Crack Defect

Cracking is a common welding defect in threaded steel pipes, which has a significant impact on pipeline safety. It not only accelerates the corrosion rate of steel pipes but also poses a risk of crack propagation, thereby creating substantial safety hazards. The conditions leading to cracking in steel pipes vary and can be classified into hot cracks and cold cracks. Hot cracks occur during the welding process when certain substances accumulate and eventually lead to cracks due to weld contraction. The propagation direction of hot cracks mainly results in transverse cracks. Cold cracks, on the other hand, develop when the weld cools to martensitic temperatures. Cold cracks are primarily influenced by factors such as stress, hardened microstructure, and diffusible hydrogen, which can lead to the formation of both transverse and longitudinal cracks.