变形高温合金纯净熔炼设备及工艺研究进展

本文试图对国内外近年来变形高温合金纯净设备及其熔炼技术的发展情况进行综述.文章总结了变形高温合金中夹杂物的分类方法,调研了国内外变形高温合金熔炼设备生产厂家,分析了真空感应熔炼炉、电渣炉、真空自耗炉的设备特点与技术,归纳了国内外变形高温合金真空感应熔炼、真空感应熔炼+保护气氛电渣重熔、真空感应熔炼+真空自耗重熔、真空感应熔炼+保护气氛电渣重熔+真空自耗重熔四类工艺的研究进展.最后提出了提升我国变形高温合金冶金质量与性能的一些建议.     

变形高温合金纯净熔炼设备及工艺研究进展

本文试图对国内外近年来变形高温合金纯净设备及其熔炼技术的发展情况进行综述。文章总结了变形高温合金中夹杂物的分类方法,调研了国内外变形高温合金熔炼设备生产厂家,分析了真空感应熔炼炉、电渣炉、真空自耗炉的设备特点与技术,归纳了国内外变形高温合金真空感应熔炼、真空感应熔炼+保护气氛电渣重熔、真空感应熔炼+真空自耗重熔、真空感应熔炼+保护气氛电渣重熔+真空自耗重熔四类工艺的研究进展。最后提出了提升我国变形高温合金冶金质量与性能的一些建议。     

夹杂物特征参数对40CrNi2Mo钢塑性的影响

用定量金相、扫描电镜和能谱分析等方法获取了用2种工艺冶炼的40CrNi2Mo钢中夹杂物尺寸特征参数,研究了这些参数对钢塑性的影响。结果表明:由于夹杂物的体积分数和尺寸比较小,夹杂物间距的增大,在塑性断裂时由夹杂物形成的微孔洞很难以内颈缩形式聚合,微孔洞间的局部剪切也不容易扩展。由此判断,真空自耗重熔钢的断面收缩率比电渣重熔钢的高。钢中的夹杂物对其均匀延伸率、形变硬化指数和拉伸强度没有影响。     

双真空冶炼高合金轴承钢后真空表面渗碳疲劳性能的研究

采用光学显微镜、扫描电子显微镜、能谱仪和透射电子显微镜等分析手段,研究了Cr-Co-Mo-Ni轴承钢经真空感应+真空自耗冶炼后真空表面渗碳的旋转弯曲疲劳性能。结果表明:采用双真空冶炼后能明显提高钢的纯净度,该钢中夹杂物直径小于3μm的个数所占96.41%,大于3μm的个数所占3.59%。经过真空表面渗碳后,钢表面硬度为1000 HV,其轴向残余压应力值超过400 MPa,周向残余压应力值超过200 MPa,高的残余应力阻止裂纹的萌生和降低裂纹扩展速度。心部的残余奥氏体以层状分布在板条马氏体之间,体积分数为8.51%,为心部提供良好的韧性。此时钢的中值疲劳极限高达1016 MPa,起裂源由渗层次表面夹杂和渗层近表面基体引起的开裂概率都为35%。因此,提高冶金质量和控制表面渗碳工艺能够提高钢的旋转弯曲疲劳性能。     

热加工对硫化物及氧化物夹杂的影响

随着制造业的发展,人们对钢材的质量提出了更高的要求,而夹杂物是影响钢材质量十分重要的因素之一.特别是对高强钢而言,夹杂物对其韧性的影响更加敏感.因此,研究冶炼过程中对夹杂物的控制及后续热轧和热处理工艺对钢中夹杂物的影响,是钢铁材料制造和加工过程中的一个重要课题.夹杂物对钢材的强度、塑性、韧性、抗疲劳性能、耐腐蚀性能都会产生重要影响.要减少夹杂物对钢材性能的影响,需从优化冶炼工艺开始.随着气泡去除夹杂物技术、真空碳脱氧技术及中间包电磁搅拌技术在冶炼过程中的应用,钢材中的夹杂物含量明显降低.然而,在目前工业化的生产环境中,仍然无法实现将钢中的非金属夹杂物完全消除.目前的研究已经表明,热轧和热处理过程对夹杂物也有重要影响,这对进一步控制夹杂物的尺寸、分布、形态,达到减轻夹杂物对钢材性能影响的目的具有重要的意义.因此,目前除了发展新的冶炼工艺以进一步降低钢中的夹杂物含量外,研究和阐明热加工工艺对夹杂物的影响也是研究重点.文中归纳了冶炼过程中先进的夹杂物控制技术及其原理,评述了热变形和热处理过程对夹杂物的数量、尺寸、分布、形态特征及类型产生的影响,对研究钢材在制造、加工过程中夹杂物的变化规律及控制具有参考价值.     

零夹杂钢精炼的理论与工艺

零夹杂钢即夹杂物高度弥散分、尺寸小于1 μm的钢.论文从理论上分析其制备的可能性,展望其性能.具体工艺措施为:经过预脱铝处理的超低S、P工业纯铁,在50 kg真空感应炉中依靠碳氧脱氧反应进行初脱氧、深脱氧和合金化处理,炼成42CrMo钢,最后在电子束炉中经过两次重熔,得到全氧量为T.O.=4×10-6的42CrMo锭.精炼钢锻造成材后,非金属夹杂物非常细小用常规金相检验(×100倍)很难定量评级,在扫描电镜检测下发现有少量1～4 μm 的Al2O3夹杂,其主要来自铁合金原料.疲劳寿命由107转数提高到109转数.     

论真空冶金工艺的设备技术

本文论述真空技术对冶炼铁和非铁工程材料的意义，真空冶金的压强范围和典型的泵系统。概要地介绍最重要的应用。 钢的去气；真空感应炉内熔炼；电子束炉或真空电弧炉内的重熔。电子熔渣重熔工艺的可能性，铝液的真空处理以及钛铸锭的制取。还展望了真空冶金的前景。     

电渣重熔马氏体时效钢中的非金属夹杂物研究

本文应用电子扫描法(SEM+EDS)和金相法,对真空感应熔炼(VIM)及随后进行电渣重熔(ESR)的改进型18NiNb马氏体时效钢中的非金属夹杂物进行了定性和评级分析。结果表明,电渣重熔对去除钢中的硫化物和尺寸较大的单颗粒夹杂效果明显,电渣重熔后钢中的夹杂物主要为细小的氧化物夹杂,数量明显减少、且呈弥散分布,进一步提高了18NiNb合金钢的钢锭质量。     

真空自耗电弧炉用Φ720mm坩埚的优化和改进

真空自耗电弧炉是生产钛及钛合金铸锭的主要设备.坩埚是真空自耗电弧炉必不可少的部件,是真空自耗电弧炉重要的组成部分.坩埚筒体材料的性能和坩埚结构不仅影响到坩埚的寿命,亦对生产效率和生产成本产生巨大影响.本文就8t真空自耗电弧炉用Φ720 mm×3000 mm坩埚的失效原因做了分析,提出了优化方案及改进方法.     

真空碳脱氧对非金属夹杂物的影响

非金属夹杂物对电站转子锻件的质量产生重大的影响。多年来,它是不允许用碱性平炉冶炼这一类高级优质合金钢的主要原因。本文在真空碳脱氧碱性平炉转子钢的试验中,就非金属夹杂物的特性,分析了真空碳脱氧这一新的工艺对转子锻件中非金属夹杂物的影响。分析结果表明,经真空碳脱氧处理后,非金属夹杂物含量下降56％,同通常作为生产电站转子锻件的主要冶炼设备——酸性平炉冶炼、大气浇注的转子钢相比,平均低77％,比真空浇注的低27％。夹杂物的颗粒更加细小,颗粒度更均匀。尤其是经过真空碳脱氧处理后,转子锻件中的硫化物,由酸性平炉的条状、线状,改变为球状或纺锤形。分析了硫化物形态变化的原因,揭示了真空碳脱氧以改善转子锻件质量(尤其是横向冲击韧性)的实质。     

Improvement in mechanical properties of C300 maraging steel by application of VAR process

The prime objective of this research was to improve the mechanical properties of C300 maraging steels originally cast in the vaccum induction melting (VIM) and AIM furnaces by application of vaccum arc remelting (VAR) process. For this purpose two sets of C300 maraging steel with different amounts of Ti were cast in two different types of furnaces. Three bars with 1, 1.5 and 2 wt% of Ti were produced in the argon induction melting (AIM) furnace and two bars with 0.65 and 1 wt% Ti in the VIM furnace. Then all of the bars were subjected to VAR process in order to study the effects of this process on the reduction of N and O gases and inclusions, hence improvement in the mechanical properties. The results show that the total reduction of N and O gases in the bars cast in the AIM furnace was up to 40%, the amounts of inclusions irrespective of their kind reduced up to 30% while ductility and impact energy increased up to 40%. However, these parameters in the bars cast in the VIM furnace changed as follows: total gas reduction decreased by 12%, ductility and impact energy increased by 30% and 47%, respectively. So this research provides a very informative data base for those who are interested in studying the effect of VAR process on the mechanical properties of this kind of cast steel.     

Electric arc modeling of the EAF using differential evolution algorithm

?tore Steel Ltd. makes more than 1400 steel grades. The highest costs in steel production from scrap stems from the electric arc furnace electric energy consumption. Electrical energy is used to produce heat energy generated by the burning arc between the graphite electrodes and steel scrap. In general, the balanced heat input of all electrodes is essential. Based on the input of thermal energy from all electrodes, also the possibility of occurrence of hot and cold spots in the electric arc furnace can be determined. Perception of and the elimination of the unequal heat load of electrodes have a major impact on reducing operating costs and increasing the efficiency of the electric arc furnace production. Most authors have modeled the arc furnace as an electrical equivalent circuit, where the electric arc is modeled using the macroscopic approach. In this paper, the microscopic approach to the electric arc model is described, where a set of equations (electrical neutrality, Dalton law, Saha–Eggert) was solved using differential evolution algorithm. The results of modeling were practically confirmed by measuring electric parameters (voltage, current, active power) during the electric arc furnace operation. In November 2016, the investment in a new electrode controller using implemented logic will be carried out.     

钢渣超微粉/橡胶复合材料的性能及补强-阻燃机制

以磁选热闷渣、未磁选热闷渣、电炉渣和风淬渣作为研究对象,以乙二醇、三乙醇胺和无水乙醇制备钢渣助磨剂,钢渣助磨剂与钢渣进行复合获得钢渣超微粉。将钢渣超微粉与炭黑N220、促进剂、硫磺、 ZnO、硬脂酸、天然橡胶进行复合,制备钢渣超微粉/橡胶复合材料。研究钢渣种类和钢渣助磨剂用量对钢渣超微粉/橡胶复合材料力学性能和阻燃性能的影响。利用XRF、 XRD、 LPSA和FTIR对化学成分、矿物组成、粒度分布和组成结构进行测试。结果表明,以电炉渣制备的钢渣超微粉/橡胶复合材料的力学性能最佳,以磁选热闷渣或未磁选热闷渣制备的钢渣超微粉/橡胶复合材料的阻燃性能最佳。钢渣助磨剂可以减小钢渣超微粉的粒度尺寸,改善钢渣超微粉的粒度分布均匀程度。随着钢渣助磨剂用量的增加,钢渣超微粉的粒度分布均匀程度改善,钢渣超微粉/橡胶复合材料的力学性能提高,阻燃性能降低。     

Limited impact endurance of 30CrMnSiNiN steel

The aim of this investigation was to study the effect of tempering temperature and metal purity on limited impact endurance under tensile loads at room and subzero temperatures. The tests were carried out on quench-hardened specimens of two grades of 30CrMnSiNiN steel: electric-arc smelted, i.e., in the initial condition (0.29% C, 1.3% Mn, 1.09% Si, 1.58% Ni, 1.04% Cr, 0.2% Cu, 0.012% S, 0.015% P, 0.01% O₂, 0.01% N₂) and subjected to a vacuum-arc refining (VAR) treatment (1.08% Mn, 0.007% S, 0.004% O₂, 0.003% N₂; the remaining impurities as in steel in the initial condition). VAR produces a substantial reduction in the content of O₂, N₂, S, and nonmetallic inclusions in the steel which, after this treatment, had a higher impact strength but virtually the same static strength properties.     

影响VAR炉熔炼安全的因素及对策

总结了影响VAR炉熔炼安全的多种因素,通过理论分析,总结出在设计和控制方面采取的应对方案和方法.     

Improved Electric Arc Furnace Operation Via Implementation of a Geno-Fuzzy Control System

The U.S. steel industry is growingly increasingly interested in the process of slag foaming in their electric arc furnace plants. Although slag foaming has been shown to improve plant efficiency, this highly dynamic process can be very difficult to consistently control. This article describes a computer control system developed to effectively manipulate the slag foaming process, and the implementation of the controller in an electric arc furnace plant. The control system is a model-following controller based on fuzzy logic. It uses a neural network to simulate the slag foaming process. Furthermore, the control system uses an evolutionary algorithm to effectively tune its fuzzy rule base in response to the dynamic behavior of the slag foaming process. Results are presented, which demonstrate the effectiveness of the control system in this process characterized by relatively slow process dynamics.     

Effect of smelting method on static and fatigue strength of low-carbon steel at elevated temperatures

Static and fatigue strength of St. 20 steel smelted by various methods were determined at room and elevated temperatures. The results showed that vacuum-arc melted steel has the optimum physicomechanical properties.     

Interfacial transition zone of cement composites with steel furnace slag aggregates

As previous studies of mortar and concrete with steel furnace slag (SFS) aggregates have shown increases or decreases in the bulk mechanical properties, this study investigated the microstructural cause of these opposing trends through characterization of the interfacial transition zone (ITZ) with quantitative image analysis of backscatter electron micrographs. Three SFS types – basic oxygen furnace (BOF), electric arc furnace (EAF), EAF/ladle metallurgy furnace (EAF/LMF) – were examined as aggregates in a portland cement mortar. The ITZ size for all SFS mortar mixtures was similar, with the ITZ of BOF and EAF/LMF being slightly more porous than mortar mixtures with EAF or dolomite. Microstructural examinations of the SFS particle revealed that BOF and EAF/LMF aggregates have different outer and interior compositions, with the outer composition consisting of a porous layer, which likely contributes to the reduced strength relative to EAF. The imaging results demonstrated that the type of SFS and its spatial composition greatly influences the bulk properties of mortar and concrete, mainly as a function of porosity content in the ITZ and the outer layer and interior porosity of the SFS aggregate.     

感应加热对奥氏体不锈钢弯管组织和性能的影响

采用感应加热技术热煨奥氏体不锈钢弯管,对热煨后弯管的组织、性能及外观进行了分析研究.结果表明感应加热的奥氏体不锈钢弯管不仅可以不进行固溶和消除应力处理,而且具有各部分性能相差小、弯管表面氧化层薄,良好的外观和形状,是其它加工方法无法比拟.