热轧钢材氧化及表面质量控制技术的发展及应用

热轧钢材表面质量是生产控制的重要指标之一,越来越受到重视。热轧钢材表面氧化铁皮的结构、厚度受氧化热力学、动力学及固相反应的影响,氧化铁皮的结构、高温力学行为和物理特性直接影响其去除效果。钢材的化学成分设计,以及热轧生产过程中加热、轧制和冷却过程中氧化铁皮的去除与控制,直接决定了最终产品氧化铁皮的厚度和结构,从而决定了其表面质量控制效果。热轧钢材表面氧化控制技术已经开始在表面缺陷控制、不同深加工方式钢材的氧化层设计、减量酸洗和免表面处理等方面得到了应用。为了充分挖掘该技术的潜力,还要根据热轧产品的用途进行深度的研究与开发。     

新一代TMCP的实践和工业应用举例

介绍以超快速冷却为核心的新一代TMCP技术在钢材生产中的广泛应用和由此而导致的钢材性能的提升.这些应用包括棒线材控轧控冷技术突破和应用、轴承钢的轧后超快速冷却控制碳化物分布、利用超快速冷却技术进行热轧带钢组织复相化控制,以及热轧带钢轧机实施超快速冷却装置的改造和中厚板轧机实施超快速压力喷射式冷却 ACC的新式冷却系统的建立.     

轧钢生产过程计算机控制(四)

4.钢材轧后冷却控制钢材轧后冷却是利用热轧完成时的余热,对钢材进行热处理的过程,它可以取代热处理工序,节省成本,还可大幅度提高成品钢材的性能。因此,近年来在钢筋、线材、中厚板及热轧带钢的生产中,得到了广     

钢材表面氧化铁皮结构演变机理与应用控制技术研究进展

从氧化铁皮机械除鳞、钢材表面红色氧化铁皮(红锈)、热轧钢材表面抗腐蚀氧化层、热轧无酸洗钢材表面镀锌及氧化铁皮抗摩擦磨损等方面阐述了氧化铁皮应用控制机理。结合当前市场需求与已有控制技术,指出了未来关于氧化铁皮研究的主要发展方向。     

RAL关于钢材热轧信息物理系统的研究进展

回顾了轧制技术及连轧自动化国家重点实验室(RAL)关于热轧钢材组织性能预测与控制-热轧钢材信息物理系统(CPS)研究项目的发展历程,分析了各个发展阶段的主要研究内容和取得的重要进展及应用情况,最后展望了CPS应用于钢铁智能制造的前景。     

二辊粗轧机的高压水除鳞随动装置

高压水除鳞装置是提高热轧钢材,特别是钢板表面质量的重要设备,因此,设计合理的高压水除鳞装置具有重要意义。在轧钢机的前后一侧或两侧设置高压水除鳞装置,用来清除轧制过程中坯料表面的再生氧化铁皮,对改善板材表面光洁度有明显效果。重钢五厂二辊粗轧机是为四辊精轧机开坯     

湍流式高效穿水冷却工艺对棒材组织性能的影响

针对南昌钢铁有限责任公司生产的Ⅲ级带肋钢筋成本过高、轧机产量提高后冷床冷却能力不足问题,研制了高效的棒材轧后穿水冷却装置。通过对小规格热轧带肋钢筋进行轧后穿水冷却,钢材上冷床温度降低了200～300℃,从而使产品质量提高,力学性能改善,抗拉强度平均提高35～60MPa,钢材性能合格率也有很大提高,解决了冷床冷却能力不足、制约生产的瓶颈问题。     

热轧宽带钢再加工 钢材宽度规格优化的探讨

为适应国民经济高速发展的需要,冶金企业用热轧宽带钢再加工的钢材量逐年增加。但以热轧宽带钢为原料再加工的冷轧板、冷轧带、冷弯型钢、焊接钢管等在连续加工过程中,存在严重的切边余量损失。因而对采用热轧宽带再加工的钢材,实现宽度规     

热轧钢材表面氧化铁皮微观结构表征技术综述

热轧钢材氧化铁皮控制不当会引起表面缺陷,为了提高热轧钢材的表面质量,需要对其氧化产物结构和状态进行系统的分析检测,包括了解氧化铁皮的种类和结构、氧化铁皮的表面及断面形貌、氧化铁皮或氧化铁皮与钢基体界面处的元素分布等。由于目前表面分析技术种类多,且新技术不断得到应用,本文按照钢材氧化铁皮研究的表征步骤归纳了各种技术的特点和应用情况,可为钢材高温氧化理论研究和生产现场工艺优化提供帮助。     

东大RAL新一代控轧控冷技术为涟钢实现资源节约型高性能钢材升级换代

<正>日前,由东大RAL和湖南华菱涟源钢铁有限公司合作完成的"高品质节约型热轧钢材生产技术与装备的研发及应用"获得2014年湖南省科学技术进步一等奖。应用该技术,实现了传统热轧材向资源节约型高性能钢材升级换代的目标。该项目针对传统控轧控冷(TMCP)工艺     

连铸板坯实现CC-DR温度场数值模拟

采用自行开发的温度场二维有限元求解程序 ,数值模拟了我国某厂现有连铸板坯空冷过程的温降情况和温度场 ;同时也求解了为实现CC DR的连铸板坯从连铸机出口至粗轧除磷机前 ,全过程的温降情况及不同时刻的温度场。结果表明 ,现有板坯计算温度与实测温度吻合 ;要想实现CC DR ,除炼钢提供高温无缺陷板坯以外 ,需要在除磷之前设置边部加热装置。数值模拟结果对于指导轧制过程工艺参数 ,实现CC DR等具有重要的理论意义和实际指导意义     

Anomalies in Hall-Petch strengthening for nanocrystalline Au-Cu alloys below 10 nm grain size

The mechanical behavior of an electrodeposited nanocrystalline alloy is assessed with regards to the experimentally measured strain-rate sensitivity. Foils are characterized with grain sizes as small as 3 nm, a nano-scale regime that has previously gone without detailed experimental examination. It is found from micro-scratch measurements that hardness, hence strength, approaches ideal values as the grain size decreases to 7 nm. Below 7 nm, softening in strength and departure from Hall-Petch behavior is related to an increase in the activation volume for deformation as grain size decreases further.     

Thermodynamic analysis of alloys Ti–Al, Ti–V, Al–V and Ti–Al–V

Thermodynamic analysis of three binary Ti-based alloys: Ti–Al, Ti–V, and Al–V, as well as ternary alloy Ti–Al–V, is shown in this paper. Thermodynamic analysis involved thermodynamic determination of activities, coefficient of activities, partial and integral values for enthalpies and Gibbs energies of mixing and excess energies at four different temperatures: 2000, 2073, 2200 and 2273 K, as well as calculated phase diagrams for the investigated binary and ternary systems. The FactSage is used for all thermodynamic calculations.     

IGBT弧焊逆变器的红外遥控研究

介绍IGBT弧焊逆变器的红外遥控的设计 ,详细介绍系统设计、主电路设计、红外遥控系统硬件设计和红外遥控系统的软件设计。按设计研制出的遥控逆变焊机试验样机。经试验表明该样机遥控距离达 10m ,控制范围为± 45° ,能在焊接车间可靠工作。逆变焊机输出电流为 2 5 0A ,具有良好的外特性和动特性。     

Corrosion inhibition of some metals using lawsonia extract

The aqueous extract of the leaves of henna (lawsonia) is tested as corrosion inhibitor of C-steel, nickel and zinc in acidic, neutral and alkaline solutions, using the polarization technique. It was found that the extract acts as a good corrosion inhibitor for the three tested electrodes in all tested media. The inhibition efficiency increases as the added concentration of extract is increased. The degree of inhibition depends on the nature of metal and the type of the medium. For C-steel and nickel, the inhibition efficiency increases in the order: alkaline < neutral < acid, while in the case of zinc it increases in the order: acid < alkaline < neutral. The extract acts as a mixed inhibitor. The inhibitive action of the extract is discussed in view of adsorption of lawsonia molecules on the metal surface. It was found that this adsorption follows Langmuir adsorption isotherm in all tested systems. The formation of complex between metal cations and lawsone is also proposed as additional inhibition mechanism of C-steel and nickel corrosion.     

Pulsed microwave plasma polymerization of silicon oxide ?lms: Application of efficient permeation barriers on polyethylene terephthalate

A microwave driven low pressure plasma reactor is developed based on a modi?ed Plasmaline antenna for plasma processing of polyethylene terephthalate (PET) foils and bottles. It allows for the treatment of thermolabile packaging materials, e.g. plasma sterilization and permeation barrier coating. Silicon oxide ?lms are deposited on PET foils as a permeation barrier coating. A pulsed hexamethyldisiloxane:oxygen plasma is ignited under various conditions and the oxygen permeation is investigated. A criterion for the homogeneous deposition of SiO_x coatings is described depending on the residence time of process gases. Additionally, the composition of the coatings is analyzed by means of Fourier transform infrared spectroscopy regarding carbon and hydrogen content. A strong relation between barrier properties and ?lm composition is found: good oxygen barriers are observed as carbon content is reduced and ?lms become inorganic, quartz-like. A residual permeation as low as J = 1.0 ± 0.3 cm³ m^− 2 day^− 1bar^− 1 for SiO_x coated PET foils is achieved. The dependencies of important plasma parameters, such as gas mixture, process pressure, power and pulse conditions on oxygen permeation through packaging foil are shown to optimize the coating process.     

Ballistic performance of nanocrystalline and nanotwinned ultrafine crystal steel

Because of their remarkable mechanical properties, nanocrystalline metals have been the focus of much research in recent years. Refining their grain size to the nanometer range (<100 nm) effectively reduces their dislocation mobility, thus achieving very high yield strength and surface hardness—as predicted by the Hall-Petch relation—as well as higher strain-rate sensitivity. Recent works have additionally suggested that nanocrystalline metals exhibit an even higher compressive strength under shock loading. However, the increase in strength of these materials is generally accompanied by an important reduction in ductility. As an alternative, efforts have been focused on ultrafine crystals, i.e. polycrystals with a grain size in the range of 500 nm to 1 μm, in which “growth twins” (twins introduced inside the grain before deformation) act as barriers against dislocation movement, thus increasing the strength in a similar way as nanocrystals but without significant loss of ductility. Due to their outstanding mechanical properties, both nanocrystalline and nanotwinned ultrafine crystalline steels appear to be relevant candidates for ballistic protection. The aim of the present work is to compare their ballistic performance against coarse-grained steel, as well as to identify the effect of the hybridization with a carbon fiber-epoxy composite layer. Hybridization is proposed as a way to improve the nanocrystalline brittle properties in a similar way as is done with ceramics in other protection systems. The experimental campaign is finally complemented by numerical simulations to help identify some of the intrinsic deformation mechanisms not observable experimentally. As a conclusion, nanocrystalline and nanotwinned ultrafine crystals show a lower energy absorption than coarse-grained steel under ballistic loading, but under equal impact conditions with no penetration, deformation in the impact direction is smaller by nearly 40%. This a priori surprising difference in the energy absorption is rationalized by the more important local contribution of the deviatoric stress vs. volumetric stress under impact than under uniaxial deformation. Ultimately, the deformation advantage could be exploited in the future for personal protection systems where a small deformation under impact is of key importance.     

Investigation of electroless copper plating on polyurethane foam,as an initial step of open cell foam production process

Abstract

Coating of polymeric foams is known as a method for production of metallic foams, which produces foams with high volume of porosity and controllable pore size. In this research, this method was employed to produce open cell copper foam by use of polyurethane foam with an average pore size of 0.4?mm as the substrate. Since polyurethane foam as a non-conductive material is not able to be coated directly by electrolytic deposition, the substrate was initially metallised by electroless copper plating. In the electroless plating process, the effects of the main parameters such as bath chemical composition, solution pH and temperature on deposition rate and thickness of the coatings obtained were investigated. The results showed that the optimum condition of the process is obtained when CuSO₄ concentration in the deposition bath is 12?g?L^??1, pH is 13 and plating temperature range is 55–60°C.     

The dependence of the Eshelby model predictions on the microstructure of metal matrix composites

The present work discusses an important modification to the classical Eshelby model, as used on metal matrix composites. It is shown that including the reinforcement orientation distribution in the model improves its agreement with experimental data, taken on 6061Al–15 vol.%SiC_w composites. In particular, a density of hydrostatic, deviatoric as well as axial and radial matrix stress as a function of the angle with respect to the extrusion axis is calculated. It is found that the orientation distribution density is such that the whiskers oriented near to the extrusion axis contribute significantly to the transverse (i.e. radial) deviatoric matrix stress. It is also found that a dramatic increase (400%) of the matrix deviatoric stress occurs as a function of the amount of oriented reinforcement, while the hydrostatic matrix stress has a range of variation of ±40%. Finally, the influence of the equivalent Eshelby temperature of mixing ΔT_E is discussed to show that (a) the residual stress (RS) depends linearly on ΔT_E; and (b) the deviatoric RS is more sensitive to its variation. An estimation of ΔT_E is recommended, by means of mechanical properties and RS measurements in order to avoid incongruence.