调质42CrMo钢的弯曲微动疲劳实验研究

针对循环软化材料调质42CrMo钢进行了常规弯曲疲劳实验和弯曲微动疲劳实验,分析了常规弯曲疲劳和弯曲微动疲劳之间的差异,并讨论了循环弯曲载荷对疲劳寿命的影响。通过分析不同弯曲载荷下弯曲微动疲劳试样断口的形貌和不同循环次数下微动损伤的情况,揭示调质42CrMo钢弯曲微动疲劳过程中的损伤特性。研究结果表明:同一循环载荷作用下,弯曲微动疲劳的寿命明显低于常规弯曲疲劳的寿命;随着循环弯曲载荷的增大,弯曲微动疲劳的寿命降低更明显;微动引起的局部接触疲劳和局部塑形变形促进了弯曲微动疲劳裂纹的萌生和进一步扩展。

EXPERIMENTAL STUDY ON BENDING FRETTING FATIGUE OF TEMPERED 42CrMo STEEL

Experiments on the plain bending fatigue and bending fretting fatigue for cyclic softening material tempered 42CrMo steel are carried out in this study. The difference between the plain bending fatigue and bending fretting fatigue mechanisms is identified, and the influence of cyclic bending load on the fatigue lives is discussed. The morphology of fracture surface under different bending loads and the fretting damage characteristics under different numbers of loading cycles in the bending fretting process are also investigated, with a view to studying the damaging mechanisms of bending fretting fatigue. Results show the lifespan of tempered 42CrMo steel under the bending fretting fatigue is much shorter than that under the plain bending fatigue, subjected to the same bending load. The fatigue lifespan of tempered 42CrMo steel decreases as the cyclic bending load increases under bending fretting fatigue. The local contact fatigue and the local plastic deformation due to bending fretting cause initiation and further propagation of fatigue cracks.