Porosity Effect on the Scratch Tests of Austenitic Stainless Steel (AISI 316L)

<div class="section abstract"><div class="htmlview paragraph">Austenitic stainless steel (AISI 316L) is highly valued in various industries for its properties, especially related to wear and corrosion resistances. There are several applications of austenitic stainless steel in the automotive industry. This study investigates the effects of porosity of SS316L samples fabricated using powder metallurgy (uniaxial pressure). Two different compaction pressures, 300 MPa, and 600 MPa, were applied to analyze their influence on the material’s density, porosity, microstructure, hardness, and abrasion responses. The SS316L samples were sintered at 1120 °C for 30 min. The microstructural analysis revealed that the sample pressed at 600 MPa exhibited higher density and lower porosity (18.9%) compared to the sample pressed at 300 MPa (29.2%). This increased compaction pressure led to a more uniform microstructure with smaller grain sizes and a more consistent distribution of circular pores. Consequently, the hardness of the 600 MPa sample was significantly higher across all testing loads, attributed to grain refinement and higher density. Tribological performance was evaluated through scratch tests using a Rockwell C tip, and considering 20 N as the normal load applied. The 3D interferometry technique was used to analyze the profiles of the wear track and surface roughness. The 600 MPa sample provided superior wear resistance, with lower scratch depth and coefficient of friction (COF) compared to the 300 MPa sample. The specific energy values indicated that the 600 MPa sample dissipated more energy due to increased resistance to plastic deformation, resulting in less material removal and enhanced abrasion resistance. Scanning electron microscopy (SEM) analysis of the wear tracks confirmed micro-ploughing as the predominant wear mechanism in both samples. However, the 300 MPa sample exhibited more irregular pore distribution, leading to localized slight transitions from micro-ploughing to micro-cutting, which increased susceptibility to material removal and wear. This study shows that optimizing compaction parameters to minimize porosity is critical for enhancing the abrasion resistance of SS316L. Therefore, controlling porosity is highlighted in this research, which shows how important it is to achieve abrasion resistance materials for critical applications in automotive tribosystems.</div></div>