低氧特殊钢中大尺寸DS类夹杂物生成机理

为了探讨低氧特殊钢中大尺寸DS类夹杂物的生成机理,通过ASPEX PSEM explorer自动扫描电镜对比分析国内外低氧特殊钢试样中夹杂物特征（国内、外试样各两个）,发现国内试样中夹杂物平均尺寸大于国外试样,夹杂物的最大尺寸则数倍于国外试样:国内试样中夹杂物的最大尺寸分别为24.9和13.1μm,国外试样分别为7.6和7.5μm.对比国内外特钢试样中大尺寸与小尺寸夹杂物可发现二者成分基本相同,推断大尺寸DS类夹杂物可能是细小夹杂物碰撞长大而形成.通过分析大尺寸夹杂物的可能来源,在实验室通过高温共聚焦激光扫描显微镜观察夹杂物在钢中固/液相界面处的行为.结果发现,总氧降低至7×10-6时,尺寸5μm以下的微细夹杂物可被固/液相界面所捕捉,并在固/液相界面处发生碰撞、聚集、长大而生成大尺寸（>12μm）DS类夹杂物.      

Change of Inclusion Characteristics during Vacuum Degassing of Tool Steel

The inclusion characteristics were studied during vacuum degassing by interrupting the operation at five different times after the start of operation. Slag and steel samples were collected and thereafter assessed with respect to steel and slag composition, total oxygen content, size distribution of inclusions and chemical composition of inclusions. The main conclusion is that the number of inclusions in the different size classes as well as the total oxygen content seem to reach a minimum value after around ten minutes of vacuum degassing. Furthermore, it seems to be a consistent trend that, during vacuum degassing, the top slag influences the inclusion composition.     

20SiMn合金结构钢精炼渣系优化

为控制20SiMn锻件用结构钢中氧含量和钢中夹杂物，首先采用热力学软件FactSage 8.1计算了1 600℃下CaO-SiO₂-Al₂O₃-5%MgO系精炼渣与20SiMn钢液平衡时的等氧线，并优化了精炼渣成分。同时，计算了不同氧含量下钢中Fe-Mg-Al-O体系优势区图。其次，实验室中设计了4组精炼渣成分，并在1 600℃下采用高温电阻炉进行渣-钢平衡试验，试验后采用X射线荧光光谱分析测定渣成分，采用等离子体光谱仪对钢样成分进行分析，采取红外碳硫分析仪、氧氮联合分析仪分别测定钢中碳硫和全氧含量，采用场发射扫描电子显微镜对试样中的夹杂物进行成分和形貌分析，并对钢中夹杂物数量与成分进行统计，试验研究了不同精炼渣对钢中氧含量、夹杂物组成、数量和尺寸的影响。最后，建立了动力学模型来描述“钢渣”界面上的夹杂物去除行为。试验和热力学模型结果揭示了钢中典型Al₂O₃、MgO·Al₂O₃夹杂物与钢中氧、镁和铝含量的关系，动力学模型描述了夹杂物分...     

410S不锈钢脱氧及冶炼过程的夹杂物

通过脱氧热力学计算410S铁素体不锈钢AOD还原后钢水中全氧质量分数,并对冶炼各工艺阶段所取钢样的全氧、夹杂物类型及形貌、渣样的化学成分进行检测,探究夹杂物的形成原因。结果表明,脱氧热力学计算的AOD还原后钢水中全氧质量分数跟检测值具有较好的一致性,随着还原硅质量分数的增加,钢水中全氧质量分数依次减小;随着冶炼过程的进行,钢液中全氧质量分数不断降低,夹杂物尺寸逐渐变小。AOD冶炼末期和LF冶炼末期夹杂物类型均主要为CaO-SiO2-MgO-Al2O3,但成分不同,跟这两个阶段炉渣的化学成分接近。连铸中间包中夹杂物成分跟钢液的温度降低有关。     

Effect of Top Slag Composition on Inclusion Characteristics during Vacuum Degassing of Tool Steel

The focus of the study was to investigate the effect of the chemical composition of the top slag on the inclusion chemical composition during vacuum treatment of a plastic mould tool steel. Sampling was done before and after vacuum degassing. The chemical composition of the inclusions was determined by using SEM combined with EDX. The results showed that several inclusion compositions were found before vacuum degassing, while only one main composition of inclusions was present after vacuum degassing. Furthermore, the composition of the top slag was found to have a great influence on the composition of the inclusions found in samples taken after vacuum degassing. The present study also shows that the vacuum degassing effectively reduces the number of inclusions in steel. Finally, the thermodynamic calculations of the activities using Wagner's equation were found to predict a lower oxygen activity value than the calculations made using the Thermo‐Calc software.     

钢中氧化物夹杂控制的研究

通过分析钢铁中夹杂物在各钢材炼制过程中的转变过程和钢液炼制过程中总含氧量与各夹杂物的对应关系,提出降低钢中氧含量应采取的一系列措施。生产实践表明,采取措施后,可最大程度降低钢中氧化物夹杂含量,保证成品总氧含量(氧的质量分数)维持在30×10-6以下。     

特殊钢精炼中的脱氧及夹杂物控制

 特殊钢是针对客户提出的质量要求,钢厂不断改进工艺,逐步提高成分、尺寸精确度和洁净度的各类钢的总称。钢中总氧量 ［TO］是衡量钢洁净度的重要标识,对于不同的钢种,其控制要求也不尽相同。在脱氧精炼过程中,存在着脱氧元素-钢中溶解氧、钢-渣、钢液-夹杂物、钢液-耐火材料、渣-耐火材料的反应与平衡,对钢中夹杂物的数量、组成和形态具有重要影响。通过热力学计算,比较了不同脱氧剂的脱氧能力,并介绍了典型特殊钢种（轴承钢、弹簧钢、帘线钢、电工钢、易切削钢等）精炼过程中的脱氧及夹杂物控制,分析和讨论了不同脱氧元素与钢液、熔渣以及耐火材料之间的相互作用机制。     

总氧含量对齿轮钢中非金属夹杂物的影响

为了保证齿轮钢中非金属夹杂物的控制,并确定齿轮钢经济合理的总氧含量控制目标,开展了总氧含量对齿轮钢中非金属夹杂物的影响研究。以三种不同总氧含量的Mn–Cr系齿轮钢为研究对象,利用Aspex扫描电镜、极值法、疲劳测试等不同方法研究了齿轮钢中非金属夹杂物数量、分布、尺寸等,获得了夹杂物与齿轮钢总氧含量的对应关系。在本文实验条件下,随着总氧含量的降低,钢中氧化物夹杂数量不断减小,其中5～10 μm的小尺寸夹杂物减小最明显,而10 μm以上的大尺寸夹杂物数量变化规律不明显。另外,极值法和疲劳试验结果表明,总氧含量高时（质量分数为0.0013%）,钢中最大氧化物夹杂尺寸也较大,比总氧质量分数为0.0010%和0.0005%的实验钢的最大夹杂物尺寸高10 μm以上,且当总氧含量比较低时（质量分数≤0.0010%）,实验钢总氧质量分数变化（0.0010%、0.0005%）对钢中最大夹杂物尺寸影响不大。      

低碳铝脱氧钢连铸开浇阶段钢中非金属夹杂物的变化

较系统地研究了开浇阶段钢中非金属夹杂物的变化.对板坯连铸生产SPHC钢开浇阶段钢水连续取样,并对试样全氧和氮以及非金属夹杂物进行分析.结果表明:开浇初期中间包钢水二次氧化较严重;开浇大约21min后中间包内达到较为稳定状态;钙处理可使夹杂物变性,防止水口粘结、堆积.     

Minimisation of calcium additions to low carbon steel grades

Abstract

This investigation aimed to determine the in plant feasibility of decreasing, to an amount close to the minimum literature value, the calcium addition to liquid steel for prevention of alumina buildup during continuous casting. Six plant trials were carried out at calcium additions of 0·14 kg/t of steel (reduced from the original 0·19 kg/t), added to the second ladle of a two or three ladle sequence. Total oxygen samples were taken at the ladle furnace and tundish to determine total oxygen and nitrogen contents of the steel. The total oxygen content at the ladle furnace varied between 19 and 26 ppm, with a slight degree of reoxidation between the ladle furnace and the caster. Alumina clogging was successfully prevented by the addition of 0·14 kg calcium/t of steel during the first five trials. During the sixth trial the submerged entry nozzle (SEN) failed and, although the stopper behaved as if clogging occurred, this behaviour was caused by the poor perfomance of the SEN rather than actual clogging. Microanalysis of inclusions in steel samples revealed a distribution in degrees of modification between different inclusions, and the formation of a substantial amount of CaS (which is taken to indicate overmodification, based on equilibrium calculations). However, the CaS is mostly associated with at least partly liquefied oxide inclusions, which is likely to reduce the potential clogging effect of solid CaS.     

Inclusion Characterization of Titanium Stabilized Ultra Low Carbon Steels: Impact of Oxygen Activity before Deoxidation

At an ArcelorMittal steel‐producing plant, heats deoxidized with initial oxygen activity greater or equal to 750 ppm were automatically downgraded. After analyzing liquid steel samples using automated SEM and remelt button techniques, it was concluded that higher oxygen levels before killing do not necessarily correlate to an increase in inclusion content of the heats. Results from both automated scanning electron microscope (SEM) and remelt button technique showed that the frequency of inclusions decreases with increasing inclusion size regardless of oxygen levels. The cleanliness of the heats with temperature correction following deoxidation at the RH degasser was also determined. It was observed that the number density of inclusions significantly increased in the ladle samples and more than doubled in the tundish samples for the heats with late temperature correction at the degasser and, therefore, this practice should be controlled.     

不同钛含量的钢与Al2O3和MgAl2O4界面润湿行为

高温下钢液中会生成大量的非金属夹杂物,对钢的浇铸工艺和钢产品性能产生不利影响。通过研究高钛钢与夹杂物的界面润湿行为,以期为高钛钢成分设计以及夹杂物的控制研究提供理论依据。以不同钛含量的钢样品以及Al₂O₃和MgAl₂O₄为研究对象,采用改进后的座滴法进行高温润湿试验得到表观接触角;通过电子探针对样品界面的微观形貌和元素进行表征,并结合热力学计算对钢与夹杂物的界面润湿行为进行解释。当钢中钛质量分数分别为0.01%、0.31%和0.68%时,Al₂O₃/钢润湿系统的表观接触角分别为96°、90°和112°,润湿后的样品界面均匀,无新反应相的存在和明显的元素富集。MgAl₂O₄/钢润湿系统的表观接触角分别为113°、106°和130°;低钛含量(w(Ti)=0.01%)时,界面无反应相生成,高钛含量时,界面存在不连续的反应层,为MgS、MgO、Ti₄S₂C₂     

硫化锰对钢中Sb析出行为的影响

研究了钢中不同夹杂物对Sb的析出和高温氧化过程中富集行为的影响.Fe-1.5%Sb合金1100℃水冷试样中Sb在钢中主要析出位置是晶界.与单一的氧化物夹杂相比,硫化锰是更为有效的Sb异质形核核心,且Sb析出相成分组成接近于FeSb相.实验结果与二维错配度理论计算结果相一致.通过降低氧含量,钢中加入Ti变质硫化锰夹杂等方式,增加了MnS数量,使得更多的Sb在夹杂物上析出,从而减少钢中Sb的偏析和固溶量,改变Sb在钢中的析出位置.      

Control of inclusion characteristics in direct cast steel billets

Two main criteria are used to characterize steel cleanliness. First the number and size of inclusions must be at the minimum level achievable with state-of-the-art steelmaking and casting equipment and procedures. Second the remaining small inclusions must have a chemical composition suitable for the steel application. In high carbon steel destined for wire drawing, inclusions need to be as deformable as possible.In this paper the inclusion behavior during hot rolling continuously cast (c.c.) billets to wire rods is reviewed. The relationship between inclusion deformability and composition was investigated at the laboratory scale and the results were applied to the control of cleanliness in c.c. billets. Production parameters affecting steel cleanliness are discussed.     

基于激光诱导击穿光谱技术的重轨钢中铝系夹杂物含量分析方法研究

钢中夹杂物对钢铁材料的性能存在着重要的影响,钢水中凝固的夹杂物会降低钢的物理性能。为排除钢中夹杂物的影响,需要建立检测夹杂物的方法。基于重轨钢样品中铝夹杂物的异常信号响应及阈值选择,实验研究了一种新的钢中铝系夹杂物含量的激光诱导击穿光谱分析(LIBS)检测方法。由于钢材中夹杂铝大多以酸不溶铝的形式存在,故研究中采取的计算模型中夹杂铝的含量默认与酸不溶铝含量相同。实验中由于检测的中低合金钢中夹杂铝含量过低,故随机选择9块重轨钢待测样中5块作为标准样品,通过结合LIBS结果中异常信号的筛选和已发表文献的模型进行计算,发现在置信区间阈值K=2.6时,激光诱导击穿光谱法得到的结果中夹杂物计算值与真实值基本符合,由此确立了激光诱导击穿光谱对铝夹杂分析的计算数学模型。将所建立的夹杂物检测方法模型实际应用于剩余4块重轨钢样品的检测,并将测定结果与化学湿法进行结果比对,结果显示二者基本一致。     

国内外95CrMo中空钢成品洁净度及组织性能分析

对国内外95CrMo中空钢成品进行了对比研究,结果表明：国内中空钢中S含量低,虽然脱氧元素Al、Ca含量也高,剩余wT［O］相比不低,但wAls/wAlt比值明显低于国外,废钢带入Ti和残余元素高于国外中空钢;国内中空钢中夹杂物数量较多,尺寸较大,CaS包裹的球型复合夹杂物多于国外中空钢,国外中空钢中含有Al2O3的夹杂物相对较多,但尺寸小,几乎没有钛类夹杂;国内外中空钢组织和硬度差别不大,夹杂物的数量、尺寸和类型可能是影响中空钢疲劳寿命的主要原因。     

在精炼处理和连铸阶段采集的低碳铝和硅镇静钢试样中非金属夹杂物的性质分析

非金属夹杂物的数量、分布、尺寸和化学成分对钢的性能有直接影响。通过控制这些夹杂物的尺寸和化学成分可以生产出优质产品。区分夹杂物的性质和控制夹杂物的形成对钢的清洁度十分重要。通过检验非金属夹杂物的化学成分可以预测夹杂物在钢中的性能。为了研究夹杂物的化学成分、尺寸和分布，某钢厂在二次精炼和连铸阶段采集了低碳铝和硅镇静钢的试样。试样用扫描电子显微镜（SEM）采用EDS系统进行分析。通过分析结果可以判定夹杂物的性质，分析精炼过程对减少夹杂数量和减小比表面积的效果。还可以确定处理后残留的夹杂对钢的性能和连铸过程（浸入式水口的堵塞）的影响大小。     

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。     

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.     

钢液成分对钙处理夹杂物改性效果的影响

钙处理是解决铝镇静钢水口结瘤问题的常用手段。通过热力学计算和工业试验研究了钢液成分对钙处理夹杂物改性效果的影响。FactSage热力学计算表明,在一定温度下,钙处理夹杂物改性效果与钢液中氧、硫相对含量密切相关。氧含量一定时,一定范围内的硫含量越高,平衡时夹杂物能达到的最大液相率越小,喂钙量的工艺窗口越窄;硫含量一定时,一定范围内的氧含量越高,平衡时夹杂物能达到的最大液相率越大。工业试验中,对中间包取样,低氧高硫炉次钢中典型夹杂物主要相是高熔点镁铝尖晶石和CaS复合夹杂物,高氧低硫炉次钢中典型夹杂物主要相是低熔点钙铝酸盐。工业试验分析结果与理论计算的趋势一致。