{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,19]],"date-time":"2026-10-19T23:36:29Z","timestamp":1792452989453,"version":"4.5.0"},"reference-count":30,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2021,3,26]],"date-time":"2021-03-26T00:00:00Z","timestamp":1616716800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005308","name":"Amada Foundation","doi-asserted-by":"publisher","award":["AF-2019009-B2"],"award-info":[{"award-number":["AF-2019009-B2"]}],"id":[{"id":"10.13039\/501100005308","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Ductile-to-brittle transition (DBT) temperature and brittle fracture stress, \u03c3F, are important toughness criteria for structural materials. In this paper, low-carbon steels with an ultrafine elongated grain (UFEG) structure (transverse grain size 1.2 \u03bcm) and with two ferrite (\u03b1)-pearlite structure with grain sizes 10 \u00b5m and 18 \u00b5m were prepared. The UFEG steel was fabricated using multipass warm biaxial rolling. The tensile tests with a cylindrical specimen and three-point bending tests with a single-edge-notched specimen were performed at \u2212196 \u00b0C. The local stress near the notch was quantitatively calculated via finite element analysis (FEA). The \u03c3F for each sample was quantified based on the experimental results and FEA. The relationship between \u03c3F and d\u03b1 in the wide range of 1.0 \u03bcm to 138 \u03bcm was plotted, including data from past literature. Finally, the conditions of grain size and temperature that cause DBT fracture in low-carbon steel were shown via the stress\u2212d\u22121\/2 map. The results quantitatively showed the superiority of \u03b1 grain size for brittle fracture.<\/jats:p>","DOI":"10.3390\/ma14071634","type":"journal-article","created":{"date-parts":[[2021,3,26]],"date-time":"2021-03-26T13:17:53Z","timestamp":1616764673000},"page":"1634","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":40,"title":["Ductile-to-Brittle Transition and Brittle Fracture Stress of Ultrafine-Grained Low-Carbon Steel"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7366-7688","authenticated-orcid":false,"given":"Tadanobu","family":"Inoue","sequence":"first","affiliation":[{"name":"National Institute for Materials Science, 1-2-1, Sengen, Tsukuba 305-0047, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hai","family":"Qiu","sequence":"additional","affiliation":[{"name":"National Institute for Materials Science, 1-2-1, Sengen, Tsukuba 305-0047, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6969-3165","authenticated-orcid":false,"given":"Rintaro","family":"Ueji","sequence":"additional","affiliation":[{"name":"National Institute for Materials Science, 1-2-1, Sengen, Tsukuba 305-0047, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuuji","family":"Kimura","sequence":"additional","affiliation":[{"name":"National Institute for Materials Science, 1-2-1, Sengen, Tsukuba 305-0047, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,3,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"023001","DOI":"10.1088\/1468-6996\/13\/2\/023001","article-title":"Progress in thermomechanical control of steel plates and their commercialization","volume":"13","author":"Nishioka","year":"2012","journal-title":"Sci. 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