A C–Mn dual-phase steel was soaked at 800°C for 90 s and then either rapidly cooled to 450°C and held for 30 s(process A) or rapidly cooled to 350°C and then reheated to 450°C(process B) to simula...A C–Mn dual-phase steel was soaked at 800°C for 90 s and then either rapidly cooled to 450°C and held for 30 s(process A) or rapidly cooled to 350°C and then reheated to 450°C(process B) to simulate the hot-dip galvanizing process. The influence of the hot-dip galvanizing process on the microstructure and mechanical properties of 600-MPa hot-dip galvanized dual-phase steel(DP600) was investigated using optical microscopy, scanning electron microscopy(SEM), transmission electron microscopy(TEM), and tensile tests. The results showed that, in the case of process A, the microstructure of DP600 was composed of ferrite, martensite, and a small amount of bainite. The granular bainite was formed in the hot-dip galvanizing stage, and martensite islands were formed in the final cooling stage after hot-dip galvanizing. By contrast, in the case of process B, the microstructure of the DP600 was composed of ferrite, martensite, bainite, and cementite. In addition, compared with the yield strength(YS) of the DP600 annealed by process A, that for the DP600 annealed by process B increased by approximately 50 MPa because of the tempering of the martensite formed during rapid cooling. The work-hardening coefficient(n value) of the DP600 steel annealed by process B clearly decreased because the increase of the YS affected the computation result for the n value. However, the ultimate tensile strength(UTS) and elongation(A80) of the DP600 annealed by process B exhibited less variation compared with those of the DP600 annealed by process A. Therefore, DP600 with excellent comprehensive mechanical properties(YS = 362 MPa, UTS = 638 MPa, A_(80) = 24.3%, n = 0.17) was obtained via process A.展开更多
In hot-dip galvanizing process, air jet wiping control is so crucial to decide the coating thickness and uni- formity of the zinc layer on the steel strip. The mathematical models developed predict the zinc coating th...In hot-dip galvanizing process, air jet wiping control is so crucial to decide the coating thickness and uni- formity of the zinc layer on the steel strip. The mathematical models developed predict the zinc coating thickness as a function of pressure and shear stress. The required pressure and shear stress profile on the strip surface were calcu- lated using regression analysis, and carried out using numerical simulation as FLUENT, a finite element analysis software. The influences of the outlet pressure, the nozzle to strip distance, the slot opening, the edge baffle plate, as well as the tilting angle of air knife were discussed. Combining with these results and regression analysis on the practical data, four first-order polynomial multi-parameter models were established for different targeted coating thicknesses with better regression coefficients. The validated model was used to carry out sensitivity analysis to de- termine the favorable controlling regime for the air jet wiping process.展开更多
The effect of dew points(-50,-l0 and+10℃)on the galvanizing properties of a high-manganese twinning-inducedplasticity(TWIP)steel was studied.Scanning electron microscopy(SEM),glow discharge optical emission spectrome...The effect of dew points(-50,-l0 and+10℃)on the galvanizing properties of a high-manganese twinning-inducedplasticity(TWIP)steel was studied.Scanning electron microscopy(SEM),glow discharge optical emission spectrometry(GDOES)and X-ray photoelectron spectroscopy(XPS)were used for microscopic observation and qualitative analysis of the interfacial layer between the steel surface and the zinc layer after hot-dip galvanizing.SEM analysis results show thatthree diffcrent morphologies of metallic oxides are formed on the interfacial layer under the different dew points.GDOES results show that Al is present in the molten zinc,reacting with Fe on the steel surface to form Fe2Al5,which can increasethe galvanizing properties.XPS results show that the valence states of Mn in the interfacial alloy layer are Mn'*and Mn*+,and the valence stales of Fe are Fe^0,Fe^2+and Fe^3+.The experimental results show that the hot-dip galvanizing performanceis the best at-10℃ and the formation of Mn and Fe intermetallic oxides has a bad effect on hot-dip galvanizing behaviorof the high-manganese TWIP steel.The types of the formed surface oxides(MnO,Mn3O4,Mn2O3,FeO3,and Fe2MnO4)onthe surface of the steel sheet are confirmed.It can obtain the best hot-dip galvanizing performance of the high-manganese TWIP steel by controlling the dew point from-10 to-5℃.展开更多
A roll shape setting model was built for the hot galvanizing and planishing mill. The uniform transversal distributions of the front tension in the exit and the unit pressure were considered as the objective function....A roll shape setting model was built for the hot galvanizing and planishing mill. The uniform transversal distributions of the front tension in the exit and the unit pressure were considered as the objective function. At the same time, the quality of the products, the stability of zinc layer, and the homogeneity of spangles were of considerable significance in the planishing process. The model was applied to the roll shape setting of the 1800 cold rolling 3# CGL hot galvanizing and planishing mill of Baosteel Co Ltd. After being planished, the flatness of a strip that was less than 6 I was more than 97%, and the flatness of others were less than 10 I; the pass percentage of the zinc lay- ers reached 100%.展开更多
A new processing method for producing hot dip galvanized steel is designed and tested, in which pickling is skipped. Hot-rolled low carbon steel sheets are roiled with oxide scale in an experimental mill at room tempe...A new processing method for producing hot dip galvanized steel is designed and tested, in which pickling is skipped. Hot-rolled low carbon steel sheets are roiled with oxide scale in an experimental mill at room temperature, prior to annealing under a 20% hydrogen reducing atmosphere and galvanizing on a hot-dip galvanizing simulator. Micro-cracks formed in the oxide scale during cold rolling roughen the steel surface and enlarge the specific surface. Through-thickness cracks provide transport channels for hydrogen, and hence the reduction of oxide scale is en- hanced. When the sheet is dipped in the zinc bath, cracks are submerged by liquated zinc and the defects are not dis- tinct after hot-dip galvanizing. The overlay coating occludes with rough surface of the sheet, whereby a superior coat- ing adherence is realized.展开更多
Baosteel has excelled in automotive steel sheets in the past three decades.It has made a significant contribution to the development of China’s automotive industry by producing a wide range of high-quality steel prod...Baosteel has excelled in automotive steel sheets in the past three decades.It has made a significant contribution to the development of China’s automotive industry by producing a wide range of high-quality steel products.Some milestones achieved by Baosteel automotive steel sheet were briefly reviewed.The current challenges in producing ultra-high strength steel(UHSS),especially hot-dip galvanized UHSS,were summarized.The most current advancements in UHSS and the corresponding hot-dip galvanizing processes were discussed.The galvanizability of Si-Mn-added QP steel and DP steel, Mn-added TWIP steel, and Al-added low-density steel has been improved by different techniques in Baosteel.展开更多
This paper presents a study on the cracking of steel pieces during their galvanization in alloyed liquid zinc. An experimental design was developed to show the effect of the amount of the various alloying elements (Sn...This paper presents a study on the cracking of steel pieces during their galvanization in alloyed liquid zinc. An experimental design was developed to show the effect of the amount of the various alloying elements (Sn, Bi, Pb) on this phenomenon. The characterization of the effect was obtained by 1) deformation by three-point bending of a piece of steel with different levels of deflection;2) galvanizing and 3) observation and measurement of the cracks. A model of the critical deflection (deflection for crack starting) with the amounts of Sn, Pb, and Bi is presented and the predictions are described.展开更多
Based on the continuous hot(aluminizing) galvanizing lines and related non-standard equipment of Meishan Steel,this paper presents the main contents of such integrated engineering and designing of equipment for the tw...Based on the continuous hot(aluminizing) galvanizing lines and related non-standard equipment of Meishan Steel,this paper presents the main contents of such integrated engineering and designing of equipment for the two hot-dipped galvanizing lines,as well as innovative techniques and their features.Led by Cold Rolling Project Department of Meishan Steel,Baosteel Engineering and Technology Group Co.,Ltd. ,working as the responsible unit of this project,develops key technologies and integrates the system by combining the equipment design and development capacity of Baosteel Engineering,research and development capacity of Research Institute of Baosteel,process production and equipment maintenance experience of Cold Rolling Plant,Equipment Department and Manufacture Department of Baosteel Corporation.Core technologies of the two lines are developed and designed through original and integrated innovation and innovation after digestion,focusing on eight core techniques in process equipment,annealing furnace,fluid installation and EIC system.As a result of integration in key process equipment,industrial furnace and EIC control,the cold rolling hot dipped(aluminizing) galvanizing lines take on a new look and reach an annual capacity of 200 000 t galvanized products and 250 000 t galvanized aluminium base strips respectively.These two world advanced lines are able to produce hot-dipped galvanizing products with high quality surface and fine shape,such as household appliance board and senior construction board.As a result, the process and equipment technology of the lines have formed domestic intellectual property.Thus,the technology has reference value for self-integration and equipment technology innovation of similar lines.展开更多
In this paper,the recent state and problems of the sink roll in CGL are described.Several methods of increasing its operational life span are introduced,such as surface coating technology and sleeve material technolog...In this paper,the recent state and problems of the sink roll in CGL are described.Several methods of increasing its operational life span are introduced,such as surface coating technology and sleeve material technology.Fundamentally they cannot solve the problems of surface quality caused by the contact between strip and roll.On this basis,the newly developed principle and solutions for hot dip galvanizing technology without sink roll are highly emphasized,they are Float Technology,Electromagnetic pump technology,Electromagnetic enclosed slot by high-frequency AC,Electromagnetic enclosed slot by high-frequency DC.A comparison among their functions and characteristics is made and the possibility of its application is also discussed.Finally it comes to a conclusion that electromagnetic enclosed slot represents the direction of a continuous hot-dip galvanizing steel strip in the the 21st century.It has a very broad application prospects.Baosteel Technology Center is focused on the research and development of this technology.As technology advances,industrial applications is possible.展开更多
With the rapid development of the automobile industry, the use of galvannealed and galvanized steel sheets in automobiles is on the rise. These sheets must meet very high surface quality requirements. The surface trea...With the rapid development of the automobile industry, the use of galvannealed and galvanized steel sheets in automobiles is on the rise. These sheets must meet very high surface quality requirements. The surface treatment of line rolls is known to have a great impact on strip quality. To prevent dusts such as zinc ash from pressing into the strip surface, we used a composite thermal spray surface treatment technique to treat rolls. The successfully developed tungsten carbide （WC） ＋ Ni-P composite plating technology improved the quality of the tungsten carbide thermally sprayed WC roll surface. This technique is also helpful to control defects such as adhered foreign materials in hot-dip galvanized automobile outer panel surfaces.展开更多
An iron and steel company＇ s hot galvanizing technology was chosen as the object. An orthogonal experimental scheme with 5 factors of mixed level was designed, according to the various factors affecting the distribut...An iron and steel company＇ s hot galvanizing technology was chosen as the object. An orthogonal experimental scheme with 5 factors of mixed level was designed, according to the various factors affecting the distribution of slag. For each scheme, the amount of slag and slag height in different orthogonal schemes by simulation were obtained with FLUENT software. Then, range and variance analyses were selected to compare the trend of slag height in the different process parameters of the hot dip galvanizing process. Finally, the optimal combination of the process parameters was obtained.展开更多
Galvanization is the process of applying a protective zinc coating to iron or steel to prevent rusting. In the batch hot-dip galvanizing process, large amounts of wastes originate in liquid, solid and gaseous forms. A...Galvanization is the process of applying a protective zinc coating to iron or steel to prevent rusting. In the batch hot-dip galvanizing process, large amounts of wastes originate in liquid, solid and gaseous forms. Acidic waste containing iron and zinc ions is produced due to the cleaning of steel prior to zinc coating, which is considered the galvanizing acid waste. The galvanizing effluent used was collected from LTL Galvanizers Pvt. Ltd., Sapugaskanda, Sri Lanka, and converted into antimicrobial hematite (α-Fe<sub>2</sub>O<sub>3</sub>) nanoparticles. These nanoparticles were synthesized using a chemical precipitation method. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to characterize the nanomaterials produced. Two pathogenic bacteria and one pathogenic fungus were used to analyze the antimicrobial activity of the nanomaterials. All the samples showed excellent antibacterial and antifungal properties. And the material can inhibit the growth of both Gram-positive and Gram-negative bacteria. According to the SEM images, some of the hematite particles were around 100 nm in size or less, which confirms that the describing method is viable in synthesizing hematite nanostructures. As shown in the XRD, the major diffraction peak, located at 2θ of 35.617° (110) in addition to minor peaks at 24.87° (012), 33.07° (104), 42.08° (113), 51.18° (024), 53.52° (116) and, 57.46° (018) confirm the spinel structure of iron oxide (α-Fe<sub>2</sub>O<sub>3</sub>). The estimated average crystallite size of the nanomaterial is calculated to be 36.74 nm. The durability of the manufactured nanomaterial is excellent. This method is a time-efficient, environmentally friendly, cost-effective and industrially viable way to manufacture antimicrobial hematite (α-Fe<sub>2</sub>O<sub>3</sub>) nanomaterials from a galvanizing effluent.展开更多
Taking the intelligent improvement of hot-dip galvanizing production line as the object, the whole production line is upgraded through the accumulation and comparison of empirical data, so as to improve the intelligen...Taking the intelligent improvement of hot-dip galvanizing production line as the object, the whole production line is upgraded through the accumulation and comparison of empirical data, so as to improve the intelligent, standardized and functional design of hot-dip galvanizing production line, improve the ability of hot-dip galvanizing enterprises in production cost, product quality and delivery date, and enhance the competitiveness of their products in the market, so as to obtain the ability of sustainable development.展开更多
A new type of transformation induced plasticity （TRIP） steel with not only high strength and high ductility but also superior welding and galvanizing properties was designed and developed recently. Low carbon and lo...A new type of transformation induced plasticity （TRIP） steel with not only high strength and high ductility but also superior welding and galvanizing properties was designed and developed recently. Low carbon and low silicon content were preliminarily selected with the aim of meeting the requirements of superior quality in both welding and galvanizing. Phosphorus was chosen as one of the alloying elements, because it could reduce carbon activity in cementite and increase the stability of austenite. In addition, the possibility of phosphorus segregating at grain boundary was also discussed by thermodynamics as well as kinetics. Phase diagram was estimated at high temperature and the composition of the steel was then selected in the hyperperitectic range to avoid problems, which might occur in sheet steel continuous casting. Phase diagram in the inter.critical temperature was estimated for the steel to obtain the starting temperature of fast cooling. For understanding the minimum rate of fast cooling, pearlite growth kinetics was calculated with self-developed diffusion coefficients of elements in grain boundary. Overaging temperature was determined through the calculation of To temperature by both equilibrium and para-equilibrium assumptions, which was different from the current determination, which is only based on an equilibrium estimation.展开更多
In the process of protecting ferrous materials,aluminum coating usually forms a dense oxide film on the surface of the iron-based alloy.However,the capacity of the sacrificial anode is rather insufficient.In order to ...In the process of protecting ferrous materials,aluminum coating usually forms a dense oxide film on the surface of the iron-based alloy.However,the capacity of the sacrificial anode is rather insufficient.In order to solve this problem,the microstructure and electrochemical corrosion properties of Al-8Si-3Fe-xIn alloy under low chlorine conditions were studied.The results show that indium(In)dissolves to form In^(3+)and In^(+)reverse plating on the surface of the bare substrate to form a passivation film defect.When the In content is high,the segregated In forms an activation point in the form of a cathode phase.In activatesτ_(6)phase to form a micro-couple,which improves the non-uniform corrosion.The In-containing corrosion products at the phase boundary hinder the diffusion of Cl−.With an increase of In content,the self-corrosion potential(Ecorr)of the alloy shifts negatively,and the self-corrosion current density(Jcorr)decreases from 6.477μA/cm^(2)to 1.352μA/cm^(2),and then increases gradually.However,when the In content is 0.1%,the Ecorr of the alloy changes from−0.824 V to−0.932 V,and the Jcorr decreases from 6.477μA/cm^(2)to 4.699μA/cm^(2),suggesting that the use of sacrificial anode will give the best effect.展开更多
This study aimed to investigate the effect of varying pyrite(Py)content on copper(Cu)in the presence of different regrinding conditions,which were altered using different types of grinding media:iron,ceramic balls,and...This study aimed to investigate the effect of varying pyrite(Py)content on copper(Cu)in the presence of different regrinding conditions,which were altered using different types of grinding media:iron,ceramic balls,and their mixture,followed by flotation in the cleaner stage.The flotation performance of rough Cu concentrate can be improved by changing the regrinding conditions based on the Py content.Scanning electron microscopy,X-ray spectrometry,ethylenediaminetetraacetic acid disodium salt extraction,and X-ray photoelectron spectroscopy studies illustrated that when the Py content was high,the use of iron media in regrinding promoted the generation of hydrophilic Fe OOH on the surface of Py and improved the Cu grade.The ceramic medium with a low Py content prevented excessive Fe OOH from covering the surface of chalcopyrite(Cpy).Electrochemical studies further showed that the galvanic corrosion current of Cpy-Py increased with the addition of Py and became stronger with the participation of iron media.展开更多
Gas wiping is a decisive operation in hot-dip galvanizing process. In special, it has a crucial influence on the thickness and uniformity in coating film, but may be subsequently responsible for the problem of splashi...Gas wiping is a decisive operation in hot-dip galvanizing process. In special, it has a crucial influence on the thickness and uniformity in coating film, but may be subsequently responsible for the problem of splashing. The progress of industry demands continuously the reduction of production costs which may relate directly with the increase of coating speed, and the speed up of coating results in the increase of stagnation pressure in gas wiping system in final. It is known that the increase of stagnation pressure may accompany a harmful problem of splashing in general. Together with these, also, from the view point of energy consumption, it is necessary to design a nozzle optimally. And there is known that the downward tilting of nozzle using in air knife system is effective to prevent in somewhat the harmful problem of splashing. In these connections, first, we design a nozzle with constant expansion rate. Next, for the case of actual coating conditions in field, the effects of tilting of the constant expansion rate nozzle are investigated by numerical analysis. Under the present numerical conditions, it was turned out that the nozzle of constant expansion rate of p = having a downward jet angle of 5^0 is the most effective to diminish the onset of splashing, while the influence of small tilting of the nozzle on impinging wall pres- sure itself is not so large.展开更多
In the continuous hot-dip galvanizing process, the gas-jet wiping is used to control the coating thickness of moving steel strip. The high speed gas-jet discharged from the nozzle slot impinges on the strip, and at th...In the continuous hot-dip galvanizing process, the gas-jet wiping is used to control the coating thickness of moving steel strip. The high speed gas-jet discharged from the nozzle slot impinges on the strip, and at this moment, wipes the liquid coating layer dragged by a moving strip. The coating thickness is generally influenced on the flow characteristics of wiping gas-jet such as the impinging pressure distribution, pressure gradient and shear stress distribution on the surface of strip. The flow characteristics of wiping gas-jet mentioned above depends upon considerably both the process operating conditions such as the nozzle pressure, nozzle-to-strip distance and line speed, and the geometry of gas-jet wiping apparatus such as the height of nozzle slot. In the present study, the effect of the geometry of nozzle on the coating thickness is investigated with the help of a computational fluid dynamics method. The height of nozzle slot is varied in the range of 0.6mm to 1.7mm. A finite volume method (FVM) is employed to solve two-dimensional, steady, compressible Navier-Stokes equations. Based upon the results obtained, the effect of the height of nozzle slot in the gas-jet wiping process is discussed in detail. The computational results show that for a given standoff distance between the nozzle to the strip, the effective height of nozzle slot exists in achieving thinner coating thickness.展开更多
The hot-dip galvanizing line(HDGL) is a typical order-driven discrete-event process in steelmaking. It has some complicated dynamic characteristics such as a large time-varying delay, strong nonlinearity, and unmeasur...The hot-dip galvanizing line(HDGL) is a typical order-driven discrete-event process in steelmaking. It has some complicated dynamic characteristics such as a large time-varying delay, strong nonlinearity, and unmeasured disturbance, all of which lead to the difficulty of an online coating weight controller design. We propose a novel neural network based control system to solve these problems. The proposed method has been successfully applied to a real production line at Va Lin LY Steel Co., Loudi, China. The industrial application results show the effectiveness and efficiency of the proposed method, including significant reductions in the variance of the coating weight and the transition time.展开更多
Two sets of alloys,Mg-Zn-Ca-xNi(0≤x≤5),have been developed with tunable corrosion and mechanical properties,optimized for fracturing materials.High-zinc artificial aged(T6)Mg-12Zn-0.5Ca-x Ni(0≤x≤5)series,featuring...Two sets of alloys,Mg-Zn-Ca-xNi(0≤x≤5),have been developed with tunable corrosion and mechanical properties,optimized for fracturing materials.High-zinc artificial aged(T6)Mg-12Zn-0.5Ca-x Ni(0≤x≤5)series,featuring a straightforward preparation method and the potential for manufacturing large-scale components,exhibit notable corrosion rates up to 29 mg cm^(-2)h^(-1)at 25℃ and 643 mg cm^(-2)h^(-1)at 93℃.The high corrosion rate is primary due to the Ni–containing second phases,which intensify the galvanic corrosion that overwhelms their corrosion barrier effect.Low-zinc rolled Mg-1.5Zn-0.2Ca-x Ni(0≤x≤5)series,characterizing excellent deformability with an elongation to failure of~26%,present accelerated corrosion rates up to 34 mg cm^(-2)h^(-1)at 25℃ and 942 mg cm^(-2)h^(-1)at 93℃.The elimination of corrosion barrier effect via deformation contributes to the further increase of corrosion rate compared to the T6 series.Additionally,Mg-Zn-Ca-xNi(0≤x≤5)alloys exhibit tunable ultimate tensile strengths ranging from~190 to~237 MPa,depending on their specific composition.The adjustable corrosion rate and mechanical properties render the Mg-Zn-Ca-x Ni(0≤x≤5)alloys suitable for fracturing materials.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.U1360202,51472030,and 51502014)
文摘A C–Mn dual-phase steel was soaked at 800°C for 90 s and then either rapidly cooled to 450°C and held for 30 s(process A) or rapidly cooled to 350°C and then reheated to 450°C(process B) to simulate the hot-dip galvanizing process. The influence of the hot-dip galvanizing process on the microstructure and mechanical properties of 600-MPa hot-dip galvanized dual-phase steel(DP600) was investigated using optical microscopy, scanning electron microscopy(SEM), transmission electron microscopy(TEM), and tensile tests. The results showed that, in the case of process A, the microstructure of DP600 was composed of ferrite, martensite, and a small amount of bainite. The granular bainite was formed in the hot-dip galvanizing stage, and martensite islands were formed in the final cooling stage after hot-dip galvanizing. By contrast, in the case of process B, the microstructure of the DP600 was composed of ferrite, martensite, bainite, and cementite. In addition, compared with the yield strength(YS) of the DP600 annealed by process A, that for the DP600 annealed by process B increased by approximately 50 MPa because of the tempering of the martensite formed during rapid cooling. The work-hardening coefficient(n value) of the DP600 steel annealed by process B clearly decreased because the increase of the YS affected the computation result for the n value. However, the ultimate tensile strength(UTS) and elongation(A80) of the DP600 annealed by process B exhibited less variation compared with those of the DP600 annealed by process A. Therefore, DP600 with excellent comprehensive mechanical properties(YS = 362 MPa, UTS = 638 MPa, A_(80) = 24.3%, n = 0.17) was obtained via process A.
基金Sponsored by National Natural Science Foundation of China (50604006)National Development and Reform Commission of China (2009-354)
文摘In hot-dip galvanizing process, air jet wiping control is so crucial to decide the coating thickness and uni- formity of the zinc layer on the steel strip. The mathematical models developed predict the zinc coating thickness as a function of pressure and shear stress. The required pressure and shear stress profile on the strip surface were calcu- lated using regression analysis, and carried out using numerical simulation as FLUENT, a finite element analysis software. The influences of the outlet pressure, the nozzle to strip distance, the slot opening, the edge baffle plate, as well as the tilting angle of air knife were discussed. Combining with these results and regression analysis on the practical data, four first-order polynomial multi-parameter models were established for different targeted coating thicknesses with better regression coefficients. The validated model was used to carry out sensitivity analysis to de- termine the favorable controlling regime for the air jet wiping process.
基金This work is financially supported by the National Key R&D Program of China(2017YFB0304402)the National Natural Science Foundation of China(51971127).
文摘The effect of dew points(-50,-l0 and+10℃)on the galvanizing properties of a high-manganese twinning-inducedplasticity(TWIP)steel was studied.Scanning electron microscopy(SEM),glow discharge optical emission spectrometry(GDOES)and X-ray photoelectron spectroscopy(XPS)were used for microscopic observation and qualitative analysis of the interfacial layer between the steel surface and the zinc layer after hot-dip galvanizing.SEM analysis results show thatthree diffcrent morphologies of metallic oxides are formed on the interfacial layer under the different dew points.GDOES results show that Al is present in the molten zinc,reacting with Fe on the steel surface to form Fe2Al5,which can increasethe galvanizing properties.XPS results show that the valence states of Mn in the interfacial alloy layer are Mn'*and Mn*+,and the valence stales of Fe are Fe^0,Fe^2+and Fe^3+.The experimental results show that the hot-dip galvanizing performanceis the best at-10℃ and the formation of Mn and Fe intermetallic oxides has a bad effect on hot-dip galvanizing behaviorof the high-manganese TWIP steel.The types of the formed surface oxides(MnO,Mn3O4,Mn2O3,FeO3,and Fe2MnO4)onthe surface of the steel sheet are confirmed.It can obtain the best hot-dip galvanizing performance of the high-manganese TWIP steel by controlling the dew point from-10 to-5℃.
文摘A roll shape setting model was built for the hot galvanizing and planishing mill. The uniform transversal distributions of the front tension in the exit and the unit pressure were considered as the objective function. At the same time, the quality of the products, the stability of zinc layer, and the homogeneity of spangles were of considerable significance in the planishing process. The model was applied to the roll shape setting of the 1800 cold rolling 3# CGL hot galvanizing and planishing mill of Baosteel Co Ltd. After being planished, the flatness of a strip that was less than 6 I was more than 97%, and the flatness of others were less than 10 I; the pass percentage of the zinc lay- ers reached 100%.
基金Item Sponsored by National Science and Technology Pillar Program of China(2011BAE13B04)
文摘A new processing method for producing hot dip galvanized steel is designed and tested, in which pickling is skipped. Hot-rolled low carbon steel sheets are roiled with oxide scale in an experimental mill at room temperature, prior to annealing under a 20% hydrogen reducing atmosphere and galvanizing on a hot-dip galvanizing simulator. Micro-cracks formed in the oxide scale during cold rolling roughen the steel surface and enlarge the specific surface. Through-thickness cracks provide transport channels for hydrogen, and hence the reduction of oxide scale is en- hanced. When the sheet is dipped in the zinc bath, cracks are submerged by liquated zinc and the defects are not dis- tinct after hot-dip galvanizing. The overlay coating occludes with rough surface of the sheet, whereby a superior coat- ing adherence is realized.
文摘Baosteel has excelled in automotive steel sheets in the past three decades.It has made a significant contribution to the development of China’s automotive industry by producing a wide range of high-quality steel products.Some milestones achieved by Baosteel automotive steel sheet were briefly reviewed.The current challenges in producing ultra-high strength steel(UHSS),especially hot-dip galvanized UHSS,were summarized.The most current advancements in UHSS and the corresponding hot-dip galvanizing processes were discussed.The galvanizability of Si-Mn-added QP steel and DP steel, Mn-added TWIP steel, and Al-added low-density steel has been improved by different techniques in Baosteel.
文摘This paper presents a study on the cracking of steel pieces during their galvanization in alloyed liquid zinc. An experimental design was developed to show the effect of the amount of the various alloying elements (Sn, Bi, Pb) on this phenomenon. The characterization of the effect was obtained by 1) deformation by three-point bending of a piece of steel with different levels of deflection;2) galvanizing and 3) observation and measurement of the cracks. A model of the critical deflection (deflection for crack starting) with the amounts of Sn, Pb, and Bi is presented and the predictions are described.
文摘Based on the continuous hot(aluminizing) galvanizing lines and related non-standard equipment of Meishan Steel,this paper presents the main contents of such integrated engineering and designing of equipment for the two hot-dipped galvanizing lines,as well as innovative techniques and their features.Led by Cold Rolling Project Department of Meishan Steel,Baosteel Engineering and Technology Group Co.,Ltd. ,working as the responsible unit of this project,develops key technologies and integrates the system by combining the equipment design and development capacity of Baosteel Engineering,research and development capacity of Research Institute of Baosteel,process production and equipment maintenance experience of Cold Rolling Plant,Equipment Department and Manufacture Department of Baosteel Corporation.Core technologies of the two lines are developed and designed through original and integrated innovation and innovation after digestion,focusing on eight core techniques in process equipment,annealing furnace,fluid installation and EIC system.As a result of integration in key process equipment,industrial furnace and EIC control,the cold rolling hot dipped(aluminizing) galvanizing lines take on a new look and reach an annual capacity of 200 000 t galvanized products and 250 000 t galvanized aluminium base strips respectively.These two world advanced lines are able to produce hot-dipped galvanizing products with high quality surface and fine shape,such as household appliance board and senior construction board.As a result, the process and equipment technology of the lines have formed domestic intellectual property.Thus,the technology has reference value for self-integration and equipment technology innovation of similar lines.
文摘In this paper,the recent state and problems of the sink roll in CGL are described.Several methods of increasing its operational life span are introduced,such as surface coating technology and sleeve material technology.Fundamentally they cannot solve the problems of surface quality caused by the contact between strip and roll.On this basis,the newly developed principle and solutions for hot dip galvanizing technology without sink roll are highly emphasized,they are Float Technology,Electromagnetic pump technology,Electromagnetic enclosed slot by high-frequency AC,Electromagnetic enclosed slot by high-frequency DC.A comparison among their functions and characteristics is made and the possibility of its application is also discussed.Finally it comes to a conclusion that electromagnetic enclosed slot represents the direction of a continuous hot-dip galvanizing steel strip in the the 21st century.It has a very broad application prospects.Baosteel Technology Center is focused on the research and development of this technology.As technology advances,industrial applications is possible.
文摘With the rapid development of the automobile industry, the use of galvannealed and galvanized steel sheets in automobiles is on the rise. These sheets must meet very high surface quality requirements. The surface treatment of line rolls is known to have a great impact on strip quality. To prevent dusts such as zinc ash from pressing into the strip surface, we used a composite thermal spray surface treatment technique to treat rolls. The successfully developed tungsten carbide （WC） ＋ Ni-P composite plating technology improved the quality of the tungsten carbide thermally sprayed WC roll surface. This technique is also helpful to control defects such as adhered foreign materials in hot-dip galvanized automobile outer panel surfaces.
文摘An iron and steel company＇ s hot galvanizing technology was chosen as the object. An orthogonal experimental scheme with 5 factors of mixed level was designed, according to the various factors affecting the distribution of slag. For each scheme, the amount of slag and slag height in different orthogonal schemes by simulation were obtained with FLUENT software. Then, range and variance analyses were selected to compare the trend of slag height in the different process parameters of the hot dip galvanizing process. Finally, the optimal combination of the process parameters was obtained.
文摘Galvanization is the process of applying a protective zinc coating to iron or steel to prevent rusting. In the batch hot-dip galvanizing process, large amounts of wastes originate in liquid, solid and gaseous forms. Acidic waste containing iron and zinc ions is produced due to the cleaning of steel prior to zinc coating, which is considered the galvanizing acid waste. The galvanizing effluent used was collected from LTL Galvanizers Pvt. Ltd., Sapugaskanda, Sri Lanka, and converted into antimicrobial hematite (α-Fe<sub>2</sub>O<sub>3</sub>) nanoparticles. These nanoparticles were synthesized using a chemical precipitation method. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to characterize the nanomaterials produced. Two pathogenic bacteria and one pathogenic fungus were used to analyze the antimicrobial activity of the nanomaterials. All the samples showed excellent antibacterial and antifungal properties. And the material can inhibit the growth of both Gram-positive and Gram-negative bacteria. According to the SEM images, some of the hematite particles were around 100 nm in size or less, which confirms that the describing method is viable in synthesizing hematite nanostructures. As shown in the XRD, the major diffraction peak, located at 2θ of 35.617° (110) in addition to minor peaks at 24.87° (012), 33.07° (104), 42.08° (113), 51.18° (024), 53.52° (116) and, 57.46° (018) confirm the spinel structure of iron oxide (α-Fe<sub>2</sub>O<sub>3</sub>). The estimated average crystallite size of the nanomaterial is calculated to be 36.74 nm. The durability of the manufactured nanomaterial is excellent. This method is a time-efficient, environmentally friendly, cost-effective and industrially viable way to manufacture antimicrobial hematite (α-Fe<sub>2</sub>O<sub>3</sub>) nanomaterials from a galvanizing effluent.
文摘Taking the intelligent improvement of hot-dip galvanizing production line as the object, the whole production line is upgraded through the accumulation and comparison of empirical data, so as to improve the intelligent, standardized and functional design of hot-dip galvanizing production line, improve the ability of hot-dip galvanizing enterprises in production cost, product quality and delivery date, and enhance the competitiveness of their products in the market, so as to obtain the ability of sustainable development.
基金Item Sponsored by National Natural Science Foundation of China (50671061) National Engineering and Research Center of Advanced Steel Technology , Ansteel Company and China-Belgium Bilateral Project (2001-242)
文摘A new type of transformation induced plasticity （TRIP） steel with not only high strength and high ductility but also superior welding and galvanizing properties was designed and developed recently. Low carbon and low silicon content were preliminarily selected with the aim of meeting the requirements of superior quality in both welding and galvanizing. Phosphorus was chosen as one of the alloying elements, because it could reduce carbon activity in cementite and increase the stability of austenite. In addition, the possibility of phosphorus segregating at grain boundary was also discussed by thermodynamics as well as kinetics. Phase diagram was estimated at high temperature and the composition of the steel was then selected in the hyperperitectic range to avoid problems, which might occur in sheet steel continuous casting. Phase diagram in the inter.critical temperature was estimated for the steel to obtain the starting temperature of fast cooling. For understanding the minimum rate of fast cooling, pearlite growth kinetics was calculated with self-developed diffusion coefficients of elements in grain boundary. Overaging temperature was determined through the calculation of To temperature by both equilibrium and para-equilibrium assumptions, which was different from the current determination, which is only based on an equilibrium estimation.
基金Projects(52171003,52271005)supported by the National Science and Technology Major Project of ChinaProject(KYCX23_3032)supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China。
文摘In the process of protecting ferrous materials,aluminum coating usually forms a dense oxide film on the surface of the iron-based alloy.However,the capacity of the sacrificial anode is rather insufficient.In order to solve this problem,the microstructure and electrochemical corrosion properties of Al-8Si-3Fe-xIn alloy under low chlorine conditions were studied.The results show that indium(In)dissolves to form In^(3+)and In^(+)reverse plating on the surface of the bare substrate to form a passivation film defect.When the In content is high,the segregated In forms an activation point in the form of a cathode phase.In activatesτ_(6)phase to form a micro-couple,which improves the non-uniform corrosion.The In-containing corrosion products at the phase boundary hinder the diffusion of Cl−.With an increase of In content,the self-corrosion potential(Ecorr)of the alloy shifts negatively,and the self-corrosion current density(Jcorr)decreases from 6.477μA/cm^(2)to 1.352μA/cm^(2),and then increases gradually.However,when the In content is 0.1%,the Ecorr of the alloy changes from−0.824 V to−0.932 V,and the Jcorr decreases from 6.477μA/cm^(2)to 4.699μA/cm^(2),suggesting that the use of sacrificial anode will give the best effect.
基金financially supported by the National Key Research and Development Plan of China(No.2022YFC2904603)the National Natural Science Foundation of China(No.52174268)。
文摘This study aimed to investigate the effect of varying pyrite(Py)content on copper(Cu)in the presence of different regrinding conditions,which were altered using different types of grinding media:iron,ceramic balls,and their mixture,followed by flotation in the cleaner stage.The flotation performance of rough Cu concentrate can be improved by changing the regrinding conditions based on the Py content.Scanning electron microscopy,X-ray spectrometry,ethylenediaminetetraacetic acid disodium salt extraction,and X-ray photoelectron spectroscopy studies illustrated that when the Py content was high,the use of iron media in regrinding promoted the generation of hydrophilic Fe OOH on the surface of Py and improved the Cu grade.The ceramic medium with a low Py content prevented excessive Fe OOH from covering the surface of chalcopyrite(Cpy).Electrochemical studies further showed that the galvanic corrosion current of Cpy-Py increased with the addition of Py and became stronger with the participation of iron media.
文摘Gas wiping is a decisive operation in hot-dip galvanizing process. In special, it has a crucial influence on the thickness and uniformity in coating film, but may be subsequently responsible for the problem of splashing. The progress of industry demands continuously the reduction of production costs which may relate directly with the increase of coating speed, and the speed up of coating results in the increase of stagnation pressure in gas wiping system in final. It is known that the increase of stagnation pressure may accompany a harmful problem of splashing in general. Together with these, also, from the view point of energy consumption, it is necessary to design a nozzle optimally. And there is known that the downward tilting of nozzle using in air knife system is effective to prevent in somewhat the harmful problem of splashing. In these connections, first, we design a nozzle with constant expansion rate. Next, for the case of actual coating conditions in field, the effects of tilting of the constant expansion rate nozzle are investigated by numerical analysis. Under the present numerical conditions, it was turned out that the nozzle of constant expansion rate of p = having a downward jet angle of 5^0 is the most effective to diminish the onset of splashing, while the influence of small tilting of the nozzle on impinging wall pres- sure itself is not so large.
文摘In the continuous hot-dip galvanizing process, the gas-jet wiping is used to control the coating thickness of moving steel strip. The high speed gas-jet discharged from the nozzle slot impinges on the strip, and at this moment, wipes the liquid coating layer dragged by a moving strip. The coating thickness is generally influenced on the flow characteristics of wiping gas-jet such as the impinging pressure distribution, pressure gradient and shear stress distribution on the surface of strip. The flow characteristics of wiping gas-jet mentioned above depends upon considerably both the process operating conditions such as the nozzle pressure, nozzle-to-strip distance and line speed, and the geometry of gas-jet wiping apparatus such as the height of nozzle slot. In the present study, the effect of the geometry of nozzle on the coating thickness is investigated with the help of a computational fluid dynamics method. The height of nozzle slot is varied in the range of 0.6mm to 1.7mm. A finite volume method (FVM) is employed to solve two-dimensional, steady, compressible Navier-Stokes equations. Based upon the results obtained, the effect of the height of nozzle slot in the gas-jet wiping process is discussed in detail. The computational results show that for a given standoff distance between the nozzle to the strip, the effective height of nozzle slot exists in achieving thinner coating thickness.
文摘The hot-dip galvanizing line(HDGL) is a typical order-driven discrete-event process in steelmaking. It has some complicated dynamic characteristics such as a large time-varying delay, strong nonlinearity, and unmeasured disturbance, all of which lead to the difficulty of an online coating weight controller design. We propose a novel neural network based control system to solve these problems. The proposed method has been successfully applied to a real production line at Va Lin LY Steel Co., Loudi, China. The industrial application results show the effectiveness and efficiency of the proposed method, including significant reductions in the variance of the coating weight and the transition time.
基金supported by the National Key Research and Development Program(No.2022YFE0122000)National Natural Science Foundation of China under Grant Nos.52234009,52274383,52222409,and 52201113。
文摘Two sets of alloys,Mg-Zn-Ca-xNi(0≤x≤5),have been developed with tunable corrosion and mechanical properties,optimized for fracturing materials.High-zinc artificial aged(T6)Mg-12Zn-0.5Ca-x Ni(0≤x≤5)series,featuring a straightforward preparation method and the potential for manufacturing large-scale components,exhibit notable corrosion rates up to 29 mg cm^(-2)h^(-1)at 25℃ and 643 mg cm^(-2)h^(-1)at 93℃.The high corrosion rate is primary due to the Ni–containing second phases,which intensify the galvanic corrosion that overwhelms their corrosion barrier effect.Low-zinc rolled Mg-1.5Zn-0.2Ca-x Ni(0≤x≤5)series,characterizing excellent deformability with an elongation to failure of~26%,present accelerated corrosion rates up to 34 mg cm^(-2)h^(-1)at 25℃ and 942 mg cm^(-2)h^(-1)at 93℃.The elimination of corrosion barrier effect via deformation contributes to the further increase of corrosion rate compared to the T6 series.Additionally,Mg-Zn-Ca-xNi(0≤x≤5)alloys exhibit tunable ultimate tensile strengths ranging from~190 to~237 MPa,depending on their specific composition.The adjustable corrosion rate and mechanical properties render the Mg-Zn-Ca-x Ni(0≤x≤5)alloys suitable for fracturing materials.
