二氧化碳气氛中高碳锰铁固态脱碳的工艺研究

热力学计算表明了在二氧化碳气氛下高碳锰铁固态脱碳的可行性。实验采用正交试验法来分析各因素影响程度的大小。高碳锰铁颗粒表面与CO_2发生固-气反应,颗粒内部锰的氧化物与其碳化物发生固-固反应进行脱碳。结果表明:固体颗粒度是脱碳的主要影响因素,增大目数,升高温度,减小换气间隔能促进脱碳反应进行。试验中最低含碳量可达0.025%。     

RH强制脱碳与自然脱碳工艺生产IF钢精炼效果分析

西昌钢钒厂由于转炉热量不足而以转炉—LF精炼—RH精炼—连铸工艺生产IF钢,为探究RH强制脱碳与自然脱碳工艺生产IF钢精炼效果,采用生产数据统计、氧氮分析、夹杂物自动扫描、扫描电镜和能谱分析等手段,对不同脱碳工艺对顶渣氧化性以及钢的洁净度影响进行了详细研究。结果表明:（1）与自然脱碳工艺炉次相比,采用强制脱碳工艺的炉次在转炉结束与RH进站钢中的平均[O]含量更低;（2）两种工艺脱碳结束钢中的[O]含量基本在同一水平;（3）强制脱碳工艺的炉次在RH结束时渣中平均T.Fe的质量分数降低了1.3%。在能满足RH脱碳效果的前提下,尽量提高转炉终点钢液碳含量、降低钢液氧含量,后续在RH精炼时采用强制吹氧脱碳工艺,适当增大吹氧量来弥补钢中氧,可显著降低IF钢顶渣氧化性。自然脱碳工艺与强制脱碳工艺控制热轧板T.O含量均比较理想;与自然脱碳工艺相比,强制脱碳工艺可有效降低IF钢[N]含量,这与强制脱碳工艺真空室内碳氧反应更剧烈所导致的CO气泡更多和气液反应面积更大有关。脱碳工艺对IF钢热轧板中夹杂物类型、尺寸及数量没有明显影响,夹杂物主要由Al₂O₃夹杂、Al₂O₃–TiO_x夹杂与其他类夹杂物组成,以夹杂物的等效圆直径表示夹杂物尺寸,以上三类夹杂物平均尺寸分别为4.5、4.4和6.5 μm,且钢中尺寸在8 μm以下的夹杂物数量占比高于75%。在RH精炼过程中,尽量降低RH脱碳结束钢中[O]含量,有利于提高钢液洁净度。      

The Effect of Processing Parameters on Ferromanganese Alloy Carbon Content in Mamatwan Ore Reduction

Industrial production of medium carbon ferromanganese is accomplished by decarburization of high carbon ferromanganese in an oxygen blown converter. In this study, the possible in situ refinement of high carbon ferromanganese was tested in carbon deficient mixtures of pre-reduced Mamatwan ore, coal char, and silica flux reacted at furnace temperatures of 1450°–1550°C. The resultant phase chemistry was analyzed and interpreted with the aid of thermochemical calculations. Production of carbon unsaturated ferromanganese alloy in the AlloyStream process is explained with reference to laboratory experimental results.     

转炉冶炼低碳钢脱氧合金化工艺优化

通过对碳-氧反应机理的研究分析,对转炉冶炼低碳钢脱氧合金化工艺进行优化改进。优化后,转炉冶炼低碳铝镇静钢在出钢前期采用碳粉代替部分铝进行钢水预脱氧并且在出钢前期加入低价的高碳锰铁进行合金化,利用碳-氧反应脱除高碳锰铁中的碳。结果表明:铝块消耗平均降低了0.24 kg/t,锰铁合金成本降低了2.56元/t,取得了较好的经济效益。     

Decarburization Thermodynamics of High-Carbon Ferromanganese Powders During Gas-Solid Fluidization Process

 Thermodynamic conditions of reactions between high-carbon ferromanganese powders and gas decarbonizers like O2, CO2 and water vapor were studied by thermodynamic calculation. In O2, CO2 and water vapor atmosphere, high-carbon ferromanganese powders were decarburized in a fluidized bed. When the temperature is respectively higher than 273, 1226 and 1312 K, the gas-solid decarburization reaction will occur between ferromanganese carbide on the surface of the high-carbon ferromanganese powders and different gas decarbonizers. Since metal manganese is easy to be oxidized by O2, CO2 or water vapor, the decarburization reaction will transfer into a solid-solid phase reaction of ferromanganese carbide and ferromanganese oxide, promoting external diffusion of carbon to achieve a further decarburization of high-carbon ferromanganese powders.     

Effect of Modification Treatment on Inclusions in 430 Stainless Steel by Mg-Al Alloys

 Refining process of 430 stainless steel in AOD (argon oxygen decarburization) was simulated under the experimental condition. Al was chosen as deoxidizer, Mg-Al alloy was added in process of refining, and slag used in oxidation period of AOD was chosen in the experiments. The variation of total oxygen content, the size, morphology and composition of inclusions in refining process and the mechanical properties, pitting corrosion resistance of final samples were studied. The results show that no obvious differences in total oxygen content were observed among all the experiments. Neither chain nor cluster Al2O3 inclusions were found in refining process of experiments treated by Mg-Al alloys, the average size of inclusions in the steel treated by Mg-Al alloys was less than that of inclusions in steel not treated by Mg-Al alloy. 430 stainless steel treated by Mg-Al alloy shows better tensile strength, yield strength, and pitting resistance than that in the contrast experiment.     

含钛中碳钢中钛氧化物析出热力学分析

摘要：以含钛中碳钢为研究对象,从热力学的角度分析了含钛中碳钢中钛氧化物析出行为,结果表明：浇注温度为（1535±10）℃且钢中溶解氧含量大于0.003%（质量分数,余同）时,低钛中碳钢中的溶解Ti可与钢中的溶解氧反应生成Ti3O5、Ti2O3,生成TiO2、TiO夹杂的可能性较小;高钛中碳钢中的溶解Ti可与钢中的溶解氧反应生成Ti3O5、Ti2O3、TiO2和TiO夹杂;同时钢中的溶解Ti能够还原钢中的SiO2、MnO、Cr2O3夹杂物并生成TiO2夹杂;低钛中碳钢中不会生成TiC、TiN、TiS和Ti4C2S2夹杂;高钛中碳钢中可能会生成TiN和Ti4C2S2夹杂。对于低钛中碳钢,控制钢中较低的溶解氧含量（<0.002%）,对于高钛中碳钢,控制钢中较低的溶解氧含量（<0.0007%）及较少的Cr2O3、MnO、SiO2夹杂数量,可有效抑制含钛中碳钢中高熔点含钛夹杂物的生成,实现中碳钢低成本钛合金化及相关连铸工艺开发。     

薄板坯连铸连轧中高碳钢生产技术

 薄板坯连铸连轧流程钢水凝固速率高,铸坯在炉温度低、时间短,道次压下量大,有助于抑制化学成分偏析、细化非金属夹杂物、降低表面脱碳、减小珠光体片层间距,一定程度上缓解了传统流程生产高碳板带钢存在的问题,适于生产高质量的高碳钢板带。采用金相显微镜、扫描电镜等方法分析了薄板坯连铸连轧流程生产的中高碳钢的微观组织,结果表明：碳的最大偏析度为1.16,较传统流程的2.0有明显改善;单面脱碳层深度小于板带厚度的1.0%,为传统流程脱碳层深度的30%~60%;珠光体片层间距显著减小,有利于提高材料的综合性能。基于薄板坯连铸连轧流程已开发出中高碳优质碳素钢、碳素工具钢、弹簧钢、合金结构钢及合金工具钢,最高碳的质量分数达到1.0%,产品已广泛应用于汽车制造、工程机械、特种设备、高端锯片以及专用器具等领域。     

转炉-精炼-连铸过程钢中氧的控制

结合近年来的文献和笔者的研究工作,概要论述了转炉—精炼—连铸过程中钢洁净度(以总氧含量T[O]表示)的控制及夹杂物对产品质量的影响。提高钢的洁净度应从产生夹杂物的源头抓起,尽可能降低转炉终点氧含量。根据生产统计数据,建立了转炉终点氧预报模型。介绍了硅镇静钢、硅铝镇静钢、铝镇静钢三种脱氧模式及脱氧产物的控制方法。采用钢包精炼方法把夹杂物消灭在钢水进入结晶器之前是获得“干净”钢水的关键。介绍了RH、LF、中间包钢水总氧预报模型。介绍了在连铸过程中防止钢水再污染和进一步去除夹杂物的措施。     

气泡搅拌和炉渣成分对低碳钢水洁净度的影响

在80t氧气转炉、钢包吹氩和RH真空处理工序进行净化钢水的试验,考察反应器内氩气流量、真空脱气操作和顶渣成分对低碳钢水全氧含量的影响以及夹杂物的尺寸分布和全氧的排除速率,改进操作的结果表明,二次精炼后低碳钢水全氧w[T.O]降低到0.001%。     

DC06 IF钢精炼渣成分优化及钢 渣中氧的控制

摘要：无间隙原子钢（IF钢）对含铝夹杂物要求极为严格。为冶炼洁净IF钢,采用热力学软件FactSage 7.0对IF钢精炼渣系做了优化计算,并采取6组工业实验做验证,根据结果提出改进措施。实验中采取氧传感器、碳硫分析仪及ICP AES对钢和渣成分进行检测,并通过ASPEX自动扫描电子显微镜检测钢中夹杂物成分与数量。热力学计算及实验研究发现,转炉脱碳结束时钢液中碳质量分数宜控制在0.04%,转炉渣中FeO质量分数控制在149%以内,降低钢中［O］质量分数到470×10-6。精炼时控制补吹氧炉次比在64%以下,补吹量在17m3内,精炼渣中SiO2、MgO及TFe质量分数分别控制在6%~8%、6%和5%~10%,钙铝比控制在1.4~1.6时,钢中［O］质量分数可控制在10×10-6,且该精炼渣系对Al2O3有较好的吸附性。在确保精炼脱氧的同时,降低钢液二次氧化,达到IF钢洁净冶炼目的。     

中高碳铝镇静钢形成MnS塑性夹杂的工艺开发与实践

 为提高中高碳钢产品的抗疲劳性能,利用中高碳钢的成分特点,研究开发了中高碳铝镇静钢中MnS以Al₂O₃为形核质点的非均质形核工艺,将钢中Al₂O₃脆性夹杂用塑性MnS包裹,解决了疲劳应力钢因脆性非金属夹杂引起的疲劳断裂问题。通过对微细、弥散Al₂O₃夹杂生成条件、MnS非均质形核析出热力学条件的研究,开展了钢中关键元素的成分设计、精炼及连铸集成工艺的设计与开发。工业实践表明,低活度氧条件下进行铝终脱氧可以形成3～5 μm微细弥散的Al₂O₃夹杂,并作为非均质形核的核心在二次枝晶晶间的凝固末端析出弥散、细小的粒状MnS;通过梯度脱氧、真空碳脱氧以及保护浇铸等操作可以有效稳定控制钢中全氧含量,提高钢水洁净度,成品T[O]质量分数平均为0.000 618%,较原工艺的0.000 739%降低了16%;成品的夹杂物中MnS及MnS包裹Al₂O₃夹杂所占比例大于96%,与世界领先产品的夹杂物控制水平相当,考虑到产品使用过程中Al₂O₃夹杂外部的MnS包裹层必须足够厚,塑性夹杂才能起作用,建立了MnS “有效包裹率” 的概念,当硬相夹杂物被MnS包裹且硬相夹杂物的最大半径不大于MnS包裹部位半径的1/2时,认为MnS对硬相夹杂物实现了“有效包裹”;MnS塑性夹杂工艺可明显提高材料的疲劳性能,成品的平均断裂韧性为83.47 MPa·m1/2,较原工艺的67.31 MPa·m1/2提高了24%。     

RH生产超低碳钢的脱碳速率及工艺优化

 通过RH超低碳钢脱碳工业试验,对RH精炼过程工艺参数进行全程跟踪。重点对表观脱碳速率常数Kc进行了测定和评价。结果表明,RH脱碳过程分为3个阶段：抽真空阶段、吹氧脱碳阶段和自然脱碳阶段。稳定生产碳含量小于0.002%(质量分数,下同)的超低碳钢的优化工艺参数为：进站碳含量0.05%~0.06%,氧含量0.04%~0.06%;吹氧期的起始真空度12~15kPa,吹氩强度0.015m3·t-1·min-1;自然脱碳时间大于15min,吹氩强度0.015m3·t-1·min-1,终脱氧前的氧含量＜0.035%。     

涟钢RH—MFB试生产钢水质量分析

为充分发挥RH—MFB的精炼功能,了解RH—MFB的精炼效果,有必要对上RH的钢水质量进行分析,包括钢中[C]、[N]、T[O]及显微夹杂分析。结果表明：RH—MFB试生产钢水在中间包内增碳较为严重,出RH后钢液有轻微吸氮现象;RH—MFB精炼后,钢液中大于10μm的显微夹杂数量明显减少,T[O]的平均含量较前期生产也有明显下降。对精炼处理及中间包钢液中显微夹杂组成与形貌分析表明,基体为Al2O3的夹杂物是钢液存在的主要夹杂物,形貌特征各异,在工艺后期大多以球状和细小块状存在,此外,发现有少量铝酸盐或硅铝酸盐＋硫化物夹杂。为此,提出有针对性的改进措施,以期进一步提高钢水的质量,达到高效低耗生产的目的。     

Influence of ferromanganese additions on microalloyed engineering steel

Abstract

Plant trials with the addition of four different low carbon and medium carbon ferromanganese alloys to microalloyed engineering steels have been carried out at Ovako Steel, Hofors, Sweden. The process route for this type of steel at Ovako is electric arc furnace (EAF), ladle arc furnace (LAF), ASEA-SKF vacuum degasser, LAF and finally uphill teeming. For each ferromanganese alloy type, five experiments were accomplished by adding alloy at the ladle furnace station, i.e. 20 charges in total. During the experiments, liquid steel rapid solidification samples were taken to study the behaviour of inclusion formation and removal during ladle treatment. Also, samples for LSHR testing (liquid sampling hot rolling) were acquired for one heat of each of the ferromanganese containing alloys. Microinclusion assessments were carried out according to the method described in Swedish standard SS 111116. Macroinclusion assessments were carried out using immersed ultrasonic testing. Element analysis and mappings were done using a scanning electron microscope to establish the effect of ferromanganese addition on the composition of inclusions present in the steel. In samples taken 3 min after the ferromanganese addition to the LAF, about 30% of the analysed inclusions contain Al₂O₃, MnO and MnS. The Al₂O₃ content is concluded to originate from the deoxidation practice, while MnO and MnS contents are likely to originate from the addition of ferromanganese. The results also show that the addition of ferromanganese alloys leads to an increased amount of macroinclusions in the LAF up to 9 min after alloy addition. Steel samples taken after degassing but just before casting indicate that all the tested ferromanganese alloys give the same result with respect to the studied microinclusion characteristics at the end of ladle treatment. Last, the inclusion composition in the final steel samples is unrelated to the type of ferromanganese alloy used. In this case, the main compositions are Al₂O₃-MgO and MnS.     

Indirect Methods of Detecting and Evaluating Inclusions in Steel A Review

Thenonmetallicinclusionisasignificantprob lemincaststeelsleadingtoexcessivecastingrepairs orrejectedcastings.Inclusionsinsteelandinclu sions relateddefectsinsteelproductshavebeenre viewedelsewhere[1].Measurementtechniquesofin clusionsrangefromdirectmethods,whichareaccu ratebutcostly,toindirectmethods,whicharefast andinexpensive,butareonlyreliableasrelativein dicators.Indirectmethodsincludetotaloxygen measurement,nitrogenpickup,slagcomposition measurement,andsoon.Anextensivereviewon indirectmet…     

真空感应熔炼碳脱氧研究

为制备无固相脱氧产物的高洁净钢，在真空感应炉内用碳对无铝高纯铁进行脱氧。研究发现，在较高的真空度下炉衬材料的热稳定性对钢液终点氧含量产生决定性的影响。当钢液实际氧含量高于炉衬分解平衡氧含量时，碳脱氧反应速度决定于钢液中氧的扩散速度；当钢液中实际氧含量低于炉衬分解平衡氧含量时，碳脱氧反应速度受炉衬向钢液供氧速度控制。     

炼钢过程钢中氧的控制

为了实现对钢中氧含量的控制,提高产品的内在质量,通过对转炉-RH精炼-连铸生产超低碳钢工艺的研究,探讨了影响钢中氧含量及夹杂物的因素和控制技术,建立了相应的氧含量预报模型。研究结果表明：转炉中控制合适的出钢碳含量、温度和终渣氧化性,RH中保持合适的下渣量、纯脱气时间以及钢包渣的氧化性,连铸过程中减少耐火材料的SiO2含量、改善保护浇注等措施均有利于降低钢中的总氧含量、改善钢材的质量。     

太钢80t RH脱碳工艺分析

对太钢第二炼钢厂80t RH生产冷轧硅钢脱碳原理及影响脱碳的主要因素进行了分析。经分析可知,真空度、到站钢水碳氧含量、脱碳时间以及合金含量都直接影响冷轧硅钢碳含量。采用快速提高真空度、降低到站钢水碳含量、使用高品位合金都有助于提高脱碳效果,降低冷轧硅钢碳含量。     

微合金高碳硬线钢的研制

通过实验室研究与酒钢现场生产工艺相结合,对微合金高碳钢在中小型转炉条件下的生产技术进行了研究。试验表明,改进工艺后钢中ω（TO）平均降低至0．0038％,显微夹杂物数量降低了78％,大颗粒夹杂物数量降低了65%。铌微合金化处理后高碳钢线材的力学性能得到了改善。酒钢应用新工艺生产了铌微合金高碳硬线钢2980t,拉拔正常且钢丝性能优良。