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本文采用交流电位法研究了镍基高温合金GH33A在700℃、疲劳/蠕变交互作用下的裂纹扩展特性。用光学显微镜和扫描电镜对断裂特征进行了分析。结果表明:疲劳/蠕变交互作用加速裂纹扩展,且dα/dN和⊿K在双对数坐标上呈折线规律变化,实验证明:弹塑性断裂力学参数C作为疲劳/蠕变交互作用下裂纹扩展判据是可行的,并建立了经验关系式。疲劳/蠕变交互作用促进裂纹沿晶扩展。主裂纹与W型微裂纹的连接和沿滑移面剪切型扩展是疲劳/蠕变交互作用的两种主要微观断裂机理。
In this paper, the crack propagation characteristics of nickel-based superalloy GH33A under 700 ℃ fatigue / creep interaction were studied by AC potential method. The fracture characteristics were analyzed by light microscopy and scanning electron microscopy. The results show that the fatigue / creep interaction accelerates the crack growth, and the dα / dN and ⊿K changes regularly on the double logarithmic coordinates. The experimental results show that the mechanical parameters C of the elasticplastic fracture are regarded as the crack propagation under the fatigue / creep interaction Criterion is feasible, and established the empirical relationship. Fatigue / creep interaction promotes crack propagation along the grain. The connection between the main crack and the W-type microcracks and the shearing spread along the slip surface are the two main micro-fracture mechanisms of the fatigue / creep interaction.