Diffusion Kinetics of Chromium in a Novel Super304H Stainless Steel

Abstract

Diffusion behavior and diffusion kinetics of chromium (Cr) from the pure chromium coating in the matrix of Super304H and TP304H steels were investigated in a temperature range of 600–900 ℃ by using energy-dispersive spectrum (EDS) quantitative line scanning and Fick’s second law of diffusion. Pure Cr coating was obtained by electroplating. Experimental results show that the diffusion depth and diffusivity of Cr increase gradually with the increase in temperature. The diffusion activation energy of Cr is found to be lower and the diffusion coefficient of Cr to be higher in the Super304H steel than those in the TP304H steel at the same temperature. Furthermore, the diffusion equation of Cr in the Super304H and TP304H steels is DCr/Super304H=1.08×10−15exp (−6.08×104/RT)${D_{{\rm{Cr/Super304H}}}} \, {\rm{=\, 1}}{\rm{. 08 \times 1}}{{\rm{0}}^{{\rm{- 15}}}}{\rm{exp\ (- 6}}{\rm{. 08 \, \times \, 1}}{{\rm{0}}^{\rm{4}}}{\rm{/RT)}}$ and DCr/TP304H=2.29×10−15exp (−7.44×104/RT)${D_{{\rm{Cr/TP304H}}}}{\rm{= 2}}{\rm{. 29 \times 1}}{{\rm{0}}^{{\rm{- 15}}}}{\rm{exp\ (- 7}}{\rm{. 44 \times 1}}{{\rm{0}}^{\rm{4}}}{\rm{/RT)}}$, respectively.

Keywords

• super304h austenitic stainless steel
• cr diffusion kinetics
• diffusion coefficient