42CrMo钢M+F双相组织接触疲劳、多冲疲劳及弯曲疲劳性能研究

用42CrMo钢经亚温淬火获得马氏体 未溶铁素体双相组织(M F)，未溶铁素体含量分别为0％、3％、10％、15％和20％。就未溶铁素体含量对接触疲劳、多冲疲劳及弯曲疲劳性能的影响机理进行研究，局部的应力集中因铁素体发生塑变而得到松弛和细化晶粒是提高疲劳寿命的主要原因。试验结果表明，M F双相组织的接触疲劳、多冲疲劳、弯曲疲劳寿命均比单-M组织的疲劳寿命高。三种试样的疲劳寿命均随未溶铁素体含量的增加而相应提高，且有最佳值。在文中试验条件下，未溶铁素体含量达到最佳值(10％)时，三种试样的疲劳寿命皆为最高。

STUDY ON CONTACT, IMPACT AND BENDING FATIGUE LIFE OF 42CrMo STEEL WITH M + F DUAL-PHASE STRUCTURE

M+F dual-phase structures were gained through subcritical quenching in 42CrMo steel. The amount of undissolved ferrite were 0%,3%,10%,15% and 20%, respectively. The effect of undissolved ferrite amount on contact, impact and bending fatigue properties were studied. The stress relaxation and grain refinement due to occurring of plastic deformation are main reasons of improving the fatigue life. The experimental results show that the contact, impact and bending fatigue life of M+F dual-phase structure is longer than that of mono-martensite structure. The contact, impact and bending fatigue life elongates with the increase of amounts of undissolved ferrite before the amount of undissolved ferrite reaches 10%. Under the experiment conditions, when the amount of undissolved ferrite is 10%, the contact, impact and bending fatigue life will be the longest.