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研究了IN718合金在360℃、550℃和650℃下的低周疲劳行为及疲劳裂纹扩展速率da/dN,包括循环应力-应变行为、Massing效应、低周疲劳寿命的能量表达以及疲劳裂纹扩展速率,并讨论了保持时间对da/dN的影响。实验结果表明,该合金在各种温度下表现出循环软化,在本文所试温度下具有Massing特性,其塑性应变能与疲劳寿命在双对数坐标中呈现出很好的线性关系,其da/dN随温度的升高而增大,在650℃下保持时间对da/dN的影响很明显,而550℃时则很轻微。
The low cycle fatigue behavior and fatigue crack growth rate da / dN of IN718 alloy at 360 ℃, 550 ℃ and 650 ℃ were investigated. The energy expresses including cyclic stress-strain behavior, Massing effect, low cycle fatigue life, and fatigue crack growth rate , And discusses the effect of hold time on da / dN. The experimental results show that the alloy exhibits a cyclic softening behavior at various temperatures and a Massing property at the temperature tested in this paper. The plastic strain energy and the fatigue life show a good linear relationship in double logarithmic coordinates. The da / dN increases with increasing temperature, and the effect of holding time at 650 ℃ on da / dN is obvious, while it is slight at 550 ℃.