反向凝固复合奥氏体不锈钢薄带的实验研究

采用１．２ｍｍ厚的１５Ｆ热轧板为母带，以奥氏体不锈钢１Ｃｒ１８Ｎｉ９作为覆层材料，在实验室条件下研究了反向凝固法生产复合奥氏体不锈钢带的可行性。实验表明，随着母带在钢液中浸渍时间的增加，新相层的生长经历“快速生长”、“平衡相持”和“迅速回熔”三个阶段；新相层厚度则随着钢液过热度的增加而近似线性地减少。此外，母带表面状态、母带在钢液中的浸渍时间及钢液过热度对铸带质量均有显著的影响，但通过控制合格的工     

反向凝固连铸碳素钢铸带中新相层的凝固生长规律

在实验室条件下,采用碳素钢板为母带,以08Al低碳钢为新相层材料,对反向凝固连铸薄带工艺过程中新相层在母带表面上凝固生长的规律进行了详细研究。研究表明,母带在钢液中的浸渍时间、母带厚度、钢液过热度对新相层厚度有显著影响,各个工艺参数间存在交互作用;新相层的变化经历“快速生长”、“平衡相持”和“迅速回熔”三个阶段,这三个阶段在新相层厚度－浸渍时间图上显示出“∩”形特征曲线;较低的钢液温度和较厚的母带可促使新相层厚度增加。     

反向凝固连铸碳素钢带中复合层的凝固生长规律

在实验室条件下,用市售碳素钢板作为母带,用08Al低碳钢作为复合层材料,对反向凝固连铸薄带生产过程中复合层在母带表面的凝固生长规律进行了研究,研究结果表明,母带在钢水中的浸渍时间、母带厚度和钢水过热度对复合层厚度有显影响,而且这些工艺参数之间存在交互作的浸渍时间、母带厚度和钢水过热度对复合层厚度有显影响,而且这些工艺参数之存在交互作用;复合层的变化经历了“快速生长”、“平衡相持”和“迅速回熔”三个阶段,这三个阶段在复合层厚度－浸渍时间图上共同组成具有较长平台 的反向凝固“∩”形特征曲线;较低的钢水温度和较厚的母带有利于增加复合层厚度。     

反向凝固法凝固层厚度的变化规律研究

讨论了反向凝固钢带凝固层厚度的变化规律，分析了一些因素对凝固厚度的影响，结果表明，母带厚度，钢液过热度及浸入时间对凝固层厚度均有不同影响。     

反向凝固08Al／15F复合钢带凝固传热过程的有限元分析

采用大型有限元分析软件ANSYS，对08Al／15F复合钢带的反向凝固传热过程进行了有限元分析。数值计算的复合层厚度随时间的变化与实际的实验测量值基本一致。计算域内温度分布和变化规律显示，在浸渍过程的初始阶段与母带表面接触的复层钢液温度急剧下降至固相线以下，发生液固相变，在界面处形成固一固接触。此外，数值分析还揭示了‘∩’形的复合层厚度一浸渍时间曲线上出现较长“平台”的实质。     

超级奥氏体不锈钢的发展

日益增长的工业需求推动着超级奥氏体不锈钢的研发,以研发时间为序阐述超级奥氏体不锈钢3个发展阶段。第1个阶段主要是为解决硫酸介质环境的耐腐蚀性而开发的不锈钢;第2个阶段是在第1阶段研发钢的基础上添加质量分数约为0.2%的N元素、并将Mo元素质量分数增加到约6%而研发的几种耐腐蚀性能良好的超级奥氏体不锈钢;第3个阶段是在6%Mo钢的基础上将Cr、Mo、N含量都进行较大幅度的提高,其中Mo元素质量分数增加到约7%,N元素质量分数控制在0.5%左右,并加入适量Mn元素而研发出耐腐蚀性优异的超级奥氏体不锈钢。阐述了超级奥氏体不锈钢研发过程中的2个重要技术,即炉外精炼与氮合金化技术,并展望了超级奥氏体不锈钢的未来发展及推广应用。     

1Cr21Ni5Ti真空感应冶炼浇注质量分析和工艺改进

真空感应炉冶炼的奥氏体－铁素体不锈钢１Ｃｒ２１Ｎｉ５Ｔｉ在浇注过程中,中间包内的钢液的流动性较差,钢液散流严重,使浇注无法顺利进行,为此我们从原材料、冶炼的真空度,中间包的材质及烘烤温度等方面采取措施,使１Ｃｒ２１Ｎｉ５Ｔｉ的真空冶炼浇注质量大为改善。     

双辊浇铸过程中18Cr—8Ni不锈钢的凝固组织形成机制

为了阐明双辊浇铸过程中凝固组织形成的机制，使用一台小型双辊连铸机对ＳＵＳ３０４奥氏体不锈钢进行了连铸实验。铸带中有两种凝固组织，即柱状枝晶区和等轴晶区。随辊区和液态金属间接触时间的增加，铸带厚度枝晶区深度增大，而等轴晶区几乎不变。增加初始辊缝尺寸，仅使等轴晶区扩大。另外，已弄清了钢液过热和结晶辊承支力对形成凝固组织的影响。钢液在与两结晶辊相接触时凝固的表层内形成柱状枝晶区。铸带剩余的未凝固层离开轧     

N08904超级奥氏体不锈钢的连铸实践

采用理论计算与热分析相结合的方式对N08904超级奥氏体不锈钢的液相线温度进行了计算测试,提出了合理的过热度参数,解决了连铸易漏钢问题,实现了连铸生产。     

GA-BP渣系活度预测模型及不锈钢脱氧机理

采用GA-BP神经网络模型对熔渣组元活度进行预测,通过对不同温度条件下不同组元渣系活度值的验证,证明了GA-BP渣系活度预测模型有较好的预测精度。在此基础上建立了奥氏体不锈钢、铁素体不锈钢冶炼过程中钢液脱氧热力学模型。热力学模型表明,钢液中铬质量分数越高,脱氧越困难;奥氏体不锈钢铝脱氧条件下,镍质量分数越高,脱氧能力越差;任何情况下降低熔渣中脱氧产物的活度都有利于降低平衡条件下钢液中溶解氧质量分数。     

Strip properties and processing in twin roll casting of stainless and low carbon steels

Metallurgical features of the twin‐roll strip casting process are discussed. The as‐cast structure of two austenitic stainless steels is evaluated using EPMA and metallography. Cleanness levels as reached in twin‐roll strip casting are compared with conventional and thin slab casting. In‐line annealing is described as a method for grain refinement. The scale layer on twin‐roll cast strip is characterised for low carbon and stainless steels.     

反向凝固复合不锈钢带界面结构的研究

借助光学显微镜,扫描电镜和电子探针,分析了反向凝固轧制后的不锈钢带的熔合区及碳的扩散,并研究了铬元素和铁元素沿横截面的分布情况,试验结果表明,母带和凝固层靠相互扩散形成固溶体而实现良好的冶金结合。     

The key technologies of controlling low carbon steel as-cast strip surface quality

This article is try to explain or analyze the key technologies of controlling the surface quality of low carbon steel as cast strip through investigation of interface heat transfer between solidified shell and liquid steel.The one of the key technologies of controlling surface quality of low carbon steel as cast strip is through the casting roll surface texture in order to achieve the homogeneous solidification on the casting roll.Another is through forming a thin film on the casting roll surface in order to achieve a balance between rapid solidification and homogeneous solidification.This film formed between the twin roll and the molten steel can be controlled by adjusting the chemical composition and inclusion in liquid steel through controlling the amount of all[O]and free[O].     

Advances in the Optimization of Thin Strip Cast Austenitic 304 Stainless Steel

This study is about the latest advances in the optimization of the microstructure and properties of thin strip cast austenitic stainless steel (AISI 304, 1.4301). Concerning the processing steps the relevance of different thin strip casting parameters, in‐line forming operations, and heat treatments for optimizing microstructure and properties have been studied. The microstructures obtained from the different processing strategies were analysed with respect to phase and grain structures including the grain boundary character distributions via EBSD microtexture measurements, the evolution of deformation‐induced martensite, the relationship between delta ferrite and martensite formation in austenite, and the texture evolution during in‐line deformation. It is observed that different process parameters lead to markedly different microstructures and profound differences in strip homogeneity. It is demonstrated that the properties of strip cast and in‐line hot rolled austenitic stainless steels are competitive to those obtained by conventional continuous casting and hot rolling. This means that the thin strip casting technique is not only competitive to conventional routes with respect to the properties of the material but also represents the most environmentally friendly, flexible, energy‐saving, and modern industrial technique to produce stainless steel strips.     

薄带连铸与常规生产流程条件下 Cr17铁素体不锈钢的织构及成形性能

研究了薄带连铸条件下Cr17铁素体不锈钢薄带坯的初始组织及织构,并重点对常规连铸坯和等轴晶薄带坯在轧制及退火过程中的织构演变进行了对比研究.研究结果表明:在薄带连铸条件下,通过调整熔池内钢水的过热度可以实现对薄带坯初始组织、织构的有效控制.在较低的过热度(20～40℃)条件下,可以获得具有全等轴晶组织和随机织构的薄带坯...     

Solidification and microstructure of a high alloy stainless steel

The steel considered in the present work can be classified as a 6Mo austenitic stainless steel, which has a much higher corrosion resistance than many other commercially available stainless steels. However, because of macrosegregation during solidification of ingot casting, the high alloy content in the steel, especially Mo, N, C, enhances precipitation of intermetallic phases such asa phase. Such precipitation mainly occurs in the center of the material and has normally no significant effect on mechanical properties or surface corrosion resistance. The introduction of modern production methods such as continuous casting of slabs for stainless sheet production has reduced the macrosegregation tendency and related precipitation. However, the microsegregation in a small scale may be enhanced as the higher cooling rate prevents the diffusion in the solidified region. In the present work, the continuous casting solidification process was simulated in a laboratory gradient     

Analysis and prevention of microcracking phenomenon occurring during strip casting of an AISI 304 stainless steel

This study was concerned with the effects of microstructural parameters on the microcracking phenomenon occurring during strip casting of an AISI 304 stainless steel. Detailed microstructural analyses of the microcracked regions showed that microcracks were formed mainly along tortoise-shell-shaped depressions and that their number and size were considerably reduced when strip casting was done right after a shot-blasting or pickling treatment of the casting roll surface. This microcracking phenomenon was closely related to the formation of a black oxide layer, which was mainly composed of manganese-rich oxides, on the roll surface. The black oxide layer acted as a barrier of thermal transfer between the rolls and melt, led to an increased gas gap and inhomogeneous solidification of cast strips, and, thus, played a role in forming both tortoise-shell—shaped depressions and microcracks on the strip surface. The installation of brush rolls behind the casting rolls was suggested as a method to prevent microcracks, because the brush rolls could continuously scrape off the black oxide layer affixed on the roll surface during strip casting.     

双辊连铸不锈钢薄带凝固组织特点

 通过金相观察分析了同径双辊薄带连铸机上生产的奥氏体不锈钢薄带的凝固组织,结果表明：铸带凝固组织包括2个柱状晶区和1个等轴晶区,其等轴晶呈近球形或蔷薇形。与传统连铸板坯相比,其柱状晶区一次及二次枝晶的间距较小,等轴晶粒内部为非枝晶结构,其尺寸大约是连铸坯等轴晶的1/10,凝固组织更致密。