Development of Micro-plasma Arc Welding System for Different Thickness Dissimilar Austenitic Stainless Steels

With the miniaturization of the components, micro-fabrication has gained significant attention for the application in micro-devices. The current work aims to weld dissimilar austenitic stainless steels with different thickness (average ~ 700 µm) by downscaling the traditional arc-based joining process. Micro-plasma arc welding (µ-PAW) with less than 15 A current is used to fabricate the weld joints at different heat input, which can be reviewed as a substitute for laser and electron beam welding process in terms of cost-effectiveness. The welding fixture employed to hold the small workpiece contributes significantly to achieve the complete establishment of the µ-PAW process. A low amount of heat input leads to reduced dendritic and secondary dendritic arm spacing, which increases the joint efficiency up to ~ 115%. A high value of heat input changes the mode of failure from ductile to mixed mode due to micro/macro-voids’ existence, decreases the corrosion resistance due to chromium depletion from 25 to 17 wt.%, and increases the number and size of the pores. A finite element-based computational model is also employed to presume the geometrical dimensions of the weld joint that agree well with the experimentally determined values with a maximum error of 9%. © 2021, The Institution of Engineers (India).