Effects of dilution on microstructure and wear behaviour of NiCr hardface deposits

The effect of dilution on the microstructure, hardness and wear properties of two nickel base NiCr hardfacing alloys deposited using the gas tungsten arc welding (GTAW) process has been studied. Dilution from the base metal altered the microstructure, volume fraction and type of precipitates in the deposit, all of which varied with the distance from the deposit/substrate interface. The microstructural variation in the deposit was accompanied by corresponding variation in the deposit hardness. A pin on disc wear test, carried out using pins with varying thickness of deposit, showed that the wear resistance of the deposit increased with increasing thickness of the deposit, indicating that the wear resistance decreases with increasing dilution from the base metal. The present study brings out the effect of dilution from the substrate material on the properties of NiCr hardface deposits and the need to ensure a minimum thickness of GTAW deposits of these hardfacing alloys for obtaining the desired wear resistance.