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Dong P.,Chinese Society for Metals | Wang X.,Peking University | Zhang M.,University of Science and Technology Beijing | Seshadri S.,KTH Royal Institute of Technology
Science China Technological Sciences | Year: 2012

The thermal diffusivity and heat capacity of β-SiAlON ceramics with different Z values (0.6, 1.5, 3.0) were measured by laser flash technique and differential scanning calorimetry (DSC), respectively. The thermal conductivity of β-SiAlON was calculated from thermal diffusivity, heat capacity and density and it decreased and then kept almost constant with increasing of temperature. Two different models representing effective thermal conductivity were established and the various parameters of these models were simulated based on the results from the present work. The fitted regression lines were in good agreement with the experimental values. © Science China Press and Springer-Verlag Berlin Heidelberg 2012.

Lang Y.-P.,Control Iron and Steel Research Institute, China | Zhou Y.,Beihang University | Rong F.,Control Iron and Steel Research Institute, China | Chen H.-T.,Control Iron and Steel Research Institute, China | And 2 more authors.
Journal of Iron and Steel Research International | Year: 2010

With hot rolling in laboratory and Gleeble thermal simulator, the hot working of a high nitrogen austenitic stainless steel (HNASS) was researched. The results showed that dynamic recovery (DRV) and dynamic recrystillization (DRX) in HNASS occurred during hot working, and both of them had well-defined stress peaks in flow curves under different conditions. During hot rolling experiment at temperature from 950 to 1050 °C, recrystallization phenomenon does not take place in test material until the deformation ratio is up to 40%. Recrystallization influences remarkably the strength and ductility of material, and the test HNASS possesses better combination of strength with ductility. According to the curve of θ-σ (strain hardening rate-steady state stress), the DRX critical strain of test material was determined. Also, the activation energy of hot working was calculated to be 746. 5 kJ/mol and the equation of hot working was obtained. © 2010 Central Iron and Steel Research Institute.

Zhao C.,Tsinghua University | Zhao C.,Control Iron and Steel Research Institute, China | Zhang C.,Tsinghua University | Cao W.,Control Iron and Steel Research Institute, China | And 3 more authors.
ISIJ International | Year: 2014

Formation of the reversed austenite by intercritical annealing has been studied in the 0.2C-5Mn steel by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. It is found that the volume fraction of reversed austenite increases solely with increasing annealing temperature. While the volume fraction of retained austenite begins to go up around 575C and exhibits a maximum value of 33.0% at 650C; and when above 650C, the retained austenite volume fraction decreases with increasing annealing temperature. At the same time, the concentrations of C and Mn in austenite which contribute a lot to the thermal stabilization of austenite are investigated to explain the variation of retained austenite volume fraction. And the microstructure evolution of different annealing temperatures is also observed.. © 2014 ISIJ.

Zhao C.,Tsinghua University | Zhao C.,Control Iron and Steel Research Institute, China | Cao W.Q.,Control Iron and Steel Research Institute, China | Zhang C.,Tsinghua University | And 3 more authors.
Materials Science and Technology (United Kingdom) | Year: 2014

Microstructure evolution of 0?2C-5Mn steel during the intercritical annealing at different temperatures was studied. It was found that the microstructure gradually evolved from martensite structure into a structure consisted of austenite and ferrite during the intercritical annealing process. The retained austenite volume fraction reached the maximum value of 36?5% after about 10 min annealing at 680uC. It was also found that carbides precipitated during initial annealing stage and gradually dissolved during following annealing process for all annealing temperatures; and interestingly, the fresh martensite was found, indicating that part of the newly forming austenite was unstable and would transform into martensite when quenching. Based on the microstructural analysis and the calculation by Thermo-Calc software, it was proposed that the different evolution behaviours of the microstructure during annealing were not only controlled by the thermal kinetics of the austenite, but also affected significantly by the thermal stability of the austenite. © 2014 Institute of Materials.

Weng Y.,Chinese Society for Metals
Energy Materials 2014, Conference Proceedings | Year: 2014

Combined with the development of energy in China during the past 30 years, this paper clarified that high steam parameters ultra-supercritical (USC) coal-fired power plants and 1000MW nuclear power plants are the most important method to optimize energy structure and achieve national goals of energy saving and CO2 emission in China. Additionally, requirement of materials technology in high steam parameters USC coal-fired power plants and 1000MW nuclear power plants, current research and major development of relevant materials technology in China were briefly described in this paper.

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