Abstract
To evaluate the effects of pulsed laser welding on the microstructure characteristics and mechanical properties of nickel-based superalloy (C-276) and austenitic stainless steel (304) lap-welded joint, the analyses of morphology, microstructure, phase structure, element distribution, tensile–shear strength and microhardness were carried out. The results indicated the unmixed zone was found at the interface between the weld metal (WM) and 304. A small number of inter-dendritic precipitates were also found, and the precipitates were most probably p or μ phases. Compared with the phase structure in C-276, the dominated phase structure in the WM was also austenite phase, however, the lattice constant was reduced due to the decrease of Ni, Mo and W content. The macro-element distribution was inhomogeneous in the WM due to the rapid cooling rate in pulsed laser welding, and the element transition region adjacent to C-276 was wider than that adjacent to 304. The fracture mode of lap-welded joint in tensile–shear test was tensile fracture, and the tensile strength was decreased by 17% compared with that of C-276. The microhardness value in the WM was not lower than that in the base metals.
Published Version
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