Optimization of TIG welding process parameters on chrome alloy steel using Box–Behnken method

Chrome steel is a quality high-carbon alloy steel that offers a high degree of hardness with compressive strength, abrasion resistance, good ductility relatively good impact properties at low temperatures. This paper aims to determine the best set of process parameters for TIG welding on chrome steel alloys (EN31 and AISI 52100) to achieve higher ultimate tensile strength (UTS) and hardness (BHN). Current (A: 150–200 A), weld speed (B: 2–4 mm/s), and electrode diameter (C: 2–3 mm) were used as input parameters for TIG welding process. The Box–Behnken method of the RSM approach was used to conduct the Design of Experiments (DoE). Analysis of variance (ANOVA) employs an arithmetical approach to determine the perfect amount of dependent variables to make best-designing limitations via confirmation readings. UTS and BHN values are observed from 225 to 321.5 MPa and 78.5 to 97.5 HV respectively. From the SN ratio response table, it is noticed that the optimal conditions for UTS are obtained at current-175 A (level 2), welds speed-4 m/s (level 3), and electrode diameter-2.5 mm (level 2) and the current is the main parameter to improve the UTS and BHN of the joint followed by weld speed and electrode diameter. Based on SEM analysis, it is been noted that the presence of voids in the weld pool can be attributed to the absorption of oxygen and nitrogen from the surrounding atmosphere as well as inadequate shielding gas. The primary cause of fracture is overload with the failure being predominantly influenced by the coalescence of microporosity.