钛稳定不锈钢的冶炼与连铸（摘译）

生产汽车工业用钛稳定不锈钢材料损耗率较高。同时，由于易形成含钛的氧化物或氮化物，导致连铸水口结瘤或结晶器结鱼以及轧材表皮分层或线状缺陷而使连铸操作困难。本文对哥伦布不锈钢厂在炼钢、连铸过程中所遇到的问题进行了全面、系统的阐述，     

不锈钢冶炼工艺最新进展

本文对不锈钢冶炼工艺路线作了概述，重点对ＡＯＤ、川崎、奥特 的不锈钢冶炼工艺进行了描述，对选择工艺路线提出了想法。     

AOD冶炼不锈钢工艺模型的研究

以45t AOD-L冶炼304不锈钢的实际生产数据为依据,根据系统模化、质量、能量守恒及热力学原理,建立了AOD冶炼奥氏体不锈钢的工艺模型(AOD M&H),包含操作、化学反应、冶金计量和热化学计量4个层次,共涉及469个变量。使用该模型进行模拟,由139项输入变量,包括各物料的用量、成分和温度,可方便地求出39项输出变量,如钢液成分、温度等。应用结果表明,冶炼过程中各阶段的钢液碳含量与温度的预报值和实测值的相对误差≤11.1%。     

电渣熔铸低碳马氏体不锈钢内部质量研究

研究了电渣熔铸ZG06Cr13Ni4Mo后的凝固组织及不同位置的二次枝晶间距,以及电渣熔铸前后不同位置夹杂物的数量、尺寸、形貌、成分的变化规律.研究结果表明:电渣熔铸低碳马氏体不锈钢的组织致密均匀,无疏松、气孔等低倍缺陷.电渣熔铸低碳马氏体不锈钢的二次枝晶间距最大值为44.98μm,最小值为31.13μm,明显小于电极中的二次枝晶间距.电渣熔铸过程有利于减小二次枝晶间距,提高组织致密性与均匀性.电渣熔铸锭中夹杂物在面积百分比、最大当量直径和平均直径上均明显小于电极中的夹杂物,电渣熔铸去除夹杂物的效果明显.     

提高铁水质量满足不锈钢冶炼要求

为了达到转炉冶炼不锈钢对铁水质量的要求，采取了各种措施，降低生铁硅含量，同时，配合炉前脱硅工艺，取得了比较好的成绩。     

AOD冶炼16％Cr铁素体不锈钢洁净度的提高

通过工业热力学软件预测钢液中氧化物组成，证明了AOD处理工艺仅用硅脱氧而不用铝和钛也能控制钢液中夹杂物组成。     

30Cr13马氏体不锈钢连铸坯的实验研究

针对30Cr13马氏体不锈钢连铸坯质量情况,通过金相显微镜、扫描电镜、X射线衍射实验研究了铸坯的夹杂物分布及类型、金相组织、物相组成等.结果表明:铸坯均为细小柱状晶,无明显等轴晶区域,存在"白亮带"现象;铸坯中以5～10μm夹杂物为主,近表面、芯部存在15～20μm大颗粒夹杂;夹杂物为CaO-AL2 O3-SiO2-M...     

含氮不锈钢在AOD炉的冶炼

本文简介含氮不锈钢在ＡＯＤ炉的冶炼工艺。     

水电用马氏体不锈钢的冶炼工艺实践

通过生产数据分析与探讨,得出水电用马氏体不锈钢的冶炼主要有两大问题:VOD吹氧脱碳技术控制及  气体质量分数控制。分析结果表明:影响VOD吹氧脱碳技术的主要因素有吹氩流量、极限真空度、VOD吹氧脱碳  温度;气体质量分数主要通过控制钢液吸气及钢液去气两个方面。针对以上问题进行了VOD工艺技术的优化,提 高了VOD冶炼不锈钢铸件的一次脱碳成功率以及Cr合金回收率,同时使钢液气体质量分数控制到了较低水平,  降低了生产成本的同时提高了产品质量。     

M-EMS对马氏体不锈钢连铸坯质量的影响

根据工业试验结果,分析了结晶器电磁搅拌（M-EMS）对马氏体不锈钢连铸坯的中心疏松、等轴晶率、缩孔及表面质量的影响,并对电磁搅拌对铸坯凝固的影响机理进行了探讨。结果表明：经结晶器电磁搅拌后,当平均磁感应强度B为0．066T时,铸坯中心等轴晶率平均达到了50％,最高达57％,中心疏松均在1.5级以下,中心缩孔90％在1．0级内;铸坯表面质量由使用二冷区电磁搅拌的85％提高到97％,为结晶器电磁搅拌工艺参数的优化及设计提供了一定的依据。     

Strain induced martensite formation in stainless steel

The Conversion Electron and X-ray M?ssbauer studies of the surface of Type 316 stainless steel at 400 K, 300 K, and 100 K show that both the substitutional and interstitial elements perturb the cubic symmetry at the iron site. The single peak of austenite is a superposition of at least five quadrupole split doublets whose magnitudes and intensities depend on the type and concentration of the impurity elements. However, when the surface of the stainless steel is plastically deformed, a layer of martensite about 5000 ? thick is formed on the austenite base. This layer consists of a mixture of 31 pct martensite with the rest being the original austenite. The magnetic environment of the iron in this martensite is controlled by the concentration of alloying elements, and the distribution of the hyperfine fields is determined by the number of nearest and next nearest neighbor impurity atoms. The magnetic field decreases linearly at first as the number of nearest neighbors increases and then follows a nonlinear trend for a number of nearest neighbors. The temperature dependence of the sublattice magnetization is different for each number of neighbors, and a Curie temperature has been estimated for each site.     

The martensite phases in 304 stainless steel

A detailed analysis of martensite transformations in 18/8 (304) stainless steel, utilizing transmission electron microscopy and diffraction in conjunction with X-ray and magnetization techniques, has established that the sequence of transformation is γ → ∈ → α. ε is a thermodynamically stable hcp phase whose formation is greatly enhanced as a result of plastic deformation. Comparison with the ε → α transformation in pure Fe-Mn alloys lends further support to the above sequence and suggests that a transformation line between ε and α in Fe-Cr-Ni alloys can be expected. In the 304 stainless steel used in this investigation, formation of α was induced only by plastic deformation and subsequent to formation of ε. Nucleation of α occurs heterogeneously at intersections of ε bands or where ε bands abut twin or grain boundaries (which represent unilaterally compressed regions). From electron diffraction, the Nishiyama relationship between γ and α phases appears to predominate at the start of the transformation, but then changes to that of Kurdjumov-Sachs. Based on these observations, a sequence of atom movements from the hcp structure to the bcc structure is proposed which has the basic geometric features of the martensitic transformation. Formerly with Department of Materials Science and Engineering, University of California, Berkeley, Calif.     

Strain induced martensite formation in stainless steel

The Conversion Electron and X-ray Mössbauer studies of the surface of Type 316 stainless steel at 400 K, 300 K, and 100 K show that both the substitutional and interstitial elements perturb the cubic symmetry at the iron site. The single peak of austenite is a superposition of at least five quadrupole split doublets whose magnitudes and intensities depend on the type and concentration of the impurity elements. However, when the surface of the stainless steel is plastically deformed, a layer of martensite about 5000 Å thick is formed on the austenite base. This layer consists of a mixture of 31 pct martensite with the rest being the original austenite. The magnetic environment of the iron in this martensite is controlled by the concentration of alloying elements, and the distribution of the hyperfine fields is determined by the number of nearest and next nearest neighbor impurity atoms. The magnetic field decreases linearly at first as the number of nearest neighbors increases and then follows a nonlinear trend for a number of nearest neighbors. The temperature dependence of the sublattice magnetization is different for each number of neighbors, and a Curie temperature has been estimated for each site.     

In situ observations of the formation of martensite in stainless steel

Specimens of stainless steel have been deformed at room temperature, or cooled to below M_s in an HVEM and the formation of martensite observed. The M_s temperature, orientation relationships and habit planes of the martensites formed in specimens thicker than 0.5 μm were found to be identical to those of the bulk material. It has been shown that the ϵ-martensite occurs in regions where appropriately, but usually irregularly, spaced stacking faults are formed, while α-martensite nucleation is associated with dislocation pile-ups on the active slip plane.     

Ferromagnetic properties of deformation-induced martensite transformation in AISI 304 stainless steel

Ferromagnetic properties of plastically deformed AISI 304ss have been studied using magnetic hysteresis and Barkhausen emissions methods. The present study has been concentrated on low volume fraction of martensite, i.e., below 58 pct, as compared to the available literature for a higher percentage of martensite. In measured materials, the coercivity increased with deformation and had a tendency to go toward saturation value. A linear increase in remanence with the deformation was observed. A large number of small amplitude of Barkhausen emissions were found at low percentage of martensite, indicating that magnetization rotation took place within a small region. However, large amplitude Barkhausen emissions were observed with the increase of deformations. Angular variation of Barkhausen emissions indicated the formation of rolling texture within the materials. A model has been proposed to explain the results. At the initial stage, small martensite clusters are formed, which grow with the deformation, and the intracluster exchange interaction becomes predominant. With the increase of deformation, martensite volume fraction increases. In this process, existing clusters grow and new clusters are formed. As a result, martensite clusters come closer and intercluster exchange interaction becomes important.     

不锈钢冷轧污泥配矿压球工艺及冶金性能研究

冷轧污泥成分复杂、产量大、危害严重,已成为不锈钢企业环保治理的难点,国内外尚无妥善安全又经济实用的利用途径.针对不锈钢冷轧污泥的特点,进行了配矿压球、高温焙烧的正交试验,考察了污泥球团的主要冶金性能.结果表明,污泥掺量30％时,球团抗压强度、化学成分和主要冶金性能满足高炉要求;按照10％进行配料,对高炉顺行无影响,是一条工艺简单、技术可行的无害化处理途径.     

Study on metallurgical properties and pellet proportioning technology of stainless steel cold-rolling sludge

With a complicated composition,large production and serious damage to the environment,stainless steel cold- rolling sludge has been a focal point concerning environmental protection for stainless steel enterprises. Up to now , neither at home nor abroad have any technologies come into being that are not only proper,safe and economical but also suitable for bulk utilization of stainless steel cold-rolling sludge. Based on the characteristics of the stainless steel cold- rolling sludge,orthogonal experiments were carried out on pellet proportioning and high-temperature roasting,and major metallurgical properties of sludge pellets were also tested. As the results show ,pellets with 30% addition of cold-rolling sludge are qualified regarding their compressive strength,chemical composition and major metallurgical properties. No adverse impact happens to the blast furnace operation when sludge pellets account for 10% of the blast furnace raw materials. Therefore,the technical route applied in this paper is proved simple,feasible and environmentally friendly for cold-rolling sludge treatment.