EFFECT OF CURRENT PULSATION ON WELD MICROSTRUCTURE DURING MICRO-PLASMA ARC WELDING OF INCONEL 718

The current investigation focused on micro-plasma arc welding of Inconel 718 sheets by constant current (CC) and pulse current (PC) mode. Formation of Nb-rich Laves phase in the solidified microstructure of weld fusion zone has detrimental effect on the weld mechanical properties. The effect of current pulsation on the weld microstructural morphology, formation of Laves phase and its consequence on mechanical properties are meticulously studied herein. The tensile properties of the welded joints are found to be inferior to the base material due to the formation of intermetallic Laves phase in the inter-dendritic region during solidification. PC mode weld have shown improvements in hardness and tensile properties as compared to the CC mode welding.