The artificial interrupted creep-fatigue test was carried out to quantitatively investigate crack initiation and propagation rate of the CrMoV steel welded joint at 520 °C. The evolution of crack and the role of oxide could be clarified clearly by several stages. A crack of 1.6 μm length initiated on the oxide in the first 10 cycles. Then, crack propagated inside the oxide layer with a low rate, forming a periodic multilayer bamboo-like structure. Meanwhile, further oxidation resulted in deepening of oxide notches. Finally, cracks penetrated the oxide with a rate of 50 μm/cycle into the matrix resulting in the rupture.

中文翻译：

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CrMoV钢焊接接头蠕变疲劳试验裂纹演化行为的定量研究

采用人工断续蠕变疲劳试验，定量研究了CrMoV钢焊接接头在520℃时的裂纹萌生和扩展速率。裂纹的演变和氧化物的作用可以分几个阶段清楚地阐明。在前 10 个循环中，氧化物上开始出现 1.6 μm 长的裂纹。然后，裂纹以低速率在氧化层内部扩展，形成周期性的多层竹状结构。同时，进一步氧化导致氧化缺口加深。最后，裂纹以 50 μm/周期的速率穿透氧化物进入基体，导致破裂。