soldered joints, mutual influence exists between them during soldering process, and the soldering temperature is improper. It is suggested to control the soldering process strictly and improve the soldered structure of the components.