The relationship between denitrification rate of molten steel and initial w [N] and vacuum degree cycle number and thickness of slag layer is analyzed through denitrification process of 210 t RH refining furnace in Sheet Plant of Baotou Steel. Test results show that: The denitrification rate under vacuum is controlled by many process factors; the influence of initial w [N] on denitrification rate exhibits ladder characteristics; low vacuum is a necessary condition for obtaining higher denitrification rate; the effect of denitrification is the best when cycle number keeps within 10~12 times; the thickness of slag layer has double influence on denitrification, and the slag quantity should be controlled reasonably so that the thickness of slag layer can be avoided from 130 to 150 mm interval.

In the paper, it is introduced and analyzed the effects of main alloying elements, impurity elements and special elements on magnetic properties for cold rolled non-oriented electrical steel of low carbon and low silicon, and the mechanism of action for these elements effects on magnetic properties. The results show: Si, Al, Mn and other major alloying elements are the main determinants of magnetic properties, with their contents increasing, iron loss increasing, the magnetic susceptibility values decreasing; C, N, O, S, Ti and other impurities are not conducive to magnetic properties; after the addition of Sn, RE and other special elements, the composition of favorable texture can be increased obviously, and the magnetic properties can be optimized.

In the paper, the cause of longitudinal crack in the production of SS400Ti from CSP thin slab caster is analyzed, and through the electron microscopic scanning analysis of crack source, the real cause of longitudinal crack is degeneration of mould fluxes. Combined with production practice of CSP production line for many years, the control and solving path of longitudinal crack of SS400Ti production line in CSP production line are summarized. Provide help to reduce the longitudinal crack defects and improve the qualified rate of hot-rolled products.

Aiming at problems existing in the ultra-fast cooling system of CSP production line in Sheet Plant of Baotou Steel, the problems are transformed and optimized. Based on technical advantages of ADCOS-HSM (Advanced Cooling System-Hot Strip Mill) after being transformed, the quality problems in production of dual phase steel in hot rolling are solved through research and application of dual phase steel production process, microscopic structure and mechanical property.

355QK, 460QK are steel plates produced in wide plate production line of Baotou Steel and used in automotive axle housing for some large enterprise, and they are used in the rear axle of loading truck. Based on the study of color difference on the surface of axle housing steel plate, the pressure fluctuation in descaling process is analyzed by means of quality tools. The reasons causing color difference on the surface of axle housing steel plate are found, and improvement measures are put forward, having achieved a good effect.

The shape of strip steel, as an important quality index of plate and strip, has been highly concerned by users. In the paper, it is briefly introduced the process characteristics of CSP production line in Baotou Steel, combined with on-site production characteristics, and factors affecting the shape of strip steel are analyzed from the impact of roll gap shape as the main entry point. In addition, other factors affecting the final shape of strip steel are added. Finally, according to the cause analysis, measures conforming to the site requirements are worked out, and the shape control is improved obviously.

In view of the high fuel consumption for heating furnace in heavy plate production line of Baotou Steel, in the paper it is mainly analyzed six factors that affect the fuel consumption of heating furnace, including production efficiency, combustion efficiency, waste gas heat loss, furnace surface heat loss, slab heat recovery and slab discharge temperature. The fuel consumption of heating furnace is greatly reduced through seven rectification measures, such as reducing heating capacity, enhancing heat preservation, improving air gas mixing way, increasing slab charging temperature, decreasing slab discharge temperature, optimizing the cooling system for slab to be rolled and stabilizing furnace pressure.

In view of supercooling problem of steel plate head in Baotou Steel heavy plate production line, the longitudinal temperature difference of steel plate after cooling is reduced from 40 ℃ to 20 ℃ through optimizing roller speed to improve the tracking accuracy, reducing the temperature difference of steel plate before cooling, improving flow control accuracy, optimizing head masking parameter in cooling model. The supercooling problem of steel plate head after cooling has been solved, and the first pass yield of steel plate has increased by 2.09%.

Adhesion defect is a common surface quality defect in cold-rolled coil. Slight adhesion will affect the appearance quality, and severe adhesion will cause strip steel cannot be used. In the paper, it is primarily analyzed the characteristics causing adhesion defects, then reasons for the occurrence of adhesion are judged through the probability of adhesion defects occurrence by comparing different coiling tension and annealing process. According to the actual product situation, summing up the way to eliminate the defect in cold-rolled coil surface.

The open flame burner used in galvanizing furnace is now exposed to many defects as it is used for a long time. Since the production of building production line, there has been many times of brick falling in the NOF furnace, which seriously damaged the equipment in the furnace, and produced a lot of defects at the same time, which will lead to the strip breakage accident. Through reinforcing the connection between brick body and cover plate, changing the support method for supporting brick and optimizing refractory material layout, effectively reduce and control the occurrence of brick fall accident in annealing furnace.