Latest ArticlesThe effects of different TiO2 contents on the basic characteristics of sintering and quality index of sinter are studied with small sintering method and sintering cup. The study results showed that the liquid phase fluidity index and generative capacity of calcium ferrite decreased, the strength of binder phase tended to decrease and strength of crystal stock tended to increase with the increases of TiO2 content in iron charge and assimilative temperature; the yield and drum strength of sinter decreased as well as solid fuel consumption tended to increase; the magnetite content in mineral composition of sinter tended to increase, crystal obviously increased, production of calcium ferrite decreased, perovskite content tended to increase and the change of hematite was not obvious; the low-temperature reduction degradation index of sinter tended to get worse and melting range became narrower.
In this paper, it is introduced the baking-free high-performance permeable brick is prepared with the process tests of compression moulding and extrusion molding respectively by taking the tailings after beneficiating iron of an abandoned mine in China as the object of study. The blending strategies for compression moulding and extrusion molding processes are put forward. The permeable bricks prepared with the two processes are with excellent properties and could meet the requirements of building materials so that the business cycle of treatment of wastes with processes of wastes against one another is realized.
The causes for surface crack defect of 25Mn2RE seamless steel pipe are analyzed and detected with the metalloscope, scanning electron microscope and energy dispersive spectroscopy. The results showed that its defects were mainly due to the cracks on the surface of billet and a large amount of iron oxide was formed inside the crack by heat with high temperature. Moreover, the serious banded structure of matrix caused transverse crack defect on the outer wall of pipe and bumps formed due to the banded structure of the inner wall of pipe delaminated when the pipe was subject to bigger circumferential extrusion stress during the tubulation and forming process of user.
The product design, production as well as the tests of microstructure and properties for X42MS hot rolled coil for pipeline steel resistant to H2S corrosion are carried out aiming at the technical demands of user. The design content includes chemical component, hot rolling process and production technology process. The performance tests include stretch, bending, impact, hardness, metallographic phase, nonmetallic inclusion, hydrogen induced cracking (HIC) and sulfide stress corrosion cracking (SSCC). The experimental results showed that the X42MS hot rolled coil for pipeline steel resistant to H2S corrosion manufactured by Inner Mongolia Baotou Steel Metal Manufacturing Co., Ltd. could meet the technical requirements and its batch production was realized.
In this paper, it is introduced the development process for 340 MPa grade high strength galvanized auto steel sheet with IF steel of Baotou Steel. It is successfully developed through chemical composition design, formulating hot rolling and galvannealing processes as well as the r value for products reaches over 1.5. After the successful test mold by user, the product has been with supply mass at present.
Different types of fracture morphology of DWTT sample for X80 pipeline steel are analyzed. It is found that the causes are related to such as the microstructure, segregation and inclusions of materials by metalloscope, scanning electron microscope and energy spectrum analysis.
At the preliminary stage of production test, there were cracks on the DP590 dual phase steel of Baotou Steel in the metal spinning process of user. It is found that the main cause for cracks is the martensite banded structure in the center of steel plate by analyzing and studying the position with cracks. The measures for improving the center segregation of casting blank are proposed so that the problem is solved.
In the article, the welding preheating temperature, welding cold crack sensitivity and welding heat-input of weathering bridge steels Q370qNH and Q420qNH are studied with different welding experiment parameters. The reasonable range of welding heat-input, welding material selection and welding process parameters of Q370qNH and Q420qNH are determined by comparing the comprehensive mechanical properties and metallographic structure of welded joint so that the performances of welded joint can meet the operating requirements of product.
Under the condition of commercial production, the effects of rare earth addition in steel on low temperature impact performance of rail are studied. The results showed that the rail treated with rare earth was with good low temperature toughness and its impact value at-40 ℃ was twice as high as that of experimental steel without rare earth; the microstructure of experimental steel was pearlite and ferrite. The inclusions could be spheroidized as well as the plasticity and toughness of rail could be improved by adding the rare earth.
It is found that the main cause for surface defect of billet is low straightening temperature aiming at the problem that the surface crack rate of Q355B casting blank produced with the 280 mm × 380 mm billet and 5# casting machine of Baotou Steel is higher through studying the correlation between straightening temperature of billet and surface cracks. The high temperature thermoplasticity of steel could be changed by adding trace Ce element so that the probability of surface cracks for billet is greatly reduced within the straightening temperature range of 850~950 ℃.
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