Mechanical and wear behaviors of 316L stainless steel after ball burnishing treatment

The performance and durability of orthopedic implants are mainly determined by their surface integrity. Ball burnishing (BB) is a kind of finishing treatment which improves the surface dependant mechanical properties of metallic biomaterials. In this work, this process was applied on the flat surface of 316L stainless steel to enhance its microhardness and wear resistance. The mathematical modeling of microhardness Vickers was performed by the response surface method (RSM) based on Box–Behnken plans, and the optimum regime was applied under several passes to investigate the effect of number of passes (i) on the surface properties. The evolution of microhardness, nano-hardness and elastic modulus was then examined. Wear resistance, in terms of variation of Coefficient of friction and wear loss, was also investigated. Finally, XRD analysis was performed to evaluate any change in structure produced by BB. The results show that burnishing treatment permits to raise the microhardness by up to 38.3% and to reduce the wear loss by up to 65.2%. Nano-hardness and elastic modulus were also increased after application of the process. XRD patterns indicate that grain refinement was induced with no change in phases composition. The number of passes is proved effective in increasing the depth of the hardened layer, which influences subsequently on the frictional behavior of 316L stainless steel.