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Fang Q.,Inner Mongolia University of Science and Technology | Fang Q.,Key Laboratory of Integrated Exploitation of Bayan Obo Multi Metal Resources | Li C.-L.,Baotou Iron & Steel Group Co. | Bai H.-R.,Inner Mongolia University of Science and Technology | And 5 more authors.
Chinese Rare Earths | Year: 2015

Effects of La on austenite grain growth behavior and room temperature microstructure of high niobium steel were studied through tube furnace, optical microscope (OM) and scanning electron microscopy (SEM). The main experimental parameters were heating temperature 1250℃ and holding time 20 h. After heating, the samples were quenched by ice brine or slow cooling in furnace. Results show that with increase of RE content, austenite grain growth is inhibited and the original austenite grain size decreases from 146.5 μm to 70.2 μm. Furthermore, the microstructure of slow cooling in furnace is improved, the grains are fine and uniform and the average ferrite grain size decreases from 27.3 μm to 17.4 μm. The results provide theoretical basis for application of La in high niobium steel. ©, 5015, Editorial Office of Chinese Rare Earths. All right reserved.

Baotou Iron & Steel; Group Co. | Date: 2010-05-11

Steel sheets; steel tubes; railway points; steel wire; rivets of metal; flanges of metal; casks of metal.

Zhou L.-Y.,University of Science and Technology Beijing | Zhou L.-Y.,Baotou Iron & Steel Group Co. | Cui T.-H.,University of Science and Technology Beijing | He J.-Z.,Baotou Iron & Steel Group Co. | And 2 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

The crack initiation and propagation in process of SPCD steel plate stamping was observed by SEM and EBSD, and the main reason leading to the cracking was investigated. The results show that in situation that the micro texture is advantageous to the plastic potential, the carbide separates out cracks early than the ferrite, and micro crack first occurs in the junction of the ferrite and separated carbide; because of the plasticity of ferrite matrix and the carbide precipitation is different as well as uncoordinated deformation, stress concentration is easy to occur on the interface between two phases, which provides a channel for crack propagation, and carbide is attractive for the crack propagation. Separated carbide whose size is bigger than 20 μm has a strong impact on the plastic of deep drawing sheet and the nonuniform size of ferrite grain causes the local buckling along a wavy path and bigger roughness on the surface of deep drawing sheet after deep drawing, and then causes the "orange peel" characteristics. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.

Li C.-L.,Baotou Iron & Steel Group Co. | Li X.-G.,Baotou Iron & Steel Group Co. | Xu G.-Y.,Baotou Iron & Steel Group Co.
Chinese Rare Earths | Year: 2015

The article mainly introduced series of new processes such as Baiyun Obo oxidized ore comprehensive recycling beneficiation process, niobium-titanium ferroalloy smelting process, high-purity scandium oxide extraction, the process of making anhydrous hydrofluoric acid by in self-produced fluorite ore concentrate, potassium-rich slate comprehensive utilization process and thorium recovery process. It described the key technology of the comprehensive utilization of niobium, scandium, fluorine, potassium, thorium, titanium and other important elements. In strong support of "State Model Base" platform and "Yellow River into the Baiyun Obo" pipeline project, Baiyun Obo resource comprehensive utilization industrialization projects have been built successfully. The project will achieve the comprehensive recovery of six kinds of concentrate products of iron, rare earths, niobium, scandium, fluorite and sulfur, among which niobium is used to smelt niobium-titanium ferroalloy for the production of high strength low alloy steel, scandium concentrate is used to extract high-purity scandium oxide for the production of solid oxide fuel cell and Sc-Mg-Al alloy lightweight materials, fluorite is used to produce anhydrous hydrofluoric acid and thoria reserve for nuclear energy development. Baogang will continuously optimize mineral smelting process and extend industrial chain including niobium, scandium, fluorine deep processing and comprehensive utilization of potassium by the projects. At the same time it has very important significance for the tailings emissions reduction, environmental protection, broadening of enterprise development direction, increasing economic benefits and the national resources as well as energy security, etc. ©, 5015, Editorial Office of Chinese Rare Earths. All right reserved.

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