Abstract：Microstructure and mechanical properties of newly developed 40Si2Ni2CrMoV steel （code name N1） and the existing 45CrNiMoVA steel were investigated by scamning electron microsope (SEM)，transmission electron microscope (TEM)，X-rany diffraction (XRD) and chemical phase analysis，and hydrogen embrittlement of these two steels was also investigated by slow strain rate tensile. The results show that N1 steel can keep high strength at higher temper temperature of 300 ℃ due to the addition with silicon and molybdenum element，which improve resistance to tempering softening. The fine ε-carbide in N1 steel can improve the yield strength，which keeps the yield ratio above 0.8，while the yield strength of 45CrNiMoVA steel is 1 550 MPa at the lower temper temperature of 180 ℃，and the yield ratio is only 0.72. The hydrogen embrittlement of N1 steel significantly lower than of 45CrNiMoVA steel，which is shown in the following aspects： the slow strain rate tensile strength of N1 steel decreases slightly compared with 45CrNiMoVA steel，and there is no intergranular fracture feature observed in tensile sample fracture.
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2017, Vol. 52 
