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利用旋转弯曲疲劳试验方法研究了新开发的一种锻造用贝氏体型非调质钢的高周疲劳性能,并与典型的钒微合金化的铁素体-珠光体型非调质钢F38MnVS和调质钢40Cr进行了对比。结果表明,开发的贝氏体型非调质钢具有细小均匀的粒状贝氏体组织,在锻态的疲劳极限比达到了调质钢40Cr水平,但在正火后的疲劳性能有所降低。与同样钒微合金化的铁素体+珠光体钢F38MnVS相比,具有粒状贝氏体组织的试验钢的疲劳极限比较低。对疲劳断口的分析表明,贝氏体钢的疲劳裂纹均起源于试样的基本表面,疲劳裂纹以准解理机制扩展。进一步裂纹扩展速率试验表明,贝氏体钢的疲劳裂纹扩展速率da/dN明显低于铁素体+珠光体型非调质钢F38MnVS。
The high cycle fatigue behavior of a newly developed bainitic non-quenched and tempered steel for forging was studied by means of rotational bending fatigue test. The results were compared with the typical ferritic-pearlite non-quenched and tempered steel F38MnVS 40Cr compared to the quality of steel. The results show that the bainitic non-quenched and tempered steel developed has fine and uniform granular bainite structure, and the fatigue limit ratio in forged state reaches 40Cr of quenched and tempered steel, but its fatigue performance decreases after normalizing. The fatigue life of the test steel with granular bainitic structure is lower than that of the same vanadium microalloyed ferritic + pearlite steel, F38MnVS. The analysis of fatigue fracture shows that the fatigue cracks of bainitic steel all originate from the basic surface of the sample, and the fatigue crack expands with quasi-cleavage mechanism. Further crack growth rate tests showed that the fatigue crack growth rate da / dN of bainitic steels was significantly lower than that of ferritic + pearlite non-quenched and tempered steels F38MnVS.