Abstract
Dry rolling-sliding tests were carried out on plasma nitrided and heat treated Fe–Mo–C sintered alloys. Whereas the heat treated alloy undergoes oxidative wear independently of the load condition and duration of the test investigated, the plasma nitrided alloys show distinct wear stages characterised by different wear rates. In particular, while the white layer is able to remain in place the wear rate is lower than that shown by the reference heat treated material. The durability of the white layer increases on decreasing the applied loads and/or submitting the materials to heat treatment before plasma nitriding, to improve the load bearing capacity of the subsurface layers. Fatigue cracks nucleate in the subsurface layers because of the stress concentrating effect of pores, but no fatigue wear was observed during the tests. After loss of the white layer due to oxidation or microcracking, the wear rate increases because both oxidation and plastic shearing control the wear behaviour.
MST/2067
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