Room and High Temperature Sliding Wear Characteristics of Laser Surface Melted Stellite 6 and Mo-Alloyed Stellite 6 Hardfacings

In this work, a post treatment of laser surface melting (LSM) has been employed on Stellite 6 and 10 wt.% Mo-alloyed Stellite 6 hardfacings deposited by plasma transferred arc (PTA) process. LSM process refined the microstructures of both hardfacings, while favoring a network-like complex carbide dominated microstructure in the Mo-alloyed version. With reference to the PTA Stellite 6 hardfacing, LSM process led to an increment in surface hardness albeit a subsequent reduction of wear loss at room temperature, where abrasive wear mechanism was dominant. At 500 °C, oxidative wear contributed to the progress of wear by favoring CoO and Co3O4 type tribo-oxides on the contact surfaces of the PTA and LSM’ed hardfacings, respectively. However, Co3O4 type tribo-oxides exhibited poor mechanical stability, than CoO, which led to easier removal from the contact surface and aggravated the wear loss by abrasive wear mechanism. In this respect, LSM’ed hardfacings exhibited higher wear loss than PTA Stellite 6 hardfacing at 500 °C, unlike room temperature.