Effect of laser welding process parameters on dissimilar joints of AISI 316 and nickel 201. (2020) - Krishna Kumar, G.
Abstract: The dissimilar butt welding of nickel 201 and AISI 316 was investigated using 4 kW CO2 laser welding machine. The effects of welding power (2580 - 3420 W), welding speed (450 - 1150 mm/min), focal position (-1 to 0 mm), beam angle (84 - 96 degrees) and Beam offset (0 - 0.2 mm) on the welded bead geometry like depth of penetration (DP), bead width (BW), area of penetration (AP) and heat input (HI) were analyzed with Response Surface Methodology (RSM). The central composite design was used for this experimental plan. Mathematical equations were formed to find the required heat input and weld profile responses dissimilar butt welding process. Output responses reflect the results for mathematical models within the range of process parameters used. Numerical optimisation technique was used to identify the optimal condition region of all this laser welding process. It helps to achieve better process parameter combination for the controlled responses of this process. Depth of penetration is the most important output response to achieve the good dissimilar joint. The welding power and welding speed are the two factors which influencing more on the strength of dissimilar joint even though all the other three factors are involving. The beam angle does not show any considerable change on bead width and Fusion Zone Area (FZ) and also there is no significant influence of the beam offset on bead width. An optimization results were confirmed by experiments to validate values of the process parameters values found from RSM. In microstructure studies some delta ferrite is seen in the interdendritic region and also the solidification shows columnar grains. The tensile test results the fracture in the base metal which proves that the weld strength is good as expected