液芯大压下对薄板坯低倍组织的影响

通过在马钢股份有限公司CSP连铸连轧生产线上进行了液芯大压下的工业性试验,研究了最大液芯压下量从原设计的20 mm增加到35 mm时对低碳钢、中碳钢和硅钢低倍组织的影响.研究结果表明:在试验研究的范围内,压下量对铸坯内裂纹和三角区裂纹没有明显影响;液芯大压下能够改善铸坯中心偏析,随着压下量的增加,中心偏析程度降低,对中碳钢Q235B和硅钢MGW1300效果更明显.     

薄板坯连铸连轧液芯压下工艺研究

针对薄板坯连铸工艺中的关键技术液芯压下特点,选取沿柱状晶方向的铸态钢试样分别在不同温度和应变速率下进行热压缩模拟试验,为液芯压下结构提供材料高温流变应力模型。通过建立液芯压下过程数值模型,研究和分析液芯压下工艺中铸坯变形特征和凝固坯壳的应力应变分布规律,以及液芯形态变化情况。为了找到薄板坯连铸液芯压下工艺的最佳工艺参数组合,对坯壳厚度、压下量和辊间距三个参数进行优化设计。通过建立响应面来构造液芯压下近似模型,描述各工艺参数与液芯压下结果之间的关系。在近似的模型的基础上,利用遗传算法,通过全局最优优化算法寻找出构造近似模型的最优解,从而得到板坯液芯压下最佳工艺参数组合,并进行了压下试验。     

CSP连铸液芯压下技术改造与实践

通过对马钢CSP连铸液芯压下技术改造及其实践的试验研究,分析了增加液芯压下量对铸坯形状、铸坯内部质量及其轧制工序的影响,得出了在马钢CSP连铸现有装备条件下,将液芯压下量从原设计的20 mm增加到35 mm是可行的,压下率达到了38.8％.该技术成功开发不仅增加了生产的灵活性,也获得了良好的冶金效果.     

薄板坯液芯压下方式的探讨

结合河钢唐钢薄板坯连铸生产实践,阐述了动态和静态两种液芯压下方式在实际生产中的应用,分析了其对铸坯质量、扇形段寿命、液位波动的影响。研究表明,动态液芯压下有利于改善铸坯内部疏松和偏析,但是对设备、控制和工艺条件要求比较苛刻;静态压下在铸坯内部质量改善方面不如动态压下,但是对设备、控制和工艺条件要求比较简单,实际使用效果好于动态压下。     

液芯压下过程中压下量分配对铸坯变形的影响

为了优化液芯压下工艺参数,达到改善铸坯中心处偏析和疏松的目的。基于有限元法,以结晶器出口处薄板坯横截面的温度为初始条件,利用Marc软件模拟计算了薄板坯三维热-力耦合模型带液芯压下过程,分析了压下量分配对铸坯各节点应力和应变的影响。研究结果表明,总压下量相同时,均匀的压下量有利于降低铸坯表面的应力,而局部大压下更有利于改善铸坯的中心质量。     

板坯连铸带液芯轻压下过程的力学分析

利用热力学耦合模型对板坯连铸带液芯轻压下过程的铸坯变形抗力、拉坯阻力及其变化特性进行了理论计算.分析比较了不同轻压下和连铸过程工艺参数的影响.结果表明压下量、压下速率、拉坯速度及坯壳温度对铸坯变形抗力和拉坯阻力均有很大影响.计算结果为实际板坯连铸带液芯轻压下工艺设计提供了依据.     

热芯大压下轧制连铸坯再加热时的组织遗传性

 热芯大压下轧制工艺在改善连铸坯内部缩孔、疏松缺陷的同时,可以破碎粗大的铸态组织,并通过影响再加热奥氏体化后的组织来影响最终产品的组织和性能。为了研究热芯大压下轧制后的铸坯再加热过程的组织演变,选用微合金钢和中碳钢2种具有代表性的钢种为研究对象,采用炼钢-连铸-轧制一体化试验,研究了热芯大压下轧制对连铸坯显微组织及再加热后奥氏体组织形貌的影响。研究结果表明,热芯大压下轧制可改善铸态组织,获得均匀细小的室温组织。对于中碳钢,热芯轧制获得的细小组织经再加热后无法继续保持,与无形变的坯料相比,再加热后的奥氏体晶粒反而更加粗大;而对于微合金钢,由于第二相粒子的钉扎作用,热芯大压下轧制获得的细小组织经再加热后可继续保持。     

微合金钢薄板坯连铸边角裂纹控制

微合金钢薄板坯连铸过程高发边角部裂纹,致使热轧卷板边部产生翘皮、烂边等质量缺陷,是钢铁行业的共性技术难题。本文立足于某钢厂QStE380TM低碳含铌钛微合金钢薄板坯连铸生产,检测分析了铸坯角部组织金相结构与碳氮化物析出特点、不同冷却与变形速率条件下钢的断面收缩率,并数值仿真研究了不同结构结晶器和二冷区铸坯温度与应力的演变规律。结果表明:微合金钢薄板坯连铸过程存在明显的第三脆性区,且变形速率越大,第三脆性区越显著。传统薄板坯连铸工艺条件下,结晶器的中上部及其出口至液芯压下段的二冷高温区,铸坯角部冷速较低,致使其组织晶界含铌钛微合金碳氮化物呈链状析出。铸坯在液芯压下过程,低塑性角部因受较大变形与应力作用而引发裂纹缺陷。实施沿高度方向有效补偿坯壳凝固收缩的窄面高斯凹型曲面结晶器及其足辊区超强冷工艺,可分别提升铸坯角部冷速至10和20 ℃·s?1以上,从而促使铸坯角部组织碳氮化物弥散析出,并促进铸坯窄面在液芯压下过程金属宽展流动而降低角部压下应力,大幅降低了微合金钢薄板坯边角部裂纹发生率。      

带液芯方坯重压下的变形特点

应用有限元仿真软件研究了带液芯方坯重压下的变形特点。结果表明,施加不同压下量,铸坯的宽展变形和应变均随压下量的增加而增加,组合压下较单辊压下的宽展量大,铸坯应变最大值逐渐增大,最大应变位置逐渐向铸坯中心移动,压下量的临界值为12~14 mm,超过该值后,铸坯的最大应变位置出现在铸坯中心。     

轻压下改善42CrMo钢300mm×400mm大方坯内部质量的工艺实践

以中碳钢42CrMo为试验钢,通过建立300mm×400 mm连铸大方坯凝固传热模型,确定合理压下区间4#～7#辊压下量分别为"1 mm-2 mm-3 mm-1mm",并进行工业试验.试验结果表明,轻压下工艺对铸坯凝固各组织占比影响不大,但可明显改善中心致密性和偏析.铸坯芯部最大疏松点尺寸由1106 μm×608 μm...     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

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)     

Comparison of rates of infection of two methods of emergency ventricular drainage

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.     

浅析《野草》的版画特征

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".     

四辊破碎机车刀架的改造

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。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

Comparison of the results of surgical and conservative treatment of fractures of the diaphysis of the tibia

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.     

焦炭热性能指标意义浅析

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。     

Results of treatment of cancer of the cardia

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.     

参与式农业基地建设行动方案设计

为了编制实用性强的基地建设行动方案,首先,确定参与式发展的主体,搭建一个"决策框架";其次,针对行动目标,提出不同参与主体,如管理者、农民、消费者等团队与个人的目标及行动内容;最后,工作应向重塑伙伴式合作关系,挖掘农民自我发展潜力,完成三大角色的转换,打造农业基地文化等方向推进.