大型铁塔角钢质量改进措施

针对大型铁塔角钢生产过程中存在的质量问题及国家电网公司对铁塔角钢较高的质量标准,采取多项有效技术质量改进措施,全面提高了铁塔角钢的综合质量,满足了用户需求,提高了产品的市场竞争力。     

热轧铁塔角钢的质量要求与市场前景研究

围绕铁塔角钢的质量要求与国内外市场需求,针对津西集团依托打造“国内最大、世界一流型钢基地”开发铁塔角钢产品。满足终端用户需求的探讨。     

铁塔角钢生产工艺优化

针对唐钢铁塔角钢生产过程中出现的表面质量缺陷及合同定尺率偏低问题,结合现场实际生产工艺,分析了影响铁塔角钢表面质量和合同定尺率的主要原因,通过采取多项有效技术质量改进措施,全面提高了铁塔角钢的综合质量,满足了用户需求,提高了产品市场竞争力,为企业创造了可观的经济效益和良好的社会效益。     

铁塔用热轧耐候电力角钢轧制过程开发实践

电力角钢是我公司型材生产线主要生产产品之一,而铁塔用热轧耐候电力角钢对环境友好,具有成本优势,未来应用前景和市场广阔,作为多年角钢生产基础的企业有必要对铁塔用热轧耐候电力角钢进行开发。文章重点从轧制过程阐述铁塔用热轧耐候电力角钢(下文简称耐候角钢)的开发,包括开发试验过程的具体方法、试验结果与分析等,做好热轧耐候电力角钢生产的技术储备,使将来新形势下产品推广后迅速量产成为可能。     

高性能电力铁塔角钢Q420TE 成分设计与制备

电力铁塔角钢目前广泛应用于输电线路,文中主要对高性能电力铁塔角钢Q420TE进行了实验研究,讨论了化学成分设计的理论依据及其对铁塔角钢组织性能的影响.结果表明:通过化学成分优化设计可获得屈服强度420 MPa以上的角钢,且微合金元素可以改善角钢的综合性能;轧后试样其组织主要为铁素体加珠光体,并有少量的粒状贝氏体,晶粒度等级约为9.0级;热轧钢材产品的屈服强度大于425 MPa,抗拉强度大于560 MPa,20℃时的冲击功为121.9 J,其综合性能均已满足Q420TE铁塔角钢国标所需要求.     

300 mm肢宽大规格角钢品种的开发与应用

随着我国能源和电力需求持续增长,电网建设逐步向特高压方向发展,河钢唐钢大型线结合产线特点及国家电网公司要求,完成了300 mm大规格角钢化学成分设计、坯料选型、孔型设计、加热制度设计、轧制规程设计,最终成功开发出特高压电力铁塔用300 mm肢宽大规格角钢。实际应用后,提高了电力铁塔的负载强度,延长了铁塔的使用寿命,使铁塔质量减轻10%以上,节约了制造成本。     

耐候钢在输变电铁塔制造中的应用前景分析

在国家电网建设中,铁塔用角钢需求量巨大,而在角钢加工过程中,仍然采用了热浸镀锌工艺对角钢进行防腐处理,造成成本高、严重污染环境。耐候钢具有优良的耐候性能,可降低加工成本、有利于环保,但在输变电铁塔制造中的应用还是空白,为此我国有必要大力推广使用。宣钢将耐候钢生产技术率先应用于角钢生产,成功地开发出了耐候角钢产品,可应用于铁塔制造,比普通钢材具有明显的优势。     

铁塔角钢镀锌主要质量问题及改进

近几年来,河钢集团宣钢公司型材产品以铁塔角钢为主,重点供向国网公司、南网公司,用于国家电网高压、特高压输变电工程线路建设。目前宣钢铁塔角钢市场占有率约在30%左右。铁塔厂加工角钢原料主要工序为:下料-号料-制弯-冲孔-切角-开合角-组对-焊接-校正-试组装-酸洗-镀锌-包装-检验等。铁塔厂在加工使用过程中,如出现质量问题会影响整体工作进度,尤其是表面质量出现问题一般会在镀锌工序后发现,出现废品造成较大的浪费甚至拖延工期。     

减少铁塔角钢隐性折叠的措施

本文分析了在铁塔角钢生产中隐性折叠的产生原因,结合生产实践,提出了减少铁塔角钢隐性折叠的措施。实践证明 ,产生了效果明显,措施是合理可行的。     

输变电铁塔用Q420B角钢的冶炼工艺优化

从冶炼工艺角度,分析了输变电铁塔角钢Q420B产品由于炼钢工艺控制不当导致角钢产生开裂、黑斑的机理。开裂的主要原因是钢水洁净度不高、铸坯内部裂纹严重,角钢黑斑的主要原因是钢水洁净度不高。通过调整冶炼工艺,理顺生产节奏,调整连铸的冷却制度,铸坯质量得到了大幅改善,降低了轧制缺陷的发生率,角钢的轧制开裂和黑斑显著减少。     

角钢成品孔存在的问题及改进

角钢成品孔型的设计直接关系到成品的质量,同时对矫直效果、调整难度、轧机调整、负差控制等都有很大影响。尤其是角钢的成品容易出现尺寸超差的质量问题。通过轧制角钢的生产实践,对成品孔进行了改进,将成品孔顶角放大1°~1°20';根据腿部的磨损情况,腿厚适当增加0.2~0.5 mm。通过改进,完全满足角钢生产和质量的要求。提高了轧辊的轧制吨位和经济效益。     

Modeling and control of dynamic soft reduction in continuous slab casting

The centerline segregation in continuous casting steel is known to be formed by the interdendritic enriched liquid flow at the solidification end in strand.At present,several methods,such as thermal soft reduction, electromagnetic stirring and dynamic soft reduction,are available to reduce the center segregation and to improve the internal quality.Although some methods could alleviate center segregation to some extent,they can also give rise to new problems.For instance,thermal soft reduction can lead to surface cracking during casting of some steels and electromagnetic stirring can result in white band.Dynamic soft reduction is an effective technology for the improvement of strand quality in continuous slab casting.In this paper,the key parameters of dynamic soft reduction technology,such as soft reduction region,the total reduction amount,for low carbon steel have been studied based on experimental and theoretical analysis.The soft reduction region was related to the segregation of chemical composition,slab bulging of narrow side and avoiding internal crack of slab.The total reduction amount was composed of natural thermal shrinkage and actual reduction amount depending on critical strain.For low carbon steel with slab dimension of(950 - 1 950) mm×170 mm,the solid fraction range in soft reduction region was recommended from 0.4 to 0.8,the total reduction amount was 2.0 -2.8 mm,and the optimized reduction rate was 0.4 - 1.2 mm/min,respectively.Furthermore,a dynamic soft reduction system in continuous slab casting, Visual Cast-Dynamic,has been developed by multithreading method.It demonstrated that the dynamic soft reduction model in this study was correct with the ability of online control.     

大规格Q420B热轧角钢轧制中间道次开裂缺陷分析

 为了解决Q420B大规格角钢热轧过程出现折叠和划伤较多的问题,利用数值模拟的方法对W蝶式孔型的变形特点进行研究,通过对W蝶式孔型第5道次孔型斜度进行优化,大规格角钢生产过程出现的表面质量问题得到了明显的改善。结果表明,W蝶式孔型变形虽然可以用小型钢坯轧出大规格的角钢,但是需要对角钢的侧翼进行多次弯折,表面的金属流动剧烈,易产生表面质量缺陷;利用W蝶式孔型生产22号角钢时,第6道次有出现折叠的倾向,经过孔型工艺优化后,现场划伤和折叠缺陷率明显降低。     

Missed joint induced by thermoelectric magnetic field in electron-beam welding dissimilar metals—Experiment and scale analysis

A missed joint, resulting from an induced thermoelectric magnetism in welding dissimilar metals with a high-intensity electron beam, is experimentally and analytically investigated. Election-beam welding is a very useful process for joining a wide range of dissimilar metals, which may be difficult or impossible to weld by other techniques. Certain combinations of materials, unfortunately, readily give rise to a missed-joint defect because of thermoelectric-magnetic deflection of the beam. Combinations of dissimilar metals chosen for this study are low-carbon steel and type 304 stainless steel, low-carbon steel and Ni-Cu alloy, and type 304 stainless steel and Ni-Cu alloy. The experimental results find agreement with a previous study showing that the electron beam deflects toward the metal with a larger Seebeck coefficient (denoted by metal 1). A general and algebraic expression for predicting deflection angle as a function of dimensionless beam power, accelerating voltage-to-Seebeck electromotive force (EMF) parameter, Peclet and Prandtl numbers, and electrical conductivity ratio between metals 1 and 2 has been derived from a scale analysis for the first time. The predicted results agree well with experimental data obtained from the literature, this work, and three-dimensional theoretical prediction.     

角钢滚动导卫在安钢φ400mm型材机组上的应用

型钢生产因轧件断面复杂,多使用滑动导卫装置,滚动导卫使用有较大难度.为提高产品表面质量,安钢φ400mm型材机组在∠80 mm～/100 mm角钢成品入口成功应用滚动导卫装置,成品质量稳定性大为提高,解决了大规格角钢易产生刮痕缺陷的难题,万吨钢检验废由原来的50 t降到20t,起到了较好的质量改进效果.     

Surface phenomena and continuous casting

Understanding the transformation of liquid steel to solid steel is the most fundamental aspect of continuous casting;however,it remains a complex subject with a number of unresolved issues.In this paper,the following aspects of mold operation which give rise to sub-surface defects will be discussed;meniscus solidification,surface and interfacial energies,effects of gas bubbles,and the dynamic nature of the liquid slag-liquid steel interface.     

表面现象与连铸

了解钢从液态到固态的转变是连铸最基础的方面,然而它还是一个很多问题尚未解决的复杂课题。论述了结晶器操作导致皮下缺陷的形成,包括钢液在弯月面凝固、表面能和界面能变化、气泡的影响以及钢液与液渣界面的动力学现象。     

无缝钢管生产线电力拖动调速系统合理选用的探讨

根据无缝钢管生产线工艺设备对电力拖动调速系统的要求,通过对全数字直流及交流电力拖动调速系统特点和性能的比较分析,从性价比的角度对无缝钢管生产线电力拖动词速系统的合理选用进行了深入的探讨.对无缝钢管及类似生产线的电力拖动调速系统的合理选用有所借鉴.