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本文总结了30 Cr Mn SiA钢的疲劳裂纹起始寿命及正、负超载对疲劳裂纹起始寿命影响的实验结果,并用公式Ni=C′_(pr)(ΔK_I/ρ~(1/2))~k_p对实验结果进行了拟合。实验结果表明,对于调质处理的30 Cr Mn SiA钢,其疲劳裂纹起始寿命为Ni=9.27×10~(12)(ΔK_I/ρ~(1/2))~(-2.94);经(ΔK_I/ρ~(1/2))_(OV)=2254 MPa的正超载后,Ni=1.74×10~(16)(ΔK_I/ρ~(1/2))~(-3.85)。正超载的主要作用看来是增大k_p的绝对值,这一作用难以用残留应力的叠加模型给以完满的解释;本文试图用切口根部塑性区内金属性能在超载后发生变化来说明。未观测到同等数值的负超载对30 Cr Mn SiA钢的疲劳裂纹起始寿命有任何影响。
In this paper, the experimental results of fatigue crack initiation life and positive and negative overload on fatigue crack initiation life of 30 Cr Mn SiA steel are summarized. ) ~ k_p The experimental results were fitted. The experimental results show that for quenched and tempered 30 Cr Mn SiA steel, the fatigue life of the fatigue crack is Ni = 9.27 × 10-12 (ΔK_I / ρ ~ (1/2)) ~ (-2.94) Ni = 1.74 × 10 ~ (16) (ΔK_I / ρ ~ (1/2)) ~ (-3.85) after positive overload with ΔK_I / ρ ~ (1/2)) _ (OV) = 2254 MPa. The main effect of positive overloading appears to be to increase the absolute value of k_p, which is hard to interpret satisfactorily with the overlay model of residual stresses; this article attempts to illustrate the behavior of the metal in the plastic zone at the root of the incision after it is overloaded. No negative overload of the same magnitude was observed to have any effect on the fatigue crack initiation life of 30 Cr Mn SiA steels.