Hot ductility of the Nb- and Ti-containing line-pipe steel CC slab specimens were measured under the sirain rate of 1 x 10-3/s. Three types of precipitates were found in the fractured specimens. One was the block-shap...Hot ductility of the Nb- and Ti-containing line-pipe steel CC slab specimens were measured under the sirain rate of 1 x 10-3/s. Three types of precipitates were found in the fractured specimens. One was the block-shaped coarse TiN particles precipitated at high temperature. Another type was the fine dynamic precipitation products precipitated at 950～900℃ which caused remarkable ductility reduction of the steel. The third type was the co-existed precipitates formed by fine Nb precipitates nucleating and growing on TiN paricles. Compared with Nb-containing steel which contains no Ti, there was no ductility drop for Nb- and Ti-containing steel at temperature between 850℃ and Ar3 and, the γ→α transformation inside the grain matrixes proceeded faster, which both improved the ductility of the steel in the low ductility temperature Region Ⅲ.展开更多
The fact that the amount of the mold flux components differs at differentlocations on the cracking surface indicates that the longitudinal surface cracks are initiallyformed in the mold and are enlarged in the seconda...The fact that the amount of the mold flux components differs at differentlocations on the cracking surface indicates that the longitudinal surface cracks are initiallyformed in the mold and are enlarged in the secondary cooling zone. Based on the hot ductilitymeasurement of two typical container used steels, it is known that the steels are in severeembrittlement state in the temperature range of 825-775 deg C. By means of increasing Cr/Ni platingthickness on the upper part of the mold, reducing mold heat flux, adopting new secondary coolingpattern, etc., the occurrence of the surface longitudinal cracks on the steel CC (continuouscasting) slabs has been significantly reduced.展开更多
The hot ductility of the V-containing micro-alloying steel CC (continuouscasting) slabs and precipitation of vanadium carbide in the tensile specimens were investigated. Theresults indicate that the precipitation rati...The hot ductility of the V-containing micro-alloying steel CC (continuouscasting) slabs and precipitation of vanadium carbide in the tensile specimens were investigated. Theresults indicate that the precipitation ratio and precipitation rate of vanadium in the specimensreach maximum respectively at 900, -825 and 825 deg C. There is still l0 percent-l7 percent ofvanadium precipitated when the deformation temperature decreases to 800-700 deg C. Vanadium largelyaffects the ductility of the steel in the low ductility temperature Region III. Embrittlement ofsteel with higher V content is severer in the region and the embrittlement extends to lowertemperature.展开更多
The status quo and future development trend of Baosteel continuous casting （CC） technology is introduced. Since its commissioning over ten years ago, Baosteel＇ s CC process has made great progress. The construction...The status quo and future development trend of Baosteel continuous casting （CC） technology is introduced. Since its commissioning over ten years ago, Baosteel＇ s CC process has made great progress. The construction of Baosteel CC research and development base is also introduced. Two aspects of the future CC technology development in Baosteel are stressed. One is to follow the advanced CC technology and solve problems in real production, making full use of pilot plants, while the other is to integrate the present CC technology and make technical breakthroughs in engineering proiects.展开更多
To promote the application of green renewable materials in concrete composite slabs(CCSs)and study the flexural behavior of CCSs with different shapes,the bending performances of three CCSs with a SFRRAC base plate,on...To promote the application of green renewable materials in concrete composite slabs(CCSs)and study the flexural behavior of CCSs with different shapes,the bending performances of three CCSs with a SFRRAC base plate,one cast-in-site concrete slab of ordinary concrete and one CCS of ordinary concrete by steel bar truss(as recommended in the technical specification for precast concrete structures in Chinese)were compared through experiments.The carrying capacity,flexural behaviour and bi-directional mechanical properties of the specimens were systematically analyzed from the failure modes,load-deflection curves,load-bar strain curves,load-slip curves and crack distributions.Results show that the bending failure process of CCSs with a SFRRAC base plate is similar to that of the cast-in-site concrete slab of ordinary concrete and CCS of ordinary concrete by steel bar truss,as all of them went through the plastic phase,elastic plastic phase and failure phase with fully developed cracks and deflection.No sudden breakage or horizontal cracking of the connecting interface between the base plate and concrete topping was observed.The shape of the base plate has a major impact on the bearing capacity of the CCS with the SFRRAC base plate.When calculating the ultimate bearing capacity with the plastic yield line theory,the influence of the base plate shape on the plastic yield line position should be taken into account.展开更多
测试了3X-52钢连铸坯试洋的高温延性。变形试样中主要有三类碳、氮化物析出:高温下析出的块状粗大 TiN 析出物;950～900℃沿晶界和在晶粒基体内部析出的微细动态析出产物;依附在 TiN 颗粒上生成的复合析出物。与不含钛的含铌钢相比,X-5...测试了3X-52钢连铸坯试洋的高温延性。变形试样中主要有三类碳、氮化物析出:高温下析出的块状粗大 TiN 析出物;950～900℃沿晶界和在晶粒基体内部析出的微细动态析出产物;依附在 TiN 颗粒上生成的复合析出物。与不含钛的含铌钢相比,X-52钢试样在850℃～Ar_3温度之间没有出现进一步的延性降低,γ→P转变温度的提高,减轻了其在第Ⅲ脆性温度区的脆性程度。展开更多
文摘Hot ductility of the Nb- and Ti-containing line-pipe steel CC slab specimens were measured under the sirain rate of 1 x 10-3/s. Three types of precipitates were found in the fractured specimens. One was the block-shaped coarse TiN particles precipitated at high temperature. Another type was the fine dynamic precipitation products precipitated at 950～900℃ which caused remarkable ductility reduction of the steel. The third type was the co-existed precipitates formed by fine Nb precipitates nucleating and growing on TiN paricles. Compared with Nb-containing steel which contains no Ti, there was no ductility drop for Nb- and Ti-containing steel at temperature between 850℃ and Ar3 and, the γ→α transformation inside the grain matrixes proceeded faster, which both improved the ductility of the steel in the low ductility temperature Region Ⅲ.
文摘The fact that the amount of the mold flux components differs at differentlocations on the cracking surface indicates that the longitudinal surface cracks are initiallyformed in the mold and are enlarged in the secondary cooling zone. Based on the hot ductilitymeasurement of two typical container used steels, it is known that the steels are in severeembrittlement state in the temperature range of 825-775 deg C. By means of increasing Cr/Ni platingthickness on the upper part of the mold, reducing mold heat flux, adopting new secondary coolingpattern, etc., the occurrence of the surface longitudinal cracks on the steel CC (continuouscasting) slabs has been significantly reduced.
文摘The hot ductility of the V-containing micro-alloying steel CC (continuouscasting) slabs and precipitation of vanadium carbide in the tensile specimens were investigated. Theresults indicate that the precipitation ratio and precipitation rate of vanadium in the specimensreach maximum respectively at 900, -825 and 825 deg C. There is still l0 percent-l7 percent ofvanadium precipitated when the deformation temperature decreases to 800-700 deg C. Vanadium largelyaffects the ductility of the steel in the low ductility temperature Region III. Embrittlement ofsteel with higher V content is severer in the region and the embrittlement extends to lowertemperature.
文摘The status quo and future development trend of Baosteel continuous casting （CC） technology is introduced. Since its commissioning over ten years ago, Baosteel＇ s CC process has made great progress. The construction of Baosteel CC research and development base is also introduced. Two aspects of the future CC technology development in Baosteel are stressed. One is to follow the advanced CC technology and solve problems in real production, making full use of pilot plants, while the other is to integrate the present CC technology and make technical breakthroughs in engineering proiects.
基金The National Natural Science Foundation of China(No.51578446).
文摘To promote the application of green renewable materials in concrete composite slabs(CCSs)and study the flexural behavior of CCSs with different shapes,the bending performances of three CCSs with a SFRRAC base plate,one cast-in-site concrete slab of ordinary concrete and one CCS of ordinary concrete by steel bar truss(as recommended in the technical specification for precast concrete structures in Chinese)were compared through experiments.The carrying capacity,flexural behaviour and bi-directional mechanical properties of the specimens were systematically analyzed from the failure modes,load-deflection curves,load-bar strain curves,load-slip curves and crack distributions.Results show that the bending failure process of CCSs with a SFRRAC base plate is similar to that of the cast-in-site concrete slab of ordinary concrete and CCS of ordinary concrete by steel bar truss,as all of them went through the plastic phase,elastic plastic phase and failure phase with fully developed cracks and deflection.No sudden breakage or horizontal cracking of the connecting interface between the base plate and concrete topping was observed.The shape of the base plate has a major impact on the bearing capacity of the CCS with the SFRRAC base plate.When calculating the ultimate bearing capacity with the plastic yield line theory,the influence of the base plate shape on the plastic yield line position should be taken into account.
文摘测试了3X-52钢连铸坯试洋的高温延性。变形试样中主要有三类碳、氮化物析出:高温下析出的块状粗大 TiN 析出物;950～900℃沿晶界和在晶粒基体内部析出的微细动态析出产物;依附在 TiN 颗粒上生成的复合析出物。与不含钛的含铌钢相比,X-52钢试样在850℃～Ar_3温度之间没有出现进一步的延性降低,γ→P转变温度的提高,减轻了其在第Ⅲ脆性温度区的脆性程度。
