Novel Cost-Efficient Method of Producing Ausferritic Steels Displaying Excellent Combination of Mechanical Properties
2020 (English)In: Metallography and Fractography XVII: Selected full text papers from the 17th International Symposium on Metallography, Fractography and Materials Science (2019) / [ed] Peter Horňak; Margita Longauerová; Miloš Matvija, Trans Tech Publications, 2020, p. 11-18Conference paper, Published paper (Refereed)
Abstract [en]
ound bars Ø 53 mm were hot-rolled from a 1.4 tonne ingot forged to 165 × 165 mm. The composition of the steel was 0.45 wt. % C and 3.33 wt. % Si plus alloying elements for hardenability. Microstructure after air cooling from 1010 °C on the cooling bed was predominantly ausferritic. Tensile testing of as-rolled bars resulted in yield strength 846 ± 22 MPa, ultimate tensile strength 1169 ± 99 MPa and A5-elongation of 1.7 ± 0.8 % (without prior necking). When as-rolled steel was baked in air at T = {Ms initial -30 K} for six hours, the yield stress raised to 1121 ± 4 MPa, the ultimate tensile stress raised to 1447 ± 5 MPa and the elongation raised to 22.6 ± 1.6 % (with necking > 18 %). For as-rolled bars during continuous cooling, the exposure time within the temperature range 460 – 320 °C was estimated to be about 10 minutes. The microstructure of as-rolled “semi-finished” bars is stable at room temperature. The first baking was done six months after hot-rolling. Optical and scanning electron microscopy showed that remaining areas of austenite, not transformed during continuous cooling but stable at room temperature, transforms to ausferrite when properly baked.
Place, publisher, year, edition, pages
Trans Tech Publications, 2020. p. 11-18
Series
Defect and Diffusion Forum, ISSN 1012-0386, E-ISSN 1662-9507 ; 405
Keywords [en]
Ausferrite, Ausferritic steel, Baked, Continuously cooled, High silicon, Medium carbon
National Category
Metallurgy and Metallic Materials
Research subject
Engineering Materials
Identifiers
URN: urn:nbn:se:ltu:diva-85861DOI: 10.4028/www.scientific.net/DDF.405.11Scopus ID: 2-s2.0-85097614838OAI: oai:DiVA.org:ltu-85861DiVA, id: diva2:1571032
Conference
17th International Symposium on Metallography, Fractography and Materials Science, Nový Smokovec, April 24-26, 2019
Note
ISBN för värdpublikation: 978-3-0357-3612-0; 978-3-0357-1612-2;
Finansiär: Research Fund for Coal and Steel
2021-06-222021-06-222023-09-05Bibliographically approved