Abstract A phenomenological damage model is proposed to account for the strain rate dependency of the damaging processes at high temperature. Mechanical softening during tertiary creep and monotonic tension are modeled by an isotropic scalar internal variable D, whose evolution is described using a rate damage law d D / d t = ⋯ governed by visco-plasticity and accounting for the enhancement by stress triaxiality. A novel rate sensitive damage threshold is introduced in order to reproduce the rate dependency of the onset of damaging processes. Damage evolution is coupled with the visco-plasticity model developed by the same authors for single crystal superalloys and accounting for microstructural evolution (like γ ' -rafting and coarsening) in Desmorat et al. (2017). The curves presented in this article are identified at 1050 °C for the Ni base single crystal superalloy CMSX-4 but the proposed rate sensitive threshold modeling can be applied to other alloys showing a rate sensitive damage onset, as for example the single crystal superalloys MC2 but also the polycrystalline aggregate AD 730™.

中文翻译：

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速率相关延展性和损伤阈值：应用于镍基单晶 CMSX-4

摘要 提出了一种现象学损伤模型来解释高温下损伤过程的应变率依赖性。三次蠕变和单调张力期间的机械软化由各向同性标量内部变量 D 建模，其演变使用速率损伤定律 d D / dt = ⋯ 描述，由粘塑性控制，并考虑应力三轴性的增强。引入了一种新的速率敏感损坏阈值，以重现损坏过程开始的速率依赖性。损伤演化与同一作者为单晶高温合金开发的粘塑性模型相结合，并在 Desmorat 等人中解释了微观结构演化（如 γ '-漂流和粗化）。(2017)。