Creep and microstructural processes in a low-alloy 2.25%Cr1.6%W steel (ASTM Grade 23)

0450056 - ÚFM 2016 RIV US eng J - Journal Article
Kuchařová, Květa - Sklenička, Václav - Kvapilová, Marie - Svoboda, Milan
Creep and microstructural processes in a low-alloy 2.25%Cr1.6%W steel (ASTM Grade 23).
Materials Characterization. Roč. 109, NOV (2015), s. 1-8. ISSN 1044-5803. E-ISSN 1873-4189
R&D Projects: GA TA ČR TA02010260; GA MŠMT(CZ) ED1.1.00/02.0068
Institutional support: RVO:68081723
Keywords : Bainitic steel * Low-alloy steel * Creep strength * Microstructural changes * Carbide precipitation
Subject RIV: JG - Metallurgy
Impact factor: 2.383, year: 2015

A low-alloy 2.25%Cr1%Mo steel (ASTM Grade 22) has been greatly improved by the substitution of almost all of the 1%Mo by 1.6%W. The improved material has been standardized as P/T23 steel (Fe–2.25Cr–1.6W–0.25V–0.05Nb–0.07C). The present investigation was conducted on T23 steel in an effort to obtain a more complete description and understanding of the role of the microstructural evolution and deformation processes in high-temperature creep. Constant load tensile creep tests were carried out in an argon atmosphere in the temperature range 500–650 °C at stresses ranging from 50 to 400 MPa. It was found that the diffusion in the matrix lattice is the creep-rate controlling process. The results of an extensive transmission electron microscopy (TEM) analysis programme to investigate microstructure evolution as a function of temperature are described and compared with the thermodynamic calculations using the software package Thermo-Calc. The significant creep-strength drop of T23 steel after long-term creep exposures can be explained by the decrease in dislocation hardening, precipitation hardening and solid solution hardening due to the instability of the microstructure at high temperature.
Permanent Link: http://hdl.handle.net/11104/0251477