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2023 Volume 49 Issue 2  Published: 2023-04-25
    Expert Forum
  • Zhi-li Li , Xiao-ming Yang , Xin-long Luo , Yi-nan Yue , Xin Hui , Yan Jin

    The comparison tests for corrosion resistances of samples with and without black spots on the surface of Zn-Al-Mg coating as well as the pure Zn coating are carried out with the neutral salt spray tests. There was not red rust for the samples with and without black spots on the surface of Zn-Al-Mg coating with the neutral salt spray tests of 2 000 h and 4 000 h, while there was obvious red rust for the sample with pure Zn coating with the test of 2 000 h and it was increased obviously with the test of 4 000 h. The positions with and without black spots of Zn-Al-Mg coating are analyzed with the scanning electron microscope and energy disperse spectroscopy. The results showed that many fine magnesium-rich eutectic structures were enriched at the position with black spots. There were differences for reflection of light between them and stripy eutectic structure at the position without black spots as well as the magnesium-rich eutectic structures were easily to be oxidized by the oxygen in the air so as to form black oxide so that the visual differences appear black spots. The salt spray test results showed that the corrosion resistance at the position with black spots didn’t deteriorate as well as the corrosion resistances of samples with and without black spots on the surface of Zn-Al-Mg coating were the same good.

  • Production Practices and Management
  • Kai Lv , Guang-hui Yang

    The stability of rock slopes is mainly controlled by the spatial composing relations between the developmental structural plane in slope rock mass and slope. The stereographic projection is to project the interaction cutting relation of slopes and structural plane space onto a plane, with which the failure types and stability of rock slopes could be intuitively and preliminarily analyzed to provide support for the subsequent treatment of rock slopes. The analysis and determination for failure types and stability of rock slopes with polar stereographic projection are introduced by taking the stability evaluation of rock slope for 2# open pit of Shuangli Iron Mine of Inner Mongolia Shuangli Mining Co. , Ltd. as an example as well as the prevention measures for unstable rock slope are proposed based on the failure types of slopes.

  • Varieties and Quality and Experimental Study
  • Dong-qing Guo , Shao-bing Wang , Xiong Yang

    The axle housing is one of the main components of traveling system for vehicle. The 650QK steel developed in laborotary is with the component design of medium carbon as well as trace amount of Nb, Ti and V alloy elements are added, the microstructure is fine and even ferrite, pearlite and bainite, grain size is grade 12~13, yield strength is 664~671 MPa, tensile strength is 762~794 MPa, elongation is 20.0%~21.5%, cold bending property and low temperature impact toughness are good, low temperature impact toughness at -60 ℃ reaches 127 J, ductile-brittle transition temperature is lower than -60 ℃, ultimate fatigue strength is 270 MPa as well as synthesized mechanical properties of material are good, which could provide the technical index of basic performances of material for industrial production.

  • Varieties and Quality and Experimental Study
  • Bing-kun Jiang , Xiong Yang

    In this paper, the 390 MPa grade test steel for offshore platform is obtained with the component system of low C, high Mn and Nb-Ti microalloying and reasonable adding sequence of alloys during smelting as well as the controlled rolling and controlled cooling process. The test results showed that the upper yield strength was 488 MPa, tensile strength was 550 MPa, elongation after fracture was 30%, longitudinal and transverse impact energies at -20 ℃ were 242 J and 155 J; the microstructure was fine ferrite and pearlite as well as the inclusions were fine and with the size of 2~3 μm; after the welding thermal simulation test with welding heat input of 100 kJ/cm for test steel, the mechanical property test and metallographic structure were with the basic characteristics of steel with large heat input welding as well as the products are verified to be with good low-temperature impact toughness and welding performances.

  • Varieties and Quality and Experimental Study
  • Jiang-bo Song , Xiao-le Yao , Xue-ying Zhang , Zhi-tao Guo

    In this paper, it is mainly introduced the influencing factors and control main points of the resistance to hydrogen sulfide stress corrosion for oil casing. In order to meet the usage requirements of high strength oil casing resistant to hydrogen sulfide corrosion, the oil casing resistant to hydrogen sulfide with independent intelligent property rights is manufactured through selecting Cr, Mo, and Ti as the main corrosion resistant alloy elements, strictly controlling contents of S and P as well as reasonably optimizing microalloy elements. Its impact absorbing energy at 0 ℃ reaches over 100 J, so it is with both high strength and toughness as well as they match reasonably so that it is with good resistance to hydrogen sulfide corrosion.

  • Varieties and Quality and Experimental Study
  • Xue-ying Zhang , Bo-chao Xu , Jiang-bo Song , Lei Wang , Zhi-tao Guo , Xin Ni

    In this article, the problem of high scrap rate caused by surface defects of a batch of seamless steel pipes for high strength hydraulic cylinders produced on site is analyzed and studied. There are mainly three categories of surface defects, they are rolling skin, pits and pitted surface by analyzing their morphology. The defects are detected and analyzed with such analytical methods as metallographic examination and scanning electron microscope. The results showed that rolling skin and pits were caused by the existing surface cracks of billet before rolling as well as pitted surface was caused due to the roll compacting of surface scale onto pipe body in the process of hot rolling. In order to eliminate the above defects, the corresponding rectification measures are taken as well as the continuous casting and rolling processes are optimized. As a result, the surface quality of products is greatly improved and scrap rate is decreased from 30.6% to 1.7%.

  • Varieties and Quality and Experimental Study
  • Ying Bian , Hu-dong Xue , Jia-wei Wang , Yong-fei Chou

    The IS350 rail is medium strength rail in the American AREMA—2019 standard, which is mostly used for laying busy freight railways in North America and with a broad application prospect. Its industrial trial production is carried out combining with the requirements of American standard and the equipment conditions of universal rolling mill of rail. The results of trial production showed that its composition design was reasonable, the smelting, external refining, rolling and online heat treatment processes were proper as well as its general and special performances were in line with the requirements of American AREMA—2019 standard and with sufficient surplus so that a new way was explored for adjusting the product mix of rail of Baotou Steel and developing new markets.

  • Varieties and Quality and Experimental Study
  • Feng-ming Zhang , Zheng-wei Liang , Bin Hou , Hu-dong Xue , Hao-ran Wen

    In this paper, the experimental study on heat treatment process of forging area at heel end of 60-50 kg/m U75V hot rolled compromise rail with different finish cooling temperatures and cooling rates is carried out as well as the tensile properties, hardness of top surface of the rail and cross section, microstructure and decarburized layer of forming section, transition section and heat affected zone of the compromise rail are analyzed. The results showed that the finish cooling temperatures of forming and transition sections of the compromise rail were controlled at about 650 ℃, cooling rate was controlled at 1.3~1.7 ℃/s, finish cooling temperature of heat affected zone was controlled below 550 ℃ and cooling rate was not less than 2 ℃/s, with which the problems of high hardness at forming and transition sections, low hardness at heat affected zone and width out of limits at softened zone of the compromise rail could be effectively solved.

  • Varieties and Quality and Experimental Study
  • Gui-ying Zhao , Jia-wei Wang , Ying Bian , Hu-dong Xue

    In order to meet the demands of heavy haul railways as well as make full use of the functions of chromium and niobium in steel, the high carbon rail for heavy haul railway is researched and developed by adding such strengthening elements as chromium and rare earth into high carbon rail steels through smelting the test steel with laboratory furnace and performance study. The performance indexes of rail are that the tensile strength is not less than 1 330 MPa, elongation is not less than 9%, tread hardness of rail head (HBW) is not less than 390 and other properties could meet the requirements of standard BT/T 2344—2012. The results of trial production showed that the production process of the rail was trouble free and performances could meet the technical requirements, which could satisfy the needs of heavy haul railway.

  • Varieties and Quality and Experimental Study
  • Li-juan Liu , Xiang-dong Bu , Zhen-dong Song , Zhi-guo Hui

    In this paper, the chemical composition and production process are designed according to the technical requirements of 420 MPa grade high-strength weather-resistant H beam for residential building as well as the performances of test steel are studied by observing the microstructure with metalloscope and transmission electron microscopy (TEM), room temperature mechanical properties and periodic immersion corrosion tests. The results showed that the fluctuation of impact toughness at room temperature for test steel was small and its toughness was good. The yield strength of three test steels with different specifications was higher than 420 MPa and corrosion resistance index (I) was 6.15~6.45, which showed good resistance to atmospheric corrosion. The microstructure of test steels was mainly consisted of ferrite and pearlite as well as the average grain size of ferrite was 25.73 μm and there was nanoscale (Cu, Cr) C precipitated phases in grain.

  • Varieties and Quality and Experimental Study
  • Xiang-dong Bu , Ya Tao , Li-hong Guo , Yong-ming Wang , Xiong-hui Lu , Zhen-dong Song

    According to the use requirements of prefabricated steel structure residence, the 420 MPa grade high-strength weather-resistant anti-seismic special hot-rolled H beam with thick gauge is developed independently with the peritectic steel design of microalloy composition system of low carbon, copper and nickel as well as near-net-shape casting technology of beam blank and universal rolling technology of section steel, which is mainly applied for stand column of frame structure for steel structure residence. The subcracks and intermediate cracks inside flange of ingot blank as well as surface defects of finished product caused by rolled-in scale during rolling process are eliminated through optimizing the continuous casting and rolling processes. All the mechanical properties of finished product could satisfy the requirements of technical agreement as well as the dimension and surface quality could satisfy the requirements of standard GB/T 11263—2017 so that its stable bulk supply is realized.

  • Varieties and Quality and Experimental Study
  • Xin Wang

    The microstructure and mechanical properties of parent metal for 700L beam steel with different titanium contents and specimens with metal active gas (MAG) welding are compared and studied. The results showed that the ferrite grains in the microstructure of test steel were 3~5 μm, there were a small quantity of deformation bands, yield strength was 678 MPa, tensile strength was 760 MPa and elongation was 17.0% when Ti content was 0.11%; the ferrite grains in the microstructure was 4~8 μm, there were a small quantity of pearlite grains, yield strength was 658 MPa, tensile strength was 734 MPa and elongation was 24.0% when Ti content was 0.07%; the strength of the two types of test steel was increased by about 10 MPa, but elongation was decreased by 1.0 and 3.0 percent points respectively and property of root bending of 180° (d = 2a) was qualified after MAG welding; the content of low carbon martensite was increased and microstructure of heat affected zone for test steel was refined with the increase of Ti content.

  • Varieties and Quality and Experimental Study
  • Zhen-dong Song , Yan Zhou , Min Wang , Li-juan Liu , Zhi-guo Hui , Xiang-dong Bu , Zhen Qi

    The 09CrCuSb acid resistant steel (also known as ND steel) is the low alloy structural steel with resistance to sulfuric acid dew point corrosion as well as is applied in such industrial fields as the metallurgy, chemical engineering and petroleum. In this paper, the mass loss and mass loss rate of 09CrCuSbRE and Q235B are compared with the complete immersion of 24 h, 48 h and 72 h at constant temperature of 70 ℃ as well as take the sulfuric acid with concentration of 50% as corrosive medium. The results showed that the change of corrosion resistance rate curve was not obvious and resistance to sulfuric acid corrosion of 09CrCuSbRE was excellent with the extension of corrosion time. With the extension of corrosion time, the corrosion resistance rate curve of Q235B was risen sharply after 48 h, which indicated poor resistance to sulfuric acid corrosion. There are such elements as Cr and Cu on corrosion surface and in corrosion pit of 09CrCuSbRE through observing the corrosion surface with scanning electron microscope(SEM) and energy spectrum analysis. The elements of Cr and Cu in steel are with the effect of passivating steel surface in corrosion resistant environment to prevent the electrochemical reaction between the corrosive medium and matrix of steel. Moreover, the corrosion rate of 09CrCuSbRE is further reduced by adding such elements as Sb and rare earth(RE) in the steel.

  • Varieties and Quality and Experimental Study
  • Feng Li , Ting Wang , Yi-nan Yue , Lei Dong

    In this paper, the production technology process and technological parameters of spring steel plate 60Si2MnA are introduced as well as the microstructure that products need could be obtained through corresponding cooling technique (4~9 ℃/s) control, which guarantees the mechanical properties of products. The results showed that the spring steel plate 60Si2MnA with tensile strength not less than 1 050 MPa and elongation not less than 13% could be manufactured through choosing appropriate process parameters with the existing equipment and processes under appropriate conditions of liquid iron and other raw materials. Moreover, the thickness of decarburized layer on the surface of high carbon steel 60Si2MnA is controlled better, which is 18% of requirements of national standard GB/T 1222—2016 through controlling the atmosphere of heating furnace.

  • Equipment and Automation
  • Xiao-min Meng , Ping Li , Jian-guo Wu , Jun-feng Zhang , Wei Lian

    The maximum concentration of nitrogen oxide emissions in the flue gas of four compressor-turbine units with low heating values using blast furnace and coke oven gas in a steel enterprise is about 250 mg/m3, which could not meet the requirements of limiting values for ultra-low emissions of the steel industry, so the denitration modification is needed. Three different denitration modification schemes are proposed based on studying frequently-used flue gas denitration technologies at home and abroad. The modification scheme of built-in double-layer SCR catalyst in waste heat boiler is finally implemented by comparing such factors as the technology maturity, use risks and operating economy as well as the expected effects are achieved. This study could provide the feasible and effective technical methods for the compressor-turbine unit with low heating values and more nitrogen oxides while without prepared denitration space on site in our country.

  • Equipment and Automation
  • Xian Zhao , Jin-gui Fu , Shu-juan Han

    The green transportation is the transportation characterized by energy conservation and reduction of exhaust emissions. It is the inevitable trend of future transport development to popularize green and low carbon means of transport as well as weed out and update or remould old vehicles and ships. At present, the internal combustion locomotive is still the main power of railway transportation in plant of Baotou Steel, which is with such disadvantages as high energy consumption and costs and more pollutions so as to be replaced by new energy locomotives in the near future. In the paper, it is briefly introduced the methods for transforming GK1 type internal combustion locomotive into remote control gas-electric hybrid locomotive, focused on the process of applications in plant of Baotou Steel and analyzed the significances of energy conservation and environment protection, transportation efficiency and cost saving for reformed gas-electric hybrid locomotive through practices of applications.

  • Equipment and Automation
  • Xiao-meng Liu

    The methods for improving the measuring accuracy of resistance strain type rolling force dynamometer are analyzed from such two aspects as sensor and secondary instrument respectively. The manufacturing accuracy and on-site installation conditions of sensor are the main factors affecting accuracy. The voltage-multiplying of excitation power supply and six-wire bridge circuit are helpful to reduce the errors caused by excitation power supply. The ratio calibration of sensor could solve the problem of measurement errors caused by calibration errors, which is very convenient to apply in the steel rolling field. The modified formulas of calibration ratios are obtained through mathematical derivation considering the problem of cable between the sensor and secondary instrument in the steel rolling field.

  • Equipment and Automation
  • Zheng-feng Liu , Pei-yao Cong , Rui-jie Jia , Ai-jun Wang

    In this paper, it is introduced a design of calculating and recording the deviations of predicted and actual rolling forces for all stands of CSP hot continuous rolling mill by the VBA language environment. The deviations of predicted and actual rolling forces for all stands in a certain range are calculated and with classified statistic based on various rolling parameters in the VBA language environment so that the analysis time is greatly shortened and errors of manual computation are reduced as well as the effects of various rolling parameters and specifications on accuracy of predicted rolling forces could be reflected intuitively. Moreover, the effects of various rolling parameters on accuracy of predicted rolling forces are illustrated through analysis combining with the practical examples, which is with great reference significances for adjusting the corresponding secondary parameters for rolling mill.

  • Others
  • Hong Wang , Dian-wei Geng , Xiao-yun Wang

    In the information economy era, the drawbacks of traditional operation and management models for separation of finance and business have become more prominent. The problem that how to overcome the delayed decision-making and inner control of enterprise caused by lag of corporate financial information due to the “information isolated island” has become the urgent problem for many large enterprises. In the paper, it is described the organic integration of finance and business process is prompted through sorting out business processes so as to effectively improve the management level of large enterprises, ensure that financial data could reflect the whole production management process accurately in real time and achieve the effect of dynamic monitoring of important links in the process in detail. Moreover, the three main processes in enterprise operations, that is the business processes, financial accounting process and management process are with interworking and coordination.

  • Others
  • Wen-yao Chen , Ya-jing Wang , Zhi-hua Zhou , Fang-yu Liu

    The physical archives are archives in physical forms with important preservation significance and collection value formed in various work activities and outside communications of colleges and universities. They are the important components of archives and important supplement to documentary archives of colleges and universities. They concentrate the essence of school development as well as they are the powerful proof of historical development of colleges and universities and the crystallization of practical experiences and wisdom for teachers and students. They are with relatively obvious characteristics and are different from the traditional archives so that they are with important significances and values. In this paper, the current situation of physical archives in colleges and universities is analyzed starting from the work experiences of managing them as well as the management of them is discussed from such aspects as collection, arrangement and utilization of them. Moreover, their outlook is proposed.

  • Others
  • Gang-yao Liu , Yu-lan Xue , Yan-qiu Wang , Huan Chang

    In this paper, the boron in low-alloy steel is determined with ICP-AES and multispectral fitting analysis technology. The analytical spectral lines of elements, interference and correction of coexistence elements as well as detection limits are studied by the condition experiments with instrument. The measuring range is determined to be 0.001%~0.100%. With the method, samples are dissolved with the mixed acid of hydrochloric acid and nitric acid, then they are directly determined with instrument. As a result, a simple and rapid analysis method for determining boron content in low-alloy steel is established, which is with good accuracy and precision.