Diffusion of chromium in ferritic and austenitic 9–20 wt-%chromium steels

Abstract

Radiotracer ⁵¹Cr diffusion experiments were conducted on 9–20 wt-% chromium ferritic and austenitic steels. Volume diffusion coefficients have been determined in the temperature range 881–1281 K, and triple product values of grain boundary diffusion between 795 and 1281 K. Compared with dilute solid solutions, high ratios of grain boundary and volume diffusion activation energies have been obtained. This is discussed in view of the chemical composition of the grain boundaries measured by Auger electron spectroscopy. Furthermore, in the case of ferritic steels the effects of α–γand paramagnetic–ferromagnetic phase transitions are illustrated, while for austenitic steels a classical Arrhenius relationship has been found in the investigated temperature range.