An experimental procedure is developed to identify and quantify a connection between compressive creep and the evolution of fracture toughness. Specifically, it is determined that an accumulation of compressive creep leads to a reduction in fracture toughness. Insight into the mechanism responsible for this observed behavior is pursued. Fractography performed following the fracture toughness tests shows a transition from ductile to brittle failure caused by the presence of residual creep. The quantified effect of compressive creep on fracture toughness is applied in a thermomechanical fatigue (TMF) model to simulate crack propagation in the single crystal nickel-based superalloy PWA 1484. Considering the coupling between compressive creep and decreased crack resistance led to significantly improved TMF life prediction. Further application of the developed experimental procedure to fully quantify the evolution of fracture toughness as a function of creep accumulation will lead to greater TMF and structural life predictive capabilities. This finding has implications for a wide variety of materials and applications involving high temperature dwell fatigue including in the aerospace, energy, and manufacturing sectors.

中文翻译：

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压缩蠕变对断裂韧性的影响：应用于热机械疲劳 (TMF) 寿命预测

开发了一种实验程序来识别和量化压缩蠕变与断裂韧性演变之间的联系。具体而言，确定压缩蠕变的累积导致断裂韧性降低。深入了解导致这种观察到的行为的机制。断裂韧性测试后进行的断口分析显示，残余蠕变的存在导致从韧性破坏到脆性破坏的转变。压缩蠕变对断裂韧性的量化影响应用于热机械疲劳 (TMF) 模型，以模拟单晶镍基高温合金 PWA 1484 中的裂纹扩展。考虑到压缩蠕变和抗裂性降低之间的耦合导致 TMF 寿命显着提高预言。进一步应用开发的实验程序来完全量化作为蠕变积累函数的断裂韧性的演变，将导致更大的 TMF 和结构寿命预测能力。这一发现对涉及高温驻留疲劳的各种材料和应用具有重要意义，包括航空航天、能源和制造领域。