一种铅基快堆用高硅不锈钢的热处理工艺优化及铅铋相容性研究

Heat-treatment optimization and heavy liquid metal compatibility of Si-enriched F/M steel for LFR structure application

针对自行制备的11Cr-1Si铁素体/马氏体不锈钢开展了热处理制度探索,及力学性能、铅铋环境静态腐蚀和应力腐蚀行为研究.热处理研究结果表明,11Cr-1Si不锈钢在经过调质热处理后(950℃/60 min+750℃/120 min)能够在保证较高强度的同时获得良好的韧性.500℃静态腐蚀结果表明,11Cr-1Si在经过3368 h腐蚀后表面形成的氧化膜致密且连续,没有出现开裂和脱落,并且整体氧化速率较缓慢,没有观察到铅铋向材料基体内的渗透,表现出良好的抗腐蚀性能.应力腐蚀实验发现,11Cr-1Si不锈钢在350℃和400℃下存在本征脆化,但是在450℃下没有观察到铅铋致脆现象.

The lead-cooled fast reactor(LFR)is one of six reactor concepts selected in the Generation IV Technology Roadmap and is perhaps the first to be applied commercially.Because the heavy liquid metal coolant has a severe corrosion effect on the core structure,the compatibility of the heavy liquid metal coolant and structural materials is recognized as a key limitation in the design and application of the LFR.Corrosion by heavy liquid metals such as liquid lead or lead–bismuth eutectic(LBE)is a physical or physical–chemical process involving surface oxidation,dissolution of material constituents,erosion corrosion,and fretting corrosion.Corrosion by heavy liquid metal can change the microstructure,composition,and surface morphology of structural materials,which will affect their mechanical and physical properties and lead to system failure.Currently,LFR research institutes are devoting great effort to the research and development of structural materials with good high-temperature mechanical properties and excellent corrosion and irradiation resistances.In this study,a series of experiments and analyses were performed on self-developed 11Cr−1Si ferritic/martensitic(F/M)steel,including heat treatment tests,mechanical tests,corrosion tests in static lead-bismuth eutectic(LBE),and slow strain-rate tests(SSRT)in LBE.The heat treatment results show that 11Cr−1Si steel obtains a good combination of high strength and toughness after quenching at 950℃and tempering at 750℃.11Cr−1Si steel was found to have good LBE corrosion resistance after exposure in static LBE for 3368 h,with a sufficiently low oxidation rate and a continuous and compact surface oxide layer,which protect the base metal of 11Cr−1Si from LBE penetration.The SSRT results show that the ductility of 11Cr−1Si in contact with LBE is sensitive to temperature,with loss of ductility observed at 350℃and 400℃,but not at 450℃.