摘要
本文对各种铸铁的低周疲劳寿命进行了测试,探讨了石墨形态、基体组织对铸铁低周疲劳寿命的影响。结果表明;1)各种铸铁的总应变幅Δε_t与疲劳寿命N_f的关系可用Manson-Coffin提出的Δε_t/2=σ_f′/E(2N_f)~b+ε_f′(2N_f)~c表示;在相同的总应变幅下,球铁的低周疲劳寿命高于蠕铁,而蠕铁高于灰铁;2)在疲劳过程中,灰铁表现为循环软化特征,而球铁表现为复杂的循环软化、硬化现象,疲劳过程中的循环软化、硬化现象与铸铁中微裂纹形成及扩展机制有关。本文提出了球铁在疲劳过程中微裂纹形成及扩展的模型;3)在低应变幅下,弹性应变幅对疲劳寿命的贡献比塑性应变幅大,而在高应变幅下,塑性应变幅对疲劳寿命的贡献大。
In this paper, low-cycle fatigue life of various cas irons has been measured. The effect of the graphitic morphology and matrix struc-tures on lower-cycle fatigue life of cast irons has been discussed. The result showed that:1) For various cast irons, the relationship between total strain amplitude and fatigue life can be described by the equation presented by Manson-Coffin. Under the condition of same total strain amplitude, the life of ductile iron was higher than vermicular graphite cast iron, and vermicular graphite cast iron was higher than gray iron.2) In the fatigue process, gray iron presented the characteristics of cyclic softening, and ductile iron showed the speciality of complex cyclic soften-inghardening. The phenomena of cyclic softening and hardening were related to the formation and propagation of microcracks. A model of the formation and propagation of microcracks has been proposed in this paper.3) Under the condition of low strain amplitude, the effect of elastic str ain amplitude was higher than plastic strain amplitude; the result was contrast at high strain amplitude.
出处
《钢铁研究学报》
CAS
CSCD
北大核心
1992年第4期57-64,共8页
Journal of Iron and Steel Research
关键词
铸铁
低周疲劳
疲劳寿命
cast iron, low-cycle fatigue, fatigue life
