Heat-treatment optimization and heavy liquid metal compatibility of Si-enriched F/M steel for LFR structure application
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摘要: 針對自行制備的11Cr?1Si鐵素體/馬氏體不銹鋼開展了熱處理制度探索,及力學性能、鉛鉍環境靜態腐蝕和應力腐蝕行為研究。熱處理研究結果表明,11Cr?1Si不銹鋼在經過調質熱處理后(950 ℃/60 min+750 ℃/120 min)能夠在保證較高強度的同時獲得良好的韌性。500 ℃靜態腐蝕結果表明,11Cr?1Si在經過3368 h腐蝕后表面形成的氧化膜致密且連續,沒有出現開裂和脫落,并且整體氧化速率較緩慢,沒有觀察到鉛鉍向材料基體內的滲透,表現出良好的抗腐蝕性能。應力腐蝕實驗發現,11Cr?1Si不銹鋼在350 ℃和400 ℃下存在本征脆化,但是在450 ℃下沒有觀察到鉛鉍致脆現象。
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關鍵詞:
- 鉛基快堆 /
- 鐵素體/馬氏體不銹鋼 /
- 熱處理 /
- 鉛鉍腐蝕 /
- 液態金屬致脆
Abstract: 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 ℃.-
Key words:
- LFR /
- ferritic/martensitic steel /
- heat treatment /
- LBE corrosion /
- liquid metal embrittlement
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表 1 9/12Cr CNS和11Cr?1Si不銹鋼主要合金元素對照
Table 1. Chemical composition of 9/12Cr CNS and 11Cr?1Si steels
Material Chemical composition (mass fraction) /% Fe Cr Ni Mo W Mn V Si Ti 11Cr?1Si Bal. 10.87 0.69 0.73 0.61 0.81 0.30 0.91 0.07 9Cr CNS Bal. 9.55 0 0.48 1.21 0.6 0.26 0.05 0.05 12Cr CNS Bal. 12.0 0 1.0 1.1 1.0 0.2 0.15 0.03 表 2 11Cr?1Si不銹鋼淬火溫度對δ-鐵素體含量的影響
Table 2. Area fraction variation of δ-ferrite as a function of austenitization temperature of 11Cr?1Si steel
Austenitization temperature/℃ Area fraction of δ-ferrite/% 900 14.9 950 13.7 1000 13.4 1050 12.7 1100 14.8 表 3 11Cr?1Si不銹鋼熱處理溫度對沖擊韌性的影響
Table 3. Charpy impact energy of 11Cr?1Si steel after heat treatment at various temperatures
Category Austenitization temperature + tempering temperature/℃ Absorbing energy/J Variation of austenitization temperature 950 + 750 64.02 1000 + 750 50.15 1050 + 750 15.30 Tempering temperature variation 950 + 700 44.92 950 + 750 64.02 950 + 800 75.94 www.77susu.com -
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