EFFECT OF Ce ON THE MICROSTRUCTURE AND PROPERTIES OF 27Cr-4Mo-2Ni SUPER-FERRITIC STAINLESS STEEL WITH 800 °C AGING

The influence of Ce additions on the microstructure and properties of 27Cr-4Mo-2Ni super-ferritic stainless steel during 800 °C aging was systematically investigated via thermodynamic calculations, microstructural characterizations, impact and corrosion measurements. The results indicated that with an increase of Ce content from 0.00 w/% to 0.050 w/%, Al2O3 wrapped by TiNb(CN) were gradually modified into CeAlO3 wrapped by TiNb(CN), spheroidal Ce2O3, and Ce2O2S, the ferrite grain was noticeable refined, the  phase changed from continuously distributed with a coarser size to dispersedly distributed with a tiny size accompanied by an increase in number, the impact toughness of super-ferritic stainless was improved at 25 °C, and the cleavage facets at the morphology of a fully brittle fracture becomes smaller, the uniform corrosion resistance of super-ferritic stainless steel to 40 vol.% H2SO4 were enhanced especially at 60 °C.