建筑结构钢板热轧轧机DBN-PSO振动预报及应用

利用实时监测数据(Real-Time Monitoring Data,RMD)参数分析轧机振动状态,综合运用深度置信网络(Deep Belief Networks,DBN)与粒子群(Particle Swarm Optimization,PSO)算法构建轧机振动仿真模型,实现RMD参数的深度挖掘,并达到轧机振动的预报效果。通过融合处理能够获得非常接近实际振动过程的预测数据,具备优异预测能力。结合现场测试的初始数据预测误差在3.5%范围内,跟轧机振动情况相符。当轧制速率变慢后,振动加速度出现了降低结果;入口张力对轧机的振动加速度具有反向作用;轧机振动加速度相对出口张力表现为正相关特点;以不同宽度的轧件进行测试发现轧机振动加速度保持基本恒定的状态。该研究对提高热轧轧机运行稳定性,对保证建筑结构钢板成形精度具有很好的指导意义,可以拓宽到其它的成形设备优化领域。

Sr元素含量对Zn-2.0%Al-1.2%Mg镀层的微观组织与耐蚀性的影响

为了进一步研究微量合金元素对镀层微观组织的调控以及耐蚀性能的影响机理,采用双镀法在Q235钢板上制备Zn-2.0%Al-1.2%Mg-x%Sr(x=0、0.03%、0.06%、0.09%、0.12%,质量分数)镀层,通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、5%NaCl浸泡实验等方法探究Sr元素含量对Zn-2.0%Al-1.2%Mg镀层的微观组织与耐蚀性的影响。结果表明:添加适量的Sr元素,可以有效细化Zn-2.0%Al-1.2%Mg镀层表面凝固组织中的初生η-Zn相,引导生成Zn/Al/MgZn_(2)三元共晶组织,使中间合金层中FeAl_(3)-Zn_(x)柱状晶变得更加致密。当Sr的添加量为0.09%时,镀层表面凝固组织的细化效果最为明显,中间合金层最薄且致密,此时镀层的浸泡腐蚀速率最低,耐蚀性最好。

Effect of Reduction on Bonding Interface of Hot-rolled Wear-resistant Steel BTW1/Q345R Cladding Plate

Wear-resistant cladding plates consisting of a substrate（Q345 R） and a clad layer（BTW1） were bonded through hot rolling at the temperature of 1 200 ℃ and a rolling speed of 0.5 m/s. The microhardness of the cladding plate was also tested after being heat treated. The microstructure evolution on the interface of BTW1/Q345 R sheets under various reduction rates was investigated with a scanning electron microscope（SEM） and EBSD. It is found that the micro-cracks and oxide films on the interface disappear when the reduction is 80%, whereas the maximum uniform diffusion distance reaches 10 μm. As a result, a wide range of metallurgical bonding layers forms, which indicates an improved combination between the BTW1 and the Q345 R. Additionally, it is discovered that the unbroken oxide films on the interface are composed of Mn, Si or Cr at the reductions of 50% and 65%. The SEM fractography of tensile specimen demonstrates that the BTW1 has significant dimple characteristics and possesses lower-sized dimples with the increment in reduction, suggesting that the toughness and bonding strength of the cladding plates would be improved by the increase of reduction. The results reveal that a high rolling reduction causes the interfacial oxide film broken and further forms a higher-sized composite metallurgical bonding interface. The peak microhardness is achieved near the interface.

Hot compressive deformation of eutectic Al-17at%Cu alloy on the interface of the Cu-Al composite plate produced by horizontal continuous casting

On the interface of the Cu-Al composite plate from horizontal continuous casting,the eutectic microstructure layer thickness ac-counts for more than 90%of the total interface thickness,and the deformation in rolling forming plays an important role in the quality of the composite plate.The eutectic microstructure material on the interface of the Cu-Al composite plate was prepared by changing the cooling rate of ingot solidification and the deformation in hot compression was investigated.The results show that when the deformation temperature is over 300℃,the softening effect of dynamic recrystallization ofα-Al is greater than the hardening effect,and uniform plastic deformation of eutectic microstructure is caused.The constitutive equation of flow stress in the eutectic microstructure layer was established by Arrhenius hy-perbolic-sine mathematics model,providing a reliable theoretical basis for the deformation of the Cu-Al composite plate.

Rusting behavior and preventative measures of hot-rolled steel plates for automobile applications

As one of the important categories of hot-rolled products, hot-rolled steel plates for automobile applications generally undergo uniform corrosion or localized corrosion according to different environments of manufacturing, transportation and/or storage of the plates. General corrosion often takes place on the surface of a plate in the exterior part of a package, and only reduces the thickness of the plate and slightly increases the roughness of the surface; however, localized corrosion on the surface of a plate inside the package is likely to result in the formation of pit-like defects on the substrate of the plate, which cannot be removed thoroughly by normal acid pickling or sand blasting, and affects the application of the plate. This research report analyzes the phenomena and characteristics of the rusting behavior of hot- rolled steel plates for automobile applications, and the influencing factors are summaried. The corresponding preventative measures are proposed.

FEA technique of hot plate forming process using cell-typed die with cooling device

Hot plate forming using a cell-typed die is a process for forming a large thick plate with a spherical shape for the manufacture of a large spherical LNG tank.Cell-typed upper and lower dies made of a framework of steel plates fitted to make a grid pattern are used in this process,and an air-cooling device is separately installed inside the lower die.A finite element analysis (FEA) technique was developed,which included hot forming,air flow,cooling and thermal deformation analysis for the hot plate forming process using the cell-typed die.Further,the convective and interface heat transfer coefficients were used to reproduce analytically the effects of the cooling device in the hot plate forming analysis.A small-scale model test of the process was conducted to verify the FEA technique.The analysis results show that the curvature of the final plate agrees well with that of the designed experiment within a maximum relative error of 0.03% at the corner of the plate.

Influences of Al and Si Powders on Microstructure and Hot Mechanical Properties of Al_2O_3-C Slide Plates

The basic formulation of Al2O3- C slide plates was65%（ in mass,the same hereinafter） white fused corundum particles,25% white fused corundum fines,6% active α-Al2O3 micropowder,4% carbon black and flake graphite, and additional 4% phenolic resin.Based on this formulation,3% Al powder,3% Si powder,and 3% Al ＋ 3% Si powder were used to substitute equivalent white corundum fines to improve the hot mechanical properties of Al2O3- C slide plates. The specimens with dimensions of 140 mm × 25 mm × 25 mm were pressed at 150 MPa,dried at 200 ℃ for 24 h,and hot treated at 1 400 ℃ for 3 h in carbon embedded condition. Then hot modulus of rupture and thermal shock resistance of the specimens were tested and the phase compositions and microstructure were analyzed. The results show that specimen with 3% Al powder has the higher hot modulus of rupture but lower residual modulus of rupture after thermal shock than the specimen with3% Si powder; the specimen with 3% Al ＋ 3% Si powders exhibits the highest hot modulus of rupture and the best thermal shock resistance; the change of mechanical property is closely related with the in-situ formed nonoxides： AlN in the form of bars is formed in specimens with Al powder; fibrous SiC whiskers are formed in specimens with Si powder; in the specimens with both Al and Sipowders,besides AlN and SiC whiskers,hexagonal tabular SiAlON is in-situ synthesized,which interlocks with each other.

Microstructure and properties of Ti-bearing hot-rolled high-strength steel plates for two-sided enameling

The composition and production technology of the type of hot-rolled steel plate used in two-sided enameling were briefly described. The microstructure and mechanical properties before and after enameling were contrastively investigated,and the precipitates in the samples were analyzed using transmission electron microscope and energy dispersive spectrometer. The results show the ferrite grain size of the steel plate after high-temperature enamel firing to be fine,with a large number of TiC and Ti;C;S;precipitates dispersed throughout the ferrite matrix. After two rounds of enamel firing at a temperature range of 800-890 ℃,its yield strength can still reach342 MPa. The results of a hydrogen permeation test show that the hydrogen storage properties of the steel plate are much better than those of ordinary structural carbon steel. A better bubble structure in the enamel layer can be obtained by this steel plate,with no fish-scale defects on the enameled steel-plate surface.

Analysis of High-Cr Cast Iron/Low Carbon Steel Wear-resistant Laminated Composite Plate Prepared by Hot-rolled Symmetrical Billet

This study developed a new technology for preparing high-chromium cast iron(HCCI)/low-carbon steel(LCS)wear-resistant composite plates by hot rolling at a 1050°C and a rolling speed of 0.2 m/s.The effects of different rolling reductions(30%,45%,and 60%)on the microstructure(interface and HCCI layer)and mechanical properties(bonding strength,hardness,and wear resistance)of the composite plate were studied.SEM images showed that when the reduction was increased,no impurities and interlayers were found between the microscopic interfaces after hot rolling,and the bonding interface exhibited a wave-like shape.EDS analysis showed that the Cr element diffusion between two metals after hot rolling was promoted when the reduction was increased,thereby improving the bonding quality under the same rolling temperature and rolling speed.Experiments showed that due to the stress release effect of the LCS of the cladded layer,the macro-slab shape after hot rolling performed well,and the brittle HCCI layer underwent thermoplastic deformation without cracking.Moreover,the increase of rolling reduction improved the bonding quality.As the rolling reduction was increased,the volume fraction of Cr-carbides in the HCCI layer also increased,resulting in an increase of hardness and wear-resistance.

Cu-Ag-La_(2)O_(3)功能梯度材料的制备及其性能研究

为提高Cu、Ag、La_(2)O_(3)的界面结合强度,通过化学镀工艺在Ag、La_(2)O_(3)粉末表面镀上均匀、完整和致密的Cu粉。采用热压烧结工艺制备出含有不同成分的三层和五层Ag/Cu/La_(2)O_(3)功能梯度材料,研究成分对两种功能梯度材料的显微组织、致密度和润湿性的影响。

Reparation and Performance Testing of Free Radical Photocurable Passivation Film Modified by Titanate Coupling Agent for Hot-plated Aluminum-zinc Steel Plate

To study the effect of free radical photocurable passivation film modified by titanate coupling agent for hot-plated aluminum-zinc plate,trimethylpropane triacrylate(TMPTA)and 2-phenoxyethyl acrylate were used as active diluents,a mixture of modified epoxy acrylate and modified polyester acrylate in a certain proportion was used as an oligomer,2-methyl-1-[4-(methylothyl)benzene]-2-morpholine acetone(907)was used as a free radical photoinitiator,isopropyl thioxanthone(ITX)was used as sensitizer,and bis(dioctyl phosphate acyl)titanate ethyltitanate acrylamide chelate(FD-812)was used as corrosion inhibitor modifier.After UV-curing,the passivation film was characterized by neutral salt spray test,electrochemical testing and other methods.The general performance of the passivation film may meet the requirements of downstream users of hot aluminum-zinc steel plate.The neutral salt spray test,electrochemical testing and microscopic surface morphology analysis of passivation film are in agreement.The introduction of titanate components may effectively promote the photocuring of free radicals.There have been few reports on the titanate coupling which is added to UV-curing coating formula.The titanate coupling agent contains acrylamide groups and terminal amine groups,acrylamide group has oligomer and crosslinking monomer,the terminal tertiary amine groups can provide hydrogen protons,reduce oxygen polymerization,and a phosphating film is formed on the surface of the metal substrate to improve the adhesion and corrosion resistance of the coating.

UV-LED Curing Cationic Passivation Film for the Surface of Hot-Dip Aluminum-Zinc Coated Steel Plate

The surface treatment technology of hot aluminum-zinc steel plate and UV curing technology may be effectively combined in the present research. According to different light curing mechanisms, different formulations from UV curing surface treatment agents can be applied to the surface treatment of hot aluminum-zinc steel plate, mainly including 3-ethyl-3-benzoxy-methyl oxacyclobutane (TCM 104) and 3,4-epoxy-cyclohexylformic acid -3',4'-epoxy-cyclohexyl methyl ester (UVR 6110) as active diluents, high molecular weight polyfunctional oxacyclobutane as oligomer, triaryl sulfonium salt as a cationic photoinitiator, and an anthracene compound as a sensitizer. 385 nm LED lamp used as a radiation resource, the effects of the proportion of active diluent, the type and amount of photoinitiator, the amount of sensitizer, the curing temperature, and the amount of nano-SiO2 on the photocuring rate were investigated by photoper-scanning differential calorimetry (Photo-DSC). The experimental results show that the system has the fastest photocuring rate under the conditions of 8:2 ratio of TCM 104 to UVR 6110, 2.5% photoinitiator, 0.6% sensitizer, 0.2% nano-SiO2 additive, and 80˚C curing temperature. Based on addition of the appropriate number of various additives, the cationic photocuring surface treatment solution was prepared and further coated on the hot-dip galvalume steel plates. After curing, the passivation films were characterized by neutral salt spray test (NSST), Fourier transform infrared spectroscopy (FT-IR), electrochemical testing and other methods. The results show that the formulations could be cured at an energy of 150 mJ/cm2, and the overall performance of the passivation film could meet with the requirements of the downstream users.

Transverse stress-strain evolution during welding of thin aluminum alloy plate

The FE simulation results of transverse stresses and strains during welding of thin aluminum alloy plate are presented. The results indicate that restraint condition is the main factor that determines whether or not hot cracking will occur. With rigid restraint hot cracking (crater cracking) will occur at the arc-stopping end, and such cracking usually will not occur without external restraint. But under restraint-free condition it is easy for terminal cracks to occur.

Stream Surface Strip Element Method and Simulation of Three-Dimensional Deformation of Continuous Hot Rolled Strip

A new method,the stream surface strip element method,for simulating the three-dimensional deformation of plate and strip rolling process was proposed.The rolling deformation zone was divided into a number of stream surface(curved surface)strip elements along metal flow traces,and the stream surface strip elements were mapped into the corresponding plane strip elements for analysis and computation.The longitudinal distributions of the lateral displacement and the altitudinal displacement of metal were respectively constructed to be a quartic curve and a quadratic curve,of which the lateral distributions were expressed as the third-power spline function,and the altitudinal distributions were fitted in the quadratic curve.From the flow theory of plastic mechanics,the mathematical models of the three-dimensional deformations and stresses of the deformation zone were constructed.Compared with the streamline strip element method proposed by the first author of this paper,the stream surface strip element method takes into account the uneven distributions of stresses and deformations along altitudinal direction,and realizes the precise three-dimensional analysis and computation.The simulation example of continuous hot rolled strip indicates that the method and the model accord with facts and provide a new reliable engineering-computation method for the three-dimensional mechanics simulation of plate and strip rolling process.

Hot deformation behavior and globularization mechanism of Ti-6Al-4V-0.1B alloy with lamellar microstructure

Hot deformation behavior and globularization mechanism of Ti6A14V0.1B alloy with lamellar micro structure were quantitatively studied through isothermal compression tests with the temperature range of 850950 ℃and strain rate range of 0.011.00 s1. The results show that the peak flow stress and steady stress are sensitive to the strain rate and temperature. The value of deformation activation energy is 890.49 kJmo11 in （a＋β） region. Dynamic recrystallization is the major deformation mecha nism. Flow softening is dominated by dynamic recrystallization at 850950 ℃. TiB particles promote the recrystallization of laths. Globularization processes consist of four steps： for mation of subgrain after dynamic recovery in a plates; subgrain boundary migration caused by interracial instability; interfacial migration promoting phase wedge into a phase; disintegrating of a laths by diffusion processes; and grain boundary sliding. Globularization mechanisms during hot deformation processes of the Ti6A14V0.1B alloy with lamellar structure are continuous dynamic recrystallization.

THE INFLUENCE OF COMPOSITION AND TEMPERATURE OF BATH ANDAFTER-TREATMENT 0N COLORATION IN COLORING HOT DIPGALVANIZATION

The 08 Al steel sheets were hot dip ped into Zn - Mn bath with 0 1 % Mn and 0 2 % Mn at600 ～420 ℃ bath tem perature , and then w ere treated in different w ays . The after - treat ments include cooling in the air at room tem perature directly , holding at the upper part of thehot dip galvanizing furnace for 60 s an d then holding at 510 ±10 ℃for 90 s . The results in dicated that blue , yellow , and purple , w hose coloration varied with the co m position an d thetem perature of bath and the w ays of after - treat ment . Finally , the mechanism of coloredzinc coating w as discussed .

Bending analysis and control of rolled plate during snake hot rolling

In order to study the bending behavior of aluminum alloy 7050 thick plate during snake hot rolling, several coupled thermo-mechanical finite element(FE) models were established. Effects of different initial thicknesses, pass reductions, speed ratios and offset distances on the bending value of the plate were analyzed. ‘Quasi smooth plate' and optimum offset distance were defined and quasi smooth plate could be acquired by adjusting offset distance, and then bending control equation was fitted. The results show that bending value of the plate as well as the extent of the increase grows with the increase of pass reduction and decrease of initial thickness; the bending value firstly increases and then keeps steady with the ascending speed ratio; the bending value can be reduced by enlarging the offset distance. The optimum offset distance varies for different rolling parameters and it is augmented with the increase of pass reduction and speed ratio and the decrease of initial thickness. A proper offset distance for different rolling parameters can be calculated by the bending control equation and this equation can be a guidance to acquire a quasi smooth plate. The FEM results agree well with experimental results.

Analysis of strain variation in cross shear zone of plate during snake hot rolling

In order to study the distribution of equivalent and shear strain of aluminum alloy plate during snake hot rolling, several coupled thermo-mechanical finite element models(FEM) are established. Effects of speed ratio and offset distance on strain distribution of the plate are analyzed. The length of cross shear zone is defined to have a better understanding of the deformation characteristic in cross shear zone, which is the essential difference from symmetrical rolling in deformation zone. The results show that the equivalent strain and shear strain of lower part both increase with the increase of speed ratio, while the upper part decreases; the equivalent strain through the whole thickness decreases with ascending offset distance, while the shear strain of lower part increases. The length of cross shear zone quickly increases with ascending speed ratio and slightly decreases with ascending offset distance. The "positive" and "negative" cross shear zones are formed with the increase of speed ratio and offset distance, respectively. The value of the sensitivity coefficient of speed ratio is an order of magnitude bigger than the offset distance. However, the shear strain at center point increases with the ascending speed ratio and offset distance for different mechanism. As speed ratio increases, the asymmetry of the distribution of equivalent is becoming larger and the shear strain is generated in the same direction in cross shear zone. The FEM results agree well with experimental results.

Study on magneto-elastic-plastic deformation characteristics of ferromagnetic rectangular plate with simple supports

In this paper, the magnetic-elastic-plastic deformation behavior is studied for a ferromagnetic plate with simple supports. The perturbation formula of magnetic force is first derived based on the perturbation technique, and is then applied to the analysis of deformation characteristics with emphasis laid on the analyses of modes, symmetry of deformation and influences of incident angle of applied magnetic field on the plate deformation. The theoretical analyses offer explanations why the configuration offer- romagnetic rectangular plate with simple supports under an oblique magnetic field is in-wavy type along the x-direction, and why the largest deformation of the ferromagnetic plate occurs at the incident angle of 45°for the magnetic field. A numerical code based on the finite element method is developed to simulate quantitatively behaviors of the nonlinearly coupled multi-field problem. Some characteristic curves are plotted to illustrate the magneto--elastic-plastic deflections, and to reveal how the deflections can be influenced by the incident angle of applied magnetic field. The deformation characteristics obtained from the numerical simulations are found in good agreement with the theoretical analyses.

Influence of Hartmann Number on Convective Flow of Maxwell Fluid between Two Hot Parallel Plates through Porous Medium Subject to Arbitrary Shear Stress at the Boundary

Natural convection flow of unsteady Maxwell fluid with the effects of constant magnetic force in the course of a porous media is investigated in this research work. Fluid motion between a channel of parallel plates is tempted by time dependent shear stress applied on one plate. The governing partial differential equations of a model under consideration are transformed into ordinary differential equations by Laplace transform method and then solved for temperature and velocity fields. The obtained results for temperature fields are expressed in terms of complementary error function. The influences of involved parameters likes Hartmann number, Grashf number, Prandlt number and porosity parameter, on temperature and velocity profiles are shown graphically. There is no such result regarding Maxwell fluid in the existing literature.