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本文研究了回火温度对5CrMnMo钢疲劳裂纹扩展的影响,并着重分析了350℃回火后疲劳扩展行为与显微组织的关系。结果表明:疲劳裂纹扩展速率(da/dn)不仅与回火后的硬度有关,且与回火后的组织变化有关;5CrMnMo钢350℃回火后,晶界上析出碳化物,造成晶界弱化,使da/dn及m值提高;而且疲劳裂纹扩展对晶界弱化的敏感性主要与晶粒度及应力强度因子有关。
In this paper, the influence of tempering temperature on the fatigue crack growth of 5CrMnMo steel was studied. The relationship between the fatigue propagation behavior and microstructure after tempering at 350 ℃ was emphatically analyzed. The results show that the fatigue crack growth rate (da / dn) is not only related to the hardness after tempering but also to the microstructure after tempering. When the steel is tempered at 350 ℃, carbide precipitates on the grain boundary, resulting in the grain boundary weakening , So da / dn and m values increased; and the fatigue crack growth susceptibility to grain boundary weakening and grain size and stress intensity factor.