Impact Wear Resistance of Stellite 6 Hardfaced Valve Seats with Laser Cladding

A cobalt-based alloy, Stellite 6, was deposited on the seat face of control valves using a coaxial laser cladding process. For comparison with conventional hardfacing techniques, a plasma transferred arc (PTA) method was chosen for parallel experiments in this study. The laser-clad layers, which consisted of refined solidification structures, were characterized by increased hardness and impact toughness as compared to PTA overlays. The laser-clad valve seats exhibited superior impact wear resistance, i.e., the resistance to impact cracking at high loads, relative to the PTA-clad valve seats. Additionally, microcracks along the interface of eutectics and carbides were observed in the PTA-clad specimen, but to a lesser extent for the laser-clad specimen.