Effect of stress relief heat treatment and preheating on the microstructure and microhardness of the interface between Inconel 625 deposit and AISI 8630M and AISI 4130 steels

ABSTRACT The objective of this study was to evaluate the effect of the preheating and interpass temperature, as well as to evaluate the effect of the application of stress relief heat treatment on the microstructure, microhardness and composition gradient along the interface of AWS E NiCrMo3 alloy on AISI8630M and AISI4130 quenched and tempered steel, applied by two welding process. For this superimposed weld beads using different preheat and interpass were applied using MIG and Plasma Transfered Arc – Powder (PTA-P) welding process. The interfaces deposits were subjected to analysis of chemical composition by EDS, to metallographic examination by optical and electronic microscopy and to microhardness tests. The increase in preheat and interpass temperatures resulted in greater grain refinement of the first pass, increase of heat affected zone microhardness and in a greater Fe migration from the substrate to the applied layer. A minor frequency diversity and a lower incidence of partially diluted zones (PDZ) was observed in deposits performed by PTA-P process, where as the deposits performed with MIG process discontinuous PDZ type with different morphologies were identified. The use of stress relief heat treatment resulted in a significant reduction in microhardness values in all cases.