This study used the strengthening grinding process (SGP) to treat the surface of 30CrMnSiA bearing steels. The effect of the jet angle of SGP on the tribological properties of 30CrMnSiA bearing steels under lubrication was investigated. The principle of enhancing wear resistance of 30CrMnSiA bearing steel ascribed to SGP was discussed in detail. The results showed that the lubrication properties and surface hardness of the 30CrMnSiA steels were enhanced due to the formation of numerous microscale microscope oil pockets on the surface layer and the grain refinement of the surface microstructures, resulting in a significant improvement in wear resistance. With the jet angle of SGP increased from 0° to 90°, the friction coefficient, the wear volume, and the specific wear rate were exhibited to reduce rapidly first, then reduce slowly, and then rise slowly. With the optimal parameters at the jet angle of 60°, compared with the control sample, the average friction coefficient was reduced from 0.2235 to 0.1609, and the wear volume and specific wear rate were reduced from 9.04 × 10⁻³ mm³ to 3.82 × 10⁻³ mm³ and from 15.13 × 10⁻³ mm²/N to 6.36 × 10⁻³ mm²/N, respectively. When the jet angle was 90°, the reduced wear resistance was mainly attributed to the excessive roughness that caused the oil coating on the surface to be severely damaged.

The novel strengthen-modified grinding technique (SMGT) treatment was carried out on 30CrMnSiA bearing steels to investigate the effect of jet pressure (0.2–0.6 MPa) and jet angle (30–90°) on its surface micromorphology, microstructure, and mechanical properties. The results show that, under the compound effects of the impact of steel beads and the abrasive powder micro-cutting, the surface of 30CrMnSiA specimens treated by the SMGT has a microstructure with plenty of micropits inside the pits and overlaps between pits. The pit width, depth, and bulge height positively correlate with jet pressure. The pit depth and bulge height positively correlate with jet angle, while the pit width negatively correlates with jet angle. When a pit morphology is produced, plenty of plastic deformation leads to grain refinement, and the lattice distortion induces retained austenite transformation to martensite. Grain refinement and increased martensite content are the main reasons for the significant increase in hardness on the SMGT-treated specimen surface. With the optimized processing parameters, the grain size of the surface was reduced to 10.14 µm, and the martensite content and hardness of the surface layer rose to 51.35% and 377.6 HV_0.2.