The IF (Interstitial Free) steel plate is welded into steel pipe for manufacturing condenser pipe of household appliances by a user. There are local spot defects on the surface of steel pipe when it is subjected to conventional hydrostatic test. Such tests on chemical compositions, microstructure of defect and non-metallic inclusions of spot defects as well as mechanical properties and metallographic microstructure of the steel plate with base metal are carried out with such means as metalloscope and scanning electron microscope. The results showed that there were abnormal microstructures at the spot defects. The abnormal microstructures contain such alloying elements as Cr and Ni, which are different from the chemical compositions of matrix. When foreign matter is pressed into welded pipe, its local stress is concentrated. During hydrostatic test, the leak points of pressuring are at the foreign matter which is weakly combined with matrix. In order to avoid such surface defects, it is necessary to strengthen quality monitoring during the whole production and processing processes of welded pipe to prevent foreign matters from pressing into matrix to destroy its continuity so that the steel quality is reduced.

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.

When dry mechanical pump system is used to vacuumize for such vacuum refining systems as VD, VOD and RH, a large amount of dust generated in liquid steel will enter vacuum pipe with process gas. In order to protect vacuum pump, the precipitator needs to be installed in front of mechanical vacuum pump to remove dust in process gas. It is common to add a cyclone dust collector in front of bag filter so that occupied area is large as well as costs and operating costs are high. The precipitator introduced in this article is with the integrated structure of cyclone and bag. These two parts are installed in two compartments mode within one precipitator so that occupied area is small and costs are low. The integrated precipitator is with such characteristics as high dust removal efficiency, small pressure loss as well as convenient and rapid maintenance and repair through optimizing structural design so that long-term safe operations of dry mechanical vacuum pump are ensured.

In this paper, the combined process of low-nitrogen combustion+calcium-based desulfuration with fixed bed is proposed for flue gas treatment of heating furnace thorough comparing current common desulfurization technology with active carbon, SDS sodium-based desulfurization technology, calcium-based desulfurization technology with fixed bed and dry desulfurization technology with highly active calcium powder in metallurgical industry as well as selecting the desulfurization and denitrification technologies suitable for conventional walking beam reheating furnace of steel rolling mill by taking the ultra-low emission transformation for conventional walking beam reheating furnace of steel rolling mill as an example. After on-site implementation, the nitrogen oxides, sulfur dioxide and particulate matter in flue gas could all meet the ultra-low emission requirements so that the combined process could provide reference for enterprises in the same industry.

In the paper, the current situation of higher solid fuel consumption for 2^# sintering machine in 2^# Sintering Workshop of Iron-making Plant of Baotou Steel is systematacially analyzed. The fuel with comprehensive particle size>5 mm is controlled at 15%~20% and that with comprehensive particle size<1 mm is controlled at about 30% through classifying different fuel bands, putting them into tank and crushing them as well as controlling reasonable proportion of anthracite and coke powder; effective material layer thickness is increased and automatic heat storage effect is improved through increasing height of baffle for trolley of sintering machine to 750 mm and reducing thickness of bed charge from 85 mm to 70 mm; overdamp layer of sintering is reduced through reducing moisture of sinter mixture from 7.2% to 6.9%. The solid fuel consumption in 2^# sintering workshop is reduced significantly through taking the above measures. It reached 50.33 kg/t in 2023, which is 2.13 kg/t lower than that in 2021, which lays the foundation for further reducing energy consumption in working procedure before iron-making.

In the paper, it is introduced a new type of wear resistant and low temperature resistant pearlitic rail with excellent performances is developed through designing material compositions and studying heat treatment process aiming at the operating environment of railway in alpine regions and performance requirements for service of rail. The test results showed that the improvement of impact energy of test steel at -40 ℃ was not obvious by adding 0.10% Ni on the basis of the chemical composition of 0.66%C-0.45%Si-1.10%Mn, but impact performance was more stable than that of test steel without Ni. After the heat treatment of test steel is started and temperature is increased to 780 ℃, the abnormal microstructure, martensite could be prevented to be generated as well as microstructure is pearlite and a small amount of ferrite and impact energy at -40 ℃ could reach 20.1 J.

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).

In this paper, it is systematically introduced the characteristics of impurity distribution for slurry pipeline and effects of pigging with different types of tube cleaner by taking the pigging and descaling for a long distance high pressure slurry pipeline of iron ore concentrate with variable diameters as an example. It is found through actual pigging that the passability of pipeline could be preliminarily detected with soft foam pig and mechanical tube cleaner with leather cups of different shore hardnesses. In addition, the effect of cleaning scale for slurry pipeline with foam pig is poorer, so the mechanical tube cleaner with stronger pigging ability should be preferred, which is with important guiding significance for pigging of similar slurry pipelines in the future.

There is often flocculent flow at nozzle during casting rare earth steel products with continuous casting machine so that the casting with normal casting speed could not be met. In severe case, the flocculation at tundish nozzle causes interruption of production so that continuous casting production is seriously affected. The steelmaking technologies of rare earth steel are optimized by studying the reaction mechanisms after adding rare earth elements into molten steel as well as analyzing the effects of oxygen content of molten steel, oxidizability of slag, protective casting of continuous casting machine and casting temperature on yield of rare earth Ce. As a result, the yield and castability of rare earth elements in molten steel are improved as well as the number of continuous casting heats for rare earth steel products reaches 25 so that scale production of rare earth steel products is ultimately achieved.

The locations of disqualification of flaw detection for defects are accurately positioned through manual flaw detection of Q355NE plates with disqualification of online flaw detection as well as the microstructure and defects of the locations of disqualification of flaw detection are analyzed with optical microscope and electron microscope. The results showed that the defect corresponding to disqualification of flaw detection for Q355NE wind power steel was the microcrack in the center of steel plate, microstructure of the microcrack area in the center was martensite and bainite with poorer plasticity, which was caused by segregation of C and Mn. At the same time, MnS inclusions with long strip shape as well as compound of titanium and niobium distributed in chain are found at the crack. The interfacial bonding energy of them and matrix is low, continuity of matrix is destroyed so that cracks are easily initiated with the effects of stress. The microcracks in the center are avoided and qualification rate of flaw detection for wind power steel is increased by improving the segregation during solidification process of casting blank and adopting the mode of offline slow cooling of steel plate.