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

The oxide dispersion strengthened ferritic-martensitic steels with a nominal composition of Fe-9Cr-1.5 W-0.45Mn-0.1Ta-0.2 V-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 3 h 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 14 nm and 20 nm, respectively. The uniform elongation, ultimate tensile strength of the 9Cr-ODS alloy of sample II with thermal treatment is about 2.5% and 950 MPa.