PT Journal
AU Rehorek, J
TI Effect of PWHT of X6Cr-NiNbN 25-20 Steel on the Evolution of the Sigma Phase during Creep Exposure at 700 °C
SO Manufacturing Technology Journal
PY 2023
BP 893
EP 899
VL 23
IS 6
DI 10.21062/mft.2023.091
DE HR3C; Weld joint; σ phase; Creep; PWHT; A-USC
AB Superheaters and reheaters made of heat-resistant austenitic steels are being replaced in existing fos-sil fuel power plants to operate at Advanced Ultra Super Critical (A-USC) parameters of steam. New-ly developed and used high nickel content austenitic steels, such as in X6Cr NiNbN 25-20, are pre-dicted to significantly suppress the precipitation of a hazardous σ-phase during long-term creep expo-sure. The σ-phase causes premature failure of the component during creep, which is usually support-ed by a local change in hardness in the case of welded assemblies. Experimental results show that PWHT significantly improved reduction of area. However, for the PWHT specimen with a shorter exposure time of 15,712 hours, there was an acceleration in the precipitation of σ-phase particles dur-ing creep at 700 °C compared to the specimen in the AW state, after 20,557 hours.
ER