7#铸机大方坯断面生产重轨钢铸坯质量评价

文章通过对7#铸机设备改造后生产的大方坯断面重轨钢坯内外部质量对比,分析了结晶器电磁搅拌、动态二冷配水、动态轻压下对铸坯的中心碳偏析指数、疏松及铸坯凝固组织的影响,得出7#铸机两个大方坯断面重轨钢在合理拉速、过热度匹配下,采用结晶器电磁搅拌+轻压下工艺后,铸坯内部质量良好,不仅使铸坯等轴晶比率为52.3%~58.3%,也可使铸坯中心碳偏析指数控制在1.07以下。     

Φ270 mm圆坯末端电磁搅拌工艺的研究

试验分析了不同凝固末端电磁搅拌(F-EMS)参数对Φ270 mm断面铸坯中心等轴晶比率和碳偏析指数等的影响。结果表明,连铸中碳钢时,末端电磁搅拌参数采用300 A/10Hz,可使铸坯中心等轴晶率达到35%以上,铸坯中心碳偏析指数小于1.05。     

Φ210mm断面末端电磁搅拌的应用研究

文章主要介绍了凝固末端电磁搅拌技术在包钢圆坯连铸机上的应用情况。结果表明,当铸坯断面为Ф210mm,钢种为中碳钢时,末端电磁搅拌参数采用250 A/11 Hz,可使铸坯中心等轴晶率达到30%以上,铸坯中心碳偏析指数小于1.10。     

末端电磁搅拌对 Φ390 mm铸坯内部质量的影响研究

文章主要介绍了凝固末端电磁搅拌技术在包钢圆坯连铸机上的应用情况。结果表明,当铸坯断面为Φ390 mm,钢种为中碳钢,最优末端电磁搅拌参数为450 A/8 Hz,采用优化的末端电磁搅拌参数降低了铸坯的中心碳偏析指数,增加了铸坯的等轴晶率,从而提高了连铸坯的内部质量。     

320 mm×410 mm断面重轨钢连铸坯宏观偏析控制关键技术

为控制大断面生产重轨钢连铸坯碳偏析指数和中心偏析,开展了电磁搅拌、提高轻压下总量、过热度与拉速匹配技术研究,形成了攀钢320 mm×410 mm大方坯连铸重轨钢偏析控制关键技术。确定了该断面生产重轨钢的最佳连铸工艺参数为:结晶器电搅电流强度600 A、2.4 Hz,凝固末端电搅电流强度330 A、7 Hz,轻压下总压下量9~12 mm,过热度控制在20~35℃、拉速控制在0.70~0.72 m/min。生产的重轨钢连铸坯中心等轴晶率平均为41.2%,连铸坯中心偏析≤0.5级的比例达到85%,断面碳偏析指数控制在0.95~1.07,连铸坯质量较好,生产的钢轨质量满足标准要求。     

高速轨用钢连铸坯内部质量控制的关键技术

简述了攀钢提高350 km/h高速轨用钢连铸坯内部质量的控制技术,包括大方坯连铸结晶器电磁搅拌技术、二冷控制技术和凝固末端动态轻压下技术及其在重轨钢连铸中的应用效果.近3年的生产实践表明,课题研究解决了重轨钢连铸大方坯中心疏松、中心偏析、中心裂纹等内部缺陷较严重的技术难题,重轨钢连铸坯内部质量优异,铸坯收得率达到98.55%,铸坯合格率达到99.97%,铸坯中心疏松≤1.0级,中心偏析≤1.0级,中心缩孔≤1.0级,中心裂纹≤0.5级,中间裂纹≤0.5级,中心碳偏析指数≤1.05,为攀钢开发生产350 km/h高速铁路用钢轨提供了合格铸坯.     

电磁搅拌对重轨钢凝固组织及均质性的影响

为提升重轨钢均质性和致密性,通过试验对比分析连铸电磁搅拌对大方坯重轨钢凝固组织及均质性的影响.结果表明:无电磁搅拌工艺条件下,铸坯凝固组织无明显分区,枝晶组织致密且铸坯窄面至距离窄面80 mm区域的均质性较好,但铸坯中心偏析严重;通过取消结晶器电磁搅拌(M-EMS)并采用凝固末端电磁搅拌(F-EMS)有利于重轨钢均质性...     

320 mm×410 mm大方坯连铸重轨钢质量改进与应用

为了提高大断面重轨钢连铸坯内部质量,满足钢轨探伤要求,针对大断面生产重轨钢铸坯宏观偏析及中心疏松较难控制的难点,采用合适的二冷制度、凝固末端电磁搅拌技术、动态轻压下控制技术、钢水过热度控制以及拉速控制等技术措施,开发了攀钢320 mm×410 mm大方坯连铸重轨钢生产工艺。生产的大方坯重轨钢连铸坯中心等轴晶率稳定控制在40%以上,中心疏松控制在不大于0.5的比例为91%以上,中心偏析在0.5级的比例为87%以上,等柱晶率不小于40%的比例为100%,碳偏析指数控制在0.95~1.07,铸坯及钢轨质量较好,满足了标准要求并通过了CRCC认证。     

大方坯连铸关键装备技术应用研究

简述了攀钢大方坯连铸结晶器电磁搅拌技术、二冷控制技术和凝固末端动态轻压下技术在重轨钢连铸中的应用效果。生产统计表明,铸坯表面无清理率达到100％,中心疏松≤1．0级,中心偏析≤1．0级,中心缩孔≤0．5级,中心碳偏析指数≤1．05,等轴晶率≥38％,为攀钢生产高速铁路用钢轨提供了合格铸坯。     

结晶器电磁搅拌对轴承钢大方坯碳偏析的影响

针对南钢大方坯连铸机轴承钢连铸电磁搅拌冶金效果不明显的问题,开展了优化轴承钢连铸结晶器电磁搅拌工艺参数的试验,对不同电磁搅拌参数及搅拌方式下铸坯和轧材碳偏析进行了研究。结果表明:大方坯心部和边部均为负偏析,1/4处为正偏析,320 mm×480 mm大方坯碳偏析指数基本在0.87～1.05,轧材碳偏析指数基本在0.94～1.03;正反交替的电磁搅拌有利于降低碳偏析,电磁搅拌的电流参数较大时,心部的负偏析较严重,随着搅拌电流的增大,产生的白亮带向铸坯中心移动并且白亮带宽度增大;轴承钢铸坯中的碳偏析会遗传到轧材上。     

高速铁路用钢轨生产技术

采用铌稀土(BNbRE)钢种,进行了钢的高纯净度、无缺陷连铸坯、高精度轧制、在线检验及相关技术研究,形成高级别钢轨生产工艺.结果表明:生产的钢轨能够满足<时速200公里客运专线60 kg/m钢轨暂行技术条件>的技术指标.     

关于高职教育终身化理念的思考

为了发挥高职院校在终身教育、终身学习、学习化社会的建设中的积极作用.对终身教育及高职教育终身化的理念进行了论述,提出了高职教育终身化的原则和构建终身教育及终身学习的体系.     

Guidelines for clinical use of drugs for involutional osteoporosis

Guidelines for clinical use of drugs for involutional osteoporosis will be released soon in Japan. Seven different types of drugs for osteoporosis are in market for clinical use in Japan. Those includes calcium, estrogens, anabolic steroids, calcitonins, active vitamin D3, ipriflavon, and etidronate. The guidelines recommend to clarify the risk factors in each patient before to start administration of drug. Patients with osteopenia are basically recommended to be followed without any drug treatment, but, patients with osteoporosis are generally recommended to be treated with drug after evaluation of risk factors. After menopause, inhibitors of bone resorption would be recommended as a first choice drug. For monitoring effects of treatment, bone mass measurement is so far the first choice, but bone metabolic markers would be used as well.     

Criteria for selection of patients for emergency portacaval shunt

A computer program analysis of the effect on survival of 74 preoperative factors was performed as part of a prosepctive study of the emergency portacaval shunt in 146 unselected patients with bleeding esophageal varices due to alcoholic cirrhosis. Only ascites, a serum glutamic oxalacetic transaminase level of 100 units or more, and a requirement for 5,000 ml or more of blood transfusion were associated with a statistically significant decrease in survival. However, none of these factors are contraindications to operation because their presence permits a survival rate of 37 to 40%. The only contraindication to emergency portacaval shunt is the combined presence of ascites, jaundice, encephalopathy, and severe muscle wasting, a constellation that was incompatible with survival beyond one year.     

The use of dimethylsulfoxide for fixation of yeasts for electron microscopy

Increasing numbers of young women with ovarian failure and women of advanced reproductive age (> 40 yrs) utilize oocyte donation to treat their infertility. In both groups, women who become pregnant frequently experience multiple gestation, occurring in up to 30% of pregnancies. Advanced maternal age and high-order multiple gestations are associated with an increased risk for obstetric complications. We reviewed the pregnancies of patients with high-order multiple gestations (> or = 3 gestational sacs) with respect to their antepartum course and neonatal outcomes. Mothers were divided into two groups according to age at conception; Group I (> or = 40 yr, n = 20) and Group II (< 40 yr, n = 10). These 30 high-order multiple gestations were found among 127 successful oocyte donation cycles (23.6% of all pregnant patients). Data regarding pregnancy outcomes were gained by chart review and telephone interview. Results demonstrated spontaneous reductions in the number of implantation sites were similar between groups (Group I: 21.4% vs. Group II: 17.6%). Multifetal pregnancy reduction (MFPR) was more often chosen by older women (Group I: 45% vs. Group II: 10%; P < 0.05). Antenatal complications were commonly experienced by both groups (> 80%) as were operative deliveries (> 85%). However, neonatal outcomes were generally good, with only one death occurring in the 79 delivered infants (1.3%). We conclude transferring supernumerary embryos to women undergoing ovum donation places patients at great risk for high-order multiple gestations. These pregnancies are associated with increased antenatal and neonatal complications. Although advanced maternal age is normally an added risk factor, well-screened older patients carrying high-order multiple gestations experienced similar outcomes as younger mothers.     

介绍一种生产冲挤用铝合金坯料的新工艺

哈兹列特铝板带连铸连轧工艺已被成功地用于铝和铝合金冲击挤压用坯料的生产。在对哈氏四个有关用户扫描的基础上，列举了其产品及其用途，并介绍了相关工艺及其优点。     

重轨孔型设计软件的编制

随着计算机在轧钢领域的广泛应用，重轨孔型设计利用计算机技术是今后发展的必然趋势，结合鞍钢大型厂的实际情况，编制了重轨孔型设计软件，应用该软件后，明显地提高了设计工作效率，加快了新产品的开发速度。介绍了该软件的编制方法、系统的功能及程序结构。