Accelerated grain boundary migration in nanolaminated interstitial-free steel during chromizing

Abstract

A nanolaminated surface layer was produced on interstitial-free steel by surface mechanical rolling treatment. While the microstructure showed relatively high thermal stability during annealing at 500°C, significant grain boundary (GB) migration occurred in the nanolaminated surface layer during chromizing at the same temperature. GB diffusion of Cr was observed under the Harrison B-type regime in the chromized surface layer. The accelerated GB migration was discussed to be influenced by enhanced GB energy and mobility due to the GB diffusion and enrichment of Cr in nanolaminated structures. Meanwhile, the high stresses introduced during sample preparations also enhance the coarsening kinetics.

Keywords

• nanolaminated structure
• diffusion
• grain boundary migration
• thermal stability
• surface mechanical rolling treatment