Cr12MoVCo模具钢1.2t电渣锭重熔工艺

原采用 1 80方耐火砖铸棒电渣母材生产Ｃｒ1 2ＭｏＶＣｏ模具钢 1 2ｔ电渣锭 ,充填比为 0 2。为了降低成本 ,易于组织生产 ,采用新工艺路线Φ32 0ｍｍ铁模铸棒生产 1 2ｔ电渣锭 ,充填比提高到 0 5。采用该工艺后钢材质量良好 ,提高了生产率 ,取得了较好的经济效益。1　电渣重熔工艺Ｃｒ1 2ＭｏＶＣｏ钢试验工艺流程为 :2 0ｔ电弧炉→ＬＦ→浇Φ32 0ｍｍ铁模铸棒→电渣重熔 1 2ｔ锭(充填比 0 5 )→锻制成材 (Φ85ｍｍ)→成品探伤、检验。该工艺中试验二元和三元两种渣系、两种电制度 ,分别定为工艺 1、工艺 2。利用现有渣料 (精选萤石…     

用于制造600MW汽轮机低压转子的180t电渣锭生产

报告了我国发电设备主力机组６００ＭＷ汽轮机低压转子电渣锭的生产结果。锭重１８０ｔ,为世界上最大的电渣锭之一,△「Ｃ」≤±０．０１％,「Ｈ」＝（０．８￣０．２×１０＾－６,「Ａｌ」＝０．００５％￣０．００７％,「Ｏ」、「Ｓ」＝（１８￣２５）×１０＾－６。转子锻件约１３０ｔ,未发现≥１．６ｍｍ当最缺陷,芯料冶金质量和性能与转子本体一致。     

Φ315mm双极串联电渣锭崩块夹渣的控制

分析了Φ315mm双极串联电渣锭发生崩块夹渣的原因，通过采取电极棒热重熔和电极棒埋砂缓冷等工艺措施，大幅度减少了电渣锭崩块夹渣缺陷。     

优化4145H锭型，提高定尺材成材率

通过分析4．9t锭轧制成210mm方坯及Ф180mm钢材后的各种质量数据及825初轧机及精轧机设备监测数据得出,825初轧机及825精轧机主生产线的设备通过精心维护,可以使用4．9t锭生产钢材;冶炼正常的4145H 4．9t锭生产Ф180mm钢材的内在性能能够得到保证,正常浇注的4145H 4．9t锭生产Ф180mm定尺钢材的长度能够得到保证,与使用3t方锭相比可以大大地提高定尺材成材率,从而为企业创造显著的经济效益。     

提高不锈钢重熔锭底部表面质量的工艺探索

我公司的锻件产品人多采用“电炉+电渣重熔”生产钢锭的工艺路线,生产不锈钢重熔锭时,底部常产生夹渣和渣沟,这一问题困扰我们多年.本文介绍了这一问题的解决过程,希望能对我们技术人员提供一些借鉴.     

GH2036合金电渣重熔锭气孔分析

不含Ａｌ、Ｔｉ的铁基高温合金ＧＨ2036、ＧＨ1015、ＧＨ1040、ＧＨ1131等电渣冶炼的材料中容易出现的冶金缺陷有肉眼可见的小气孔、细小裂纹和点状偏析等。对裂纹和点状偏析进行金相观察的结果为硅锰铝氧化物,属ＭｎＯＳｉＯ2Ａｌ2Ｏ3三元系夹杂物,碳化物偏析等。由于采用装入法冶炼,浇注的180ｍｍ方和Φ310ｍｍ母材中氢含量达10×10-6。使用未烘烤的石棉板水分达2.11%～2.47%、铸钢护锭板及结晶器内表面吸附水分和渗漏水等原因造成电渣锭下部气孔较为严重。对上述问题采取有效措施后,统计了1997～1999年电弧炉浇注的Φ310ｍｍ母材13炉,电…     

热轧大压下量对18Cr2Ni4WA钢树枝状晶形态的影响

１热轧１８Ｃｒ２Ｎｉ４ＷＡ钢的试验条件及方法轧制设备为Φ８５０ｍｍ可逆式初轧机，箱型孔型系统，使用２．７ｔ矩型镇静钢锭，钢锭尺寸为（５４０ｍｍ×４６０ｍｍ～４６０ｍｍ×３８０ｍｍ）×１５９０ｍｍ，钢坯尺寸为１６０ｍｍ×１６０ｍｍ。钢锭的化学成分见表１...     

提高高速工具钢电渣锭到精整方坯成材率的工艺研究

提高高速工具钢电渣锭到精整锻坯成材率的工艺研究，从中频炉料、中频冶炼、浇铸、电渣重熔、锻造加热等工艺方面进行了研究。对每个工序或环节易出现或已出现的问题，分析了产生的原因以及拟定采取相应措施。经过2001年近6个月的试验，该工艺基本成熟，特别是经过2002年的生产进一步验证，该工艺研究是成功的。     

GCr15轴承钢连铸方坯与电渣重熔铸锭的 原位统计分布分析

GCr15轴承钢作为高碳钢,其元素偏析尤其是碳元素的偏析对于钢的组织和性能有很大影响。实验应用原位统计分布分析技术对GCr15轴承钢连铸方坯整个横截面以及GCr15电渣锭的中心区域进行了对比分析,并重点研究了C和Cr元素的偏析情况以及试样表面的疏松情况。通过C和Cr元素含量二维等高图以及统计偏析度的对比分析可知,连铸方坯横截面的C和Cr元素都存在严重的中心偏析现象,同时在中心偏析区域外围观察到由于树枝晶搭桥而造成的环状、不连续的C元素负偏析带;GCr15电渣锭中心区域的C和Cr元素分布则较为均匀,即偏析现象得到明显改善。此外,电渣重熔前后试样表面的统计致密度和统计疏松度表明,电渣锭的致密程度要明显优于连铸方坯。     

不锈钢022Cr25Ni22Mo2N电渣锭锻造裂纹原因分析和工艺改进

20 t EAF-VOD-LF-VD-铸棒-2.5 t电渣重熔锭锻成Φ200 mm圆棒上发现大量表面横向裂纹,采用扫描电镜对裂纹的微观形貌进行观察,分析结果表明,裂纹是由于锻造前加热温度过高,导致了晶界熔融而造成的。通过试验和生产实践得出,022Cr25Ni22Mo2N钢电渣锭加热温度由原1180℃降至1110℃时,消除了锻材裂纹。     

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。     

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.     

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。     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.