Effect of thermo-mechanical treatment on microstructure and mechanical properties of P92 heat resistant steel

The effect of thermo-mechanical treatment on the microstructure and mechanical properties of commercial P92 steel was investigated. The steels were warm-rolled in metastable austenitic state with reductions of 75 and 93%, respectively. Tempering in a certain temperature range from 650 to 765 degrees C for 1 h was subsequently used to optimize the size of precipitates and form a homogeneous steady-state dislocation structure through recovery process. The results showed that the microstructure was obviously refined and a great amount of nano-scale precipitates were increased significantly compared to the as-received material. The tensile strengths and microhardness were significantly improved by increasing plastic deformation and tempering at 650 and 700 degrees C, but were decreased dramatically after tempering at 765 degrees C. The creep tests were carried out at 600 degrees C under 210 MPa and at 650 degrees C under 160 MPa. The results demonstrated that the creep rupture life of the thermo-mechanical treated P92 steel was improved significantly. High density of homogeneously distributed precipitates reduced creep rates by pinning the grain boundaries and blocking the motion of dislocation. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.