超低碳钢方坯连铸生产工艺研究

介绍了邢台钢铁有限责任公司炼钢厂方坯连铸超低碳钢的操作实践,对不同的生产工艺进行对比后,优化选择了"转炉→LF精炼→RH真空处理→方坯连铸"工艺路线。研究发现:无顶渣改质时(FeO)、(MnO)含量高,且波动较大(w(FeO)=9%~14%、w(MnO)=1%~3%),易造成水口絮流;采用三步顶渣改质工艺(转炉、LF、RH工序钢包顶渣改质),可将顶渣w(FeO+MnO)控制在3%左右,为钢液钙处理创造有利条件,避免水口絮流,实现多炉连浇,且成品平均w(C)=0.008%("转炉→RH→LF→方坯连铸"工艺成品平均w(C)=0.010 2%)。     

150t转炉冶炼弹簧钢脱氧工艺优化实践

150t转炉生产弹簧钢通过将终点碳控制在0.10%~0.20%、根据终点碳调整预脱氧剂电石的加入量及采用铝进行终脱氧的工艺优化;LF炉采用CaO-SiO2-Al2O3-MgO-CaF2渣系;对钢中Al2O3进行钙处理避免小方坯连铸浇注含铝钢中包水口结瘤等工艺措施,有效降低了弹簧钢成品材的氧含量。     

精炼渣对SUS444铁素体不锈钢中夹杂物的影响

在1 873K,MgO坩埚内进行了VOD精炼渣与SUS444铁素体不锈钢之间的脱氧平衡试验,考察了精炼渣对不锈钢中T.O含量及夹杂物组成、数量和尺寸分布的影响。结果表明,脱氧终点钢中w(T.O)=0.006 3%~0.007 4%,提高精炼渣碱度,降低渣中Al2O3的活度,有利于降低钢中T.O含量。精炼渣碱度增加,试样中单位面积夹杂物的个数及夹杂物的平均面积分数都减小。降低渣中Al2O3含量,夹杂物平均粒径也降低。加入脱氧合金后,钢中夹杂物主要为Al2O3、MgO·Al2O3及含有少量SiO2、MnO的复合氧化物;钙处理后,钢中夹杂物主要为球形的MgO·Al2O3-CaO。随着精炼渣中a(MgO)/a(Al2O3)的增加,MgO·Al2O3夹杂物中xMgO/xAl2O3随之增加。根据试验,R=3.5、w(Al2O3)=10%、w(MgO)=10%、w(CaF2)=5%的精炼渣具有良好的精炼效果。     

LF-VD高效脱硫工艺

 为了研究LF-VD精炼工艺的脱硫效果,进行了9炉工业试验。通过对BOF-LF-VD和KR-BOF-LF-VD工艺冶炼中厚板钢中硫含量和炉渣成分的分析,研究了炉渣成分和工艺参数对脱硫的影响。结果表明,采用适宜的精炼渣系,通过LF-VD精炼能把钢中硫质量分数从转炉终点200×10-6左右脱至20×10-6以下;炉渣成分[w((MgO))]=4%～7%、[w((SiO2))]=7%～11%、[w((CaO))/[w((Al2O3))+w((SiO2))]]=1.62时,实现最高硫分配比接近500;VD精炼比LF精炼钢液搅拌强烈,能进一步脱硫。研究结果对优化中厚板炉外精炼脱硫工艺具有指导意义。     

Q345钢精炼过程夹杂物成分的变化

通过工业试验研究了Q345钢在钢包精炼过程和RH处理过程中夹杂物成分的变化。结果表明:通过与高碱度、低氧化性渣的反应,钢水中的大部分Al2O3夹杂物转变为具有较低熔点的CaO-Al2O3-MgO夹杂物。研究了RH处理后钙的加入量对夹杂物成分的影响。结果表明:当钢包顶渣的成分控制在w(CaO)=50%～55%、w(CaF2)=5%～8%、w(Al2O3)=25%～30%、w(SiO2)=5%～8%、w(MgO)=5%～10%、w(FeO)<1%,经过钢包精炼和RH处理,每吨钢水中加入0.12 kg钙后,钢水中夹杂物的平均成分处于低熔点(≤1 500℃)区。     

120t转炉冶炼低磷钢深脱磷技术

为了达到低磷钢对成品磷质量分数小于0.010%的要求,根据温度、炉渣碱度、渣中w(Fe O)以及搅拌等对钢液脱磷的影响,马鞍山钢铁股份有限公司120 t转炉应用烟气分析动态控制炼钢技术,采用留渣双渣操作法,制定合理的装入、造渣、供氧制度,优化脱磷参数,通过500多炉次实践对比分析,确定合适的倒炉温度为1 540~1 580℃,w(C)=0.10%~0.25%,终渣碱度3.0~3.5,w(Fe O)=15%~23%,及适合的搅拌强度以达到脱磷率95.2%良好效果,实现了转炉出钢磷质量分数小于0.007%,以及终点碳温双命中96.4%的目标。     

X80管线钢硫含量控制研究

基于首钢京唐公司X80管线钢的生产数据,从热力学上分析了转炉终点渣和LF精炼渣硫容量与钢中硫含量的对应关系,给出了精炼渣成分的调节方向。结果表明:精炼渣成分应控制在如下范围:w(CaO)为55%～60%;w(SiO2)为10%～12%;w(Al2O3)为20%～25%;w(MgO)为6%、w(FeO+MnO)小于1.5%。该成分的精炼渣最终硫分配比范围可控制在198～542。     

不同RH冶炼工艺对低碳铝镇静钢洁净度的影响

对比分析了生产低碳铝镇静钢采用RH两种不同处理模式的工艺特点和洁净度差异,结果表明:工艺路线1的RH到站渣中w(T.Fe+Mn O)=5%~12%,而工艺路线2的RH到站渣中w(T.Fe+Mn O)稳定控制在2%以内,工艺路线1精炼过程中w(Als)损失较工艺路线2高约54×10-6;工艺2夹杂物有效去除时间平均为64 min高于工艺路线1的45 min;工艺路线1结晶器钢水w(T.O)较工艺路线2高13×10-6,工艺路线1结晶器钢液中的夹杂物分布面积比高于工艺路线2,同时工艺路线1钢水样中,尺寸在5μm以上的夹杂物占10.6%,高于工艺路线2的3.6%。针对不同RH精炼工艺分别提出了相应的优化措施。     

IF钢生产工艺研究及实践

对比分析柳钢150t转炉炼钢系统两种(转炉-钢包炉精炼-RH精炼-连铸和转炉-RH精炼-连铸)生产IF钢的工艺。结果表明,采用转炉-RH精炼-连铸工艺生产的IF钢:(1)洁净度相对更高,生产成本更低;(2)RH精炼结束w(C)≤10×10-6、w全(O)≤31×10-6、w(N)≤20×10-6,中间包w(C)≤11×10-6、w全(O)≤25×10-6、w(N)≤20×10-6;(3)造成钢水洁净度偏低的主要原因是RH脱氧合金化后循环时间偏短,且RH精炼炉渣控制不稳定。     

低磷钢生产过程中钢液回磷的研究

为满足低磷钢生产要求,结合南钢现场试验,从热力学角度分析了从转炉出钢到LF精炼结束的回磷过程。结果表明:转炉出钢处于回磷状态,通过提高出钢时渣中w(FeO+MnO),可以降低出钢时钢液的回磷趋势,有利于降低精炼终点钢中的w(P);采用Mn弱脱氧出钢,可使钢液中w(O)降低至0.032%左右,平均回磷量为3.7×10-6,Si-Mn脱氧可使钢液中w(O)降低至0.01%以下,平均回磷量为14.56×10-6;采用留钢留渣操作的炉次回磷量平均为7.5×10-6,未采用留钢留渣操作的炉次回磷量平均为13.2×10-6。     

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.