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对调质42CrMo钢进行室温下各种应力循环和对称应变循环的低周疲劳实验,揭示材料的循环软化特性,棘轮变形和低周疲劳特性以及棘轮-疲劳交互作用。结果表明,调质42CrMo钢体现出明显的循环软化;在应力幅值或平均应力较高时,试样的棘轮变形较大,其破坏形式为延性破坏,而在应力水平较低时,材料的破坏由疲劳裂纹扩展所致的脆性断裂引起;材料在应力循环下的低周疲劳寿命由于有棘轮变形的产生而受到平均应力、应力幅值、最大应力和应变比等多种因素的影响。
Low-cycle fatigue experiments were conducted on the tempered 42CrMo steels at various room temperature cycles under various stress cycles and symmetrical strain cycles to reveal the material’s cyclic softening characteristics, ratcheting deformation and low cycle fatigue characteristics, and ratcheting-fatigue interaction. The results show that the tempered 42CrMo steel shows obvious cyclic softening. When the stress amplitude or average stress is high, the ratchet deformation of the sample is larger and its failure mode is ductile failure. When the stress level is lower, Which is caused by the brittle fracture caused by the fatigue crack propagation. The low cycle fatigue life of the material under stress cycling is affected by many factors such as average stress, stress amplitude, maximum stress and strain ratio due to the ratcheting deformation.