Prediction of tensile strength and assessing the influence of process parameters of magnetically impelled arc butt welded AISI 409 ferritic stainless steel tubes

Magnetically impelled arc butt (MIAB) welding is the modern version of the ancient forge welding. The abutting edges are preheated by a rotating arc and upset subsequently. This research work is focused on joining 4-mm thick AISI 409 ferritic stainless steel (FSS) tubes using MIAB welding. Three process parameters namely arc rotation current, upset current, and arc rotation time were varied during welding at five levels according to the chosen central composite design (CCD) of experiments. An empirical relationship was developed to predict the effect of process parameters on the joint strength. The macrostructure and microstructure observations were used to comprehend the predicted plots. Weld zone was composed of fine-grained and deformed structure due to the application of heat and pressure and called as thermo mechanically affected zone (TMAZ). Factors such as poorly forged structure, voids, and oxide particles influenced the joint strength adversely. In spite of significant strengthening of the TMAZ, a clearly forged interface was essential to obtain higher joint strength.