Heat Treatment of Metals ›› 2021, Vol. 46 ›› Issue (7): 233-237.DOI: 10.13251/j.issn.0254-6051.2021.07.045

• TEST AND ANALYSIS • Previous Articles     Next Articles

Effect of nitrogen-methanol atmosphere on hydrogen-induced fracture of45CrNiMoVA high strength steel

Jia Dongsheng1, Hong Zhenjun1,3, Wang Xiaohai1, Wang Maoqiu2, Mao Lu1, Zhang Ruijun1   

  1. 1. Inner Mongolia First Machinery Group Co.,Ltd., Baotou Inner Mongolia 014032, China;
    2. Institute of Specical Steel, Central Iron & Steel Research Institute, Beijing 100081, China;
    3. School of Materials Science and Engineering,Shanghai Jiao Tong University, Shanghai 200240, China
  • Received:2021-02-15 Online:2021-07-25 Published:2021-12-10

Abstract: A fractured high-strength torsion bar made of 45CrNiMoVA steel was analyzed by means of chemical composition analysis, fracture morphology analysis, microstructure analysis and mechanical property tests. The hydrogen content on the surface of the parts under nitrogen methanol protective atmosphere was measured, and the influence mechanism of hydrogen induced defects on torsion fatigue of the high-strength steel parts was discussed. The preventive measures to prevent hydrogen permeation were put forward and verified by experiments. The results show that the heating of high strength steel in nitrogen-methanol protective atmosphere can lead to hydrogen invasion and hydrogen embrittlement, which affects the torsional fatigue life of high strength steel parts. The surface oxidation decarburization can be effectively prevented by changing the nitrogen-methanol controlled atmosphere to nitrogen protection and applying the anti-decarburization coating on the spline parts artificially. No fracture occurs in the high-strength steel torsion bars by the improved processes.

Key words: 45CrNiMoVA high strength steel, nitrogen-methanol atmosphere, hydrogen permeation, dehydrogenation, hydrogen induced fracture

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