Abstract The present investigation deals with low cycle fatigue (LCF) behavior of the IN-617 alloy, after oxidation at 850 °C for varying durations, without and with mixed salt coating. LCF tests were conducted under fully reversed axial strain controlled mode at a strain rate of 5 × 10−3 s−1 and strain amplitude of ±0.25% at 850 °C to examine the influence of oxidation and mixed salt coating of 10%NaCl+90%Na2SO4, on fatigue life and deformation behavior under cyclic loading. Oxidation of the samples up to 1000 h did not show any significant effect on fatigue life, whereas fatigue life of the salt coated and pre-exposed samples was drastically reduced with increase in duration of the exposure. Stress amplitude decreased with increase in the duration of the exposure. Salt coated samples exhibited lower stress amplitude compared to that of the oxidized samples. XRD analysis and Electron Probe Micro Analysis (EPMA) elemental mapping confirmed formation of effective Cr2O3 layer on the surface and Al2O3 layer beneath the surface which provided good oxidation resistance at this temperature. The depth of oxide layer increased with increase in the duration of oxidation. Under salt environment, these oxide layers were broken and the substrate was exposed to corrosive environment, which caused severe intergranular hot corrosion of the samples. The depth of intergranular corrosion was increased with increase in the duration of exposure. Chromium sulphide was found to be the detrimental product formed along the grain boundaries and was the prime reason for rapid crack propagation and reduction in the fatigue life.

中文翻译：

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盐涂层预暴露IN-617合金的低周疲劳行为

摘要 本研究涉及 IN-617 合金的低周疲劳 (LCF) 行为，在 850 °C 氧化不同时间后，没有和有混合盐涂层。LCF 测试在完全反向轴向应变控制模式下进行，应变速率为 5 × 10−3 s−1，应变幅度为 ±0.25%，在 850 °C 下进行，以检查氧化和 10%NaCl+ 混合盐涂层的影响90%Na2SO4，关于循环载荷下的疲劳寿命和变形行为。样品氧化长达 1000 小时对疲劳寿命没有任何显着影响，而盐涂层和预暴露样品的疲劳寿命随着暴露时间的增加而急剧降低。应力幅值随着暴露时间的增加而降低。与氧化样品相比，盐涂层样品表现出较低的应力幅度。XRD 分析和电子探针显微分析 (EPMA) 元素映射证实在表面上形成了有效的 Cr2O3 层，在表面下方形成了 Al2O3 层，在该温度下提供了良好的抗氧化性。氧化层深度随着氧化时间的增加而增加。在盐环境下，这些氧化层被破坏，基体暴露在腐蚀环境中，导致样品发生严重的晶间热腐蚀。晶间腐蚀深度随着暴露时间的增加而增加。发现硫化铬是沿晶界形成的有害产物，是裂纹快速扩展和疲劳寿命缩短的主要原因。