连续热镀锌过程带钢边部气流特性的研究

为探究连续热镀锌气刀射流拭锌过程中发生的带钢边部压力衰减问题,设计了气流冲击平板实验,对带钢表面气流流向及压力进行测定.基于测量的参数,对该气刀射流喷吹过程进行数值模拟,并结合所推导的镀层厚度计算模型,对为减少带钢边部压力衰减所增设的边部挡板进行了厚度优化.研究结果表明:气刀喷吹时带钢边部气流发生横向偏转,使得带钢边部压力较中心处低,气压衰减率随气刀与带钢的间隔距离增加而增加,增设边部挡板能有效阻碍带钢边部压力衰减和降低边部过镀锌缺陷发生,且挡板厚度为2 mm时的作用效果最佳.     

Heteroepitaxial growth of Fe2Al5 inhibition layer in hot-dip galvanizing of an interstitial-free steel

This work presents characterization results on inhibition layers formed on a TiNb-stabilized interstitial-free steel after short time galvanizing. The Fe-Al and steel interface was free from oxide, so that the Fe-Al intermetallic compound could directly nucleate on ferrite grains. Electron diffraction performed in a transmission electron microscope showed that only Fe₂Al₅ was formed and it had a well-defined orientation relationship of [110]_{Fe(sub/2)Al(sub/5)}// [111]_Fe, (001) _{Fe(sub/2)Al(sub/5)}//(01?1)_Fe and (11?0) _{Fe(sub/2)Al(sub/5)}//(21?1?)_Fe with Fe substrate. The structure of the interfaces between Fe₂Al₅ and Fe is discussed. The epitaxially nucleated Fe₂Al₅ grains on Fe substrate had very small grain size, 20 nm or less, and several variants were intimately mixed. The grains grew rapidly to hundreds of nanometers toward the Zn side.     

The effects of zinc bath temperature on the coating growth behavior of reactive steel

The purpose of this work is to identify the influence of zinc bath temperature on the morphology and the thickness of reactive steel (Fe–0.1 wt.%Si alloy) coatings. The Fe–0.1 wt.%Si samples were galvanized for 3 min at temperatures in the range of 450–530 °C in steps of 10 °C. The coatings were characterized by using scanning electron microscopy/energy dispersive X-rays analysis. It was found that the coating thickness reaches the maximum at 470 °C and the minimum at 500 °C, respectively. When the reactive steel is galvanized at temperatures in the range of 450–490 °C, the coatings have a loose ζ layer on the top of a compact δ layer. With the increase of the galvanizing temperature, the ζ layer becomes looser. When the temperature is at 500 °C, the ζ phase disappears. With the increase of temperature, the coatings change to be a diffuse-Δ layer (δ+ liquid zinc).     

Effects of organic and inorganic treatment agents on the formation of conversion layer on hot-dip galvanized steel: An X-ray photoelectron spectroscopy study

The formation of a Cr-free conversion layer on hot-dip galvanized (HDG) steel involves various interfacial processes which radically influence the composition of the coating and thus its performance. Here, we investigate the role of the main constituents contained in the treatment bath, the polymeric compounds and manganese phosphate species, by using derivative versions from the standard solution. A detailed X-ray photoelectron spectroscopy (XPS) analysis allowed distinction between oxygen originating from polymeric compounds and oxygen of inorganic nature in oxides/hydroxides or phosphate species. Our results revealed that manganese phosphate present in the treatment bath promotes the polymer adsorption on HDG substrate. Angle-resolved XPS and depth profile showed the presence of TiO₂ layer on the outer part of the conversion layer, when polymeric compounds are not detected.     

Optical on-line monitoring for the long-term stabilization of a reactive mid-frequency sputtering process of Al-doped zinc oxide films

Closed-loop feedback control systems have shown to be able to stabilize optimum process conditions for reactively sputtered aluminum doped zinc oxide (ZnO:Al) films on glass, but the problem of long term drift has not been addressed so far. In the present work we describe an online control method which is able to detect process drifts and offers the possibility to adjust operation point settings in long-term operation. The control system is based on the evaluation of spectroscopic photometry measurements in the visible and near-infrared wavelength regime. The measured spectra are evaluated with respect to their band-gap and free carrier absorption.We found that the band gap and the plasma frequency are directly correlated with the oxygen partial pressure during deposition. Comparing the plasma frequency with Hall measurements, it was shown that the carrier concentration in the films can be monitored. This enables a control of free carrier absorption during a production process.     

Discovery of marageing steels:machine learning vs.physical metallurgical modelling

Physical metallurgical (PM) and data-driven approaches can be independently applied to alloy design.Steel technology is a field of physical metallurgy around which some of the most comprehensive under-standing has been developed,with vast models on the relationship between composition,processing,microstructure and properties.They have been applied to the design of new steel alloys in the pursuit of grades of improved properties.With the advent of rapid computing and low-cost data storage,a wealth of data has become available to a suite of modelling techniques referred to as machine learning (ML).ML is being emergingly applied in materials discovery while it requires data mining with its adoption being limited by insufficient high-quality datasets,often leading to unrealistic materials design predictions outside the boundaries of the intended properties.It is therefore required to appraise the strength and weaknesses of PM and ML approach,to assess the real design power of each towards designing novel steel grades.This work incorporates models and datasets from well-established literature on marageing steels.Combining genetic algorithm (GA) with PM models to optimise the parameters adopted for each dataset to maximise the prediction accuracy of PM models,and the results were compared with ML models.The results indicate that PM approaches provide a clearer picture of the overall composition-microstructure-properties relationship but are highly sensitive to the alloy system and hence lack on exploration ability of new domains.ML conversely provides little explicit physical insight whilst yielding a stronger pre-diction accuracy for large-scale data.Hybrid PM/ML approaches provide solutions maximising accuracy,while leading to a clearer physical picture and the desired properties.     

摩托车铝合金缸体压铸工艺参数优化

为解决摩托车铝合金缸体压铸件存在的缺陷问题,利用Any Casting铸造数值模拟分析软件,采用正交试验方法,并借助Image J软件统计铸件的孔洞面积(缩孔缩松或气孔),系统研究了压铸工艺参数:快压射速度、快压射切换点位置及模具温度对摩托车铝合金缸体孔洞面积的影响规律.研究表明,铸件内的孔洞总面积随着快压射速度的增加而增加,随着快压射切换点位置和模具预热温度的增加而减小.本实验条件下的最优工艺参数为:快压射速度2.0 m/s、快压射切换位置280 mm、模具温度240℃.采用该组参数,使铸件致密度增大,上、下端面孔洞所占面积分别减少21%和68%,铸件废品率从14%降低到5%.     

Optimization of process parameters of friction welding of UNS S31803 duplex stainless steels joints

This article presents an approach based on Taguchi method and Grey relational analysis to optimize process parameters of friction welding of UNS31803 duplex stainless steel. The main objective is to maximize mechanical properties like tensile strength, hardness and impact toughness and to minimize corrosion rate. Heating pressure, heating time, upsetting pressure and upsetting time were the four process parameters taken each at three levels. According to Taguchi quality design concept, an L9 orthogonal array was selected for experiments. The best combination of process parameters was found by both Taguchi method and Grey relational analysis. The influence of the process parameters on overall quality characteristics of the friction welding process was evaluated by the analysis of variance (ANOVA) method. The confirmation test results with optimal parameters confirmed the effectiveness of the proposed method in this study. Later, comparison was done between Taguchi method and Grey relational analysis on the basis of improvement in multiresponse signal to noise (S/N) ratio over initial process parameters. Grey relational analysis was proved to be a better technique than Taguchi method for optimization of multiple responses.     

Model of reactive precipitation process of preparation nano-ZnO in rotating packed bed: Contribution ratio

With excellent micromixing characteristic of rotating packed bed (RPB), many nanoparticles with small average size, narrower distribution and good morphology had been successfully and continuously prepared. To reveal complex crystal process, an empirical model were developed to simulate nano-ZnO by considering mass changed, population balance equation, growth rate G, nucleation rate B, drop sizes D_i, and resident time t. The predicted particle sizes were shown good agreement with experimental data with error of ±10%. Therefore, it was further adopted to predict the effects of rotating speed, liquid flow rate and reactant concentration on the mean particle size. To look more deeply insight in this process, their contribution ratios were further analyzed. The proposed empirical models were of great helpful to obtain suitable operation conditions for preparing much better properties of nanoparticles with fewer experiments. It was also beneficial to produce other nanoparticles in RPB.     

高强钢板冲压成形的回弹规律与工艺参数研究

高强钢板冲压成形的回弹问题在很大程度上制约了其深入应用,合理的工艺是减少回弹的关键和有效途径之一.建立了曲面扁壳件冲压成形的有限元模型,基于正交试验法研究了工艺参数,包括压边力、摩擦系数、板厚以及拉深筋的布置方式对回弹的影响规律,采用普通钢板和高强钢板分别进行了冲压成形实验,并与数值模拟结果进行对比.结果表明,高强钢板冲压成形的回弹较大,但通过合理的压边力和拉深筋布置方式可以实现高强钢板冲压成形回弹的有效控制.     

Optimization of fused deposition modeling process parameters:a review of current research and future prospects

Fused deposition modeling(FDM) is one of the most popular additive manufacturing technologies for various engineering applications.FDM process has been introduced commercially in early 1990 s by Stratasys Inc.,USA.The quality of FDM processed parts mainly depends on careful selection of process variables.Thus,identification of the FDM process parameters that significantly affect the quality of FDM processed parts is important.In recent years,researchers have explored a number of ways to improve the mechanical properties and part quality using various experimental design techniques and concepts.This article aims to review the research carried out so far in determining and optimizing the process parameters of the FDM process.Several statistical designs of experiments and optimization techniques used for the determination of optimum process parameters have been examined.The trends for future FDM research in this area are described.     

Analysis of process parameters effects on friction stir welding of dissimilar aluminum alloy to advanced high strength steel

Thin sheets of aluminum alloy 6061-T6 and one type of Advanced high strength steel, transformation induced plasticity (TRIP) steel have been successfully butt joined using friction stir welding (FSW) technique. The maximum ultimate tensile strength can reach 85% of the base aluminum alloy. Intermetallic compound (IMC) layer of FeAl or Fe₃Al with thickness of less than 1 μm was formed at the Al–Fe interface in the advancing side, which can actually contribute to the joint strength. Tensile tests and scanning electron microscopy (SEM) results indicate that the weld nugget can be considered as aluminum matrix composite, which is enhanced by dispersed sheared-off steel fragments encompassed by a thin intermetallic layer or simply intermetallic particles. Effects of process parameters on the joint microstructure evolution were analyzed based on mechanical welding force and temperature that have been measured during the welding process.     

基于数值模拟的冷拉钢丝表面精度Ra的优化

为研究拉拔参数对冷拉钢丝表面精度Ra的影响,采用有限元软件MARC建立了钢丝表面微观形态的分析模型,对钢丝拉拔过程进行了模拟仿真,利用正交试验设计法研究了主要拉拔参数(拉拔速度v、过渡圆弧半径R、模具定径带长度L、模具入模角α、摩擦系数μ)对钢丝成形表面精度Ra的影响,并对模拟结果进行了极差分析和方差分析.结果表明:冷拉钢丝在一定断面缩减率的条件下Ra最佳的拉拔参数组合为v=30 mm/s、R=1 mm、L=3 mm、α=11°、μ=0.4);各因素对Ra的影响程度次序为B(R)C(L)E(μ)A(v)D(α);随v和L的增大Ra先减少后增大,α、R及μ对Ra的影响并无明显规律.在此基础上对优化方案进行模拟仿真,发现钢丝表面粗糙度有了显著改善,这表明正交试验设计对冷拉钢丝表面精度优化的有效性.     

高强度热冲压钢板强韧性工艺优化研究

为改善强韧性,本文基于热冲压高强度钢板强度、塑性和韧性指标,选取加热温度、保温时间和开始淬火温度为设计因子,引入Kahn试验获得高强度热冲压硼钢撕裂强度和单位面积裂纹形核功来表征材料断裂韧性,进行多指标综合评分的L9(34)正交试验设计,以研究不同淬火工艺参数对热冲压高强钢强韧性的影响规律.结果表明:在加热温度为920~950℃、保温时间1 min、开始淬火温度为650~700℃条件下,热冲压硼钢SPFH具有优良的成形性能和强韧化指标.采用优化后工艺进行典型车身结构件热冲压试验,其撕裂强度、单位面积裂纹形核功和强韧比分别提升10.91%、20.32%和22.17%,在保证强度的基础上韧性得到了大幅度提高.     

Optimization of process parameters in fused deposition modelling of thermoplastics: A review

Among the several techniques for additive manufacturing (AM), fused deposition modelling (FDM) is widely used. Fused deposition modelling process uses a thermoplastic material, which is melted and then extruded layer by layer through a nozzle, in order to create a three-dimensional object. As a result of the default setting of process parameters provided by the manufacturers, produced parts normally have a poor surface finish, low mechanical properties, low dimensional accuracy, and increased residual stresses compared to the parts produced using conventional manufacturing processes like molding (casting). Qualities of fused deposition modelled (FDMed) parts are generally affected by process parameters including the layer thickness, extrusion temperature, build orientation, printing speed, raster angle, infill density, raster width, nozzle diameter, and air gap. Increasing infill density, printing temperature, and decreasing print speed and layer thickness lead to increase mechanical strength and improve the surface finish of the printed parts. The optimal process parameters are preferred to achieve superior properties of the parts. This paper reviews the optimal fused deposition modelling process parameters on part qualities for making the stability of used deposition modelled parts for use. Various process parameters are identified in order to obtain desirable qualities in the manufactured parts. Areas for future research are proposed.     

TiO2 quantum dots: Energy consumption cost,germination, and phytotoxicity studies,recycling photo and solar catalytic processes of reactive yellow 145 dye and natural industrial wastewater

The germination of Lycopersicon esculentum tomato seeds that had been planted with water containing TiO₂QDs1(2.9 nm), TiO₂QDs2 (3.2 nm), and TiO₂ (Degussa) without no phytotoxicity effect on the germination process. TiO₂QDs1 (2.9 nm) and TiO₂QDs₂ (3.2) were successfully synthesized at low calcination temperatures: 280 and 310 ⁰C for 180 min, respectively, using the sol–gel process. The synthesized TiO₂QDs1(2.9 nm) and TiO₂QDs2 (3.2 nm) were characterized by: XRD, FE-SEM, HRTEM, and EDX to analyze the structure, shape, and size of the generated TiO₂QDs samples. The photocatalytic activities of the TiO₂QDs in the photodegradation of Reactive yellow 145 dye as a commercial dye and actual industrial wastewater samples using both a Xenon lamp light irradiation source and direct sunlight were assessed. They showed highly photocatalytic performances recorded at 85 to 90 percent, and the photodegradation rate was still distinguishable till ten repetition times for the photodegradation process of the reactive yellow 145 dye and till six repetition times for the natural industrial wastewater samples used in this study. Also, an analysis of the photodegradation efficiency of the Reactive yellow 145 dye has been done in terms of the positive effect on the energy consumption ratio (E_E/O) as pricing estimations.     

Experimental study of friction taper plug welding for low alloy structure steel: Welding process,defects, microstructures and mechanical properties

A research investigation has been undertaken to identify the various stages and variation of welding parameters in friction taper plug welding (FTPW) process and to explore their effects on the performance and properties of the welds. According to the variation of axial force, the overall FTPW process is divided into feeding phase, pressing phase, welding phase, and forging phase. The rotating speed, welding force, and burn-off rate remain nearly constant in welding phase. However, the torque peaks in welding phase when after few seconds of welding force setting is reached. Rising the welding force would increase the peak torque, welding torque, and burn-off rate, but decrease the welding time. When improper welding parameter is used lack of bonding and incomplete filling defects would form within the weld. The microstructure of the weld metal is consist of retained austenite, pearlite, and various Widmanstätten ferrite. In heat affect zone, it is mainly of lathy upper bainite. Defect free welds exhibit favorable tensile properties of which 548.3 MPa tensile strength and 27.5% elongation that equal to the base metal could be found.     

Self-assembled liquid crystalline nanoparticles as an ophthalmic drug delivery system. Part I: influence of process parameters on their preparation studied by experimental design

To develop self-assembled liquid crystalline nanoparticles as a drug delivery system for keratoconus treatment, a formulation containing riboflavin a water-soluble drug, two surfactants (poloxamer 407 and mono acyl glycerol – monoolein-) and water was optimized and prepared by emulsification and a homogenization process. A fractional factorial design was applied to estimate the main effects and interaction effects of five parameters on two responses, namely particle size and encapsulation efficiency. The five parameters are the temperature of the two phases, the duration of emulsification, the presence of heating during homogenization, the number of passes and pressure. The most influent parameters are the presence of heating during the homogenization and the pressure that led to the production of nanoparticles with an average size of 145?nm and an average encapsulation efficiency of 46%.