Effect of Oil Quenching and Shot Peening to Improve Hardness Behavior of S45C Carbon Steel

Abstract

S45C carbon steel is widely used as a raw material for tools and automotive components. In machine components, a material that has hard and ductile properties is also needed, with this problem, of course, it is necessary to have material engineering to improve the mechanical properties of steel in order to obtain good quality. The heat treatment process on the material has the advantage of improving mechanical properties. The purpose of this study was to determine the effect of heat treatment and shot peening on the mechanical properties and microstructure of the S45C carbon steel surface. S45C carbon steel was heat-treated at 900 oC and held for 15 minutes, then quenched using oil media. Next, the shot peening process was carried out with pressure variations of 4, 5, 6, and 7 bar for 20 minutes. Hardness testing was carried out using micro Vickers with a load of 0.49 N for 10 seconds. The results of the heat treatment on S45C material experienced an increase in hardness of 251.56 VHN compared to non-treatment, namely 187.38 VHN. Specimens that have been heated treated and shot peening with pressure variations of 4, 5, 6, and 7 bar experienced an increase in hardness of 286.18, 289.22, 357.24, and 450.22 VHN. The microstructure of the heat treatment material is formed by the phases of ferrite, pearlite, and martensite. The pearlite structure is denser and denser, showing increased hardness compared to non-treated S45C. Furthermore, the cross-sectional microstructure shows the depth of the shot peening effect as far as 130 μm. The surface of the specimen has a denser structure than the raw material.