Effect of precipitated phase on resistance to hydrogen embrittlement of high Co- Cr- Mo- Ni bearing gear steel

High Co- Cr- Mo- Ni bearing gear steel was used as the test material, and hydrogen induced fracture process of the test steel was studied by TDS test, slow strain rate drawing and micro analysis. The results show that the high plasticity of the test steel is obviously decreased. Most of the hydrogen in the test steel is diffusible hydrogen, which is controlled by the weaker hydrogen trap. By comparing the grain size, the size of the strip, the number of residues, the dislocation density and the precipitation of the two kinds of test steels, the main influencing factors of the anti- hydrogen brittleness of test steel are the carbon density and distribution, and dispersed fine carbides are more conducive to improve hydrogen embrittlement resistance. The critical hydrogen concentration is obtained and the critical hydrogen concentration is deduced, which provides a reference for the high reliability and safe service of the components.