The Effect of Boron on the Sliding Wear Behavior of Iron-Based Hardfacing Alloys for Nuclear Power Plants Valves

A new iron-based wear resistance alloy was developed to replace the Co-containing Stellite 6 alloys in nuclear power industry. The effect of B addition on the wear resistance was investigated. Sliding wear tests of Fe-Cr-C-Si-xB (x = 0.0, 0.3, 0.6, 1.0 and 2.0 wt%) alloys were performed in air at the room temperature under a contact stress of 103 MPa. Low-boron alloys containing less than 0.6 wt% boron showed an excellent wear resistance than any other tested alloys. The improvement was associated with the matrix hardening by promotion of the γ→α′straininduced martensitic transformation occurring during the wear test. However, the alloys containing more than 1.0 wt% boron showed slightly increased wear loss compared to the low-boron alloys because of the absence of the strain-induced martensitic transformation and the presence of the brittle FeB particles, aiding crack initiation.