Precipitate composition regulation and corrosion resistance improvement of boron-containing S31254 steels through a pre-aging treatment

Boron (B) at the grain boundary (GB) influences the segregation of Cr and Mo in S31254 super austenitic stainless steels, which inhibits the formation of precipitates. In this work, to make full use of B at the GB, a pre-aging treatment schedule at 300 ℃ for 50 and 150 min was proposed. After pre-aging treatment and high-temperature aging at 950 ℃, B-containing S31254 was used to investigate the effect of heat treatment on the precipitates. Results verified that pre-aging treatment for 50 and 150 min could promote the segregation of B at GB, and the nucleation of precipitates was inhibited during high-temperature aging. Consequently, the B-containing and Mo-rich precipitates were formed at 950 ℃. Especially, pre-aging treatment for 50 min showed the optimum effect on regulating precipitate compositions. B-containing and Mo-rich phase reduced the Cr-depleted region near the precipitates, which could remarkably improve corrosion resistance. Pre-aging treatment and high-temperature aging can regulate precipitate compositions, which can in turn improve corrosion resistance.