It can be obtained that the concentration and granularity of pulp into fine sieve are positively correlated through experiment. The finer the granularity, the lower the concentration of pulp. The screening efficiency of sieve mesh with aperture of 75 μm is higher than that of the other three types of sieve mesh and it could reach 42.55% after using for 180 days under the conditions that the maximum concentration of pulp is 51.57% and minimum is 35.19% as well as experimental conditions of granularity of pulp into fine sieve and service time. The increase of run load for ball mill caused by low screening efficiency of fine sieve, pressure of staff who need to frequently change sieve mesh and potential safety hazard on site caused by frequently changing sieve mesh could be effectively reduced by selecting optimal operating conditions of sieve mesh for fine sieve.

The effective volume of 7^# blast furnace of Baotou Steel is 4 150 m³. On October 23rd, 2022, it was blown down for gunning of lining and remolding inner profile. In the blowing down, the method of dropping stockline by spraying water was adopted and the stockline was dropped to a position below center line of tuyere. The methods of reducing the basicity of furnace slag ahead of time and increasing furnace temperature were taken to increase wall temperature, the match of air and oxygen quantities and assessment method of depth of stockline different from the past as well as the method of spraying water, that is, monitoring the mean value and difference value trend of four points of top temperature to control the water quantity were adopted. After taking the above measures, stockline could be dropped safely and rapidly.

In the production technology of continuous casting, oriented silicon steel, as a type of “soft steel” in the traditional sense, shows unique physical properties. Its thermal conductivity is relatively poorer, liquid thermal conductivity is approximately 27% lower than that of ordinary carbon steel so that it shows significant weak thermal conductivity. This property makes it easy to be deformed in high temperature environment. Consequently, there are often such surface defects as liquid level fluctuation of crystallizer, bulge and dimple of ingot blank as well as such internal quality issues as center segregation, center porosity and cracks during the continuous pouring production process. These issues directly impact the number of continuous pouring heats. In order to solve these problems, it becomes the key strategy for increasing the number of continuous pouring heats to design and implement reasonable cooling regime and casting speed.

The effects of adding rare earth element Ce on microstructure and magnetic properties of non-oriented silicon steel 50W470 are studied from such aspects as inclusions, precipitates, grain size and texture. The proportion of central equiaxed crystal in the billet of non-oriented silicon steel after adding rare earth element is 41%~45%, size of rare earth inclusions existed in forms of globularity and rod without sharp corner is about 664 nm. There is obvious inhomogeneity of microstructure on the RD-ND plane of hot rolled microstructure, it is mainly recrystal microstructure with a small amount of banded microstructure on surface layer and mainly banded microstructure in the center as well as there are part of recrystallized grains among banded microstructure. For the finished product of rare earth doped non-oriented silicon steel 50W470 produced with complete process, its magnetic properties, iron loss P1.5/50 is 3.142 W/kg and magnetic induction intensity B50 is 1.705 T.

The studies on hardenability and heat treatment test of steel tube for trenchless drill pipe are carried out combining with its service condition requirements and main failure modes in the paper. The experimental results showed that the depth of hardening layer for obtaining minimum 50% martensite was 11 mm and that for obtaining minimum 95% martensite was 7 mm for the seamless steel tube for trenchless drill pipe containing rare earth, which was with good hardenability; the optimal recommended heat treating regime was obtained after the heat treatment test with adjusting tempering temperature.

With the incremental production of small size products, coil shape control gradually becomes the key link to restrict quality and benefits. The defective coil shape not only affects operation rate and economic and technical indexes of high speed wire rod production, but also causes such problem as there are troubles in the process of using wire for downstream users so that the efficiency of downstream processing is affected. In this paper, it is analyzed some factors affecting the spinning state of wire rod in high speed wire rod production line, briefly elaborated several cases of defective coil shape in production process, analyzed causes of problems and proposed solutions so as to improve the production efficiency and quality of product. The regular coil shape could ensure smooth wire and reduce rate of fracture of wire for drawing of users so that the quality improvement in the whole process is realized.

In this paper, the causes of surface defects for 310 zed beam rolled by YQ450NQR1 continuous casting billet produced with cross section of bloom (320×415 mm) by 7^# continuous casting machine in Steel-making Plant of Baotou Steel are analyzed and control scheme is proposed so that the yield of product is improved. The tongue-shaped defects in rolled products are determined to be caused by the surface crack at corner of continuous casting billet by analyzing the macrostructure and microstructure of continuous casting billet and rolled products with metallographic microscope and scanning electron microscope. The qualified rate of YQ450NQR1 continuous casting billet is improved from 90.5% to 98.5% and stable control of product quality for 310 zed beam is realized through reducing the water amount and optimizing uniformity of water crevice for crystallizer to improve the uniformity of continuous casting billet cooled in crystallizer as well as taking such measures as reducing the specific water amount of secondary cooling, increasing casting speed to increase the surface temperature of entering tension leveler and optimizing slow cooling regime.

In the paper, the typical rollover defect at edge on surface of stainless steel plate is studied. The morphology, microstructure and composition of cross section for rollover at edge are analyzed by metallographic microscope and scanning electron microscope. It is found that the rollover defect at edge has formed on hot rolled intermediate billet as well as micro morphology is the crack with opening pointing to edge and there is delamination for subscale, which is caused by uneven transverse deformation of metal in rolling process under high temperature condition. According to this, a type of formation mechanism of the defect is proposed. This defect could be reduced or even eliminated through effective prevention measures so that the impacts of it on yield of finished products could be reduced.

The 590CL wheel steel is formed by spinning and stamping technologies to be made into automobile spoke. There is cracking in the process of stamping air hole. The cracking position is determined to be between the air hole on outer edge of spoke and shear end as well as fracture origin is at the air hole end of wheel steel, which is about the central part of plate thickness through macroscopic observation of cracked wheel steel as well as such comprehensive analysis as scanning electron microscope and metallographic examination; the zone of segregation in the core of wheel steel with inclusions those are mainly C and Nb in shape of dot string could all hinder normal deformation of ferrite in pre-forming process so that the fluidity of metal is inconsistent. As a result, the work hardening is generated and stress concentration in segregation in the core induces cracks, then stress is released through punching so that cracking is caused. It is suggested to adjust the composition to ensure appropriate proportions of niobium and carbon as well as optimize processes of steelmaking, continuous casting and rolling in the future production and processing processes.

The assembly for pretwisted blades of turbine has significant effect on its overall performance. In this paper, its deformation mechanism is studied and simulation experiments are carried out through finite element model to verify the accuracy of assembly system for pretwisted blades. The process parameters of manually tapping blades are obtained using high speed camera and piezoelectric type impact sensor as well as corresponding mathematical model is established. The parameters of this model are adjusted in software to design the assembly system for pretwisted blades of turbine. The final results indicated that sufficient impact could be generated by the assembly system to meet assembly requirements when the range of air source pressure was between 0.4 MPa and 0.6 MPa so that feasibility and effectiveness of the system were verified.