Hot Cracking and its Characteristics of SMAW Weld Metal of T/P92 Steel

To research the performances and characteristics of a kind of short and tiny defect in SMAW weld metal of T/P92 steel, the defect morphology were observed and the alloy elements on defect surfaces were analyzed with EDAX by both an engineering sample obtained from a welding engineering and a laboratory sample made in the laboratory. Results show that, dendrites with uniform direction and cells with free solidification crystal surfaces are observed on the defects fracture surfaces. Moreover, it is also observed in the laboratory sample that the defect emerges under high temperature. According to the results, it can be confirmed that the defect is the welding hot cracking, furthermore, the solidification cracking. Cracking tendency of welded metal expands as the increasing weld layer thickness and prolonged time of weld metal under high temperature. Due to the characteristics of its shape and size, the defect is difficult to be detected and positioned in ultrasonic inspection which easily leads to an erroneous or an omissive assessment on it.