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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.


Wang Z.,Tsinghua University | Wang Z.,Control Iron and Steel Research Institute, China | Yong Q.,Control Iron and Steel Research Institute, China | Sun X.,Control Iron and Steel Research Institute, China | And 4 more authors.
ISIJ International | Year: 2012

This paper presents an analytical model to describe the precipitation kinetics during isothermal holding following high temperature deformation in Ti micro-alloyed steels. This model was based on the classical nucleation and growth theory (CNGT) and Avrami equation. Using this model, the precipitation-timetemperature (PTT) diagrams for the kinetics of precipitation were easily obtained, and results show a good agreement between the experimental observation and the predictions of the model in terms of the characteristics of the PTT curves, including the shape and nose temperature and chemical composition dependence. © 2012 ISIJ.


Li Z.,Control Iron and Steel Research Institute, China | Li Z.,Tsinghua University | Sun X.,Control Iron and Steel Research Institute, China | Cao W.,Control Iron and Steel Research Institute, China | And 4 more authors.
Science China Technological Sciences | Year: 2012

In order to clarify effects of prior pancaked austenitic structure on microstructure and mechanical properties of transformed martensite in ausformed steel, a super-thin pancaked austenite was processed by multi-pass rolling in a 0.03-2.6Mn-0.06Nb-0.01Ti (wt%) low alloy steel. The evolution of prior pancaked austenite grain during multi-pass rolling was studied using Ni-30Fe model alloy. Related with the structure and texture in the prior super-thin pancaked austenite in Ni-30Fe alloy, the texture and anisotropy of mechanical properties of transformed martensite in the studied ausformed steel were focused on. There were mainly three kinds of rolling texture components in the super-thin pancaked austenite: Goss {110}〈001〉, copper {112}〈111〉 and brass {110}〈112〉. They were further transformed into the weak {001}〈110〉 and strong {112}〈110〉, {111}〈112〉 texture components in the martensitic structure. The orientation relationship (OR) of lath martensite transformation from pancaked austenite in the ausformed steel deviated larger from the exact Kurdjumov-Sachs (K-S) OR than in the case of equiaxed austenite without deformation. The tensile and yield strengths of the ausformed martensitic steel first decreased and then increased as the angle between tension direction and rolling direction increased. The main reason for the anisotropy of strength was considered as the texture component {112}〈110〉 in martensite. However, the anisotropy of impact toughness was more complex and the main reasons for it are unknown. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.


Sun X.,Control Iron and Steel Research Institute, China | Li Z.,Control Iron and Steel Research Institute, China | Li Z.,Tsinghua University | Yong Q.,Control Iron and Steel Research Institute, China | And 3 more authors.
Science China Technological Sciences | Year: 2012

On-line thermo mechanical controlled processing (TMCP) was conducted to develop the third generation high strength low alloy (HSLA) steel with high toughness economically. The ultra-low carbon content ensured a high level of upper shelf energy while ultrafine lath martensitic structure transformed from super-thin pancaked austenite during controlled rolling and cooling. The reduction of martensite block size decreased ductile-to-brittle transition temperature (DBTT) and compensated the strength loss due to carbon reduction. Consequently, the excellent balance of strength and toughness values was obtained as 950-1060 MPa for yield strength, 180 J for Charpy V-notch impact absorbed energy at -30°C, which is much superior to that of traditional martensitic steel. Two mechanisms for the refinement of lath martensite block were proposed: One is the austenite grain refinement in the direction of thickness, and the other is the reduction in the fraction of sub-block boundaries with small misorientation and the increase in the fraction of block boundaries with large misorientation, possibly due to austenite hardening. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.


Zhang X.-G.,Chinese Society for Metals | Yang C.-F.,Control Iron and Steel Research Institute, China | Shang C.-J.,University of Science and Technology Beijing
7th International Conference on High Strength Low Alloy Steels, HSLA Steels 2015, International Conference on Microalloying 2015, Microalloying 2015 and International Conference on Offshore Engineering Steels 2015, OES 2015 | Year: 2015

During the last decade, the adjustment and upgrade of steel product structures always be very important tasks in China's iron and steel industry. Since there is a fast growth of steel production in China, a series of research achievements in the technology area of HSLA steels have been made and applied successfully in the actual production, and thereby promoted a rapid development and application of China's HSLA Steel products. However, The China's iron and steel industry is now facing the excess production capacity and under pressure from respects of resource, energy and environment, therefore, it would be an effective way to realize the sustainable development in China's iron and steel industry by strengthening the applications of HSLA steels continuously and positively..


Weng Y.,Chinese Society for Metals | Kang Y.,University of Science and Technology Beijing
Proceedings of the 10th International Conference on Steel Rolling | Year: 2010

The steel rolling technology progress in China during past ten years is summarily introduced, which includes five parts: (1) Development of steel production and product ranges and structures in China in nearly ten years; (2) The technology integration and development of hot rolling wide strip steel, widen and heavy plate, large cold continuous rolling, three-roll continuous rolling unit production line, and the development of modem equipment of thin slab casting and rolling; (3) The rolling technology progress of semi-endless rolling, thin strip rolling, 100m long rail rolling, and new generation controlled cooling; (4) Research and application of structure and properties during rolling process, and production technology and variety development of high perfonuanee and high strength medium heavy plate, cold rolled strip, long products and tubes; finally, prospecting the future development of steel rolling technology.


Wang Q.,Control Iron and Steel Research Institute, China | Qiu S.,Control Iron and Steel Research Institute, China | Tian Z.,Control Iron and Steel Research Institute, China | Zhu G.,Control Iron and Steel Research Institute, China | Zhao P.,Chinese Society for Metals
8th Pacific Rim International Congress on Advanced Materials and Processing 2013, PRICM 8 | Year: 2013

The slag-steel equilibrium reaction which is simulating the composition and properties changes of the newly developed mold slag for 20Mn23AlV steel was carried out at high temperature in the laboratory. The crystal morphology of the newly developed original slag and final slag was studied by the SEM and XRD analysis. The composition and properties changes of the newly developed mold slag were also compared with the two currently used mold slag for 20Mn23AlV steel. Results show that the SiO2 is increased by 0.7 Wt Pct and the Al2O3 is decreased by 8.18 Wt Pct, and the melting temperature, viscosity and crystallization rate are increased by 62 K, 0.66 dPa.s and 15 Pct respectively. The final slag of the newly developed slag has precipitated NaAlSi3O8 and CaAl2Si 2O8, and both the original slag and final slag have a small amount of LiF crystal and have a good glass form. The newly developed mold slag has small composition and properties changes compared with the two used mold slag.


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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