Effect of testing temperature on the impact-sliding wear behaviour of a 316L austenitic stainless steel

In this study impact-sliding wear performance of a 316L austenitic stainless steel (ASS), having widespread usage in various engineering applications under complex loading conditions, has been examined at room temperature (RT) and 180 °C under contact pressures as high as 2.5 GPa. Impact-sliding wear tests were carried out against 10 mm diameter 52100 grade bearing steel balls for 1000 loading cycles. The wear tracks formed on the samples were then examined by a 2-D contact profilometer, an energy dispersive X-ray spectroscopy (EDX) equipped scanning electron microscope (SEM) and a Raman spectroscopy. Despite the detection of tribo-oxides on the impact and sliding zones, mainly plasticity dominated wear was operative at RT. Tests conducted at RT and 180 °C favoured hematite + magnetite and hematite type tribo-oxides on the worn surface, respectively. The increase of test temperature to 180 °C caused an increase in the wear rate at the impact zone but a decrease at the sliding zone of the wear track. While the former was the result of softening of the ASS, the latter was due to the formation of thicker tribo-oxides on the contact surface. Although the reduction of sliding wear rate above a critical temperature (300–400 °C) was previously associated with the formation of protective tribo-oxides on the worn surfaces, this study revealed that higher contact pressure reduces this critical temperature via increasing the frictional heating under sliding contact. Thus, contact pressure of 2.5 GPa favoured the formation of protective tribo-oxides at a lower temperature (i.e. 180 °C) for the examined ASS/bearing steel tribo-pair.