Effect of Deposition Current on Microstructure, Hardness and Residual Stress Distribution of NiCrBSiC Hardfacing Alloy

This study investigates the influence of deposition current on the characteristics of NiCrSiBC alloy hardfacing deposited onto a 316L stainless steel substrate using the gas tungsten arc welding (GTAW) process. The research focuses on evaluating the effect of deposition current on key properties such as Fe dilution, hardness distribution, microstructural features including secondary dendritic arms spacing (SDAS), and lattice strain. Microstructural analysis was conducted using optical microscopy and scanning electron microscopy (SEM), while dilution analysis performed using energy-dispersive x-ray spectroscopy (EDX). The microstructural examination revealed a dendritic microstructure typical of such hardfacing, where SDAS increased proportionally with deposition current. Hardness profiling indicated an initial increase away from the fusion line, reaching a plateau beyond a certain distance. Higher deposition currents led to increased temperatures during welding, resulting in greater Fe dilution over a larger area within the hardfacing deposit. Numerical simulations of residual stress distribution demonstrated a significant dependency on deposition current, influencing both the hardfacing bead and substrate.