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本文论述淬火工艺及显微组织对5CrMnMo钢疲劳扩展特性的影响,并分析在350℃回火使晶界弱化的条件下,疲劳裂纹的扩展行为。研究结果表明:随淬火温度升高,则较低ΔK下的疲劳裂纹扩展速率da/dn降低,疲劳扩展寿命Np升高;经双重处理(1200/60O+880℃)的组织具有最低的da/dn和最高的Np,超高温(1200℃)淬火组织也具有较低的da/dn和较高的Np。350℃回火会使疲劳裂纹扩展曲线斜率m值和da/dn增大,提高淬火温度会使da/dn及m值均有所下降。
In this paper, the effect of quenching process and microstructure on the fatigue properties of 5CrMnMo steel is discussed. The fatigue crack propagation behavior under the condition of tempering at 350 ℃ is also analyzed. The results show that with the increase of quenching temperature, the fatigue crack growth rate da / dn decreases and the fatigue life extension Np increases at lower ΔK. The microstructure of the double treated (1200 / 60O + 880 ℃) has the lowest da / dn and the highest Np, ultra-high temperature (1200 ℃) quenched tissue also has lower da / dn and higher Np. The tempering at 350 ℃ will increase the slope m and da / dn of the fatigue crack growth curve, while increasing the quenching temperature will decrease the values of da / dn and m.