|About this Abstract
||2022 TMS Annual Meeting & Exhibition
||Phase Transformations and Microstructural Evolution
||Z-phase Formation in a 12% Cr Tempered Martensite Ferritic Steel during Long Term Creep
||Johan Westraadt, William Goosen, Aleksander Kostka, Hongcai Wang, Gunther Eggeler
|On-Site Speaker (Planned)
The formation of Z-phase in a 12% Cr tempered martensite ferritic (TMF) steel subjected to interrupted long term creep testing at 550 °C and 120 MPa was investigated. Four samples were tested up to defined creep-strain values of 0.5%, 1.0%, 1.6%, and 11.9% (failure-139 kh). Z-phase and MX precipitates were quantified from EFTEM elemental maps taken on thin-foils prepared from the (non-deformed) gauge and grip sections. Z-phase precipitated in both the gauge (fv: 0.4%) and grip regions (fv: 0.3%) of the sample tested to failure. The formation of Z-phase was accompanied by a progressive dissolution of the important creep-strengthening MX precipitates, which decreased from an initial fv of 0.17% to less than 0.05% in the gauge section of the sample tested to failure. The preferred nucleation sites, MX/Z-phase transformation mechanism, and the effects of stress (gauge vs grip) and creep-deformation in the failure zone on Z-phase formation will be discussed.
||High-Temperature Materials, Characterization, Other