低碳铝镇静钢铸坯长度方向上T.O和夹杂物的分布规律研究

研究了"转炉-RH-双流板坯连铸"工艺生产的SPHD低碳铝镇静钢铸坯火焰清理前后沿长度方向上的全氧含量及夹杂物数量、尺寸的变化规律。结果表明:随着拉坯长度的增加,铸坯T.O含量逐渐降低,坯头T.O含量比坯尾的高15ppm-20 ppm。同时,夹杂物数量密度和面积率减小。未经火焰清理的铸坯存在尺寸100μm以上的大型夹杂物。火焰清理后,铸坯中40μm以上的夹杂物显著减少,未见100μm以上的夹杂物。     

LD-BAr-CC工艺生产低碳铝镇静钢纯净度研究

研究武汉钢铁股份有限公司炼钢总厂四分厂LD-BAr-CC工艺条件下生产的低碳铝镇静钢的纯净度,分析各工艺阶段钢中显微夹杂、大型夹杂以及全氧、氮含量的变化情况。结果表明,在该厂现行工艺条件下,采用吹氩工艺可明显降低钢中夹杂物含量和全氧含量,全氧含量从精炼前的109.30×10-6降至30.75×10-6。各工序中钢的显微夹杂物主要为Al2O3和SiO2,这是脱氧产物和钢液二次氧化产物在钢中的残留物;大型夹杂物主要是Al2O3、SiO2以及硅铝酸盐等复合夹杂,与浮渣的卷入有很大关系。     

抗酸压力容器钢SA516Gr60连铸坯质量研究

对抗酸压力容器钢SA516Gr60连铸工艺参数进行优化,并采用化学成分分析、金相显微镜、SEM观察及EDS分析研究了铸坯厚度方向化学成分、微观组织、二次枝晶臂间距和夹杂物形态、尺寸、数量的变化规律.研究表明:通过对连铸工艺的优化,SA516Gr60铸坯成分偏析在允许范围之内,二次枝晶臂间距较小,铸坯质量较好.夹杂物80%以上都是Al-Mg-Ca-S-O系复相夹杂物,尺寸较小呈球形,表面平滑致密,不易萌生裂纹.提高压力容器钢铸坯的质量,减轻偏析和控制夹杂物水平,有助于提高钢板抗HIC性能.     

连铸工艺对冷轧镀锌板表面缺陷的影响

分析马钢CSP冷轧镀锌板的表面缺陷,得出镀锌板中夹杂物主要成份为氧化钙、氧化硅、氧化镁及硅酸钙等,来源于脱氧产物、卷渣、二次氧化和耐火材料。调整精炼吹氩强度、加强连铸保护浇注、改进保护渣成份等,可以改善冷轧镀锌板表面质量,表面缺陷废品率下降到2．59％。     

DDQ钢连铸坯洁净度

采用金相观测、扫描电镜、电子探针等方法,研究了某钢厂DDQ钢连铸坯的洁净度,对铸坯中夹杂物的数量、粒径、分布、形貌及组成等进行了讨论。研究结果表明,该DDQ钢连铸坯中w（O）〈14×10-6、w（N）=18×10-6,P、S含量低,没有进行钙处理及真空处理;夹杂物大部分在4μm以下,数量少且分布均匀;夹杂物纯Al2O3居多,有MnS夹杂及以Al2O3为中心的外面是MnS的复合夹杂     

开发应用钢包渣还原处理技术提高钢的纯净度

通过对钢水二次氧化的分析,揭示了钢包渣对钢水二次氧化的主要作用.钢包渣还原处理技术的开发及应用,为降低钢水氧含量、降低板坯夹杂物进而提高产品质量起到了重要作用,同时促进了钢水进一步脱硫.     

304奥氏体不锈钢铸锭中非金属夹杂物研究

研究304不锈钢铸锭中非金属夹杂物的类型和数量,通过示踪剂分析不锈钢中夹杂物的来源.结果表明:不锈钢铸锭中显微夹杂物主要是以Al2O3-SiO2-CaO系硅酸盐夹杂为主,粒度＜5μm的显微夹杂物中同时存在大量的镁铝尖晶石夹杂;大型夹杂物主要有两类复合夹杂物Al2O3-SiO2-CaO系夹杂、Al2O3-SiO2系夹杂;...     

提高高铝钢可浇性工艺技术研究

为了提高高铝钢可浇性,在转炉出钢及LF精炼过程对钢包渣进行改质处理,连铸采用专用高铝钢保护渣,中间包采用塞棒吹氩＋密封圈等水口防堵工艺。工艺试验结果表明,夹杂物组成可控制在12CaO·7Al2O3、3CaO·Al2O3低熔点组成区域,浇铸时长为4.5~6h时,液面状况正常,无结团,渣条较少且无硬渣条,铸坯表面质量优良,连续浇铸炉数不低于6炉。     

304不锈钢连铸坯中的非金属夹杂物数量分布

为研究304不锈钢连铸坯中夹杂物的数量分布,用金相检验法对铸坯中的夹杂物数量进行了统计分析.结果显示,铸坯中由外向内非金属夹杂物数量增加.304不锈钢铸坯表层中绝大多数5μm以上夹杂物为球状或近似球状的硅酸盐夹杂物.但随着凝固的进行,在铸坯内部会新生大量氧化铝、镁铝尖晶石、氮化物等点状夹杂物和不规则夹杂物.铸坯心部10μm以上的大颗粒夹杂物数量较多.     

410S铁素体不锈钢连铸板坯中非金属夹杂物的分布和类型

本文用金相检验法对410 S不锈钢连铸板坯中的非金属夹杂物数量进行统计分析,研究了夹杂物的数量分布,并用扫描电镜对夹杂物成分进行研究.试验结果表明:410 S连铸板坯中夹杂物尺寸以0～10μm为主;距边部1/4位置处和中部从铸坯表层至心部非金属夹杂物数量有少量增加,沿厚度方向相同位置上夹杂物相比,中部夹杂物数量明显增加;在连铸坯表层宽度方向边部和1/4位置处各尺寸范围内的夹杂物数量差别甚小;连铸板坯中非金属夹杂物都呈现为球状,类型为CaO-SiO2-Al2O3-MgO-MnO.     

Influence of flow control devices on metallurgical effects in a large—capacity tundish

The influence of flow control devices on metallurgical effects in large-capacity tundish has been studied carefully with elements tracing,sampling and theoretical prospecting,The results from the studies are(1) in the continuous casting of clean steel,bad control of tundish operation may deteriorate the cleanliness of steel;(2) the cleanliness of steel is deteriorated mainly at the unstady state;(3) large amount of macro inclusions come from the top slag and the refractory of tundish;(4) installing dam and weir can improve the cleanliness of steel and lighten the influence of steel fluctuation;and (5) the result of theoretical calculation suggests that the inclusions larger than the critical size of 92.6um can be floated out from the tundish bath completely.     

Behavior of Non-metallic Inclusions in Centrifugal Induction Electroslag Castings

In order to know the behavior of non-metallic inclusions in centrifugal induction electroslag castings (CIESC), non-metallic inclusions in 5CrMnMo and 4Cr5MoSiV1 were qualitatively and quantitatively analyzed. The largest size of inclusions in the casting and the thermodynamic possibility of TiN precipitation in steel were also calculated. The results show that sulfide inclusions are evenly distributed and the content is low. The amount of oxide inclusions in CIESC 4Cr5MoSiV1 steel is close to the ESR steel and lower than that in the EAF steel, and there are some differences along radial direction. Nitride inclusions are fine and the diameter of the largest one is 3-4 μm. With the increase of the centrifugal machine's rotational speed, the ratio of round inclusions increases and the ratio of sharp inclusions decreases. According to the experiment and the calculation results, it is pointed out that the largest diameter of non-metallic inclusions in the CIESC 4Cr5MoSiV1 casting is only 6.6 μm, and [N%][Ti%] in 4Cr5MoSiV1 steel should be controlled less than 4.4× 10-5 in order to further reduce the amount and size of TiN inclusions.     

Metallurgical quality of CSP thin slabs

The casting structure, chemical composition segregation, dendrite arm space, inclusiona and during the CSP (compact strip production) rolling process were investigated. The results show that the CSP thin slab has a feature of uniform fine grains, more columnar crystals, less central porosity and segregation etc. There is no great difference in macrostructure between the CSP thin slab and conventional slab; however, the fine dendrite structure of the CSP slab is more uniform. Moreover, the central porosity and segregation are obviously improved after the first pass; and the dendrite is bent along the rolling direction rather than broken into pieces.Small inclusions with the diameter less than 10 p.m in the CSP slab are dominantly consisted of aluminates formed by A1 deoxidation and Ca treatment and not floating out of the melt. The large size inclusions found in the continuous casting slab are very few.     

连铸结晶器内钢液流场的数值模拟

采用商业软件,针对连铸机结晶器的结构和工艺参数,进行了流动过程的三维数值模拟,分析了浸入式水口的浸入深度、水口侧孔倾角和拉速对结晶器内钢液流动的影响.结果表明,合适的浸入深度、水口侧孔倾角和拉速有利于夹杂物的上浮,减小液面波动.     

结晶器内钢液流速对IF钢宽板坯表层夹杂物分布的影响

对BOF-RH—CC生产Ti-IF钢宽板坯的表层夹杂物进行研究。采用非水溶液电解法从钢中分离夹杂物,并用SEM／EDS分别对其形貌和成分进行检测,获得典型夹杂物的分布规律。通过测定钢坯不同部位的枝晶偏角,计算结晶器中钢液的流速,并用软件进行模拟比较。结果表明,实际最大流速为模拟结果的1．93倍,边缘部位钢液流速与模拟的结果基本符合;随着钢液流速的下降,铸坯表层夹杂物平均直径增大了9．5％。     

Study on Oxygen Content, Inclusions and Fatigue Properties of Bearing Steels Produced by Different Processes

The metallurgical properties and fatigue life of bearing steel processed by electric furnace (EAF), ladle refining (LF-VD), continuous casting (CC) and electroslag remelting (ESR) have been investigated. The main results obtained are as follows: (1) Due to low oxygen content and dispersion inclusions in steel, the fatigue life of LF-VD-IC or CC is three times as high as that of EAF steel; (2) The oxygen content in steel produced by CC process is about 9.0× 10-6, the carbon segregation (C/C0) is from 0.92 to 1. 10 and the fatigue life of CC steel is equal to that of ladle refining ingot casting steel; (3) Although the amount of inclusion and oxygen in ESR steel is higher than that of LF-VD-IC or CC steel, the fatigue life of ESR steel is higher than that of the latter because of its fine and well dispersed inclusions.     

Numerical simulation of flow phenomena and optimum operation of tundish

1　INTRODUCTIONDuringthecourseofcontinuouscastingsteel,theflowofliquidsteelintundishwasafairlycomplexprocesscontainingmomentumtransfer,masstransfer,energytransferandphase changeofmultiphasecomponents .Ac cordingtoRefs.[1,2 ],someinfluencingfactorsincastingsteelwerefound ,includingthecompositionofliquidsteel,thetechnicalparametersoftundishandre oxidationofmoltenmetal.Theprocesswouldaffectdirectlysurfacedefectsandinternalstructureformationofthecastingsteelproductsaswellastherealizationofhig…     

不锈钢板坯连铸温度场及凝固末端位置的研究

采用有限元法计算了不锈钢板坯在连铸时凝固过程中温度场及坯壳的生长随时间的变化，讨论了过热度，拉速及二冷配水量对温度场及凝固末端位置的影响。结果表明，影响铸坯温度场和凝固末端位置的主要因素是拉速和二冷配水，而过热度影响较小。