Effects of scanning speed on in vitro biocompatibility of 316L stainless steel parts elaborated by selective laser melting

Abstract

In this work, we investigate effects of scanning speed (800 mm s⁻¹, 900 mm s⁻¹, 1083 mm s⁻¹) on in vitro biocompatibility of 316L stainless steel (SS) parts elaborated by selective laser melting (SLM). Cytotoxicity assay and hemolytic test are adopted to assess the in vitro biocompatibility of 316L SS parts. The experimental results show that the scanning speed has strong effects on the in vitro cytotoxicity of 316L SS parts and no significant effect on the hemolysis. In order to investigate the mechanism of effects of scanning speed on in vitro biocompatibility, microstructures of 316L SS parts via SLM are obtained by scanning electron microscopy (SEM). The finer grain and less defects lead to better biocompatibility, due to the increase of corrosion resistance and decrease of toxicity ions release. In cases of 900 and 1083 mm s⁻¹, finer microstructures can be observed and the minimum manufacturing defects are formed on 316L SS parts under 900 mm s⁻¹ scanning speed. The results indicate that by changing the scanning speed, the microstructures, in terms of the quality of grain and the mount of defects, can be adjusted; as a result, controllable biocompatibility of 316L SS parts via SLM can be achieved.