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核级316H管道熔敷金属蠕变性能表征
张博俊1,2, 余华金3, 荆洪阳1,2, 徐连勇1,2, 赵雷1,2
1.天津大学, 天津 300072;2.天津市现代连接技术重点试验室, 天津 300072;3.中国原子能科学研究院, 天津 300072
摘要:
文中通过开展核级316H管道熔敷金属在525℃不同应力下的蠕变试验,对熔敷金属蠕变后的析出相演变、蠕变损伤机理和断裂机制进行研究.结果表明,316H熔敷金属的蠕变曲线由瞬时蠕变阶段、稳态蠕变阶段和加速蠕变阶段组成,其高温蠕变机制为幂律蠕变.在蠕变断裂后的熔敷金属内部发现三种析出相:在δ铁素体内部析出的具有强化作用的Laves相,在δ铁素体与奥氏体界面析出的促进空洞形核长大的σ相和链状M23C6. 在σ相和链状M23C6附近区域产生的蠕变空洞是蠕变失效的主要原因.在断口处观察到大小均匀的等轴韧窝,说明熔敷金属的断裂机制为韧性断裂.
关键词:  316H  析出相  断裂机制
DOI:10.12073/j.hjxb.2019400320
分类号:TG407
基金项目:
Study on creep properties of deposited weld metal in nuclear class 316H pipe
ZHANG Bojun1,2, YU Huajin3, JING Hongyang1,2, XU Lianyong1,2, ZHAO Lei1,2
1.Tianjin University, Tianjin 300072, China;2.Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300072, China;3.China Institute of Atomic Energy, Tianjin 300072, China
Abstract:
Microstructure evolution, creep damage and fracture mechanism of deposited weld metal in muclear class 316H Pipe were studied based on uniaxial creep tests at 525℃ under various stress. The results showed that creep curves consist of three typical stages, including:transient stage, steady-creep stage and accelerated creep regime. Power-law creep dominates the creep deformation behavior of the deposited weld metal. After creep, three types of precipitates can be observed in fractured samples. The Laves phase is considered as the main strengthening phase, which precipitated inside the δ ferrite; the σ phase and the chain-like M23C6 precipitated around the interface between the δ ferrite and the austenite, facilitating the formation and growth of cavities, which caused the failure for the weld metals. Uniform equiaxed dimples are found in fracture surfaces, indicating that the ductile fracture mechanism occurs in deposited weld metal after creep rupture.
Key words:  316H  precipitates  fracture mechanism