Microstructural Evolution of Cr-Rich ODS Steels as a Function of Heat Treatment at 475 °C

Abstract

In the current research, the effect of heat treatment on the morphology of the dispersoids and their phase composition were investigated in three Cr-rich ferritic oxide dispersion strengthened (ODS) steels: PM2000, MA956, and ODM751. The steels were aged at 475°C for times ranging from 100 to 1,000 h. The microstructure was characterized using transmission electron microscopy. Study of the as-recrystallized samples revealed nano-scale Y-Al-O complex-oxide particles dispersed in the ferritic matrix. These dispersoids, which differ in size (10-160 nm) and geometry (polygonal and spherical), were identified as Y 4 Al 2 O 9 , YAlO 3 , and Y 3 Al 5 O 12 . After heat treatment, a significant change in the morphology, size, and distribution of the dispersoids was observed. Changes in the phase composition of the oxide dispersoids were also observed: YAlO 3 (with perovskite structure) was identified as the most dominant phase, indicating that it is probably the most stable phase in the Cr-rich ferritic ODS steels.

Quantitative Phase-Field Simulation of Composition Partition and Separation Kinetics of Nanoscale Phase in Fe-Cr-Al Alloy

“…Fe-Cr-Al alloys have good corrosion resistance, radiation resistance, and mechanical strength, and they are being developed as structural materials for the next generation of nuclear reactors, such as fusion reactors, sodium fast reactors, lead-cooled fast reactors, and supercritical water reactors [1][2][3][4][5]. Also, because of the comprehensive performance of Fe-Cr-Al alloys in steam environments, these alloys are under consideration for accident-tolerant fuel-cladding applications [6][7][8].…”

Powder bed fusion additive manufacturing of Ni-based superalloys: a review of the main microstructural constituents and characterization techniques

“…3, 5, 7, 8, 9, 14, 16, 18, and 19 for example, SEM can provide reliable insights into the morphology of c, c 0 and other phases that are of sizes [ * 20 nm due to its 2 nm resolution. Further examples of the extensive uses of SEM include characterizing initial powders, cracks and porosities, and melt pool boundaries [54,149,223,[232][233][234]. SEM operates on the basis of an electron beam scanning the surface of a conductive sample in a vacuum chamber.…”

Microstructure of High‐Chromium Ferritic–Martensitic Steels for Next‐Generation Reactors

“…Both effects can be explained based on the crystallographic phase diagram of the Fe-Cr system. [29][30][31][32][33][34][35][36][37][38][39][40] The investigated steel NS219 is a high-chromium ferritic-martensitic steel, which excels in mechanical resistance, corrosion resistance, and high hardness due to the presence of chromium carbides. NS219 steel is therefore suitable candidate (in the future development) for applications where the mechanical and chemical resistance of the surface is emphasized.…”

“…Both effects can be explained based on the crystallographic phase diagram of the Fe–Cr system. [ 29–40 ]…”