Advanced type stainless steel 316FR for fast breeder reactor structures
Advanced type stainless steel 316FR for fast breeder reactor structures
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DOI：
10.1016/s0924-0136(03)00484-9
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发表时间：
2003-12
影响因子：
6.3
通讯作者：
T. Nakazawa;H. Kimura;K. Kimura;H. Kaguchi
中科院分区：
文献类型：
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作者：
T. Nakazawa;H. Kimura;K. Kimura;H. Kaguchi
研制了用于快堆结构材料的低碳中氮型316FR不锈钢。为了阐明蠕变持久性能与组织的关系，研究了316FR钢与常规中碳、低氮SUS316钢的组织变化。在550℃和600℃下进行了蠕变断裂试验，用电子显微镜观察了断裂样品的微观结构，并通过分析提取的残留物来评估溶质浓度。对于长期蠕变，316FR具有比SUS316更高的断裂强度和塑性。在316FR中，550℃和600℃蠕变10000h后，LaVes相主要析出在晶界上，同时也析出在基体中。晶界上的LaVes相不会降低断裂塑性。由于蠕变过程中析出的氮化物极少，氮化物固溶淬火在很长一段时间内都是有效的。另一方面，大量碳化物析出在晶界和SUS316的基体中。由于溶质碳含量的降低，导致了断裂强度的损失。由于晶界脆化，碳化物在晶界析出，导致塑性损失。综上所述，316FR比SUS316具有更高的断裂强度和塑性的原因是高温下的相稳定性较高。
Low carbon and medium nitrogen type 316FR stainless steel has been developed for structural materials of fast breeder reactors (FBR). In order to elucidate the relationship between creep rupture properties and microstructures, the microstructural changes of 316FR steel have been investigated in comparison with conventional medium carbon and low nitrogen type SUS316 steel. Creep rupture tests were conducted at 550 and 600°C. The microstructures of ruptured specimens were examined with an electron microscope and the solute concentrations were assessed by analyzing extracted residues. The 316FR had higher rupture strength and ductility than SUS316 for long-term creep. Laves phase precipitated mainly on the grain boundary at 550 and 600°C and also in matrix after 10000h creep at 600°C in 316FR. Laves phase on the grain boundary did not decrease rupture ductility. The solid solution hardening by nitrogen was effective for a long period of time, because of the extremely small amount of nitrides precipitated during creep. On the other hand, large amount of carbides precipitated on the grain boundary and in the matrix of SUS316. They caused loss of the rupture strength due to the decrease in solute carbon content. The precipitation of carbides on the grain boundary resulted in loss of ductility because of the grain boundary embrittlement. In conclusion, the reason why 316FR had higher rupture strength and ductility than SUS316 was due to the higher phase stability during high temperature exposure.