Surface Morphology and Human MG-63 Osteoblasic Cell Line Response of 316L Stainless Steel after Various Surface Treatments

Abstract

In this study, the effects of three distinct surface treatment techniques on 316L stainless steel were investigated: low-temperature immersion corrosion, shot peening followed by immersion corrosion, and electrochemical corrosion. These techniques were selected with a focus on their potential implications for biomedical implant applications, as research gaps persist in understanding the influence of these treatments. A comprehensive examination of surface alterations was conducted using scanning electron microscopy, Raman spectroscopy, and α-step thin-film thickness profiling. Furthermore, human MG-63 osteoblastic cell line adhesion was evaluated using Liu’s stain and metallographic optical microscopy. Notable differences in cell-adhesion behavior based on the chosen surface treatment methods were observed. Specifically, weak cell adhesion was observed after low-temperature immersion and shot peening followed by immersion corrosion. In contrast, electrochemical corrosion, especially when conducted with a high current density and low corrosive-solution concentration, resulted in a uniformly corroded surface, which, in turn, promoted dense cell adhesion. Porous oxide layers were generated using all three techniques, but the efficacy of shot peening (applied at 1 kg/cm2 for 20 s) and electrochemical corrosion (using 0.5 M HCl) as promising processes were highlighted by our experimental results. Uniformly dense corrosion pits were produced through electrochemical corrosion, while semicircular grooves with small corrosion pits were the result of shot peening, both of which were found to be favorable for cell adhesion. The superior cell adhesion observed with electrochemical corrosion further emphasizes its suitability for biomedical applications.