Analysis of hardness for dissimilar stainless-steel joint by mathematical modelling

Gas tungsten arc welding (GTAW) is very popular globally as it is capable of doing similar and dissimilar material welding. Most commonly steel and aluminium of different grades are joined using this process. In this research work, two unalike grades of stainless steel i.e., 304 and 316 were welded together with different combination of parameters. An attempt was made to find out the effect on the surface hardness of the joint. The parameters under consideration were current, welding speed and torch angle, having two limits, maximum limit (+1) and lower limit (-1). A mathematical model was developed between input parameters and the responses such as hardness was analyzed by using the factorial approach. The result of the analysis shows that increase in current and welding speed decreases the hardness whereas an increase in torch angle increases the surface hardness. Hardness is maximum at the weld zone of two dissimilar metals and minimum at the heat affected zone.