Reduction of Friction and Wear for AISI321 Stainless Steel through Surface Modification Using Nanocrystallization

Abstract

Through surface nanocrystallization and low-temperature ion sulfurization, the nanocrystalline/FeS thin film with excellent friction-reduction and antiwear properties was fabricated on the surface of AISI321 stainless steel. The nanocrystallization treatment formed the high hardness and active nanocrystalline structure on the surface of AISI321, with the harness increased from 4.6 GPa to 7.56 GPa. Furthermore, the significantly refined nanostructure strongly increased the concentration of S element in comparison with the single-sulfurized layer on the substrate. Tribological tests reveal that both the original AISI321 substrate and the single-sulfurizing-treated samples are subject to severe abrasion. Single nanocrystallization treatment can improve the wear resistance of AISI321, while the compound treatment can obviously improve the comprehensive tribological properties. The compound-modified layer presents excellent tribological properties with the lowest coefficient of friction (COF) of 0.33, which is related to the increased hardness of the substrate and increased thickness, density, and homogeneity of the sulfurized layer. Furthermore, a physical model is developed for the vacuum tribological behavior of the samples after different treatments. This model provides a reference for revealing the tribological mechanism of the compound-modified layer treated using surface nanocrystallization-assisted chemical heat treatment.

Effect of Surface Nanocrystallization on Wear Behavior of Steels: A Review

“…Ding and Li's recent investigation [45] also delved into the impact of post-surface modification on the wear resistance of 321 austenitic stainless steel that was SFPB-treated using 20-30 µm particles. They deposited a thin layer of FeS with exceptional anti-wear properties onto the resulting nanocrystalline surface layer.…”

“…However, the introduction of SNC significantly enhanced wear resistance, and the presence of the compound-modified film clearly bolstered tribological properties. The outstanding wear resistance observed in the surface nanocrystallization-and sulfurizingtreated sample was attributed to two key factors: the increased hardness of the substrate and the augmented thickness, density, and uniformity of the sulfurized layer [45].…”

“…In addition, the presence of a composite surface layer composed of a thin FeS film on the surface-nanocrystallized 321 stainless steel had a pronounced effect in reducing both the wear rate and friction coefficient [45]. This combination of a soft anti-wear surface overlaying a hard substrate effectively mitigated cutting and adhesion effects, contributing to improved tribological performance [45].…”