Strengthening Mechanism of S30432 Austenitic Heat-resistant Steel

摘要

The microstructure of as-supplied, as-aged and as-crept $30432 at 650°C (=923 K) was examined to study the strengthening mechanism, especially the precipitation behavior and the contribution of precipitated particles to the creep rupture strength were emphasized. Results show that Nb(C,N) precipitates in the as-supplied microstructure, while aging and creep result in the precipitation of e-Cu and M2;C,. High creep rupture strength of S30432 steel is attributed to the precipitation hardening of e-Cu, Nb(C,N) and M2;C.. Extremely, e-Cu plays an important role in improving the creep rupture strength of $30432, and at least 61% of the creep rupture strength of $30432 at 650°C results from the precipitation hardening of e-Cu particles.