【摘要】 超高温气冷堆（HTGR）是第四代核能系统重点研发的堆型之一，堆芯出口温度达到800～950℃，使得中间换热器（IHX）工作温度显著提升。Haynes230合金是IHX管材极具竞争力的候选材料，为了使管材在高温高压工况下长期安全运行，对合金抗蠕变性能评估具有重要意义。以Haynes230合金为研究对象，开展了800～950℃高温蠕变试验、蠕变行为分析和显微组织表征。通过分析稳态蠕变速率和应力关系，获得了800～950℃下的蠕变指数n介于3～7之间，据此推断合金蠕变机制为位错滑移和攀移。基于稳态蠕变速率和蠕变断裂时间的关系，建立了Haynes230合金Monkan-Grant关系模型。由Haynes230合金蠕变损伤容限与蠕变断裂时间关系可知，蠕变过程中因合金内部裂纹空洞长大导致有效面积减少而引起断裂。显微组织表征显示，固溶后Haynes230合金中主要析出相是富W的M₆C，分布在晶界附近；蠕变过程中合金中析出颗粒状的M₂₃C₆和M₆C；蠕变裂纹起源于晶界上粗大碳化物，沿垂直于受力方向扩展或沿条带碳化物扩展。透射电镜（T E M）分析显示，位错由晶内向晶界滑移，大量塞积在晶界上引起局部应力集中，从而萌发裂纹。更多还原

【Abstract】 Ultrahigh-temperature gas-cooled reactor（HTGR） is one of the key reactor types in the research and development of Generation IV nuclear energy systems, and the core outlet temperature reaches 800～950℃, which makes the working temperature of the intermediate heat exchanger（IHX） increase significantly. Haynes230 alloy is a competitive candidate for the IHX tubes, the evaluation of the creep-resistant properties of the alloy is of great significance for operating safely at high temperatures and high pressures over a long period of time. High temperature creep test of Haynes230 alloy was carried out at 800～950℃, the creep behavior and microstructure characterization were analyzed. The creep index n is between 3 and 7 obtained from the relationship of steady state creep rate and stress at 800～950℃, which inferred that the alloy creep mechanism for dislocation slip and climbing. The Monkan-Grant relationship model of Haynes230 alloy was established based on the relationship between steady state creep rate and creep rupture time. It can be seen that the growth of crack cavities inside the alloy during the creep process leads to the reduction of the effective area and causes fracture from the relationship between creep damage tolerance and creep rupture time of Haynes230 alloy. The main precipitated phase in Haynes230 alloy after solid solution is W-rich M₆C distributed near the grain boundaries; granular M₂₃C₆ and M₆C precipitated in the alloy during the creep process. The creep cracks originate from the coarse carbides on the grain boundaries, which extend perpendicularly to the direction of the force or along the stripe carbide extension. Transmission electron microscopy（TEM） analysis showed that dislocations slipped from the grain interior to the grain boundaries, and a large number of dislocations accumulated on the grain boundaries, which induce local stress concentration and initiation and propagation of cracks.更多还原