Recovery of creep properties of a vanadium-strengthened steel (1Cr1Mo0.75VTiB) by reheat treatment

A reheat treatment cycle for Durehete 1055 has been developed, the first stage of which removes grain boundary creep cavitation. Subsequent stages control microstructural parameters such as prior austenite grain size and allow in-service degradation of the vanadium carbide precipitate distribution to be reversed. Samples have been examined using a range of optical and electron optical techniques, and the compositions of extracted carbide precipitates have been determined using STEM-EDS X-ray microanalysis. It is shown that by reheat treatment the uniaxial creep life of creep-ruptured, ex-service material can be restored, and the creep ductility of previously coarse-grained material improved. The application of the results to life regeneration of service components is briefly discussed.