Development of 9Cr-ODS ferritic–martensitic steel prepared by chemical reduction and mechanical milling

Abstract

The oxide dispersion strengthened ferritic–martensitic steels with a nominal composition of Fe–9Cr–1.5W–0.45Mn–0.1Ta–0.2V–0.01Si–0.2Ti–0.3Y2O3–0.1/0.2C (9Cr-ODS) were fabricated by sol–gel method in combination with hydrogen reduction, mechanical alloying (MA) and spark plasma sintering (SPS) techniques. X-ray diffraction patterns show that pure Fe–0.3Y2O3 precursor was obtained at reduction temperature of 650°C for 3h and pure 9Cr-ODS alloy powders were obtained by mechanical alloying. After SPS sintering and normalizing and tempering process the relative density of the compacted ingots is about 98.1%. The microstructure analysis investigated by transmission electron microscopy (TEM) reveals that the average size of oxide particles in sample I (0.1C, wt.%) and sample II (0.2C, wt.%) are about 14nm and 20nm, respectively. The uniform elongation, ultimate tensile strength of the 9Cr-ODS alloy of sample II with thermal treatment is about 2.5% and 950MPa.