Wear behavior of 316L stainless steel obtained by additive manufacturing (laser metal deposition process)

Laser Metal Deposition (LMD) is one of the additive manufacturing (AM) processes that also offer the possibility of repairing metallic parts which have been worn out during their service. Nowadays, additive manufacturing processes start to prove that they are able to manufacture and repair parts with high density and interesting mechanical properties. However, the tribological properties, and especially the wear resistance, have not been deeply studied yet for metallic additive manufactured parts. In this study, we investigate the tribological behavior (friction and wear under dry conditions) of 316L obtained by LMD. The 316L was studied in a flat-on-flat contact configuration, in contact with an AISI 52100 steel flat pin, with a linear reciprocating motion. The main objective is to understand the wear mechanisms and to quantify the damage, as a function of the repair strategy and tribological conditions (contact pressure, sliding direction, sliding speed) with a view to optimizing the use of LMD technique for reparation of worn parts. Also, a comparison between LMD repairs and conventional rolled 316L has been performed. Microstructure, residual stresses and hardness of 316L repairs are characterized, in order to better understand their tribological behavior. The tribological results show that the main wear mechanisms are abrasion and adhesive wear, together with oxidative wear (mostly at low loads). Contact load and number of cycles have a huge impact on the wear volume, with almost linear increases, while the sliding direction and the LMD scanning strategy have no significant effect on friction and wear. Sliding frequency has an effect on wear, with a transition frequency below which wear volume decreases, due to the relative increase of oxidative wear. Rolled 316L shows a 40 % increase in wear resistance, compared to LMD 316L, due to the predominant oxidative wear of rolled 316L, especially at high loads.