The effects of microstructure of high-strength anti-seismic fire-resistant H beam for building structure on its strength, toughness and high temperature strength are studied with such analysis means as TEM (transmission electron microscope), metallographic microscope and EBSD (electron back-scattered diffraction). The results showed that the controlled rolling and controlled cooling were not needed under the premise of reasonable chemical composition design, two-phase structure of air cooling bainite and ferrite for test steel after hot rolling was obtained. It is found by observing the microstructure after holding at 600 ℃ for 3 hours that there is nano-level interphase precipitates in ferrite and their line spacing is about 24~34 nm. For the hot rolled high-strength anti-seismic fire-resistant H beam for building structure, its yield strength≥500 MPa, elongation≥22%, yield ratio≤0.85, impact energy at -20 ℃≥34 J and yield strength after holding at 600 ℃ for 3 hours≥310 MPa.

The coupling is an important part of oil casing and oil tube as well as they are connected into tubing string by coupling with the mode of screw joint. In order to improve the anti-galling property of thread of coupling, the high temperature manganese phosphating is usually adopted for coupling so that it is corrosion resistant, the friction is reduced and lubrication performance is improved. In this paper, the effects of free acidity, total acidity and acid ratio on the quality of phosphating film and phosphating reaction time are studied by experiments. The phosphating process parameters are further optimized to control the phosphating film weight to be within certain range so that more compact and homogeneous phosphating film is obtained.

The characteristics and change rules of wear behavior for rail with different load conditions are analyzed through experimental study on wear of on line heat treated U20MnH rail combining with the morphology features of wear surface and profile for samples observed by microscope and scanning electron microscope. The results showed that the wear loss of on line heat treated U20MnH rail was significantly reduced with increase of load under load conditions of 1 200 N, 1 500 N and 1 800 N respectively.

The feedback of user is that the elongation of cold rolled sheet with cold rolled base material SPCC manufactured by 2 250 mm production line after cold rolling and annealing is low, part of flow forming is not easily to form in punch forming process and cracking rate is higher. The cause analysis showed that its high Mn content was one of the causes for slightly higher strength of steel strip so that elongation was low and steel strip was easy to crack; cooling modes of the two production lines were different, the cooling mode of preconcentration was adopted by 2 250 mm production line and the cooling mode of predispersion was adopted by CSP production line so that the strength of hot rolled steel strip manufactured by 2 250 mm production line was slightly higher, elongation was low and steel strip was easy to crack. The elongation of hot rolled steel strip manufactured with raw materials with thickness of 3.0~5.0 mm by 2 250 mm production line is lower than that of hot rolled steel strip manufactured by CSP production line so that the elongation of cold rolled steel strip after cold rolling and annealing is also slightly higher due to the “heredity” of rolling.

In the paper, the fit tolerance and chamfer structure for quick-change coupler of oxygen lance as well as flexible connection mode between coupler and nozzle of medium are analyzed in detail. The fit dimension, chamfer length, surface roughness of fitting surface and type of connection of compensator are improved based on the analysis results combining with actual situations on site. On the premise of not affecting original using functions of oxygen lance, the rapid replacement for oxygen lance of 240 t converter is realized so that the duration of replacing oxygen lance is shortened, labor intensity of workers is reduced and safety of operating personnel is ensured.

In this paper, the continuous casting billet of low temperature Hi-B steel, metallographic structure and texture of plates after such processes as hot rolling, normalizing, cold rolling, decarburizing annealing and high temperature annealing are observed with metallographic microscope and X-ray diffractometer (XRD) as well as the evolution laws of microstructure and texture in the whole process are analyzed. The results showed that the macrostructure of continuous casting billet was mainly columnar crystal and proportion of equiaxed crystal zone was 7%~12%; microstructure of hot rolled plate was composed of alternant banded structure of ferrite and pearlite; microstructure of normalized pickled plate was composed of fine crystal zone and recrystal microstructure. The textures at 1/8 of thickness of hot rolled plate and normalized plate are mainly Goss texture and brass texture as well as strong Goss texture is formed with the secondary recrystallization after high temperature annealing.

The stamping simulation workstation for sheet products of Baotou Steel is the typical research platform of applied technologies. With the coordinated supports of “numerical simulation and finite element simulation” technologies, it relies on multiple high performance personal computers to complete massively parallel computation so that the joint interactions of such four main fields as “stamping simulation analysis” “construction of material database” “correlational research of surface” and “comprehensive simulation” are realized. A large amount of simulation analysis is carried out on the platform, which not only provides the basis for optimizing and adjusting the processes and performances of sheet products, but also contributes to winning market reputations for high-end products such as automotive sheet of Baotou Steel. At the same time, the construction of material database promotes the substantial progress of early vendor involvement (EVI).

The targeted optimization and improvement measures are proposed by summarizing and analyzing the existing quality problems of ER70S-6 welding wire steel. The emphasis is strictly controlling such key indicators as chemical composition range, gaseous nitrogen content, dimensional accuracy and microstructure of ER70S-6 welding wire steel. After tackling the problems, rates of reaching the standard for internal control of C, Si, Mn, and N contents are improved, class C accuracy of dimensional deviation is improved as well as abnormal duplex grain structure is eliminated. The drawing results of users showed that the quality of optimized welding wire steel were further improved, which could meet the requirements of high speed drawing with drawing speed of over 28 m/s.

In the process of producing HRB500E rebar for domestic manufacturers, there are often low strength-to-yield ratio or a small amount of nonconformity. In this paper, the comparative experiment of niobium vanadium composite rebar and vanadium nitrogen rebar manufactured with industrial trial production is carried out. The results showed that the strength-to-yield ratio of rebar was increased by 0.03 with the niobium vanadium composite process, ferrite transformation was delayed due to presence of niobium, pearlite content was increased by about 10 percentage points so that tensile strength was increased; vanadium nitrogen alloy was relatively reduced due to the addition of niobium so that its precipitation strengthening and fine grain strengthening effects were reduced as well as yield strength of rebar was slightly decreased. The practices show that the strength-to-yield ratio of rebar and seismic resistance of HRB500E rebar are significantly improved with the niobium vanadium composite process.

In this paper, it is analyzed the causes of abnormal temperature increase of side wall at tap hole for hearth of 7^# blast furnace of Baotou Steel and emphasized the treatment measures. With the long-term high-intensity smelting conditions, tap hole of hearth is relatively active and its length is controlled poorly so that scour of slag iron to carbon brick of tap hole is aggravated. As a result, the erosion of carbon brick of tap hole is the cause for temperature increase of side wall at tap hole for hearth of 7^# blast furnace. The temperature of side wall at tap hole is effectively controlled without reducing the smelting intensity and output of 7^# blast furnace through taking such measures as increasing the quantity of circulating water at tap hole to improve cooling intensity, carefully maintaining tap hole, actively eliminating air gap of hearth side wall as well as appropriately opening central gas stream and restraining gas stream at edge for the charging system.