邢钢低碳400系铁素体不锈钢AOD控氮工艺实践

在低碳400系不锈钢中,氮能恶化晶间腐蚀、低温冲击韧性、缺口敏感性和焊接等性能。因此,在低耗、高效前提下降低其氮含量成为AOD冶炼中的重要课题。结合生产试验,通过探讨回归分析法在其吹氩脱氮工艺控制中的应用,结合脱氮的热力学计算对AOD生产实践数据的分析,由拟合方程确定的AOD冶炼410S不锈钢和低碳430不锈钢时氮氩切换点为吹氮450m³时切换氩气,410S不锈钢正常冶炼时一般吹氩量控制在1550m³,低碳430不锈钢AOD吹氩量一般控制在2050m³时可以将AOD终点氮含量控制在0.009 0%以下,并降低氩气消耗。     

基于回归分析法的400系不锈钢吹氩脱氮工艺研究

400系不锈钢中的氮能恶化晶间腐蚀、低温冲击韧性、缺口敏感性和焊接等性能,在低耗、高效前提下降低氮含量成为AOD炉冶炼中的重要课题。分析了400系不锈钢冶炼中的脱氮原理,采用不同吹氩工艺研究了0Cr13钢、0Cr17钢、1Cr13钢的吹氩量与AOD炉终点氮含量的对应关系。探讨了用回归分析法确定400系不锈钢吹氩脱氮工艺控制合适的吹氩量、氮氩切换点,并进行了生产试验。     

AOD冶炼不锈钢氮合金化控制模型的研究和应用

根据氮在钢中的溶解热力学和脱除动力学理论,建立了AOD精炼氮合金化的控制模型。经45 t AOD装置精炼0Cr19Ni9N不锈钢(%:≤0.08C、18～20Cr、8～11Ni、0.10～0.16N)的应用结果表明,模型计算值与实测值吻合良好,可通过AOD氮气溶解和氩气脱除,精确控制不锈钢的N含量。     

不锈钢精炼工艺的改进

大同特殊钢公司潢川钢厂熔炼工部生产多种材质和规格的钢锭，以满足用户的不同需求。因此，很少在氩氧脱碳精炼工艺（AOD）中使用同一精炼模式来生产各种不锈钢，精炼时间、稀释气体和还原剂消耗存在一定的操作偏差。为了尽可能减少这些偏差、降低生产成本，对AOD过程中的脱碳和氮含量变化进行了研究，引入了脱碳量和氮含量估计公式。该系统能优化该工艺的精炼模式，节省稀释气体和降低还原剂消耗。     

炼钢过程中钢水氮含量控制

为控制钢中氮含量,提高产品的内在质量,通过对炼钢转炉—LF—连铸工艺的生产实践和研究,探讨影响钢中氮含量的因素和控制措施。通过生产实践数据和研究得到,要满足钢水质量对降氮要求应采取如下措施:转炉底吹氮氩气体切换时间应控制在11 min左右,避免补吹操作,加强出钢口的维护并及时更换出钢口;LF精炼时避免钢液裸露,采用大渣量埋弧操作;连铸采用保护浇注等。     

60t AOD兑脱磷铁水一步法冶炼0Cr12Mn15NiCuN不锈钢的工艺实践

邢钢一步法冶炼不锈钢的流程为铁水脱磷-扒渣-AOD-LF-CCM。分析了还原渣碱度1.5~2.2对锰收得率的影响和0Cr12Mn15NiCuN钢中氮含量对吹氩脱氮量的影响,得出控制炉渣碱度2.0~2.3可使锰收得率97%以上,在脱碳期和还原期吹氮,还原期结束后58 t钢水吹人60~80 m~3氩气,可使钢液中氮含量控制在0.18%~0.25%。60 t AOD生产结果表明,与"电弧炉+AOD"的两步法生产模式相比,采用脱磷铁水直兑AOD的一步法模式生产0Cr12Mn15NiCuN钢的总成本降低约500元/t。     

EAF→LF(VD)→CC流程生产GCr15轴承钢氮含量分析

分析了南京钢铁公司100t高阻抗电弧炉→100t钢包精炼炉→150mm×150mm方坯连铸工艺流程生产GCr15轴承钢各阶段钢中氮含量的变化及其影响因素。实践表明,为降低轴承钢中氮含量,采取电炉兑入铁水量在55%以上和泡沫渣操作,EAF出钢时钢中氮的质量分数平均达到29×10-6;LF精炼采用大渣量埋弧操作、氩气搅拌,该过程平均增氮质量分数为21.8×10-6;VD吹氩过程平均脱氮量为15×10-6;全程保护浇铸有效控制平均增氮质量分数为6.3×10-6。LF精炼过程增氮对整个过程控制至关重要,应加强LF精炼的工艺优化。     

150 t钢包炉(LF)精炼过程控制钢水增氮的工艺实践

兴澄特钢生产碳素结构钢和船板用钢的生产流程为150 t BOF-LF-RH-200~250 mm板CC工艺。统计分析了精炼过程造渣埋弧操作、送电制度、LF加热时间、钢包底吹氩等工艺因素对钢水增氮的影响。通过控制除尘吸风管道阀门开启度,保持LF内微正压操作,精炼前采用较高供电功率,后期用低供电功率,精炼前、中、后期分别采用氩气流量200,400~500,200~300 L/min,以及控制LF渣量1.2%等措施可使LF精炼过程的增氮量≤5×10^-6,不经过RH真空处理,可控制板坯氮含量≤50×10^-6。     

AOD炉冶炼含氮不锈钢氮成分控制的研究

对氮在不锈钢熔体中溶解的热力学和动力学行为进行了理论分析,指出氮在不锈钢熔体中溶解度随钢水温度降低和铬、锰、钼含量增加而升高,而随着镍和碳含量的增加而降低;对AOD炉冶炼不锈钢吹氮合金化工艺控制模型进行了理论研究和实际应用,指出在AOD炉中氮含量随着钢水碳含量、温度、供氧强度、吹氩强度的变化而变化,该工艺适合冶炼钢种的氮含量小于该钢种在常压下理论氮溶解度的90%,为保证氮成分精度,以小于80 %为宜.     

帘线钢中氮的产生原因及对策

对帘线钢各生产工序的氮含量进行了分析,提出了转炉工序采用高拉碳一次点吹、高碳出钢、降低炉后增碳剂的使用量等措施;LF精炼工序采用弱脱氧,降低搅拌氩气量,采用大渣量,造泡沫渣,VD控制保压时间和氩气量等措施;合理控制长水口密封吹氩量,使钢包到中间包的增氮量控制在0．0005％。采取合理的措施后,帘线钢成品氮含量达0．0035％以下。     

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.