Lowering the coefficient of martensite steel by forming a self-lubricating layer in dry sliding wear

In this paper, the dry sliding wear behavior of martensite steel under different friction conditions was studied. The sliding contact surface was found to form a self-lubricating layer composed of nano-oxide particles under specific strain and strain rate conditions. The heat and force field environments of surface oxidation were analyzed from the perspectives of heat transfer and contact mechanics. The protective mechanism of the self-lubricating layer was elaborated based on the 3D topography of the laser confocal results of the worn surface at different times. The essential causes of the changes in the dry coefficient of friction (COF) under different friction conditions (normal load, speed and time) were analyzed from the perspective of the formation and destruction of the nano-oxide self-lubricating layer. This study shows that in the process of dry sliding wear, martensite experienced large plastic deformation in the surface layer, and nanolamellar martensite was formed in the severe plastic deformation area. The self-lubricating layer composed of a large number of nano-oxide particles with a depth of 1 pm was formed at the contact surface due to plastic deformation and frictional heat. The self-lubricating layer reduced the dry COF from 0.5 to 0.28 as well as the surface roughness and wear trace depth.