含铈IF钢中含钛夹杂物的析出行为

通过热力学计算研究了IF钢中含钛夹杂物的形成过程以及铈对钢液中Al2O3夹杂物的变质机理,并采用扫描电镜、能谱仪观察和分析了IF钢和含铈IF钢中的含钛夹杂物。热力学计算和扫描电镜观察结果表明:TiN不能在熔炼温度下形成;在IF钢液凝固的过程中TiN以异质形核的形式生成并长大,生成TiN-Al2O3夹杂物;在含铈IF钢中TiN-Al2O3夹杂物被稀土铈变质为TiN-CeAlO3夹杂物,稀土铈减小了含铈IF钢中含钛复合夹杂物的尺寸。     

含铈IF钢中铈夹杂物的热力学分析及实验研究

研究了含铈IF钢中铈夹杂物生成的热力学规律,以及铈对钢液中Al_2O_3夹杂物的变质机理,并采用扫描电子显微镜及能谱仪观察和分析了IF钢和含铈IF钢中的主要夹杂物,结果表明,铈在氧、硫含量均小于0.0006%的超低氧、硫IF钢中仍能够同时脱氧、脱硫、脱磷,具有净化钢液作用;含铈IF钢中的稀土夹杂物主要为Ce_2O_3、Ce_2O_2S、CeAlO_3夹杂物,各稀土夹杂物呈球状或椭球状,且尺寸均小于2μm,钢中未发现稀土硫化物夹杂;含铈IF钢中的Al_2O_3夹杂物被铈变质为尺寸较小的CeAlO_3夹杂物。     

FeSi中铝对不锈钢连铸和热轧板表面缺陷影响

 针对硅脱氧条件下304不锈钢中出现的Al2O3夹杂物和热轧板表面存在分层缺陷的问题,通过对铸坯的大样电解、热轧板取样、扫描电镜检测分析以及FactSage软件计算等方法,主要研究了FeSi合金中残余铝质量分数对Al2O3夹杂物生成的影响,并分析了Al2O3夹杂物对不锈钢连铸和热轧板表面分层缺陷的影响。研究表明,硅脱氧条件下生产的304不锈钢整个冶炼过程中,产生Al2O3夹杂物的主要环节为GOR还原初期含有较高铝质量分数的FeSi合金的脱氧过程。通过FactSage软件计算得到了避免Al2O3生成时FeSi合金中所允许的最大铝质量分数。根据计算结果和现场试验得出以下结论：FeSi合金中的铝质量分数超过1.8%时,钢液中会产生Al2O3夹杂物,Al2O3进入具有较高碱度的结晶器保护渣熔渣层造成局部保护渣黏度和熔化温度快速增加形成块状的夹杂物,这些夹杂物被卷入钢液内部或者被新生铸坯表面捕捉,从而造成热轧过程中轧板的表面分层缺陷形成。当FeSi合金中的铝质量分数小于1.5%时,钢液中难以产生Al2O3类夹杂物,有效抑制了这类表面缺陷的产生。     

渣 钢反应对高强度合金结构钢中生成较低熔点 非金属夹杂物的影响

 钢中非金属夹杂物绝大多数为较低熔点夹杂物,可以显著改善钢材的抗疲劳破坏性能。对炉渣 钢液 夹杂物间相互作用进行了实验室研究,发现钢中MgO Al2O3系高熔点夹杂物的比率随渣 钢反应时间增加而减少,与Al2O3的质量分数为20％和CaO/SiO2约为5的炉渣相比,采用Al2O3的质量分数为41％和CaO/SiO2约为65的炉渣,CaO MgO Al2O3 SiO2系夹杂物的比率由24.3%增加至81.7％,大多数夹杂物位于较低熔点成分区域（≤1500 ℃）。     

铈对新型超级双相不锈钢2707HD夹杂物变性的影响

为了提高钢的洁净度,实现夹杂物无害化控制,研究了稀土铈对新型超级双相不锈钢2707HD中夹杂物变性行为的影响。通过热力学计算,初步判定了加入铈后钢液中可能生成夹杂物的类型。利用金相显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)和Image-Pro6.0软件对钢中夹杂物的尺寸、形貌和类型进行表征和分析。结果表明,当铈的质量分数为0.03%时,钢中尺寸小于1和1~2μm夹杂物的比例均增加,而大于2μm夹杂物的比例下降;当铈的质量分数为0.06%时,小于2μm夹杂物的比例下降,并且有大于5μm的夹杂物生成。铈使不规则的Al_2O_3夹杂物变性为规则的Ce_2O_3和Ce_2O_2S稀土夹杂物,并伴有Ce_2O_3-Ce_2O_2S和CeAlO_3-Ce_2O_2S复合夹杂物的生成,有效减少了钢中不规则夹杂物的数量。     

光谱分析夹杂物技术在IF钢生产中的应用

介绍了利用PDA光谱仪开发的光谱分析夹杂物技术,利用该技术分析了IF钢冷轧板合格品罐次和由夹杂引起的废品罐次精炼过程中RH终点、中间包浇铸中期钢液中Al2O3夹杂物含量,初步提出了IF钢精炼过程中夹杂物控制技术指标:RH终点夹杂物质量分数控制在0.004 5%以下、中间包夹杂物质量分数0.003 0%以下。于2009年将该技术应用于IF钢实际生产过程中,并与其它工艺相结合,大大降低了IF钢冷轧板由夹杂引起的废品率。     

铈在重轨钢中行为特性的热力学模型分析

以重轨钢为研究对象,建立可以定量描述稀土在重轨钢中行为特性的热力学模型,并通过实验验证了模型的精确度.利用该热力学模型,研究分析了在不同氧、硫的质量分数条件下,铈加入量对重轨钢液及其凝固过程中铈的赋存状态以及夹杂物组成的影响作用规律,得到以下结论:当钢中氧、硫的质量分数较低时,随着铈加入量的增加,Ce2O2S的析出量略有减少;当钢中氧、硫的质量分数较高时,随着铈加入量的增加,Ce2O2S的析出量有所增加;铈加入量的增加以及温度的下降均有利于Ces的析出;当钢中氧、硫的质量分数较低时,在凝固过程中钢中析出CeN和固溶铈;随着铈加入量的增加,CeN的析出温度和析出量均有所增加,当CeN的析出达到平衡时,固溶铈大量析出.     

吹氩钢脱氧铝消耗及脱氧工艺对夹杂物的影响

 由250 t转炉冶炼吹氩钢的生产数据分析,发现转炉脱氧工艺对脱氧铝消耗的影响大。出钢全脱氧工艺比半脱氧工艺的脱氧铝单耗高0.28 kg/t、脱氧铝利用率低8.3%;随转炉温度的上升或氧质量分数增加,脱氧铝单耗逐步增加,同时,转炉温度的上升会引起氧质量分数的增加。通过对SPHC板坯在两种脱氧工艺下的夹杂物分析,发现：宏观上两种脱氧工艺的全氧控制水平相当,约为0.002 0%;半脱氧工艺的氮质量分数为0.002 0%,全脱氧工艺时为0.002 5%。微观上,夹杂物主要为Al2O3、Al2O3-MnS、氧化物和[MnS/MnS-CuxS;]全脱氧与半脱氧工艺相比,Al2O3夹杂物平均尺寸小0.6 μm、Al2O3夹杂物比例低约25%、Al2O3-MnS夹杂物比例高约20%、硫化物比例低约5%。Al2O3夹杂物尺寸的减小易于Al2O3-MnS夹杂物的生成。     

精炼渣控制82B帘线钢中夹杂物形态的实验室研究

在实验室条件下,采用高温钼丝炉对用45钢和重轨钢熔炼成的帘线钢进行脱氧和渣钢平衡试验,研究了精炼渣组分对夹杂物形态的影响。结果表明:在精炼渣碱度为0.8～1.2时,夹杂物中Al2O3含量和钢中Als随精炼渣中Al2O3含量的增加而增加。把精炼渣Al2O3质量分数控制在10%以下时,能够使CaO-SiO2-Al2O3夹杂物处于塑性范围内。因此,在低碱度条件下,通过Si、Mn脱氧和调整精炼渣中Al2O3含量来控制夹杂物的形态是可行的。     

洁净钢中Al_2O_3夹杂物预测模型

介绍了洁净钢中Al2O3夹杂物预测模型的开发原理。依托PDA直读光谱仪,建立低碳铝镇静钢中Al2O3夹杂物含量和粒度预测模型。将模型应用在IF钢冶炼过程中,结果表明该预测模型具有一定的准确性,对IF钢生产具有一定的指导意义,同时对开发其它类型钢中夹杂物预测模型提供了理论雏形。     

Evolution of Al2O3 inclusions by cerium treatment in low carbon high manganese steel

The influence of cerium (Ce) treatment on the morphologies, size and distributions of Al2O3 inclu-sions in low carbon high manganese steel was investigated by OM, SEM-EDS and theoretical calcula-tion.The results showed that Ce can modify the morphologies and types of Al2O3 inclusions.After Ce treatment, the irregular Al2O3 inclusions were replaced by smaller and dispersive spherical cerium oxysulfides.The effects of treatment time and Ce content on the evolution of Al2O3 inclusions were examined.It indicated that Al2O3 inclusions were wrapped by rare earth inclusions to form a ring like shape Ce-enriched band around the inclusions.Model was established to elucidate the evolution mech-anism of Al2O3 inclusions.Evolution kinetics of inclusions was discussed qualitatively to analyze the velocity controlled step.It was found that diffusion of Ce3 + and Al3 + in solid inclusion core and the formed intermediate layer would be the limited step during the evolution process.     

A Coupled Thermodynamic Model for Prediction of Inclusions Precipitation during Solidification of Heat-resistant Steel Containing Cerium

A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microsegregation of solute elements during solidification of heat-resistant steel containing cerium was established.Then the model was validated by the SEM analysis of the industrial products.The type and amount of inclusions in solidification structure of 253 MA heat-resistant steel were predicted by the model,and the valuable results for the inclusions controlling in 253 MA steel were obtained.When the cerium addition increases,the types of inclusions transform from SiO2 and MnS to Ce2O3 and Ce2O2S in 253 MA steel and the precipitation temperature of SiO2 and MnS decreases.The inclusions CeS and CeN convert to Ce2O3 and Ce2O2S as the oxygen content increases and Ce2O3 and CeN convert to Ce2O2 S,Ce3S4,and MnS as the sulfur content increases.The formation temperature of SiO2 increases when the oxygen content increases and the MnS precipitation temperature increases when the sulfur content increases.There is only a small quantity of inclusions containing cerium in 253 MA steel with high cleanliness,i.e.,low oxygen and sulfur contents.By contrast,a mass of SiO2,MnS and Ce2O2 S are formed in steel when the oxygen and sulfur contents are high enough.The condition that MnS precipitates in 253 MA steel is 1.2 w[O]+w[S]0.01%and SiO2 precipitates when 2 w[O]+w[S]0.017%(w[S]0.005%)and w[O]0.006%(w[S]0.005%).     

Effects of Cerium Addition on Inclusions and Solidification Structure of a Low-Nickel Si–Mn-Killed Stainless Steel

The effect of cerium on inclusions and solidification structure of a low-nickel Si–Mn-killed stainless steel is studied using laboratory experiments. When the cerium content in steel increased from 0 to 250 ppm, modification sequence of inclusions is Si–Mn(–Al)–O and MnS → Ce–Si–Mn–O–S → Ce(–Si)–O–S → CeS and CeC₂. The number density and area fraction of inclusion first decrease with the increase in the cerium content and then increase due to the formation of CeC₂ inclusions when the cerium content is bigger than 150 ppm, which is precipitated in solid steel during solidification. When the cerium content increases from 0 to 250 ppm, the fraction of equiaxed grain zones of steel ingot first increases and reaches a maximum value when the cerium content is 54 ppm; then the fraction of equiaxed grain zones decreases with the increase of the cerium content. 2D lattice misfit calculations are performed and it is found that there are no heterogeneous nucleation cores in the steel without cerium during solidification. For the steel with cerium, Ce_4.67Si₃O₁₃, Ce₂O₂S, and CeS inclusions act as heterogeneous nucleation cores, increasing the fraction of the equiaxed grain zone. Bigger effective heterogeneous nucleation cores number density leads to a larger fraction of the equiaxed grain zone.     

超低碳钢中Al?Ti?O夹杂物的形貌演变和生成机理

对超低碳IF钢钛合金化后的非金属夹杂物进行了分析,研究发现钛合金化后的夹杂物主要为Al₂O₃和Al?Ti?O夹杂物,没有发现纯TiO_x夹杂物。钢中生成的Al?Ti?O复合夹杂物从形貌上均可分为七种类型,四种具有Al₂O₃外层,另外三种无Al₂O₃外层。钛合金化后,钢中瞬态生成了大量无Al₂O₃外层的Al?Ti?O夹杂物,随后夹杂物表面生成Al₂O₃外层,导致有Al₂O₃外层的Al?Ti?O夹杂物数量比例逐渐增加至78.0%。热力学计算结果表明,随着钢中钛含量的增加,夹杂物的转变顺序为固态Al₂O₃→液态Al?Ti?O→固态Ti₂O₃。确定了Al?Ti?O夹杂物的生成机理过程分为两步:精炼过程钛合金化后,当钢液局部区域的钛的质量分数高于0.42%时,[Ti]与钢液反应瞬态生成Al₂O₃?TiO_x或TiO_x;随着精炼过程中钛元素的混匀,含TiO_x夹杂物被钢中[Al]还原,Al₂O₃?TiO_x和TiO_x夹杂物逐渐转变,在夹杂物表面生成Al₂O₃。      

H13钢中Mg-Al-O系夹杂物的形成机理及控制

 通过对保护气氛电渣重熔工艺和普通电渣重熔工艺H13钢的锻材成分、氧化物夹杂的组成分析,研究了电渣重熔工艺H13钢中Mg-Al-O系夹杂物的形成机理及控制问题,并通过Factsage软件对Mg-Al-O系夹杂物的各优势区进行了理论计算。结果表明,保护气氛电渣重熔工艺中氧质量分数较低,仅为0.001 5%,氧化物夹杂主要是MgO·Al2O3,1～3 μm的小尺寸占比达到了62.5%;普通电渣重熔工艺中氧质量分数较高,达到了0.002 4%,Mg-Al-O系夹杂物以72.5%Al2O3＋27.5%MgO·Al2O3为主,含有4%的5～8 μm大尺寸夹杂物,1～3 μm小尺寸占比仅为37.8%,尺寸偏大。钢液中镁、氧质量分数的变化对MgO·Al2O3的优势区域影响较大,高镁、低氧有利于MgO·Al2O3生成,减小H13钢中氧化物夹杂尺寸。但MgO·Al2O3会作为大尺寸碳氮化物(Ti,Nb,V)(C,N)异质形核核心,后期对此问题还要做进一步研究。     

镁对H13钢液析碳化物及组织的影响

摘要：为了研究镁对H13热作模具钢夹杂物、碳化物及组织性能的影响,采用蔡司金相显微镜、扫描电子显微镜、能谱仪、非水溶液电解、显微硬度仪等试验仪器,分析了经高温电阻炉冶炼的不同镁质量分数的H13钢。结果表明：由于镁较高的蒸气压,镁的平均收得率仅为2.12%;随镁质量分数的增加,钢中的氧化物夹杂由Ca-Al-O、Al2O3向MgAl2O4、MgO转变,硫化物夹杂由MnS向Mg-Mn-S转变;MgAl2O4、MgO与γ-Fe、M(CN)、M6(CN)的错配度和聚集长大能力相较于Al2O3更小,能够为钢中的液析碳化物提供更多的形核位置,减小析出碳化物的尺寸;微量镁可显著细化铸态树枝晶,减小二次枝晶间距,镁的加入,提高H13钢基体硬度、降低偏聚区硬度,H13钢整体硬度的均匀性得到改善。     

SUS436L超纯铁素体不锈钢夹杂物的形成机理

采用金相显微镜、扫描电子显微镜和能谱面扫描等仪器设备研究了钛稳定化SUS436L超纯铁素体不锈钢板材的夹杂物类型,结合热力学计算分析各类夹杂物的生成机理。结果表明,SUS436L不锈钢的夹杂物主要包括纯TiN颗粒、TiN包裹MgO·Al_2O_3尖晶石的复合夹杂以及Al_2O_3-CaO-TiO_2复合氧化物;当w([N])为0.007 0%、钢液温度为1 600~1 650℃时,平衡钛质量分数为0.23%~0.38%;当钢液温度为1 600℃、w([Al])为0.02%时,w([Mg])大于0.000 8%时生成MgO·Al_2O_3,w([Mg])大于0.004 4%则生成MgO;当钢液温度为1 600℃、w([Al])为0.02%时,钙处理后w([Ca])为0.000 14%~0.000 36%、大于0.000 36%时分别生成低熔点的12CaO·7Al_2O_3及3CaO·Al_2O_3,且在钛合金化后易生成低熔点的Al_2O_3-CaO-TiO_2复合氧化物。     

坩埚材质及顶渣成分对帘线钢夹杂物成分的影响

 使用碳管炉熔炼帘线钢72A,研究不同材质坩埚及不同成分顶渣对钢中夹杂物的影响。结果表明,MgO坩埚冶炼的帘线钢中夹杂物变形率高于ZrO2、SiO2、Al2O3坩埚。采用SiO2坩埚冶炼时,钢中夹杂物几乎不变形,其SiO2含量大于90%(质量分数,下同)。采用Al2O3坩埚,个别夹杂物Al2O3的含量达到40%左右,不适合冶炼帘线钢。钢中夹杂物成分进入较低熔点区(即不大于1500℃的区域)的条件为：采用MgO坩埚,顶渣碱度为10时,wAl2O3≤3%,或顶渣碱度为09时,wAl2O3为9%;采用ZrO2坩埚时,顶渣碱度为11~12时,wAl2O3为3%。     

Evolution of oxide inclusions in W800 non- oriented electrical steel

Inclusion is one of the major factors affecting magnetic properties of non- oriented electrical steel. Steel and slag samples were sampled in the production route of W800 non- oriented electrical steel. The composition of slags and the content of TO were measured by XRF and oxygen and nitrogen analyzer. The morphology, amount and composition of oxide inclusions were analyzed by an automated scanning electron microscope ASPEX. Before adding aluminum, the oxide inclusions are mainly spherical silicon oxide and a few SiO2- MnO wrapped by SiO2. Due to the high affinity with oxygen of aluminum, the oxide inclusions changed to alumina and MgO??Al2O3 spinel after adding aluminum. Only two types of morphologies of Al2O3 can be observed by polishing and acid etching. Sphere shape, cluster and polyhedron shape of Al2O3 can be observed after electrolysis of nonaqueous solution. Therefore, electrolysis of nonaqueous solution is more effective and accurate in revealing the morphologies of oxides. The average content of MgO in inclusions increases to 8. 1 mass% during soft blowing, due to the erosion of refractories.The inclusions grows larger and are removed effectively by argon blowing. Nearly no CaO exists in oxides because of low basicity and mass ratio of CaO to Al2O3. With the addition of Al, the inclusions are SiO2, liquid SiO2- Al2O3 and Al2O3, which are in agreement with the observed results.