常用大轴材料旋转弯曲疲劳行为研究

摘要

采用台湾产HT-8120型旋转弯曲疲劳试验机研究了汽轮发电机转子锻件材料25Cr2Ni4MoV和水轮机大轴材料20SiMn的旋转弯曲疲劳性能.结果表明,常用转轴材料25Cr2Ni4MoV与20SiMn的疲劳极限σ-1明显大于o.27(Rp0.2+Rm),设计中选用0.27(Ro0.2+Rm)作为的疲劳极限进行计算时,转轴的安全系数会高于实际值.大型转轴试样表面和内部的碳化物和氧化物夹杂容易萌生疲劳源,其中表面的碳化物和氧化物夹杂对疲劳性能的降低相近,内部的碳化物和氧化物夹杂对疲劳性能的降低亦相近,内部夹杂危害性小于表面夹杂.%The bending fatigue properties of turbine generator rotor forging 25Cr2Ni4MoV and hydraulic turbine shaft 20SiMn were studied using the HT-8120 type rotating bending fatigue testing machine.The results show that the fatigue limits σ-1 of 25Cr2Ni4MoV and 20SiMn are significantly larger than the 0.27(Rpo.2+Rm),so the safety factor becomes larger with 0.27 (Rp0.2+Rm) as bending fatigue limit in the calculation.The inclusions of sub surface carbide and oxide are similar to the reduction of fatigue properties,and the inclusions of internal carbide and oxide are also similar to the reduction of fatigue properties.The harmfulness of internal inclusion is less than that of the surface inclusion.