Wear behavior of AISI 304 stainless steel after friction stir processing

The wear behavior AISI 304 stainless steel was investigated after Friction Stir Processing (FSP). FSP was carried out using a WC pin less tool at tool rotation of 560 rpm and tool feed of 50 mm/min. Microstructure analysis was conducted by using optical and scanning electron microscopy evaluations. Wear resistance of the FS processed and base metal specimens were compared using pin-on-disk tests. The results demonstrated that FSP homogenized and refined the grain size of 304 stainless steel. A reduction in grain size throughout the stir zone (26±3) compared to that of the base metal (93±3) was achieved through FSP. These results were confirmed by microhardness evaluations. According to the wear results, wear resistance of 304 base material improved significantly (two orders of magnitude) after FSP. This behavior was attributed to the grain refinement obtained by FSP. According to SEM observations, the abrasive wear was the main mechanism of wear after FSP.