Latest ArticlesIn the paper, it is introduced the development of DH40 high-strength steel plate with studying the rolling and normalizing technologies, testing the mechanical properties as well as analyzing the microstructure and effects of normalizing technology on mechanical properties of steel plate combining with the test results. The results showed that the mechanical properties of steel plate could be adjusted appropriately by proper normalizing heat treatment process system. Due to the problem of center segregation for microstructure of plate, the process factors at each stage and their relation need to be explored continuously to eliminate the banded structure.
In the paper, it is introduced the X56M hot rolled steel strip is developed with the Nb-Ti-Mo component system and 2 250 mm production line. It is with stable mechanical properties, so it is suitable for stable industrial batch production as well as can meet the demand of pipeline steel market at home and abroad.
In this paper, the composition design, process parameters and results of trial production in laboratory for Q690CF high strength steel with rare earth and low welding crack susceptibility are introduced. Its strength level could meet the standard requirements as well as the strength and toughness match well by adopting reasonable chemical composition system, controlled rolling and controlled cooling as well as off-line quenching and tempering process; the component requirements of welding without preheating can be met by reducing the carbon equivalent (Ceq) and welding crack susceptibility index (Pcm) so that it is with an extensive market development prospect.
In the production process of 2 250 mm production line in Baotou Steel, the main quality problems are the problems of strip shape. Roller is the important large tool used in the production of hot rolling unit and its roll shape directly affects the ability of rolling mill to regulate and control strip shape. In the paper, it is introduced the corresponding technical researches on roll shape of roller in the rolling process of rare earth steel with 2 250 mm production line as well as the ability of rolling mill to regulate and control strip shape is enhanced through optimizing the roll shape of working roll for finishing mill group so that the roller can serve production better.
In the article, it is introduced the general situations for production process of 100-meter 75 kg/m U75V online heat treated rail with the 280 mm × 380 mm slab section adopted by Baotou Steel. Its industrial production is successfully completed through improving the ejection equipment of continuous casting in Steel-making Plant and commissioning the remaining heat quenching production line of Rail and Beam Plant. Its performance examinations could meet the requirements of TB/T 2344-2012 standard.
In the paper, it is introduced there is fracture in the process of drawing SWRH82B wire rod sample. It is found out that the main causes for fracture of 82B are high carbon content in the center of sample and existing fragility phase-network cementite through analyzing the SWRH82B wire rod sample, while the cause for high carbon content in the center of sample is the serious center segregation of continuous casting billet.
In this paper, the corresponding measures to such problems as large temperature fluctuations and disorder of model self-learning are formulated respectively through researching the problem of low hit rate for coiling temperature of thick strip steel produced with the hot rolling production line of Baotou Steel Metal Manufacturing Co. and analyzing with model theory combining with the actual situations. The optimization is carried out from such aspects as stabilizing rolling pace, controlling tapping temperature and model control so that the effects are good, which could be as the effective reference for formulation of production process.
In the paper, it is introduced the application of 611U in the automatic control system of gang saw in Steel Tube Co. and the upgrading scheme with S120, working modes of 611U and S120 in positioning control and the commmunication mode of Profibus-DP field bus in upgrade.
The extracting mill with shaft is the important component of PQF unit and the production practices prove that the center of stand cannot coincide with the center of roll pass in production due to there are not any detection methods for the center of stand for extracting mill with shaft at present so that 500~800 mm of head end for steel tube is bent in steel rolling process. In the paper, the method for measuring center of stand is found out by analyzing the structure of stand for extracting mill and improving the measuring implement.
The production line of Φ460 mm seamless steel tube in Steel Tube Co. of Baotou Steel adopts the world advanced PQF continuous rolling technology and the continuous rolling mill is with the retained rack of mandrel system. In the movement process of retained rack of mandrel, the fast speed response is required and the position must be accurate when it stops. For control, the position control mode of different positions of periods with different speeds is adopted to ensure reliable requirements for production and control. The torque balance control can effectively solve the problems of push-pull force and unbalanced load between motors.
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