Crack Defect

Cracking is a common welding defect in threaded steel pipes and 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 steel pipe cracking vary and can be classified into hot cracks and cold cracks. Hot cracks occur during the welding process when certain substances accumulate and eventually crack due to weld seam contraction, mainly forming transverse cracks in the direction of crack propagation. Cold cracks, on the other hand, occur during the cooling process after welding, when the material transforms at 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.