Delamination effect on impact properties of ultrafine-grained low-carbon steel processed by warm caliber rolling

Tadanobu Inoue, Fuxing Yin, Yuuji Kimura, Kaneaki Tsuzaki, Shojiro Ochiai

研究成果: ジャーナルへの寄稿学術誌査読

129 被引用数 (Scopus)

抄録

Bulk ultrafine-grained (UFG) low-carbon steel bars were produced by caliber rolling, and the impact and tensile properties were investigated. Initial samples with two different microstructures, ferrite-pearlite and martensite (or bainite), were prepared and then caliber rolling was conducted at 500 °C. The microstructures in the rolled bars consisted of an elongated UFG structure with a strong α-fiber texture. The rolled bar consisting of spheroidal cementite particles that distributed uniformly in the elongated ferrite matrix of transverse grain sizes 0.8 to 1.0 μm exhibited the best strength-ductility balance and impact properties. Although the yield strength in the rolled bar increased 2.4 times by grain refinement, the upper-shelf energy did not change, and its value was maintained from 100 °C to -40 °C. In the rolled bars, cracks during an impact test branched parallel to the longitudinal direction of the test samples as temperatures decreased. Delamination caused by such crack branching appeared, remarkably, near the ductile-to-brittle transition temperature (DBTT). The effect of delamination on the impact properties was associated with crack propagation on the basis of the microstructural features in the rolled bars. In conclusion, the strength-toughness balance is improved by refining crystal grains and controlling their shape and orientation; in addition, delamination effectively enhances the low-temperature toughness.

本文言語英語
ページ(範囲)341-355
ページ数15
ジャーナルMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
41
2
DOI
出版ステータス出版済み - 2月 2010
外部発表はい

!!!All Science Journal Classification (ASJC) codes

  • 凝縮系物理学
  • 材料力学
  • 金属および合金

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