Dwell-fatigue crack growth behaviour of Alloy 709
Dwell-fatigue crack growth behaviour of Alloy 709
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DOI：
10.1016/j.actamat.2023.118808
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发表时间：
2023-02
期刊：
影响因子：
9.4
通讯作者：
Jin Yan;Suyang Yu;R. Ding;Hangyue Li;A. Rabiei;P. Bowen
中科院分区：
文献类型：
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作者：
Jin Yan;Suyang Yu;R. Ding;Hangyue Li;A. Rabiei;P. Bowen
研究了新型奥氏体不锈钢合金709的驻留疲劳裂纹扩展行为，并与传统的316 H不锈钢进行了比较。试验程序采用1 h停留疲劳加载和0.25 Hz快速循环交替进行，以便将从停留疲劳加载获得的裂纹扩展速率（da/dN）与相同试件上纯粹从疲劳机制获得的裂纹扩展速率进行比较。在550、650和750 °C的空气中，使用0.5 T紧凑拉伸试样，在8 kN的固定最大载荷和0.1的应力比R下进行测试。在所研究的温度和ΔK范围内，观察到了疲劳、蠕变和疲劳-蠕变混合的裂纹扩展机制。进行了详细的断口和金相观察，以解释不同失效模式的失效机制和制度。与在0.25 Hz疲劳载荷下获得的裂纹扩展速率相比，驻留疲劳产生：在550 °C的测试温度下裂纹扩展速率没有明显增加;在650 °C的测试温度下适度增加（102 -5倍）;并且在750 °C的测试温度下增加超过10倍。与316 H相比，709合金对蠕变疲劳裂纹扩展的抵抗力大大提高，在650 °C的单一测试温度下得到证实。
Dwell-fatigue crack growth behaviour of an advanced austenitic stainless steel Alloy 709 has been investigated and compared with that of a conventional Type 316H stainless steel. The test procedure employed alternation of 1 h dwell-fatigue loading and 0.25 Hz fast cycling so that crack growth rates (da/dN) obtained from dwell-fatigue loading can be compared to those purely result from fatigue mechanism on the same test-piece. Tests were conducted at 550, 650 and 750 °C in air using 0.5 T compact tension test-pieces under a fixed maximum load of 8 kN and a stress ratio, R, of 0.1. For the investigated temperature and ΔK ranges, crack growth mechanisms of fatigue alone, creep alone and mixed fatigue-creep have all been observed. Detailed fractographic and metallographic observations were conducted to interpret failure mechanisms and regimes of different failure modes. Compared to crack growth rates obtained under 0.25 Hz fatigue loading, dwell-fatigue produces: no obvious increases in crack growth rates at a test temperature of 550 °C; a moderate increase (∼ 2–5 times) at a test temperature of 650 °C; and, over a tenfold increase at a test temperature of 750 °C. Compared to 316H, Alloy 709 has much improved resistance against creep-fatigue crack growth, here confirmed at the single test temperature of 650 °C.