铁素体/马氏体钢在液态铅铋中的断裂力学试验研究进展

Research Progress on Fracture Mechanics Test of Ferritic/Martensitic Steel in Liquid Lead and Bismuth

基于第四代核反应堆的发展与需要,具有低熔点的铅基快堆成为当前研究热点之一.作为铅基快堆中的冷却剂,铅铋共晶合金(LBE)对铁素体/马氏体钢断裂性能的影响成为了研究热点.论文首先介绍了铁素体/马氏体钢在液态铅铋中的相容性研究进展,包括液态金属腐蚀(LMC)和液态金属脆化(LME)两个方面,然后分析了液态金属环境下断裂力学测试方法,阐述了液态铅铋共晶合金对铁素体/马氏体钢断裂性能的影响,最后总结了铁素体/马氏体钢在液态铅铋中断裂的微观机制.

Based on the development of fourth-generation nuclear reactors,lead-based reactors with low melting point have become one of the current research hotspots.As a coolant in lead-based fast reactors,the effect of lead-bismuth eutectic(LBE)alloy on the fracture properties of ferritic/martensitic steel has become a research hotspot.However,current studies have found certain problems in the compatibility of ferritic/martensitic steel in high-temperature liquid lead-bismuth alloys.Under certain conditions,the fracture test of ferritic/martensitic steel in liquid lead-bismuth can cause metal embrittlement.At the same time,the test method in the liquid lead-bismuth environment is not perfect and the explanation mechanisms of metal embrittlement phenomenon have not reached a consensus.In view of the above problems,we analyze and summarize the research status of fracture mechanics in the lead-bismuth environment and propose the current deficiencies and solutions.At first,we summarize the research progress of compatibility of ferritic/martensitic steel in liquid lead and bismuth,including liquid metal corrosion(LMC)and liquid metal embrittlement(LME).Then,we introduce the mechanical testing system in the lead-bismuth environment developed by various institutions and the main fracture mechanics test methods in the lead-bismuth environment,including the slow tensile test,low-cycle cyclic fatigue test and fracture test.The typical phenomenon of liquid metal embrittlement is mainly manifested in three aspects in the fracture mechanics test:a decrease in mechanical properties including tensile strength,elongation and fatigue life;a“toughness valley”on the elongation-temperature curve;and a ductile-brittle transition and a unique mode of crack initiation and propagation on microscopic characterization.In the end,we introduce several typical microscopic mechanisms for the fracture of ferritic/martensitic steel in liquid lead and bismuth.According to current research findings,the surface energy reduction model has been accepted by most scholars.Based on the above-mentioned problems,optimization suggestions are given in this paper in terms of experimental device,data acquisition method,microscopic characterization and mechanism analysis.