Correlation between shot peening coverage and surface microstructural evolution in AISI 9310 steel: An EBSD and surface morphology analysis

• Published in: Surface & coatings technology Vol. 494; p. 131406
• Main Authors: Lv, Liangliang, Shao, Wen, Tang, Jinyuan, Zhao, Jiuyue, Zhou, Zhaokang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.10.2024
• Subjects: Coverage; Geometrically necessary dislocation; Grain size; Shot peening; Surface roughness; Grain size; Geometrically necessary dislocation; Shot peening; Coverage; Surface roughness
• ISSN: 0257-8972
• DOI: 10.1016/j.surfcoat.2024.131406

In this study, martensitic high-strength steel serves as the subject of investigation, with both conventional and severe shot peening experiments being conducted. The coverage levels for conventional shot peening (CSP) are set at 100 % and 200 %, while severe shot peening (SSP) sees levels of 800 % and 1200 %. For the first time, the use of kernel average misorientation (KAM) enables the calculation of geometrically necessary dislocation (GND) density after peening, facilitating the study of GND density distribution across different coverage and offering a method for the visual assessment of peening degree. Results reveal that, under CSP, the gradient distribution of grain size is relatively uniform, whereas SSP leads to a pronounced gradient in grain size distribution. Taking into account the heterogeneous distribution of the initial material microstructure, a gradient in grain size from the surface to the interior of the material will appear after the coverage reaches a certain value, which is 400 % for AISI 9310 steel. Compared with CSP, SSP will further reduce the surface roughness Sa and improve the surface quality. The research presented further understands the relationship between shot peening process parameters and martensitic steel microstructure, providing an important reference for revealing the strengthening mechanism and selecting reasonable process parameters. •Increasing the coverage level not only can obtain finer grains, but also easier to obtain gradient grain size.•The 400 % coverage level is the critical coverage of graded grain of AISI 9310 steel.•Significantly increasing the coverage can reduce the surface roughness of AISI 9310 steel.•When the coverage exceeds 800 %, the surface layer of AISI 9310 steel will form submicron grain.