Probe Pulse Conditions and Solidification Parameters for the Dissimilar Welding of Inconel 718 and AISI 316L Stainless Steel

The present work addresses the weldability of dissimilar materials Inconel 718 and AISI 316L stainless steel through metallurgical and mechanical characterization of the joint. The 3D heat transfer model analyzes the solidification behavior for a pulsed arc energy source. However, intermetallic formation deteriorates the welded joint properties and promotes solidification cracking in the weld zone. We attempt to join these dissimilar materials without using any filler materials and allowing solidification with the use of a pulse current. The use of a pulse current during microplasma arc welding assists in the formation of a beneficial microstructure that produces strong welds. Since the solidification parameters (G center dot R and G/R) largely define the weld microstructure, their effect on the weld joint properties is investigated herein. With an increase in the pulse current, the (G/R) decreases and enables the formation of an equiaxed solidified structure in the weld zone. A reduction in the amount of various intermetallic phases is observed in the equiaxed regions compared to amount present in areas with a columnar structure. The tensile strength of the joint is superior to that of AISI 316L stainless steel, and failure is observed in the heat-affected zone of this material. The best joint efficiency herein of 108 pct and elongation of 35.3 pct is achieved for the welding condition having the lowest (G/R) value. An improvement in the elongation is achieved for the weld joint with a reduction in the (G/R) value.