Experimental investigation of the ability to join hardox 450 and s355j2c+n steels robotically using gas arc welding method

In this study, the ability to combine high wear resistance Hardox 450 with low carbon general structural steel S355J2C+N by robotic gas arc welding method was investigated. In the study, pre-annealing temperature (20 °C, 50 °C, 100 °C), current (200 A, 220 A, 240 A) and voltage (26 V, 27 V, 28 V) were used as welding parameters. Experimental design was made by determining 3 levels for each parameter according to Taguchi L9. Tensile test samples were produced from welded plates produced in accordance with Taguchi L9 and tensile tests were performed. As a result of the tensile test, the damage loads and damage locations of the samples were determined. Analysis of variance (ANOVA) was performed to analyze the effect of welding parameters on the results. Accordingly, it was determined that the most effective parameters on the results were welding voltage and current, respectively. As a result of the study, it was shown that damage did not occur in the welding area since optimum welding parameters were used. No significant effect of pre-annealing temperature on weld quality was observed. Within the scope of this study, the welding parameter levels that cause damage in the weld area when welding Hardox 450 and S355J2C+N materials with the gas arc welding method were found to be 28 V and 240 A. Microhardness tests were carried out in experiments no. 7 and 8, which were determined according to damage locations and damage loads, and their microstructures were examined. Experimental parts were prepared with a metallographic sample preparation device and bakelite. Hardness measurements were taken from the base metal, the weld zone and the areas under heat influence, including the upper weld zone and the lower weld zone, and their values were examined. With microstructure imaging, images of the base metal, heat affected zone, transition zone and weld zone were taken at 100X magnification and their grain structures were examined. Keywords: Hardox 450, S355J2C+N, Gas arc welding, Taguchi method, Microhardness, Microstructure, Area under heat influence. December, 2024; 72 pages