Microstructural evolution of Fe-20Cr-30Ni-2Nb-5Al AFA steel during creep at 760 °C

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:806

Article

Peterson, Andrew¹  Baker, Ian¹ 

[1] Dartmouth Coll, Thayer Sch Engn, Hanover, NH 03755 USA

关键词: AFA steel;    Creep;    Microstructure;    Precipitates;    Precipitate-free zone;   

DOI  :  10.1016/j.msea.2020.140602

来源: Elsevier

【 摘 要 】

The microstructural evolution of an alumina-forming austenitic stainless-steel Fe-20Cr-30Ni-2Nb-5Al (at. %) was investigated after creep at 760 degrees C. It was found that the secondary creep rate was correlated with changes in the microstructure. During creep, both Laves phase and B2 precipitates in the matrix both coarsened and increased in volume fraction. In addition, nano-sized L1(2)-structured Ni3Al precipitates nucleated and then coarsened and increased in volume fraction during creep. Grain boundary coverage by Laves phase and B2 precipitates increased during creep, and a precipitate free zone (PFZ) formed along the grain boundaries at creep times great than 2000 h. The creep rate decreased for times up to similar to 2000 h primarily due to strengthening from the L1(2) precipitates, with grain boundary strengthening playing a minor role. At longer times, there was a slight increase in creep rate, due to the coarsening of precipitates in the matrix and the formation of the PFZ.

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