Growth kinetics of the borided 316L stainless steel obtained by selective laser

Selective laser melting (SLM) is a cost-effective 3D metal additive manufacturing (AM) process. However, AM 316L SS has different surface and microstructure properties as compared to conventional ones. Boriding process is one of the ways to modify and increase the surface properties. The aim of this study is to predict and understand the growth kinetic of iron boride layers on AM 316L SS. In this study, for the first time, the growth kinetic mechanism was evaluated for AM 316L SS. Pack boriding was applied at 850, 900 and 950 degrees C, each for 2, 4 and 6 h. The thickness of the boride layers ranged from (1.8 +/- 0.3) mu m to (27.7 +/- 2.2) mu m. A diffusion model based on error function solutions in Fick's second law was proposed to quantitatively predict and elucidate the growth rate of FeB and Fe2B phase layers. The activation energy (Q) values for boron diffusion in FeB layer, Fe2B layer, and dual FeB+Fe2B layer were found to be 256.56, 161.61 and 209.014 kJ/mol, respectively, which was higher than the conventional 316L SS. The findings might provide and open new directions and approaches for applications of additively manufactured steels. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(SLM)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(AM)(sic)(sic).(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic) AM 316L SS (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)AM 316L (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)AM 316L (sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)850,900 (sic)950 degrees C(sic)(sic)(sic)(sic)(sic)(sic)(sic)2,4 (sic)6 h.(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(1.8 +/- 0.3) mu m (sic)(27.7 +/- 2.2) mu m.(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)FeB (sic)Fe2B (sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)FeB (sic),Fe2B (sic)(sic)FeB+Fe2B (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) 256.56,161.61 (sic)209.014 kJ/mol, (sic)(sic)(sic)316L SS (sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic).