The systematic parameter optimization in the Nd:YAG laser beam welding of Inconel 625

This paper presents process parameter optimization for the laser welding of 0.5-mm-thick Inconel 625. The effect of laser parameters such as laser power (LP), spot size (SS), and welding speed (WS) on weld strength (WST) and microhardness of the welds has been investigated using the response surface methodology (RSM). A three-level design with 20 experimental runs was used. The analysis of variance (ANOVA) was performed and mathematical models were developed to predict the effect of input parameters on the responses. Results indicated that the maximum weld strength of 1280 MPa can be obtained when LP, WS, and SS are set at the optimum values of 260 W, 1.2 mm/s, and 180 mu m, respectively. LP of 230 W, WS of 6 mm/s, and SS of 540 mu m also resulted in minimum microhardness deviation (MHD) from that of the base metal. Higher heat input caused deeper penetration of weld joint and so higher WST. Formation of Laves phase in samples that receives higher energy density resulted in increase of microhardness and so MHD.