Abstract

The effects of short-term aging on the precipitation and corrosion behavior of a Ni-Cr-Mo-based superalloy Hastelloy C276 were studied in this work. Aging treatments were performed at 800 °C for 1 h, 2 h, 4 h, 8 h, 12 h and 15 h. It is found that M₆C carbide, which is rich in Mo and W, is prone to precipitate at grain boundary when the aging time exceeds 4 h, associated with the formation of a Mo and W depletion zone adjacent to the grain boundary. The potentiodynamic polarization curves in 3 wt.% NaCl solution show no obvious differences among the aged samples. But the surface morphologies of samples after double-loop electrochemical potentiodynamic reactivation method (DL-EPR) tests in HCl solution present typical intergranular corrosion attack. The calculated degrees of sensitization based on the DL-EPR curves increase dramatically with the increase in aging time, which is consistent with the precipitation trends. It is recommended that hot working of Hastelloy C276 superalloy should avoid high temperature exposure (e.g., at 800 °C more than 4 h) or do heat treatment again after high-temperature processing.

中文翻译：

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高温时效对Ni-Cr-Mo基哈氏合金C276高温合金析出和腐蚀行为的影响

摘要

在这项工作中，研究了短期时效对Ni-Cr-Mo基高温合金Hastelloy C276的析出和腐蚀行为的影响。在800°C下进行时效处理1 h，2 h，4 h，8 h，12 h和15 h。发现M ₆当时效时间超过4 h时，富含Mo和W的碳化物易于在晶界析出，这与在晶界附近形成Mo和W耗尽区有关。在3 wt。％NaCl溶液中的电位动力学极化曲线在老化样品之间没有明显差异。但是在HCl溶液中进行双回路电化学恒动力再活化方法（DL-EPR）测试后，样品的表面形貌呈现出典型的晶间腐蚀。根据DL-EPR曲线计算的敏化度随老化时间的增加而急剧增加，这与降水趋势一致。建议高温加工哈氏合金C276高温合金应避免高温暴露（例如，