• X. J. Shen
  • D. Z. Li
  • S. Tang
  • J. Chen
  • H. Fang
  • G. D. Wang

It is still a big challenge to obtain excellent low-temperature toughness for bulk steel materials. Delamination is an effective method to improve low-temperature toughness. In the present study, delamination toughening in a low carbon microalloyed steel plate with elongated and ultrafine-grained microstructure rolled in the dual-phase region has been investigated in detail. When toughness was measured along normal direction, the steel plate had a high upper shelf energy and no delamination occurred in the upper shelf region. A large delaminated crack parallel to rolling plane started to appear and changed the propagation path of main crack when testing temperature was lower than −60 °C. We find this kind of delamination induces a second upper shelf in the Charpy transition–temperature curve. The second upper shelf, reaching up to 300 J in the temperature range of −60 °C to −140 °C, results in excellent low-temperature toughness for the steel plate, and the ductile-brittle transition temperature is lowered to −157 °C. The developed steel plate also has high low-temperature toughness measured along transverse direction due to delamination. The effect factors on upper shelf energy, delamination mechanism and delamination toughening are discussed.

Original languageEnglish
Article number138342
Number of pages9
JournalMaterials Science and Engineering A
Volume766
DOIs
Publication statusPublished - 24 Oct 2019

    Research areas

  • Crystallographic texture, Delamination toughening, Elongated and ultrafine-grained microstructure, Steel plates

ID: 56897037