Proceedings of the Third International Conference on Metals & Hydrogen P63

Hydrogen trapping in carbon supersaturated α-iron and its decohesion effect in martensitic steel

W.T. Geng (1)1(2)2 , V. Wang (1)1(3)3 , Jin-Xu Li (2)2 , Nobuyuki Ishikawa (4)4 , Hajime Kimizuka (1)1 , Kaneaki Tsuzaki (5)5(6)6 , Shigenobu Ogata (1)1(6)6

  • (1) 1

    Department of Mechanical Science and Bioengineering, Osaka University, Osaka 560-8531, Japan

  • (2) 2

    University of Science and Technology Beijing, Beijing 100083, China

  • (3) 3

    Department of Applied Physics, Xi’an University of Technology, Xi’an 710054, China

  • (4) 4

    Steel Research Laboratory, JFE Steel Corporation, Kanagawa 210-0855, Japan

  • (5) 5

    Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan

  • (6) 6

    Center for Elements Strategy Initiative for Structural Materials, Kyoto University, Kyoto 606-8501, Japan


It is generally accepted that martensite in steels is more susceptible to hydrogen embrittlement than ferrite. The atomic-scale mechanism underlying this phenomenon, nevertheless, is not fully understood yet. Our first-principles calculations demonstrate hydrogen is more stable in carbon supersaturated martensite than in a-iron, due to the carbon-induced tetragonality in martensite lattice. The trapped hydrogen leads to remarkable decohesion between (110) planes both inside the martensite and along the martensite/ferrite interface, with the former being more significant than the latter. This decohesion can help to understand recent precise observations that in martensite/ferrite dual-phase steel the hydrogen-promoted crack was initiated in the martensite region and that in lath martensite steel it propagated not on lath boundaries but showed cleavage feature along (110) planes at very high hydrogen concentration.