Variances in Microstructure Evolution and Mechanical Properties of Dissimilar Steel Welded Joints Produced with Tungsten Inert Gas (TIG) Welding and Laser Beam Welding (LBW)
Y-L. Xu, P. Qian, J Liu, J-Y. Lin, J-Y Li and M-X. Shi
Microstructure evolution and physical property differences in tungsten inert gas (TIG) welding and laser beam welding (LBW) with a Nd:YAG laser of Q235 steel and 304 stainless steel in qualified welded joints were obtained through single factor experimental design. The results showed that the microstructure of the weld zone (WZ) is composed of lath martensite, and carbon migration occurred at the interface in the Q235 steel. Under the condition of full penetration of the welded joint, the tensile specimens fractured on the side of Q235 steel, indicating that the strength of the welded joint is higher than that of the Q235 base material (BM). These fracture morphologies presented the characteristics of ductile fracture. The distribution of microhardness in each region of welded joint in terms of heat affected zone (HAZ), BM and WZ was WZ > 304 side HAZ > 304 BM > Q235 side HAZ > Q235 BM.
Keywords: Nd:YAG laser, Q235 carbon steel, 304 stainless steel, laser beam welding (LBW), dissimilar metal welding (DMW), tungsten inert gas (TIG) welding, ,microstructure, tensile strength, microhardness, fracture