钒和铌-钒低碳微合金钢的静态再结晶行为

采用MMS-300热力模拟试验机研究了钒和铌-钒微合金钢的静态再结晶规律,绘制了试验钢的静态再结晶软化率曲线,计算出试验钢的静态再结晶激活能并建立了静态再结晶动力学模型,结合沉淀析出物的微观形貌观察,分析了铌对钒微合金钢静态再结晶行为的影响规律。结果表明,铌-钒钢的静态再结晶激活能要显著高于钒钢,在800~950℃变形保温60 s以上的试验条件下,铌-钒钢发生了形变诱导析出,细小的碳氮化物弥散分布在位错及晶界上,使得软化率曲线在此范围内出现"平台",说明铌既限制了静态再结晶的发生,又阻碍了软化行为的进行。     

Nb-Ti微合金钢的静态再结晶行为

 通过双道次压缩试验研究了Nb-Ti微合金钢的静态再结晶行为,确定了应变诱导沉淀析出前Nb-Ti微合金钢的静态再结晶激活能,并建立了静态再结晶动力学模型。采用面积法及积分-能量法计算的软化率,很好地反映了微合金钢的静态再结晶行为及应变诱导沉淀析出行为。应变诱导沉淀析出的鼻尖温度在900～925℃之间,静态再结晶的临界温度（SRCT）高于950℃。     

一种钒氮微合金钢的静态再结晶行为

 通过双道次压缩试验,研究一种钒氮微合金钢道次间隔时间内在奥氏体区变形后的软化行为,采用应力补偿法计算静态再结晶的体积分数,并建立静态再结晶动力学模型。分析变形温度与间隔时间以及钒的析出物对静态软化行为的影响。结果表明,在高于900℃时进行第一道次变形,该钒氮微合金钢很快完成了静态再结晶;在850、800℃变形后的等温阶段,发生了形变诱导析出现象,使再结晶激活能增加,静态再结晶进程受到抑制,导致软化率曲线上出现了平台。     

含铌微合金钢低温区静态软化行为

 通过两道次压缩变形实验对含Nb微合金钢静态软化行为进行了研究。结果表明：含Nb微合金钢静态再结晶临界温度随应变量增大而降低;随原始奥氏体晶粒尺寸增加而升高。温度高于静态再结晶临界温度时,含Nb微合金钢的静态再结晶激活能为常数(170589 kJ/mol);温度低于静态再结晶临界温度时,由于Nb的碳氮化物应变诱导析出,含Nb微合金钢的静态再结晶激活能为温度的函数,静态再结晶临界温度可通过再结晶激活能与温度倒数的关系曲线来确定。     

Ti-IF钢铁素体变形动态再结晶临界应变模型

用Thermecmaster-Z热模拟试验机试验得出成分为0.006 7%C-0.045 0%Ti的Ti-IF(无间隙原子)钢在变形温度750~900℃和变形速率0.1~40 s^-1时的应力-应变曲线,确定了Zener-Holloman参数Z与应变速率.ε和温度T(K)的关系式Z=.εexp(39 507/T),并建立了临界应变εc与原始晶粒尺寸d0和Z参数的临界应变方程ε_c=2.314 4×10^-3×d^{-0.8003 9}×Z^0.050。结果表明,在相同变形速率下,850℃变形时动态再结晶最易发生,当变形温度提高至900℃(两相区)时,即使在低变形速率(1 s^-1),也不发生动态再结晶。当变形速率大于1 s^-1时,Ti-IF钢热加工时不能出现动态再结晶。临界应变预测值与实测值比较,平均误差≤5%。     

Nb微合金化低碳贝氏体钢的再结晶和应变诱导析出

通过Gleeble-2000热模拟试验机研究了850～1 050℃双道次变形(第1道次60%,20 s-1,第2道次20%,10 s-1)及不同道次间隔时间(10～50 s)对含铌低碳贝氏体钢(%:0.21C、1.50Cr、0.20Mo、0.047Nb)再结晶的影响和应变诱导析出Nb(CN)与热变形奥氏体再结晶的相互作用.结果表明,该钢在1 000～900℃变形10 s后,开始应变诱导析出Nb(CN),延迟静态再结晶过程;通过双道次变形,可获得≤10 μm奥氏体晶粒.     

WNQ570桥梁钢的静态再结晶行为

 为了研究轧制工艺对WNQ570桥梁钢再结晶行为的影响,采用Gleeble-3500热模拟试验机模拟了其双道次热变形过程,测试了试验钢的应力-应变曲线,建立了静态再结晶晶粒体积分数随变形温度和道次间隔时间变化的关系模型,分析了应变诱导析出抑制对静态软化行为的影响。研究结果表明：静态再结晶体积分数随变形温度的提高或道次间隔时间的延长而增大,应变诱导析出抑制静态再结晶的进行;静态再结晶激活能为240.47kJ/mol。研究结果为制订试验钢二阶段控轧工艺提供了依据。     

Ti—10V—2Fe—3Al合金的热变形行为

本文测试了Ti-10V-2Fe-3Al合金在700～950℃温度范围内,5×10~(-3)s~(-1)～10s~(-1)七个应变速率下的真应力-应变(σε)曲线,分析了变形组织,并对β区动态再结晶的形核机制进行了探讨。结果表明,在β区850～950℃下,应变速率ε=1s~(-1)～10s~(-1)范围内变形时,动态回复是主要软化机制,经计算得:应力指数n=4.1,激活能Q=195kJ/mol;当 ε≤10~(-1)s~(-1)时,有动态回复和动态再结晶两种软化机制,此时n=3.9,Q=157kJ/mol。α+β区变形时,有动态回复和动态再结晶两种软化机制。     

TA17钛合金热力学行为及加工特性研究

为了研究TA17钛合金热轧条件下的高温变形行为及热加工特性,在热模拟机上开展变形温度为700~1100℃、应变速率为1~40 s~(-1)条件下的热压缩实验,建立基于Arrhenius模型的本构方程,以及应变分别为0.3和0.6时的热加工图,结合热变形显微组织分析,研究该合金的热塑性变形机制。结果表明:TA17钛合金流变应力随着变形温度的升高而降低,随着应变速率的升高而升高。在温度为800~1000℃、应变速率为1~10 s~(-1)时,材料的变形机制主要为动态再结晶;温度为1000~1100℃、应变速率为1~10 s~(-1)时,材料发生动态回复;温度为700~800℃或1000~1100℃、应变速率大于20 s~(-1)时,材料产生绝热剪切带;温度为700~800℃,应变速率为1~5 s~(-1)时,材料易产生裂纹。得出该合金较优的热轧工艺参数为:变形温度800~1000℃,应变速率1~10 s~(-1)。     

CSP工艺Nb微合金化技术

通过化学相分析手段测试了EAF-CSP流程Nb(C,N)析出规律,结果表明:连铸出坯后,Nb大部分已析出,析出量为79%,平均尺寸为60.7nm;铸坯均热后,Nb(C,N)明显回溶并发生Ostwald熟化,回溶比例为56.3%,平均尺寸为69nm,此时析出量为总量的34.7%;经连轧、加速冷却和卷取后,Nb又重新诱导析出,析出量为71%,平均尺寸减少为54.5nm。利用Gleeble3500热模拟实验机研究了EAF-CSP流程原始奥氏体静态再结晶规律,结果表明含0.045%Nb铸坯均热后晶粒尺寸达到700μm,1050℃变形50%后保温10s仍不能完全再结晶,这是导致混晶的根本原因。合理设计成分,调整铸轧工艺,可成功地解决EAF-CSP生产含Nb钢的混晶问题并有效细化晶粒。基于EAF-CSP流程Nb微合金化技术,开发出X52、X56、X60系列管线钢。     

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.