Mechanical Characterization of a Nano-ODS Steel Prepared by Low-Energy Mechanical Alloying

Abstract

An oxide dispersion strengthened (ODS) ferritic steel with nanometric grain size has been produced by low-energy mechanical alloying (MA) of steel powder (Fe-14Cr-1W-0.4Ti) mixed with Y 2 O 3 particles (0.3 wt %) and successive hot extrusion (HE). The material exhibits superior mechanical properties with respect to the unreinforced steel up to 400 • C; then such differences tend to progressively decrease and at 700 • C yield stress (YS) and ultimate tensile strength (UTS) values are very close. The microstructure and mechanical behaviour have been compared with those of ODS steels prepared by the most common process, high-energy MA, consolidation through hot isostatic pressing (HIP) or hot extrusion (HE), annealing around 1100 • C for 1-2 h. The main strengthening mechanisms have been examined and discussed to explain the different behaviour. In addition, heat treatments in the range 1050-1150 • C were carried out and a microstructural evolution with a relevant hardness decrease has been observed. TEM observations evidenced defect recovery and partial grain coarsening owing to the not perfectly homogeneous distribution of oxide particles.

Alloys for Aeronautic Applications: State of the Art and Perspectives

“…As shown in Figure 9 taken from ref. [138], ODS steel exhibits higher YS and UTS than the unreinforced one, even if the difference progressively decreases above 400 • C because dislocations can easier get free from nano-precipitates. Mechanical properties are also better up to 500 • C than those of ODS steel prepared through the conventional route.…”

“…Some of present authors [138,139] prepared a nano-ODS steel by means of low-energy MA without the annealing stage at high temperature, obtaining a microstructure of fine equiaxed grains. As shown in Figure 9 taken from ref.…”

“…L and T indicate samples taken along longitudinal and transverse direction, respectively. The figure is taken from[138].…”

High Temperature and Corrosion Properties of A Newly Developed Fe-Al-O Based OPH Alloy

“…If cast iron is taken as an example, its hardness is high and its tensile strength resistance is low, showing the independence between parameters. In the case of rather brittle materials the correlation can be rather weak [32,33].…”

Vacuum Hot Pressing of Oxide Dispersion Strengthened Ferritic Stainless Steels: Effect of Al Addition on the Microstructure and Properties

“…Oxide dispersion strengthened (ODS) ferritic-stainless steel (FSS) is widely used in the advanced fission and fusion reactors because of their excellent high-temperature properties [1][2][3][4][5][6][7]. In addition, the presence of highly rigid nano-sized oxide particles in ferritic ODS steels offers superior resistance to neutron irradiation.…”