In this paper, such aspects as the design background, design process and practical applications of new-type slab turnover machine are introduced. The new-type slab turnover machine in production line of wide and thick plate is designed based on analyzing the defects of traditional slab turnover machine as well as the process requirements and working condition of newly designed slab turnover machine needed to satisfy. It is with such characteristics as high load capacity, stable and reliable performances as well as large range of cover length of turnover slab so that it is suitable for various load lifting devices of slab and with low construction cost.

The goal of accurately controlling various components in smelting process of high magnetic induction oriented silicon steel is realized through process optimization of the whole production line in steelmaking area of Rare Earth Steel Plate Co., where the mass fraction of total oxygen in casting blank is controlled at 0.000 4%~0.001 5%; mass fraction of aluminum is controlled at 0.027 0%~0.030 0%; mass fraction of nitrogen is controlled at 0.007 1%~0.008 3% so that the high magnetic induction oriented silicon steel could meet the needs of next step in the rolling process. As a result, its mass production is realized.

In this paper, the effects of Nb with different contents on the microstructure and properties of high strength steel are discussed by taking the hot rolled coils with 650 MPa grade structural steel as research object. The data showed that the yield strength of high strength structural steel reduced by about 15 MPa, tensile strength reduced by about 25 MPa and elongation rate increased by about 1 percentage point with reducing content of Nb by 0.010%. It is found that the fine oval precipitates are rich in Nb and square precipitates are rich in Ti in the high strength steel containing niobium and titanium by comparing the microstructures with transmission electron microscope.

The hot-dip galvanized extra deep drawing steel for back panel of TV with good surface quality, stamping formability, mechanical properties and paint coating property is successfully developed through scientific composition design as well as reasonable smelting, hot rolling, pickling and hot-dip galvanizing process control. Its formability, corrosion resistance, performance stability and higher level of surface quality control could all satisfy users’ requirements.

The galvanized dual phase steel is the high strength steel widely applied in the field of automobile sheet. In order to meet the requirements of lightweight raw material for automobile manufacturer, the galvanized dual phase steel HC300/500DPD+Z is successfully developed through adopting the microalloying composition system of C-Si-Mn-Cr as well as such reasonable process design as hot rolling, pickling, annealing, hot galvanizing and finishing based on the characteristics of 2 030 mm hot galvanizing production line. The production process and using effects of users showed that its mechanical properties were qualified, production process was mature and it was with good formability to meet users’ requirements when applied for automotive structural parts.

The sink roll mark defect of thick gauge hot-dipped galvanization products is always the bottleneck problem of hot-dip galvanizing line of Baotou Steel. The slagging composition of sink roll is analyzed with the XRD phase analysis. The main factors influencing the defect are the temperature of liquid, Al content of liquid zinc, cleaning quality of strip steel and tension control of cooling tower after galvanizing. The effective control measures are formulated based on the influence factors so that the defect is relieved or eliminated fundamentally.

The surface quality, rimhole, center porosity, center segregation, contents of oxygen and nitrogen and inclusions for the head slab of IF steel produced by a steel mill are studied as well as the rolling defects of head slab are tracked and with the treatment of peeling with flame. The study results showed that the surface quality and rimhole of head slab were improved with the increase of slab length; level of center porosity for internal soundness exceeded the standard at slab length of 1 m, while there was no abnormality seen for center segregation; contents of oxygen and nitrogen tended to decrease with the increase of slab length; number of such inclusions as Al₂O₃, TiN and complex inclusion of Al₂O₃-TiN decreased with the increase of slab length; there was large complex inclusion of Al₂O₃-MgO-CaO at 1 m of head slab; main rolling defects of head slab were such subcutaneous inclusion defects as deoxidation product of Al₂O₃ and slag entrapment of mould level fluctuation; quality of head slab could be effectively improved with the treatment of peeling with flame.

In order to improve the problem of transverse corner crack for peritectic steel, hypo-peritectic steel, medium carbon steel and microalloyed steel containing B, Nb, V and Ti, the chamfering crystallizer successively comes into service of 1^# and 2^# conticasters. As a result, the defect of transverse corner crack is improved obviously, but due to the changes of cooling mode at corner, such defects of billet as longitudinal corner crack, scab and indentation appear easily as well as they could even cause the accident of longitudinal crack and bleed-out. In the paper, it is mainly analyzed such common defects of chamfering ingot blank as longitudinal crack, scab and indentation so that the slab defects are effectively controlled through such measures as adjusting the taper coefficient of copper plate with narrow edge and cooling intensity of secondary cooling water as well as optimizing the assembly accuracy of equipment and modification of key equipment.

There are more factors influencing the performances of ultra low carbon stamping products. In this paper, the influence rule of such parameters as contents of different strengthening elements and annealing temperature as well as levelling process on the performances of stamping products is explored. The results showed that the yield strength of product tended to increase with the increase of contents of carbon, manganese and phosphorus as well as the influence degrees of carbon content on the products with different thicknesses were different; with the increase of annealing temperature, the products mainly underwent such three stages as reverting, recrystallization nucleation and grain growth; tensile strength decreased with the running speed of steel strip in annealing decreased.

With the increase of task load for 2 250 mm hot rolling production line in Inner Mongolia Baotou Steel Rare Earth Steel Plate Co., Ltd., the effect of rolling rhythm on production increase is very important so that the causes influencing rolling rhythm are emphatically analyzed. The rolling rhythm is improved, gap time of rolling is shortened and average hourly output increases by 2.3 pieces through unscrambling and optimizing the factors restricting rolling rhythm in finishing area of 2 250 mm hot rolling production line so that its capacity exceeds the design target of 5.5 million tons per year.