In the paper, it is introduced the Ac₁ of test steel was 659 ℃ and Ac₃ of test steel was 834 ℃, which were determined with CCT curve of 15Cr3MoVTi steel for economical anti CO₂ corrosion oil well tube. Four heat treatment processes are designed based on them. The inspection of mechanical properties after heat treatment showed that the tempering temperature was increased by 60 ℃, the yield strength was decreased by about 130 MPa, the tensile strength was decreased by about 150 MPa and the elongation was improved, but it was not obvious. The impact toughness was significantly improved with the increase of tempering temperature. The impact toughness with tempering of 640 ℃ was 1.4 times higher than that with tempering of 580 ℃.

In the paper, the effect of cooling rate on microstructure and mechanical properties of steel tube after heat treatment furnace was studied by comparing the steel tube with air cooling and water cooling. The test results showed that accelerating the cooling rate of steel tube can increase the nucleation rate at the time of phase transformation and restrain the aggregation and growth of precipitation phase so as to achieve the purpose of grain refinement as well as improving microstructure and mechanical properties.

In the paper, the process of GCr15 bearing steel is improved by optimizing the LF slags and VD furnace process as well as improving the continuous casting process and controlling the rolling temperature. Moreover, its performances were studied. The results showed that the thickness of oxide layer on the surface of GCr15 bearing steel was reduced, the purity of GCr15 bearing steel, the surface quality and hot rolling metallographic structure of wire rod were improved after the process improvement.

In the paper, the cause for lamellar cracking of beam steel during stamping and shearing is introduced. It was found out that there was serious pearlite segregation band in the center of cracked specimen through such detection analysis of metallographic examination and scanning electron microscope. Moreover, there were sulfide inclusion and more hard bulk precipitate associated, the main chemical components of which were such as C, N, Nb and Ti, obtained by scanning electron microscopy and energy dispersive spectrum analysis. The serious pearlite segregation band and the bulky hard precipitate in it have worsened the whole performances of the matrix, so there is lamellar cracking in the center of shearing plane during stamping and shearing.

The article takes X65M pipeline steel produced by Baotou Steel as the research object and discusses the effect of different contents of Nb, finished product thicknesses and sampling directions on the mechanical properties of X65M pipeline steel coiled plate. The data analysis showed that the chemical element Nb could effectively refine the grain of X65M pipeline steel coiled plate. With the same hot rolling process, the thinner the finished product was, the better the low temperature toughness of X65M pipeline steel coiled plate was, the mechanical performances of lateral sampling was significantly better than those of sampling with 30° direction, which will provide a reliable theoretical basis for the actual production and product acceptance of Baotou Steel.

After microwave digestion, Pb⁺² in the sample was oxidized to Pb⁺⁴ by potassium ferricyanide. In the carrying current solution of hydrochloric acid (5+95), potassium borohydride was used as reducing agent and with the characteristics that gaseous hydrides can be produced by the reaction lead and potassium borohydride. The method of hydride generation-atomic fluorescence spectrometry for determining lead in iron containing dust was established. The detection limit of lead in iron containing dust was 0.091 9 μg/L, the upper limit was 0.5%, the relative standard deviation of iron ore standard sample and iron containing dust sample (n = 11) was less than 5.0%, and the standard recovery rate was 97%~104%. The method is fast and simple, which can be used for determining lead in iron containing dust.

With the help of two different methods, the yield strength, tensile strength, elongation after fracture, tensile strain hardening exponent (n) value and plastic strain ratio (r) value of cold-rolled sheet produced by Baotou Steel were determined. The experimental data obtained from the two different methods had been compared. The results showed that the method of automatic measurement with an optical non-contact extensometer was with better reliability and reproducibility.

The production process of iron and steel industry is often a greatly closed system model. If there is a problem at the connections of processes or the equipment components of some links cannot work normally, the iron and steel smelting process can be directly affected. In the paper, it is mainly discussed and analyzed such four aspects as the actual situations, studies effectively carried out, technologies and scientific treatment measures of present fault diagnosis for mechanical equipment of iron and steel smelting.

In the paper, it is analyzed the common faults during the operation of piston air compressors such as insufficient air displacement, abnormal noise or vibration, the air compressor stops running when the pressure air of main air reservoir does not reach constant pressure, the air compressor does not stop running when the pressure air of main air reservoir is higher than the adjusting pressure of compressor governor and the air compressor is still not running when the pressure air of main air reservoir is lower than the adjusting pressure of compressor governor. Moreover, the corresponding measures are put forward to improve the service life and efficiency of compressor so that the safe operation and productions are ensured.

The 1500/300 crusher is only with the simple thermometer and pressure gage, so it wastes time and energy for operators to observe and operate, which is not convenient. The operating condition, working condition of labor, job security, efficiency and service life of 1500/300 crusher are improved by installing the advanced, stable automatic supervisory control device on the original device so as to achieve the excellent lubrication.