Mechanical properties and thermal stability of nanostructured ODS RAF steels

Zbigniew Oksiuta , Małgorzata Lewandowska , Krzysztof Kurzydłowski

Abstract

The main goal of the research reported in this paper was to evaluate the microstructure and mechanical properties of an oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steel after a long-term and high temperature annealing. The mechanically alloyed ODS RAF steel powder with a composition of Fe-14Cr-2W-0.3Ti-0.3Y2O3 was consolidated by hot isostatic pressing at 1150 C for 3 h followed by a high speed hydrostatic extrusion at 900 C. The samples were subsequently exposed to various heat treatments, such as annealing at 850 C-1350 C for 1 h in argon and to a long-term isothermal annealing at 750 C up to 10 000 h in air. The results indicate that due to the Zener pinning of the nanoparticles at the grain boundaries, the ODS RAF steel is thermally stable up to high annealing temperature of 1250 C. However, annealing at 1050 C applied after the hydrostatic extrusion of the steel significantly improves its ductility. Further increase in the temperature up to 1350 C resulted in nanoparticles coarsening (size ∼8.0 nm, number density 2.5 × 023 m-3) accompanied by an increase in the volume fraction of the coarse grains and a reduction of microhardness from 460 to 330 HV0.1. Long-term annealing at 750 C up to 10 000 h brought about a systematic loss of both strength and ductility. However, the microhardness increases up to 500 HV0.1. TEM observations revealed that the grain size after ageing remains almost unchanged. On the other hand, the number of dislocation free larger grains and of larger precipitates with a size of ∼25 nm located at grain boundaries significantly increase. © 2013 Elsevier Ltd. All rights reserved.

Author Zbigniew Oksiuta - Bialystok University of Technology (PB)
Zbigniew Oksiuta,,
-
, Małgorzata Lewandowska (FMSE / DMD)
Małgorzata Lewandowska,,
- Division of Materials Design
, Krzysztof Kurzydłowski (FMSE / DMD)
Krzysztof Kurzydłowski,,
- Division of Materials Design
Journal seriesMechanics of Materials, ISSN 0167-6636
Issue year2013
Vol67
Pages15-24
Publication size in sheets0.5
Keywords in EnglishODS RAF steel, HIPping HSHE, High temperature-long term annealing, Tensile testing, Activation energy
ASJC Classification2211 Mechanics of Materials; 2500 General Materials Science; 3105 Instrumentation
DOIDOI:10.1016/j.mechmat.2013.07.006
URL https://www.sciencedirect.com/science/article/pii/S016766361300135X
Languageen angielski
Score (nominal)40
Score sourcejournalList
ScoreMinisterial score = 40.0, 10-06-2020, ArticleFromJournal
Ministerial score (2013-2016) = 40.0, 10-06-2020, ArticleFromJournal
Publication indicators Scopus Citations = 34; WoS Citations = 25; Scopus SNIP (Source Normalised Impact per Paper): 2013 = 1.721; WoS Impact Factor: 2013 = 2.225 (2) - 2013=2.575 (5)
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