EFFECT OF FRCTION STIR PROCESSING ON THE TRIBOLOGICALPERFORMANCE OF STEEL/TiCNANO-COMPOSITE

In this study, the almost new processing technique, friction stir processing (FSP) was employed to produce nano-composite surface layers on mild steel. Nano-sized TiC particulates were introduced to the stir Zone by means of a pre-made groove. A tungsten carbide tool was used to plasticize the mild steel substrate. The process transformed the original pearlite microstructure to acicular-type ferrite, resulting in significant increase in surface hardness. This surface hardening produced a significant benefit for fiction and wear behavior of the steel as measured by unidirectional sliding pin-on-disk testing. Under sliding, FSP reduced friction coefficient and wear rate and increase wear properties about four times more than that of the as-received mild steel. The surface nano-composite layer produced by four FSP passes showed superior wear resistance; this is attributed to its greater micro hardness value (due to presence of finer matrix grains and uniform dispersion nano-sized TiC particles).