Effect of boronizing on the dry sliding wear behavior of DC53/0.45 mass% C steel pairs

The effect of single phase boride layer of DC53 steel disk on subsurface structure evolvement in the dry sliding friction-induced surface layer of 0.45 mass% C steel pin was investigated. Microstructure and microhardness of subsurface layers of 0.45 mass% C steel pin against unboronized and boronized DC53 steel discs after dry sliding friction test were studied by means of OM, SEM, TEM and microhardness tester. Results showed that boride layer significantly affected microstructure evolvement in worn surface layer of 0.45 mass% C steel and the three layers including substrate layer, plastic deformation layer and unpeeling delamination layer were formed beneath the worn surface of pin against the boronized disc, while only two layers except unpeeling delamination layer were formed against the unboronized disc. The microhardness of subsurface layer of 0.45 mass% C steel pin decreased as the depth beneath worn surface increased without regard to the unpeeling delamination layer in BD tribopair. The ferrite grains in the worn surface layer of pin for BD tribopair were ultra-fined, of which reason was considered to be the result of joint action of frictional heat and shear deformation.