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Reduced activation ODS ferritic steel – recent development in high speed hot extrusion processing

Zbigniew Oksiuta 1Malgorzata Lewandowska 2Krzysztof J. Kurzydlowski 2Nadine Baluc 

1. Bialystok Technical University, Faculty of Mechanical Engieering, Wiejska 45C, Białystok 15-351, Poland
2. Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland


This article presents microstructure and mechanical properties of an oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) Fe-14Cr-2W-0.3Ti-0.3Y2O3 steel fabricated by hot isostatic pressing (HIP) followed by high speed hot extrusion (HSHE) and heat treatment (HT) at 1050°C.  Transmission electron microscopy (TEM) revealed significant differences in grain size and dislocation density of as-HIPped and as-HSHE materials. Heat treatment performed after HSHE however, did not cause any significant changes in microstructure of the ODS steel.

The HSHE process significantly increased tensile and Charpy impact properties of the ODS steel. Tensile strength at room temperature increased from 950MPa up to 1400MPa and at highest testing temperature of 750°C as-HSHE material has quite good strength of about 400MPa. Also, Charpy impact properties, especially upper shelf energy (USE), significantly increased from 3.0 up to 6.0 J. Ductile-to-brittle transition temperature (DBTT), however, remained relatively high (about 75°C).

These preliminary results showed that high speed hot extrusion process of the ODS ferritic steel is a promising method for grain refinement and mechanical properties improvement.

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Presentation: Oral at E-MRS Fall Meeting 2009, Symposium H, by Zbigniew Oksiuta
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-24 19:05
Revised:   2009-06-07 00:48