The evolution of microstructure and the stress rupture properties of long term thermally exposed GH3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated sample...The evolution of microstructure and the stress rupture properties of long term thermally exposed GH3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated samples. During long term thermal exposure at 700 C, fine M12 C carbides precipitated preferentially at grain boundaries. These carbides coexisted with the pre-exiting M6 C. The stress rupture life of700 C/1000 h exposed sample under creep testing at 650 C/324 MPa is 93 h. It is much longer than that of the solid solution samples. No noticeable changes could be detected in both the microstructure and stress rupture lives when the samples were exposed for time longer than 1000 h M12 C carbides were found to be beneficial to the creep properties. The cracks initiated at the interface of M6 C carbides and matrix, which led to a lower creep rupture life.展开更多
As a primary material of the thorium molten salt reactor（TMSR） that is a suitable candidate reactor of the Generation IV nuclear reactors, GH3535 superalloy was successfully welded. The effect of laser beam welding...As a primary material of the thorium molten salt reactor（TMSR） that is a suitable candidate reactor of the Generation IV nuclear reactors, GH3535 superalloy was successfully welded. The effect of laser beam welding（LBW） on microstructure evolution of fusion zone（FZ） and heat affected zone（HAZ）, such as element segregation, precipitate behavior and grain evolution, was investigated. The microhardness and tensile properties were tested and discussed. The results of microstructure evolution showed that a number of fine M6C-y eutectic phases precipitated at solidification grain boundaries and interdendritic region in FZ. Compared to base metal zone（BMZ）, the grain size of HAZ has no obvious change. While a few of M6C-y eutectic phases were observed in partially melted zone（PMZ） of HAZ. The results of microhardness indicated that the hardness of FZ was higher than that of HAZ and BMZ. The results of tensile test showed that the ultimate tensile strength of joints at room temperature, 650 and 700？C were98%, 97% and 99% of that of BM, respectively. All the tensile specimens of joints failed in BMZ rather than in PMZ where M6 C carbides had been transformed into M6C-y eutectic phases.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA020404040)the National High Technology Research and Development Program of China (Grant No. 2012AA03A511)
文摘The evolution of microstructure and the stress rupture properties of long term thermally exposed GH3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated samples. During long term thermal exposure at 700 C, fine M12 C carbides precipitated preferentially at grain boundaries. These carbides coexisted with the pre-exiting M6 C. The stress rupture life of700 C/1000 h exposed sample under creep testing at 650 C/324 MPa is 93 h. It is much longer than that of the solid solution samples. No noticeable changes could be detected in both the microstructure and stress rupture lives when the samples were exposed for time longer than 1000 h M12 C carbides were found to be beneficial to the creep properties. The cracks initiated at the interface of M6 C carbides and matrix, which led to a lower creep rupture life.
基金supported by National Key Research and Development Program of China (Grant No. 2016YFB0700404)the National Natural Science Foundation of China (Grant Nos. 51371188, 51671122, 51671154, 51501216, 51601213)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA02004210)
文摘As a primary material of the thorium molten salt reactor（TMSR） that is a suitable candidate reactor of the Generation IV nuclear reactors, GH3535 superalloy was successfully welded. The effect of laser beam welding（LBW） on microstructure evolution of fusion zone（FZ） and heat affected zone（HAZ）, such as element segregation, precipitate behavior and grain evolution, was investigated. The microhardness and tensile properties were tested and discussed. The results of microstructure evolution showed that a number of fine M6C-y eutectic phases precipitated at solidification grain boundaries and interdendritic region in FZ. Compared to base metal zone（BMZ）, the grain size of HAZ has no obvious change. While a few of M6C-y eutectic phases were observed in partially melted zone（PMZ） of HAZ. The results of microhardness indicated that the hardness of FZ was higher than that of HAZ and BMZ. The results of tensile test showed that the ultimate tensile strength of joints at room temperature, 650 and 700？C were98%, 97% and 99% of that of BM, respectively. All the tensile specimens of joints failed in BMZ rather than in PMZ where M6 C carbides had been transformed into M6C-y eutectic phases.
