Microstructure and Stress Distribution on TIG Welded Joint of CLAM Steel

摘要

China low activation martensitic steel, 5 mm, were butt-welded in tungsten insert gas welding. Mechanical properties and microstructure in joints were studied in detail. The residual stress and deformation in the joints were numerically simulated using finite element method. Hardening at WM and softening in heat affected zone is detected in weld joint. The tensile specimen always undergoes localized necking and breaks in BM when the temperature of PWHT was lower than 800 A degrees C. Until PWHT was done at 760 A degrees C/30 min, the specimen ductile fractured in local area, but the absorbed energy of each CIT specimen is much lower than that of BM. The microstructure in WM is mainly tempered martensite with a little of delta ferrite. Tempered lath martensite containing dislocations and M23C6 carbides is the primary structural feature. According to the results of numerical studies, angular distortion is the main form of residual deformation, and caused by the transverse shrinkage of WM.