Development of the laminar flow cooling control system of the No.3 hot strip rolling line at Baosteel

The coiling temperature of the hot strip rolling process plays an important role in strip quality control. The newly-built laminar flow cooling control system was independently developed by Baosteel. L2 conducts totally dynamic control （L1 only executes the result from L2, and does not conduct any dynamic control ）. The system has many advantages, such as quick real-time control, accurate model calculation, quick response after self-adaptation, etc. Compared with the 2050 mm hot strip rolling line,the new system can satisfy the strict cooling requirements of high strength steel, silicon steel and heavy plates because of its newly-developed technologies of cooling rate control, strip cooling by sections and proportion-integral-differential coefficient （PID） feedback fuzzy control.

Application of difference arithmetic in the continuous annealing process line cooling control at Baosteel

Some of the main cooling processes and equipment that are currently being used in the continuous annealing process line （CAPL） at Baosteel are introduced, as well as their cooling control model techniques, the modeling principium and their application results. With charts indicating the control trends in real processes, the powerful adjusting ability of the control models with process variable differences and their excellent control precision are shown in this study.

The comprehensive utilization of Baosteel steel slag

Summarizes the processes and development of Baosteel slag processing techniques such as the instantaneous slag chill （ISC） process, the tank-type hot disintegrating process and the rotary drum process. A detailed introduction of the slag comprehensive utilization at Baosteel is given. The details of Baosteel＇ s comprehensive utilization in the fields of simering materials, returned slag for steelmaking, road construction, cement production, mixed concrete, new construction materials, ground-filling materials and reinforced material for soft earth are given. Emphasis is placed on source management and ensuring that from both organizational and managerial perspectives, Baosteel＇ s slag processing techniques are safe and energy-saving, thus constantly demonstrating the issue of sustainable development.

Baosteel's development of cold strip technology

Throughout 30 years of importation, adoption and innovation, the Cold Rolling Plant of Baosteel has adhered to a market-oriented strategy, and gradually expanded its output and raised its technical level through the expansion of production scale ,the optimization of production lines, the development of high added value products, the improvement of product quality, environmentally friendly manufacturing and technological innovation. In this way, the plant has developed into a world class cold rolling plant that produces cutting-edge economic and technical indices.

The startup and production of the No.4 slab continuous caster at Baosteel

In order to meet the developing requirements for the output and quality of the products of Baosteel, the No. 4 slab continuous caster designed by the Danieli Company of Italy was built. Since starting up in December, 2006, the casting machine has run smoothly in the aspects of production and quality control. It is equipped with advanced apparatus and technology, such as electric magnetic braking （EMBR） and soft reduction. Some operation indices have been continually improved, in order to ensure that slab quality meets the requirements of downstream products. Its total output reached 2.17 Mt in 2007. This study analyzes the operational indices and the slab quality.

Review of the last three years since the commissioning of Baosteel's 5m heavy plate plant and future outlook

Baosteel＇ s 5m heavy plate plant was successfully tested on March 1,2005. Since then,the Heavy Plate Plant of Baosteel （hereinafter referred to as ＂the plant＂ ） has been encouraging its employees to study and trace the advanced heavy plate technologies, trying to find out the rules of heavy plate production and its quality control. The plant has gradually mastered this modem heavy plate plant and ensured that Baosteel＇ s production of heavy plates grew year by year,with 1.41 Mt product put in storage in 2007. The plant has focused on developing new technologies and products, meanwhile enhancing its capacity. It has produced a series of plate products, which can be used in manufacturing ship hulls ,pipelines ,bridges ,buildings ,boilers and pressure vessels.

The development and application of premium thread connection tubing and casing products from Baosteel

Premium thread connection tubing and casing products are non-API products that are used in severe oil field conditions, such as deep wells ,ultra deep wells, high pressure gas wells, horizontal wells and steam injection wells, etc. In order to meet the requirements of oilfields for premium thread connection oil country tubular goods （ OCTG）, Baosteel developed its own series of premium thread connection tubing and casing products that are protected by intellectual property rights. This study introduces the process of developing the premium thread connection tubing and casing products, their characteristics, and their actual application in oil fields. It hopes to give customers a better understanding of Premium thread connection tubing and casing products from Baosteel.

Corrosion action and passivation mechanism of magnesium alloy in fluoride solution

Corrosion action and passive mechanism of magnesium alloy in the fluoride solution were studied by means of scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDS), and electrochemistry methods. The results show that an insoluble MgF2 film is generated on the surface of magnesium alloy activated in the hydrofluoric acid. And the mass of the deposited MgF2 film may reach a constant value, when the mass ratio of Mg/F on the magnesium alloy surface is fixed at 11.3-1. The activated magnesium alloy gains a ‘passivation state’ in a mixture of sulfuric acid and hydrofluoric acid at a volume ratio of less than 1.2. At the same time the mass of magnesium alloy is maintained as a function of the time. When the ratio is above 1.4, the mass of magnesium alloy rapidly decreases. The passive film formed through adsorption of HF2- (or H2F3-, H3F4-) ions by the deposited MgF2 film can protect the magnesium alloy from corrosion in fluoride solution, but not in non-fluoride solutions. The passive state is maintained for activated magnesium alloy in an acidic sulfuric nickel solution with added fluoride. If fluoride and carbonate are added to the acidic sulfuric nickel solution, a replacement reaction between magnesium alloy and solution takes place.

FEM Analysis of Rolling Pressure Along Strip Width in Cold Rolling Process

Using 3-D elastic-plastic FEM, the cold strip rolling process in a 4-high mill was simulated. The elastic deformation of rolls, the plastic deformation of the strip, and the pressure between the work roll and the backup roll were taken into account. The distribution of rolling pressure along the strip width was obtained. Based on the simulation results, the peak value of rolling pressure and the location of the peak were analyzed under different rolling conditions. The effects of the roll bending force and the strip width on the distribution of rolling pressure along the width direction were determined.

Control of thermal crown in the roller inside the continuous annealing furnace

In a continuous annealing furnace, the hearth rollers are affected by heat, which in turn affects the stable operation of the steel strips. In order to ensure the stable operation of the steel strips the ability of the rollers to correct themselves and to prevent the steel strips from buckling, effective measures are required to control the surface crown of the rollers inside the furnace. Starting from production, this study analyzes the way in which the crown of the hearth rollers inside the continuous annealing furnace changes. The study suggests control measures to prevent buckling and and misalignment. The study definitely provides guidance to the stable operation of steel strips in continuous annealed furnaces.

Demand of Electric Power and Its Forecasting in Iron and Steel Complex

A systematic study on the electrical load forecasting for large-scale iron and steel companies was made. After analyzing the electrical load＇s characteristics, an algorithm framework for the load forecasting in iron and steel complex was formulated based on model combination and scheme filtration. The algorithm features data quality self- adaptation, convenient forecasting model extension, easy practical application, etc. , and has been successfully applied in Baoshan Iron and Steel Co Ltd, Shanghai, China, resulting in great economic benefit.

Baosteel's technological progress in ironmaking and future prospects

Ironmaking at Baosteel has focused on blast furnaces over the last 30 years. After passing through the stages of ＂learning＂, ＂tracking＂, ＂usage＂, ＂experimentation＂, ＂innovation＂ and ＂development＂, Baosteel ＇ s production capacity has grown steadily and its standard of technology is increasing. Remarkable progress has been made in the technologies of blending stack, thick layer sintering, low silicon and high anhydroferrite sintering, coal blending, and the high productivity with high pulverized coal injection （PCI） rate and long campaign of the blast furnaces. The entire ironmaking process is developing in the direction of high efficiency, low energy consumption, clean production, and environmental protection because the zero discharge of solid waste and industrial sewage has been achieved. After 20 years of development, Baosteel has become a modernized iron producer with an annual capacity of 28.85 Mt of sinter,7.26 Mt of coke and 22.50 Mt of hot metal （Pugang Corex furnace output included）, and its main economic and technological indices have reached a world-class level.

Development and future prospect of hot strip rolling technology at Baosteel

Since the 2050 mm hot strip mill was put into operation in 1989, Baosteel has made great achievements in increasing productivity, developing new process technologies and steel products and improving product quality. In the past 18 years from 1989 to 2007 ,Baosteel has constructed five hot strip mills with a total annual capacity of 19.8 Mt. Indices for technology standards, product categories and steel grades, product quality, both technically and economically, take the lead domestically or reached the world class level. As there are many hot strip mills that expected to be put into operation by the end of 2010 ,the overall annual capacity will exceed 30 Mt ,and the product will cover grain oriented （GO） Si steels and alloyed steels.

The optimization of mold fluxes used for casting the peritectic steel of heavy slabs at Baosteel

In order to solve the problem of the high surface longitudinal crack ratio of heavy peritectic steel slabs produced by the No. 3 continuous caster at Baosteel,the physical properties of the original mold flux and the optimized mold flux were compared in a comprehensive way by using analytical measures, such as a slag film heat-flow simulator, a thermowire molten flux crystallization tester and an X-ray diffractometer in the laboratory. The results reveal that one of the major reasons for the cracks is the poor heat transfer ability of the original mold flux. However, the optimized mold flux with a high basicity features a high crystallizing rate,low crystallization temperature and low heat-flow density. Therefore, the optimized mold flux is more suitable for casting peritectic steel by the heavy slab continuous caster. The test results show that the slabs produced by using the optimized mold flux had no surface longitudinal crack in four test casts, while the surface longitudinal crack ratio of the slabs produced by using the original mold flux was 5%. The optimized mold flux can effectively prevent slab surface longitudinal cracks from occurring.

Countermeasures for dealing with the change of blast furnace raw materials

Following the dramatic increase of iron and steel output ,iron ore is increasingly in short supply ,and the quality of blast furnace （BF） raw materials is increasingly inferior. All these factors have a strong impact on the BF operation. According to the analysis of the raw material properties at Baosteel and the combination of the BF smelting mechanism and its operational practice, this study probes into the operational countermeasures for dealing with the change of raw materials and puts forward optimized BF control technology to ensure the operation of BFs is stable and smooth.

The development and future of steelmaking technology at Baosteel

Baosteel＇s steelmaking has developed greatly over the last 30 years in the areas of hot metal pretreatment, converter, electric arc furnace （EAF）, secondary refining, continuous casting, stainless steel and the comprehensive utilization of resources. The development of technologies, such as clean steel production, mhrstahl heraeus （RH） vacuum refining,a breakout prediction system for slab continuous casting and rotary cylinder slag treatment has created a good environment for the development of value-added products and the comprehensive utilization of resources at Baosteel. This paper describes the direction of development of Baosteel＇ s steelmaking in the future.

Practice of extending the shell life of Baosteel BOF vessels

With the wide application of the magnesia-graphite refractory having a high-thermal-conductivity in BOF vessels for extending the furnace campaign, furnace shell deformation has become increasingly serious. It shortened the furnace campaign and reduced the production. The paper presents the work on increasing the life-span of the furnace shell at Baosteel, which includes the shell renovation, the study on the creep deformation resisting shell plates and the application of the air cooling method to the BOF shell. The results and limitations of these technologies are discussed.

The effect of the continuous casting process on ultrasonically-tested defects in heavy plates

A plate＇s internal quality is very critical, especially for boilers and high-pressure vessels. The ultrasonic test （UT） is the main type of non-destructive flaw detection for heavy plates, which is important because one of the main reasons for plate defects is ultrasonic flaws. This study, based on Baosteel＇ s practical experience in the manufacture of heavy plates, elucidates the cause of defect formation by analyzing ultrasonic flaw testing maps and using special equipment, such as the scanning electron microscope, electron probe and the optical microscope. The author puts forward the following improvement measures： ① Ultrasonic flaws are caused by central porosity and segregation,[H] bubbles and inclusion in slabs.②Ultrasonic flaws are more likely to occur in the bottom and top of slabs rather than the other positions in the casting sequence. It is clear that one-quarter of the inner camber＇ s thickness is accumulated inclusion.③It is clear that overheating in the tundish and the flow of the casting mould have an effect on ultrasonic flaws caused by inclusions.④Soft reduction improves central porosity and segregation,which decreases the number of ultrasonic flaws in the plate.

Detection and analysis of gas tightness of continuous annealing furnaces

When a cold rolled strip is being treated in a continuous annealing furnace which is full of protective gas, the gas tightness of the furnace body, the connected facilities and the gas channels become an important indicator that directly affects the product＇s surface quality and shows the technical level of the design, the manufacture and the installation. By considering the problems of the gas tightness of a vertical annealing furnace in the installation and maintenance, this thesis evaluates the gas tightness indicator and gas tightness related level of the furnace body and the circulation duct, while studying and analyzing the technologies of negative-pressure leak detection and sealing.

Influence of recrystallized microstructure on the mechanical properties of cold rolled microalloy high strength steel

Because of the influence of Nb-educts in cold rolled Nb-microalloy high strength steel manufactured by a continuous annealing unit, different quantities of non-recrystallized ferrite exist in the material, which leads to great fluctuation of mechanical behavior of the material. In this study, the relationship between non-recrystallized ferrite and mechanical properties is analyzed, and some factors influencing the formation of non-recrystallized ferrite are also studied.