The Precipitated Particle Refinement in High-Cr ODS Steels by Microalloying Element Addition

Abstract

Two oxide-dispersion-strengthened (ODS) steels with different compositions (14Cr-ODS and 14Cr-Zr-ODS) were investigated to reveal the influences of microalloying element addition on the microstructure and to clarify the refining mechanism of precipitated particles. TEM and HRTEM results indicated that precipitated particles in the Zr-containing ODS steel had finer sizes and dispersed more homogeneously within the grains. It was found that rhombohedral Y4Zr3O12 particles with complex lattice structures were formed and could pin the migration of the grain boundaries during heat treatment due to their high thermal stability. In addition, the Zr-containing ODS steel exhibited a finer and more uniform grain morphology. Tensile tests showed that microalloying element addition could significantly improve the comprehensive mechanical properties of 14Cr ODS steels at room temperature.

Microstructure and Mechanical Properties of Y4Zr3O12-Added Fe–13.5Cr–2W Oxide-Dispersion-Strengthened Steels, Containing High Contents of C and N, Prepared by Mechanical Alloying and Two-Step Spark Plasma Sintering

“…Wu et al [ 39 ] showed that the UTS of Fe–15Cr–2W–0.35Ti–0.6Y 4 Zr 3 O 12 ODS steel, produced by HIP, was 1006 MPa, with a UE of 15.5% at RT. Li et al [ 79 ] indicated that the UTS of Fe–14Cr–1.5W–0.9Zr–0.45Y 2 O 3 ODS steel, prepared by HIP, was 981 MPa, with a UE of 16.7% at RT. Li et al [ 80 ] reported that the UTS of Fe–14Cr–2W–0.3Ti–0.3Y 2 O 3 ODS steel, fabricated by SPS, was ~940 MPa to ~1500 MPa at RT, with sintering temperatures ranging from 950 °C to 1025 °C, and it should be noted that the UTS decreased with the increase in the sintering temperature.…”

Phase Equilibria of the Fe–Cr–Er Ternary System in the Range 973–1273 K

“…ODS steel is strengthened by dispersing oxide particles, which strongly impede dislocation motion and thereby increase the onset stress of plastic deformation and creep resistance [ 2 , 3 ]. ODS ferritic/martensitic steels containing 9–12 mass% Cr have been developed as fuel cladding material because of their high creep strength at elevated temperatures and adequate resistance to neutron irradiation embrittlement [ 4 , 5 , 6 , 7 , 8 , 9 ]. The performance of ODS steel largely depends on the particle size and stability of the dispersed oxide nanoparticles [ 10 , 11 ].…”