Effect of surface nanocrystallisation of 316L austenitic stainless steel on tribological and corrosion response of thin hard coatings

Abstract

The tribological and corrosion performance of AlCrN and duplex AlCrN/DLC (Diamond-like carbon) coated AISI 316L austenitic steel was investigated to explore the effect of severe deformation of the steel surface using surface mechanical attrition treatment (SMAT). SMAT developed a nanograined surface with a hardness gradient in the near-surface territory of the substrate, where surface hardness increased from 180 ± 4 HV<inf>0.1</inf> to 350 ± 9 HV<inf>0.1</inf>. SMAT did not affect the coatings' thickness

however, the surface quality of the AlCrN coating was better when deposited on the SMATed surface. Fewest defects were found on DLC-coated non-SMATed and SMATed specimens. The best corrosion resistance was observed for the coatings deposited on SMATed steel. Under the reciprocating wear, the AlCrN coating reduced the volume loss of the steel by 95 ± 0.6 – 98 ± 0.4 % and attained a stable and reduced coefficient of friction (COF). The DLC coating on AlCrN substantially reduced the non-SMATed steel's volume loss from 115 ± 2 × 10−3 mm3 (non-coated condition) to 0.89 ± 0.1 × 10−3 mm3 and COF from 0.56 ± 0.02 (non-coated condition) to <0.01 under 20 N. SMATed substrate further improved the tribological performance. The COF lower than 0.01 and volume loss of 0.57 ± 0.05 × 10−3 mm3 (under 20 N load) were obtained by depositing the duplex-coating on SMATed substrate. The scratch test revealed better adhesion of the coatings to the SMATed substrate than to the non-SMATed substrate. Overall, the SMAT was a beneficial pre-treatment for AlCrN and AlCrN/DLC coatings to improve the tribological and corrosion performance of soft substrates like AISI 316L steel. © 2025 Elsevier B.V., All rights reserved.