High temperature study of the evolution of the tribolayer in additively manufactured AISI 316L steel

AISI 316L is a material that is widely used in several technological applications. This material is also suitable for use in the 3D printing of metal components. In this study, the wear behavior of AISI 316L steel produced using Selective Laser Melting technology was investigated in order to determine its metallurgical evolution under high Hertzian stress. The results were compared to AISI 316L that was classically forged. A preliminary mechanical and microstructural characterization was carried out in order to characterize the material and compare the properties of 3D printed with material that has been forged. Tribological tests were then carried out under high Hertzian loads that are typical of hot/cold rolling conditions at different temperatures (25 °C, 200 °C, 400 °C, and 600 °C). The wear rates were then calculated using a stylus profilometer. The wear tracks were characterized in the top view to determine the composition of the triboxide layer using SEM-EDXS and Raman spectroscopy. Cross sections of the samples were then used to conduct SEM analysis in order to determine the thickness of the tribolayer and the characteristics of the strain hardened layer. EBSD mapping was also conducted on the same samples to determine the regions in which recrystallization had taken place. The results showed that the 3D printed material has lower wear rates than the forged material, due to the finer microstructure of the material produced by 3D. In addition, the triboxides formed on the additively manufactured component were finer, although the nature of the oxide was the same. The 3D printed material showed a dynamic recrystallization at 600 °C, while the forged material started to recrystallize at 200 °C.