Surface Morphology Evolution and Erosive Wear Mechanisms of Steel Alloys under Different Impact Angles: An Integrated Experimental and Computational Study

A comparative investigation of erosion behavior of SS304 and SKD11 through experimental and finite element analysis (FEA). Erosion tests were conducted at impact angles of 30°, 60°, and 90° with silica sand (SiO 2 ) as erodent. The results show SKD11 reinforced with M 7 C 3 and M 23 C 6 carbide at volume fractions of 9% and 6%, respectively, exhibited a higher hardness than SS304. However, hardness alone is insufficient to govern erosion resistance under impingement angle owing to a relatively small improvement (17.87%). From worn surface morphology, it was confirmed that both materials experienced micro-cutting and ploughing mechanisms at 30°, a mixed cutting-indentation regime at 60°, and indentation at 90°. Meanwhile, FEA revealed a progressive mechanistic transition with increasing strike angle, reflected in progressively longer contact times, higher stress localization, and greater plastic strain accumulation with increasing angle. Energy partitioning analysis showed that SS304 consistently absorbed greater impact energy across all tested angles, while SKD11 maintained higher rebound velocities, attributable to the stress-localizing capacity of its carbide phases. This could be a contributing factor to the improved wear resistance of SKD11 compared with SS304. Therefore, it can be concluded that the erosion behavior of steel alloys is governed by the ability of carbides to limit plastic deformation, localize stress, and reduce energy absorption at the surface.