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本文探讨了五种模具钢5CrNiMo、60Si2Mn、GCr15、3Cr2W8V、Cr12MoV的疲劳裂纹扩展速率da/dN和扩展临界长度a_(co)提高淬火温度使中碳5CrNiMo、60Si2Mn、3Cr2W8V钢的da/dN下降,使高碳低合金钢GCr15的da/dN增大。高碳高铬钢Cr12MoV采用二次硬化处理后,其da/dN小于一次硬化处理。提高淬火温度,不仅提高中碳合金钢及高碳高合金钢的疲劳扩展抗力,并且使疲劳断口的沿晶断裂百分比大幅度增加。这表明,提高淬火温度使中碳钢原奥氏体晶粒内和晶界的结合强度均升高;使高碳钢原奥氏体晶粒内和晶界的结合强度均下降。
In this paper, the fatigue crack growth rate da / dN and extended critical length a_ (co) of five kinds of die steel 5CrNiMo, 60Si2Mn, GCr15, 3Cr2W8V and Cr12MoV were investigated to increase the da / dN of medium carbon 5CrNiMo, 60Si2Mn and 3Cr2W8V steel by increasing the quenching temperature, The high carbon low alloy steel GCr15 da / dN increased. High-carbon high-chromium steel Cr12MoV secondary hardening treatment, the da / dN less than a hardening treatment. Increasing the quenching temperature not only improves the fatigue resistance of medium carbon steel and high carbon high alloy steel, but also increases the percentage of intergranular fracture of fatigue fracture greatly. This shows that increasing the quenching temperature increases the bond strength between the austenite grain boundaries and the grain boundaries in the medium carbon steel and decreases the bonding strength between the austenite grain boundaries and the grain boundaries in the high carbon steel.