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连铸大方坯动态轻压下冶金效果分析 总被引:1,自引:0,他引:1
动态轻压下技术是减轻铸坯的中心偏析与疏松缺陷、提升铸坯内部质量的有效途径.包钢新建的5号大方坯铸机的动态轻压下控制系统由北京科技大学与包钢合作设计和开发,能够在非稳态的浇注条件下进行有效的动态轻压下和动态二冷配水实时控制.针对重轨钢U71Mn、U75V等代表性钢种,在5号连铸机上进行了动态轻压下冶金效果热负荷试验.经过合理地制定试验方案、取样设计以及冶金效果分析,结果表明,采用动态轻压下工艺后,铸坯中心疏松明显减轻,中心区域等轴晶率增加,连铸坯横断面上C成分分布更加均匀,中心C偏析指数波动范围明显变窄,有效减轻了铸坯的中心偏析缺陷,铸坯内质得到明显提升. 相似文献
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应用动态轻压下改善板坯内部质量的实践 总被引:2,自引:0,他引:2
介绍了动态轻压下装置与相应的产品质量情况,分析了该工艺的优缺点。根据对动态轻压下连铸坯的低倍硫印试验结果,分析了钢液成分、轻压下量、拉速等因素对铸坯偏析等内部质量的影响。 相似文献
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简述了攀钢自主开发的360 mm×450 mm大方坯连铸集成技术及其效果.通过研究开发合理的连铸二冷技术、凝固末端动态轻压下技术和结晶器电磁搅拌技术,提高了铸坯内部质量,解决了大方坯中心疏松、中心偏析、内部裂纹等内部缺陷较严重的技术难题;通过研究设计合理的结晶器结构和冷却工艺制度,以及开发性能优良的连铸保护渣,提高了铸坯表面质量,减轻了大方坯表面凹槽和凹坑缺陷.两年多的生产实践表明,攀钢360 mm×450 mm大方坯连铸机生产的铸坯,中心疏松、偏析、缩孔、裂纹等内部缺陷的评判级别均小于1.0级的综合比例达到99.03%,中心碳偏析指数为1.01~1.05(平均1.03),铸坯表面无缺陷率平均达到99.54%.研究成果为促进攀钢品种结构调整和开发高质量、高性能、高附加值产品提供了重要的技术支撑. 相似文献
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通过连铸坯低倍腐蚀评估铸坯中心偏析、中心疏松等铸坯内部缺陷,反馈铸坯内部质量。从铸机辊缝、动态轻压下、喷嘴、钢水过热度、化学成分等方面研究铸坯内部质量的影响因素和控制措施。工艺优化后连铸低倍合格率上升8.17个百分点,提高了1#连铸机的内部质量。 相似文献
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Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies. 相似文献
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鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美". 相似文献
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针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。 相似文献
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K Ohta M Nishi M Ueda S Ohyama T Matsubara T Takahashi T Nakajima 《Canadian Metallurgical Quarterly》1998,99(9):589-594
Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients. 相似文献
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通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。 相似文献
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A Dragni? 《Canadian Metallurgical Quarterly》1977,24(2):167-175
In this paper is treated the fundamental problematic of the fracture of the diaphysis of the tibia and the therapeutic results after the conservative and operative treatment are confronted. Among 518 patients with 433 open fractures and 35 with closed fractures of the diaphysis of the tibia, successful treatment of more 2/3 was obtained in the period from 1968 to 1972. Following our casuistics and literature, whose results are similar, we find out that the average total treatment of the osteosynthesis of the fracture of the diaphysis was shortened for 2,5 months depending upon the type and the localisation of the fracture. Apolied methods of the operative and conservative and conservative treatment in relation to the velocity of the medical cure as well as to the extreme anatomical-functional results are analised. We noticed that osteosynthesis, made by the intermedullary nail and the extension of the canals or by a small AO table, by the achieved stability makes conditions of immediate motions and an early rehabilitation. Because of that it gives the best functional results. 相似文献