Microstructures and properties of cast T91-ODS alloys

Abstract

The T91-oxide dispersion strengthening alloys were fabricated by directly adding Y₂O₃ at the micrometer scale using a casting method. The microstructural observation and energy dispersive spectral analysis revealed that complex oxide particles with diameters of 2–5 mm, which contained elemental Y, were produced because of the chemical reactions between the added Y₂O₃ particles and the matrix elements. Fractures appeared after tensile testing, and a substrate beneath the complex oxide particles was formed to generate equiaxial dimples centered on the oxide particles. Moreover, the mechanical properties of the T91-oxide dispersion strengthening steel containing 0·2% (wt-%) Y₂O₃ were superior to the T91-oxide dispersion strengthening containing 0·4% Y₂O₃, and differed greatly from that of common T91 steel.

Keywords:

• T91
• Y₂O₃
• ODS
• Casting