Investigation of the capability of ST-37(S235JR) and miilux-450 steels to be welded with laser welding and gas arc welding with mechanical tests and statistical methods

In this study, using the laser welding method and the Gas arc welding (MAG) method, the appropriate parameters of 6 mm thick St-37 (235JR) and Miilux 450 steel were welded using Taguchi method. The welded joint was welded in the form of butt welding (PA) in the horizantal plane, using SG2 addational wire without opening the weld mouth and 9 samples were welded with double-sided fiber laser welding and 9 samples were welded with robotic arc welding(MAG). In the thesis study, tensile test of samples after welding, 3 point bending test, hardness test and micro struction were performed. Statistical analysis of tensile test results with minitab program was performed. In the hardness test; the Vickers hardness distribution of the main material the welding zone and the Heat Effected Zones (ITAB) were examined and the microstructures were examined with the optical microscope. According to Taguchi Signal/Noise (S/N) values, the best laser welding parameters were obtained with the best gas welding parameters. When the parameters of the drawing experiment were examined with ANOVA, the most effective parameters were determined in the gas welding and laser welding. In laser welding, it was observed that the hardness value was higher than the gas hardness value due to the fact that the melting was in a narrow region and the low heat in put. At hardness value, laser source hardness values are generally close to Miilux450, while the hardness values of the gas source are closer to 235JR. In both welding methods, the average weld seem hardness values were smaller than the Miilux450 hardness values and higher than the other hardness values except fort he 235JR main sample. In the bending test, bending occured on 235JR, while bending did not occur on any of the Miilux450 steel samples, since Miilux450 wear resistant steel is a hard material.