高温堆非纯氦气中预氧化对3种高温合金的腐蚀行为影响研究

高温气冷堆（简称高温堆）中，由于一回路冷却剂氦气中含有微量（ppm级）不纯杂质，其在高温环境中会对高温堆合金材料造成腐蚀，影响设备的性能。Inconel 617、Hastelloy X、Incoloy 800H是3种高温堆中间换热器及蒸汽发生器设备候选材料。研究表明，镍铬合金在高温下表面生成的富铬氧化层是防止合金在高温下发生严重腐蚀的重要因素。本文对3种合金在高温含杂质氦气中的腐蚀行为进行研究，探究预氧化对3种合金腐蚀行为的影响。并通过称重、扫描电镜、X射线能谱、电子探针显微分析仪以及碳硫分析仪对腐蚀结果进行分析。结果表明，3种合金均出现了不同的氧化和渗碳现象，预氧化对Hastelloy X合金抗腐蚀能力的提升不明显，对Inconel 617合金的抗氧化和渗碳能力有一定提升，对Incoloy 800H合金的抗渗碳腐蚀能力有一定提升。

Effect of Pre-oxidation on Corrosion Behavior of Three Kinds of Superalloys in Impure Helium of High-temperature Reactor

Nuclear energy is a clean, efficient and high-quality modern energy. It is of great significance to alleviate energy shortage, improve ecological environment and optimize energy structure. As a kind of the fourth generation nuclear power system, high-temperature reactor has good inherent safety and economy, high power generation efficiency and wide application of process heat. The superior performance of high-temperature reactor is closely related to the excellent alloy materials. Due to the high temperature of helium in the primary circuit of high-temperature reactor, a trace of graphite dust generates certain gas impurities after chemical reaction. At the same time, due to the introduction of impure helium and gas leakage, the helium in the main coolant of high-temperature reactor contains trace gas impurities such as CO, H₂O, CH₄, CO₂, N₂ and O₂, and the concentration of impurities is in the order of ppm. Impurities in high-temperature environment will cause corrosion, oxidation, carburization and decarburization of alloy materials in high-temperature reactor steam generator and intermediate heat exchanger, and affect the reliability and safety of equipment. Inconel 617, Hastelloy X and Incoloy 800H are three candidate materials for high-temperature reactor intermediate heat exchanger and steam generator equipment. According to the studies, it shows that the chromium rich oxide layer formed on the surface of NiCr alloy at high temperature is an important factor to prevent serious corrosion of the alloy at high temperature. In this paper, the corrosion behavior of three alloys in high temperature helium containing ppm impurity was studied, and the effect of pre-oxidation in extremely low oxygen partial pressure He-1 atmosphere on the corrosion behavior of three alloys was explored. After the test, the corrosion results of the alloy with or without pre-oxidation were analyzed by weighing, scanning electron microscope, X-ray energy spectrum analysis, electron probe microanalyzer and carbon sulfur analyzer. The results show that the three alloys have different oxidation and carburization phenomena, and the carburization behavior has ended when they are corroded for 50 h. CH₄ plays an important role in the carburizing corrosion process of alloys. Pre-oxidation has no obvious improvement on the corrosion resistance of Hastelloy X alloy, less improvement on the oxidation resistance and carburizing capacity of Inconel 617 alloy and less improvement on the carburizing corrosion resistance of Incoloy 800H alloy. According to the test results, it can be concluded that the oxide layer formed by short-time pre-oxidation in extremely low oxygen partial pressure He-1 atmosphere is not necessary to improve the corrosion resistance of the alloy.