本钢薄板坯连铸生产超深冲钢的试验研究

文章分析了本钢薄板坯连铸的设备和工艺特点,认为薄板坯连铸可以用来生产超深冲钢。而在工艺路线上,通过工业试验对比分析认为采用铁水预处理→复吹转炉→LF精炼→RH精炼→薄板坯连铸是最佳选择。     

转炉冶炼轴承钢生产工艺研究

分析了转炉冶炼轴承钢的技术优势,以GCr15轴承钢为例,采用全铁水脱硫-复吹转炉吹炼-LF＋RH精炼-大截面连铸流程生产轴承钢工艺可行。采用优质铁水并预处理脱硫,有效地控制原料中〔P〕≤0.01%、〔S〕≤0.003%;通过复吹转炉吹炼,使钢中碳-氧反应趋于平衡,弥补了因低拉碳造成的钢中氧含量高的不足;利用LF及RH精炼,使钢材中的有害元素〔Ti〕≤30×10-6、〔O〕≤8×10-6、〔N〕≤38×10-6、〔H〕≤0.8×10-6;通过大截面连铸改善了大规格轴承钢低倍缺陷。     

轴承钢GCr15矩形坯低倍质量控制技术研究

<正>一、轴承钢GCr15生产工艺流程目前,中国大部分炼钢厂均采用转炉生产轴承钢GCrl5矩形连铸坯,其生产工艺流程为:高炉铁水的氧化脱硫→立式转炉炼钢→LF炉精炼→RH炉精炼→矩形坯的连续铸钢→保温送特钢厂进行特色处理。国内特钢厂处理轴承钢GCr15矩形坯的生产工艺流程为:铸坯的加热→热送至(800/650)棒材连轧机组→棒材的保温→送修磨工     

转炉生产易切削钢45BS工艺技术

广泛应用于精密仪器零件、汽车零件、各类机械重要零件的特殊钢45BS属易切削钢,生产中通过向钢中添加S元素,改善该钢材的切削性能,为后续机械加工创造良好的条件。本钢炼钢厂采用转炉→炉外精炼(LF+RH)→连铸工艺流程生产含硫易切削钢45BS,结果表明所生产钢材的化学成份和各项性能均达到技术标准的要求。     

鞍钢ASP中薄板坯连铸机生产刃具钢的质量控制

通过对鞍钢ASP中薄板坯连铸机生产高碳刃具钢的炼钢、精炼、连铸各工序进行优化控制,有效保证了铸坯表面质量和内部质量的稳定,满足用户的需求。     

薄板坯连铸连轧技术及其ESP工艺

介绍了主要薄板坯连铸连轧工艺流程及其装备特点,分析了ESP新工艺的技术特性、工艺路线、设备参数,明确了ESP工艺在极薄带生产、"以热代冷"工艺上的显著优势。     

本钢薄板坯低碳钢种内部质量研究

通过对本钢薄板坯低碳钢种生产过程的钢水和铸坯系统取样分析研究,综合评估了本钢薄板坯低碳钢种内部质量情况,为本钢薄板坯连铸制定实际生产工艺提供现实依据。     

包钢CSP高效化生产技术及高性能钢带研究与开发

一、大型钢铁企业高效化生产管理的背景在我国以往的大部分国有钢铁企业中,由于历史原因,大都存在设备比较陈旧以及劳动生产率较低的问题。为了适应国内钢铁企业发展的需求,应对来自国际钢铁市场的竞争压力,各大钢厂纷纷引进新的生产线。自从世界上最初为短流程小钢厂开发的薄板坯连铸连轧技术获得工业生产的成功以来,该工艺在冶金界产生了巨大的反响,随之建成了大批生产线。包钢引进的德国西马克公司开发的薄板坯连铸连轧(CSP)技     

薄规格集装箱板轧制工艺优化

本钢1880mm薄板坯连铸连轧机组,利用短流程板坯温度条件好、轧机能力强等工艺设备特点,通过优化轧制工艺要点,并利用平整机组,大批量稳定生产厚度1.6mm和2.0mm的集装箱板SPA-H。     

国内薄板坯连铸用浸入式水口研究的进展

介绍了现在国内几种薄板坯连铸用浸入式水口的结构及使用要求,分析了薄板坯水口几何结构对结晶器内钢水流场、温度场的影响,提出有利于改善薄板坯浸入式水口热震稳定性和耐渣侵性能的工艺措施和水口设计思路.     

钢液真空循环精炼过程的数学模拟

1　Introduction　Withuninterruptedlyincreasinginthedemandforultracleansteel,thevacuumcirculation (RH)refiningprocesshasnowbecomeaprinciplerefiningoperationforreducingthecarbonanddegassingofmoltensteel.VariousrefiningtechnologiesusingoxygenorpowderinjectionandblowingintheRHtreatmentformakingultralow carbonandultralow sulphursteelhavebeendevelopedinrecentyears[1 10 ] .Actually ,theRHre finingprocesshasbeenextendedtobecomeamulti functionrefiningtechnology ,whichisenabledtore movecarbon ,oxygen …     

钢液真空循环精炼过程的物理模拟

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ａｓａｓｅｃｏｎｄａｒｙｓｔｅｅｌｍａｋｉｎｇｔｅｃｈｎｏｌｏｇｙ ,ｔｈｅＲＨ(Ｒｕｈｒｓｔａｈｌ Ｈｅｒａｅｕｓ)ｖａｃｕｕｍｃｉｒｃｕｌａｔｉｏｎｒｅｆｉｎｉｎｇｐｒｏ ｃｅｓｓｈａｓｂｅｅｎａｐｐｌｉｅｄｗｉｄｅｌｙａｎｄｄｅｖｅｌｏｐｅｄｒａｐｉｄｌｙｉｎｐｒｅｖｉｏｕｓｆｏｕｒｄｅｃａｄｅｓ .Ｗｉｔｈａｃｏｎｔｉｎｕｏｕｓｌｙｇｒｏｗｉｎｇｄｅｍａｎｄｆｏｒｈｉｇｈｑｕａｌｉｔｙａｎｄｈｉｇｈｌｙｃｌｅａｎｓｔｅｅｌ,ｉｔｈａｓｎｏｗｂｅｃｏｍｅ ,ｔｏａｃｏｎｓ…     

大兴安岭不同演替阶段土壤呼吸及其组分的动态

土壤呼吸及其组分随森林演替的变化对于长期碳循环模型及其地下碳储量至关重要.为了研究土壤呼吸随森林演替的变化及其影响机制,在2019年大兴安岭地区选取草地(GL)、白桦林(BF)、白桦与落叶松混交林(MF)、落叶松林(LF)4个不同演替阶段并对其进行研究.采用壕沟法测定自养(RA)和异养(RH)呼吸.结果 表明,GL、BF、MF和LF的土壤呼吸(RS)分别为3.11,5.68,5.54和4.69 μmol·m-2·s-1,RH分别为2.37,4.56,4.31和3.50 μmol·m-2·s-1,RA分别为0.74,1.12,1.23和1.19 μmol·m-2·s-1,GL、BF、MF、LF去除凋落物后Rs值分别为3.01,5.21,5.24和2.88 μmol·m-2·s-1.GL、BF、MF和LF中RA对Rs的贡献分别为23.79％,19.72％,22.20％和25.37％.演替阶段对Rs有显着影响(P＜0.05).回归分析发现,RA与细根生物量呈正相关(P＜0.01),RH与森林凋落物质量呈显著正相关(P＜0.05).试验的结果强调了演替阶段对土壤呼吸不同成分的重要性及其对估算森林碳汇潜力的重要性.     

Effect of Riboflavin Operon Dosage on Riboflavin Productivity in Bacillus Subtilis

After deregulating the purine and riboflavin synthesis in the Gram-positive bacterium Bacillus subtilis,it is critical to amplify riboflavin operon with appropriate dosage in the host strain for remarkable increase of riboflavin production. Bacillus subtilis RH13, a riboflavin-producing strain, was selected as host strain in the construction of engineering strains by protoplast fusion. The integrative plasmid pRB63 and autonomous plasmid pRB49, pRB62 containing riboflavin operon of B. subtilis 24 were constructed and transformed into the host strain respectively. Increasing one operon copy in B. subtilis RH13 results in about 0. 4 g/L improvement in riboflavin yield and the appropriate number of operon copies was about 7--8. Amplifying more riboflavin operons is of no use for further improvement of yield of riboflavin. Furthermore, excessive operon dosage results in metabolic unbalance and is fatal to the host cells producing riboflavin.     

本钢FTSC生产热轧板卷边裂的原因分析及控制

本钢采用FTSC短流程工艺生产热轧卷板时,因钢中[Al]、[N]、[B]控制不当,生成[AlN]及[BN]析出造成晶界脆性,二冷水量冷却不均、钢板在弯曲和矫直时产生边裂。文章通过控制钢中[Al]、[B]的含量,减少中碳钢生产过程中增氮、降低薄板坯二冷水量等措施,减少了边裂缺陷的发生。     

IS IT WORTH USING CAS FOR SYMBOLIC ALGEBRA MANIPULATION IN THE MIDDLE SECONDARY YEARS? SOME TEACHERS’ VIEWS

The use of Computer Algebra Systems (CAS) in years 9 and 10 classrooms as a tool to support learning or in preparation for senior secondary mathematics is controversial. This paper presents an analysis of the positive and negative aspects of using CAS identified in the literature related to these year levels, along with the perceptions of 12 experienced secondary teachers who were working with years 9 and 10 students. The literature review shows that CAS is valued for calculation and manipulation capabilities, the option of alternative representations, the opportunity for systematic exploration and for prompting rich discussion. However, the technical overhead, initial workload for the teacher and unresolved questions about the perceived relative contribution of machine and by-hand work to learning currently pose obstacles to teaching with CAS in the middle secondary years. The teachers who contributed data to this study perceived that using CAS in their teaching is, on balance, worth the effort. However, they believed that CAS is of most benefit to their high ability students and may present an obstacle to their low ability students’ learning of mathematics.     

RH真空系统测试技术分析

详述了RH真空精炼炉中真空系统各种设备的功能,对真空度测量和泄漏量测试进行了说明,并分析了真空系统出现故障的原因。分析结果对于正确判断真空度故障的发生部位,全面掌控真空系统的运行状态,具有重要的现实意义。     

Prospective teachers’ views on the use of calculators with Computer Algebra System in algebra instruction

Although growing numbers of secondary school mathematics teachers and students use calculators to study graphs, they mainly rely on paper-and-pencil when manipulating algebraic symbols. However, the Computer Algebra Systems (CAS) on computers or handheld calculators create new possibilities for teaching and learning algebraic manipulation. This study investigated the views of Turkish prospective secondary mathematics teachers on the use of advanced calculators with CAS in algebra instruction. An open-ended questionnaire and group interviews revealed prospective teachers’ views and beliefs about when and why they prefer three possible uses of CAS—black box, white box, or Symbolic Math Guide (SMG). The results showed that participants mainly preferred the white box methods and especially SMG to the black box method. They suggested that while the black box method could be used after students mastered the skills, the general white box method and SMG could be used to teach symbolic manipulation.     

RH和RH-KTB精炼过程中钢液流动和混合特性的研究

The flow and mixing characteristics of molten steel during the vacuum circulation refining,including RH(Ruhrstahl-Heraeus) and RH-KTB(Ruhrastahl-Heraeus-Kawasaki top blowing) processes,were investigated on a 1/5 linear scale water model of a 90t multifunction RH degasser,The circulation rate was directly and more accurately determined,using a new method by which the more reliable results can be obtained.The fluid flow pattern and flow field in the ladle were demonstrated,observed and analyzed.The mixing time of liquid in the ladle was measured using electrical conductivity method.The residence time distribution in the RH model was obtained by tracer response technique.The influence of the main technological and geometric factors,including the gas top blowing*(KTB) operation,was examined.The results indicated that the circulation rate of molten steel in the RH degasser can be fairly precisely calculated by the formula:Q1p=0.0333Qg^0.26Du^0.69Dd^0.80(t/min),where Qg-the lifting gas flow rate(NL/min);Du and Dd-the inner diameters of the up and down-snorkels(cm),respectively.The maximum value of circulation rate of molten steel in the case of the 30cm diameters either of the up-and down-snorkels for the RH degasser(the “Saturated” rate) is approximately 31 t/min.the corresponding gas flow rate is 900NL/min.Blowing gas into the vacuum chamber through the top lance like KTB operation does not markedly influence the circulatory flow and mixing charateristics of the RH process under the conditions of the present work.There exist a major loop and a large number of small vortices and eddies in the ladle during the RH refining process.A liquidliquid two-phase flow is formed between the descnding stream from the down-snorkel and the liquid around the stream.All of these flow situation and pattern will strongly influence and determine the mixing and mass transfer in the ladle during the refining.The correlation between the mixing time and the stirring energy density is τmε^0.50 for the RH degasser.The mixing time rapidly shortens with an increase in the lifting gas flowrate.At a same gas flow rate,the mixing times with the up-and down-snorkel diameters either of 6 and 7cm are essentially same.The 30cm diameters either of the up-and down-snorkels for the RH degasser would be reasonalble.The concentration-time curve showed that three circulation cycles are at least needed for complete mixing of the liquid steel in the RH degasser.