Microstructural observation and tensile properties of ODS-304 austenitic steel

ODS-304 austenitic steel (pre-alloyed austenitic steel powders +0.35 wt% Y2O3+0.5 wt% Ti) was fabricated by the process of mechanical alloying and hot isostatic pressing. The milled powders were characterized by XRD and SEM. New peaks of YO1.401 appeared after milling of 5 h, which indicated that Y2O3 decomposed and dissolved into the matrix during MA. A bimodal distribution of grains was found in the as-HIPed specimen by TEM. It was found that fine oxide particles enriched in Y-Ti-O were dispersed in the small grains, while there were almost no dispersoids inside the large grains. Plastic deformations, including forging and hot rolling, were subjected to the as-HIPed specimens. Tensile properties were measured at 23 and 700 degrees C At 23 degrees C. the UTS and elongation of the as-HIPed specimen reached 940 MPa and 24.5% respectively. Specimens showed much higher ductility after plastic deformations while there was just slight decrease of tensile strength at the same time. (C) 2012 Elsevier B.V. All rights reserved.