减少方坯连铸脱方缺陷的途径

从生产管理及技术分析两方面对连铸方坯脱方缺陷进行攻关，并取得成功，使一炼钢方坯连铸脱方率降为０％。     

合金钢的方坯连铸技术

对合金钢的凝固特性，钢水的质量控制，以及合金刚方坯连铸的若干关键技术进行了论述，为现场合金钢方坯连铸提供了理论依据与操作指导。     

方坯高效连铸凝固冷却的研究

建立了适应方坯高效连铸特点的凝固冷却数学模型,应用所建立的模型进行模拟计算,获得了高效方坯连铸的二次冷却制度和铸坯温度场等的变化规律。研究所获得的结果,应用于重庆钢铁设计研究所设计的方坯高效连铸机上进行生产获得了较好的效果。     

20^#钢连铸大方坯缺陷的形成与预防

分析了20^#钢240方坯连铸坯缺陷形成的原因，探讨了防止产生缺陷的措施，指出，加强冶炼控制，强化脱氧；全程保护浇注；调整二冷区的冷却强度以及合理的匹配好注温和拉速，是提高大方坯合格率的重要因素。     

气水雾化喷嘴在方坯连铸机上的应用

介绍气水雾喷嘴在方坯连铸中应用特点以及四种气水雾化喷嘴的结构和性能，根据方坯连铸的要求，选择合适的雾化喷嘴。     

改善连铸重轨钢中心偏析的技术探讨

综述了重轨钢连铸方坯中心偏析的形成机理改善措施，分析了电磁搅拌，低过热浇铸以及适当的宽厚比和轻压下技术对消除或改善重轨钢连铸方坯中心偏析的作用和效果。指出组合式电磁搅拌和低过热度浇铸是改善重轨钢连铸方坯中心偏析的有效途径。     

合金钢方坯连铸概况介绍

统计分析了国外合金钢方坯连铸机的建设情况,说明:(1)合金钢方坯连铸在国际上已是一项完全成熟的技术,包括水平连铸机在内,已能成功地连铸所有的钢种。(2)采用弧形结晶器的弧形连铸机是目前浇注低合金钢和合金钢方坯的主要机型。概略叙述了合金钢方坯连铸的技术特徵。提出了在我国消化移植推广合金钢方坯连铸需要重点抓的几项工作。     

连铸方坯低倍组织及缺陷特性分析

通过酸蚀低倍试验和金相检验，对连铸方坯内部的低倍组织及缺陷的类型、宏微观特征以及形成原因进行了分析，并提出了控制这些缺陷的主要措施。     

方坯连铸高效化技术改造的经验与教训

介绍了唐钢二炼厂连铸机高效化技术改造情况，总结了技术改造的实际效果，分析了技术改造的不足及原因，以便为方坯连铸高效化改造提供借鉴。     

国外全弧形合金方坯连铸的现状与发展

全弧形连铸机是目前浇注合金风方坯主要机型。本文主要阐述国外全弧形合金多方坯 设备、连铸技术、质量控制等方面的现状与发展。为我国建设合金钢方坯连铸机和消化、移植引进的合金钢方坯连铸设备和技术提供了经验。     

铜合金空洞缺陷形变演化研究探讨*

铜加工材的铸坯内部常存在气孔、缩孔等空洞缺陷,在后续加工过程中,这些空洞缺陷常演变为内部裂纹或表面缺陷,导致成品率降低。在生产过程中,可借助变形和升温来消除铸坯内部的空洞缺陷。空洞的形变闭合是消除缺陷的先决条件,因此有必要开展铜合金中空洞缺陷的形变演化研究。本文对金属空洞缺陷形变演化的研究进展进行了梳理;基于对某锡磷青铜连铸板坯内部空洞缺陷及铸态组织的观察,重点讨论了现有研究成果对于铜合金的适用性,指出了材料微观结构对空洞缺陷形变演化的潜在影响;针对当前研究在几何建模方面的难点,采用Python语言设计了含任意椭球空洞的体元模型自动建模程序。     

连铸坯皮下气泡缺陷成因及控制

皮下气泡是连铸坯常见的质量缺陷,严重影响钢材的质量及使用性能。通过对国内部分钢厂生产的连铸坯皮下气泡的缺陷情况进行总结分析,发现一氧化碳气泡缺陷和氩气泡缺陷占很大比例。其次,总结概述了连铸坯皮下气泡缺陷的分布特点,气泡被捕获的机理以及不同类型气泡缺陷的形成原因,发现脱氧不良、水口吹氩工艺、电磁搅拌以及过热度等均会对皮下气泡缺陷造成影响。为降低铸坯皮下气泡缺陷产生的不良影响,提出了控制连铸坯皮下气泡缺陷的有效措施,以期为实际生产提供参考。     

The introduction and solvent of cold-rolling automobile sheet surface quality defects in BX Steel

The paper shows the main surface defects of cold rolling automobile sheet in BX Steel.The main surface defects are unusual defects.The typical familiar defects are sliver and punctuates that are on the rolling direction.The inclusions of steel-making and scales of hot rolling process are the main causes of defects.They are the biggest problems puzzle cold rolled automobile sheet surface quality,and are the burning issues of BX Steel.We classify and analysis the defects.We observe the panorama of surface defects using portable video microscopy apparatus,and clean the sample using ultrasonic shaker,analysis the defects pattern and chemical composition using scanning electron microscope.At present the primary defects that impacted cold rolled automobile sheet quality are dark sliver defects.We control the steel-making and hot rolling process aiming at the cause and position of defects making.We fine control the operating of steel ladle,gating,casting system and continuous casting machine in steelmaking process.The scale defect is reduced by controlling furnace,high pressure water descaling system and finish mill descaling in hot rolling process.Alone with the reforming and renewing of equipment,gathering producing experience,the cold rolled automobile sheet quality made in BX Steel is upgrading gradually.     

冷轧镀锌板典型表面质量缺陷成因及控制措施

采用SEM、EDS等试验手段,研究了冷轧镀锌板典型的表面质量缺陷形貌及缺陷部位元素分布特征。结果表明:油脂类物质残留可导致冷轧镀锌板表面漏镀缺陷,氧化铁颗粒压入引起表面黑点缺陷,机械划伤可造成表面线状缺陷,保护渣卷入致使镀锌板表面出现孔洞缺陷。阐述了镀锌板各类表面缺陷的形成机理,并提出了相应缺陷的控制处理措施。     

SUS304不锈钢点状缺陷对研磨性能的影响

通过市场调查和缺陷分析认为:影响酒钢研磨质量的主要缺陷是点状缺陷,点状缺陷分为两类,一类为设备原因造成的周期性缺陷;第二类为研磨抛光后出现的点状缺陷,通过SEM和晶相分析,缺陷不是晶间腐蚀和夹杂物引起。研磨抛光后出现的点状缺陷是热轧氧化铁皮结构与酸洗工艺的影响导致Rmax提高,较大的Rmax经过轧制,带钢表面凹凸点相互挤压覆盖使带钢表面平滑,在后续研磨中凸点挤压覆盖凹点处研磨脱落所产生。     

Using gated technetium-99m-sestamibi SPECT to characterize fixed myocardial defects as infarct or artifact

Perfusion-scan fixed defects may result from soft tissue attenuation, decreasing test specificity for coronary disease and myocardial infarction (MI). Gated 99mTc-sestamibi SPECT may help differentiate MI from artifact since fixed defects with decreased function (wall motion and thickening) probably represent MI, whereas attenuation artifacts either have normal function or at least do not demonstrate markedly reduced function. METHODS: Ungated resting and gated stress 99mTc-sestamibi SPECT was performed in 551 consecutive patients referred for evaluation of coronary disease. From resting and summed gated stress images, 180 patients (33%) were identified with isolated fixed defects. Function of the defects was assessed subjectively from gated stress images and results were correlated with clinical (history and/or ECG Q-waves) evidence of MI. RESULTS: Of 102 patients with fixed defects and clinical MI, 98 (96%) had abnormal defect function. Of 78 patients with no clinical MI, 18 (23%) had decreased function of the defect, possibly indicating silent MI. In 60 of the 78 patients (77%) with no clinical MI, defect function was normal. Because most (91%) of fixed defects with normal systolic function occurred in women with anterior fixed defects (48%) or men with inferior fixed defects (43%), these were most likely attenuation artifacts. By reclassifying patients with fixed defects and normal function as normal, patients with unexplained fixed defects (no clinical MI) decreased from 14% to 3%. CONCLUSION: Gating provides a valuable adjunct to 99mTc-sestamibi SPECT in characterizing fixed defects and potentially improving test specificity.     

铸坯及板卷典型质量缺陷成因与控制技术

热轧板卷的表面质量缺陷主要是夹杂类缺陷(夹杂、气泡和翘皮)及裂纹类缺陷(纵裂纹、横裂纹和星状裂纹)等,内部质量缺陷主要是带状组织和分层现象等,其中大多数缺陷与连铸坯的质量有关。为解决连铸板坯轧制板卷过程中产生的表面及内部质量问题,在综合分析现场生产环境和样品检测结果的基础上,系统研究了铸坯及板卷典型质量缺陷的产生原因或机理,并针对性地提出了相关缺陷的控制技术。     

冷轧薄板表面线状缺陷分析

某炼钢厂某批次的冷轧DC03薄板出现表面黑色线状缺陷,运用扫描电镜及能谱仪对缺陷部位表面和截面进行了观察分析,结果表明,表面可见大量大小不一的呈脆性特征的铁颗粒,而从截面上看,却发现这些铁颗粒心部包含有大量的FeO。因此推断,黑色线状缺陷是由于FeO压入后经轧制演变暴露于试样表面形成,而在后续退火工艺中块状FeO表层被环境氛围中的氢还原,心部则保留为原来的FeO,应该加强工艺控制来预防。     

Thrombolytic treatment of acute myocardial infarct. 3]

In a population of close to 2.5 million infants born from 1983 to 1993 registered in the California Birth Defects Monitoring Program, we compared the prevalence of structural birth defects among 2,894 infants with Down syndrome (DS) with that of infants without DS. Among 61 defects uniformly ascertained in affected and unaffected infants, 45 were significantly more common in DS, with atrioventricular canal (risk ratio = 1,009), duodenal atresia (risk ratio = 265), and annular pancreas (risk ratio = 430) being the most common. Most defects of blastogenesis and most midline defects were either nonsignificantly associated or not observed in infants with DS. Theories on the pathogenesis of defects in trisomies must account for the lack of and for the presence of specific defects.     

An unusual case of multiple mesosternal foramina

We present an unusual example of multiple mesosternal foramina (MMF). The alignment of the paired defects is unlike any previously described. Although single sternal defects are often encountered, paired defects are quite uncommon. This is the first documented example of bilateral paired defects in the sternum.