Effects of temperature and contact stress on the sliding wear of Ni-base Deloro 50 hardfacing alloy

The sliding wear behavior of Ni-base Deloro 50 hardfacing alloy was investigated in air in the temperature range from room temperature to 350°C under contact stresses of 55, 103 and 207 MPa. At temperatures below 100°C, Deloro 50 showed severe adhesive wear and as a result the amount of wear loss was very large regardless of contact stress. With increasing temperature over 100°C, however, the amount of wear loss decreased and reached eventually to near zero value at temperatures of 200°C, 225°C and 250°C under the corresponding contact stresses of 55, 103 and 207 MPa, respectively. It was found that the decrease of the amount of wear loss was due to the wear transition from severe adhesive to mild oxidative wear which was caused by the formation of wear protective oxide layers on wear surfaces. It was considered that if the temperature was high enough to meet the oxidative wear condition, Deloro 50 could be used as hardfacing material for nuclear power plants valves even under the high contact stress of 207 MPa.