Strengthening mechanisms of precipitates in S30432 heat-resistant steel during short-term aging

Abstract

Abstract In order to optimize the precipitation strengthening of S30432 heat-resistant steel, the evolution and strengthening mechanisms of Nb(C,N), M23C6, and Cu-rich particles during short-term aging at 923 K were discussed, more emphasis was put on Cu-rich particles. It is Cu-rich particles, rather than Nb(C,N) or M23C6, that play the most important role in the strength of S30432 steel. At least 60% of the yield strength results from the precipitation hardening of Cu-rich particles. Furthermore, Cu-rich particle is the main factor to affect the variation of the strength of S30432 steel during short-term aging. When Cu-rich particles are smaller than 6 nm in diameter, cutting mechanism is dominant. After Cu-rich particles exceed 6 nm, Orowan bypass mechanism governs. The tendency of the calculated yield strength attributed to Cu-rich particles with aging time is in good agreement with experimental result.