在线热处理型线材的开发

作为在线热处理技术生产的新线材的代表实例,叙述了室兰制铁所生产在线调质（QT）线材及君津制铁所生产贝氏体线材的方法及特征。前者是通过线材轧制后用温水或冷水的控冷技术组合在线回火生产的,是无淬裂和软点的均质中碳钢及低合金钢线材。后者是线材轧制后直接通过盐溶热处理进行恒温相变所生产的以上贝氏体为主的高碳钢线材。上贝氏体组织由于肢解的渗碳体呈稀疏分散,所以对于位错移动的障碍少,具有高的延性和拉拔加工性。     

在线热处理线材的开发

作为用在线热处理技术制造的新型线材的典型实例，介绍了室兰制铁所生产的在线ＱＴ（淬火、回火处理）线材和君津制度铁所生产的贝氏体线材的生产方法及其特征。前者的生产方法是将线材轧制后的控制冷却（用温水或冷水）技术与在线回火相结合，以得到无淬火裂纹或淬火软点的均质中碳钢和低合金钢线材。后者是线材轧制后直接通过盐浴热处理，使其发生等温度转变而生产出以上贝氏体为主的高碳钢线材。由于上贝氏体组织中断开的渗碳体成稀疏分散状，因此，对位错移动的障碍较少，线材具有较高的延伸性及拉丝加工性。     

ER55-G断丝原因分析

利用JSM-6490扫描电镜分别对原材料（Φ5．5mm）和断丝严重道次的线材进行横向和纵向截面的观察,并与拉拔性能较好的线材作比较。分析ER55-G盘条钢拉拔断丝的原因,阐述贝氏体对盘条钢拉拔性能的影响。指出断丝的主要原因为组织不合格,并提出了相关解决措施。     

HRB400E高速线材性能不合格的分析

针对建筑用HRB400E高速线材性能不合格问题进行了化学成分、力学性能、金相组织的试验分析,结果表明,Mn元素含量过多,将产生回火索氏体和粒状贝氏体异常组织,从而影响钢材的力学性能。     

盘螺钢贝氏体组织的产生原因及控制

分析了利用高速线材生产线轧制小规格螺纹钢的生产过程中,钢中贝氏体组织产生的原因,并提出了相应的控制措施。分析认为,盘螺钢中锰含量偏高及轧后冷却速度过快是产生贝氏体的主要原因。通过降低轧制温度和吐丝温度,最大限度地提高奥氏体的晶粒度级别,促进过冷奥氏体向铁素体、珠光体转变;根据季节环境等客观条件的不同,适当提高或降低Mn含量及轧后冷却速度;控制钢中Nb含量≤0.04%等,可保证盘螺钢具有良好的F+P或F+P+少量B组织,从而获得优良的力学性能。     

高强度冷镦钢热机轧制工艺模拟试验研究

通过对35CrMo钢热模拟试验，研究高强度冷镦钢线材热机轧制工艺。试验表明，高强度冷镦钢经过热机轧制，可以避免形成马氏体和粒状贝氏体，提高铁素体含量12％～16％，因而材料被显著地软化。热机轧制可以促使珠光体直接球化；随热机轧制变形量增大，得到的铁素体晶粒越细，粒状珠光体的数量越多。     

离心铸造复合球墨铸铁轧辊材质的研究

本文研究了用于离心铸造复合球墨铸铁轧辊的三种球墨铸铁材质,对其组织形态,化学元素分布:力学性能及热处理工艺进行了研究分析。在实验研究基础上,用珠光体球墨铸铁材质生产了马鞍山钢铁公司高速线材轧机φ410 mm轧辊;用针状贝氏体球墨铸铁材质生产了上海宝山钢铁总厂钢管轧机张减辊。两种轧辊上机使用效果显著,轧制量均达到国外设计要求和进口轧辊水平。     

10.9级紧固件用非调质钢试制

 为开发高强度紧固件用非调质钢,在高速线材轧机上进行了试验轧制,并对试制产品的组织性能进行了检测。结果表明,在给定工艺条件下钢的组织基本上为粒状贝氏体组织,抗拉强度为897.5MPa,伸长率为21.8%。热轧材拉拔减面后达到或超过10.9级紧固件的力学性能要求。当拉拔量为25.0%时,可承受59.3%的压缩变形不开裂。     

贝氏体形态对细晶铁素体/贝氏体双相钢室温力学性能的影响

基于过冷奥氏体动态相变的思想,通过两道次压缩变形结合控制冷却的热模拟轧制工艺,获得不同贝氏体含量及形态的细晶铁素体贝氏体双相钢。通过显微组织观察及力学性能测试,考察了第二相贝氏体特征对双相钢室温拉伸变形行为的影响。研究结果表明,形变后快速冷却可获得无碳板条状贝氏体,较慢的冷速或在贝氏体转变区保温处理可获得粒状贝氏体。贝氏体体积分数大于20%左右的细晶铁素体/贝氏体双相钢具有低的屈服强度,高的抗拉强度,高的伸长率,低屈强比以及连续屈服特性。屈服强度既与铁素体晶粒尺寸相关,也与贝氏体形态和数量相关。板条贝氏体引起的屈服强度提高大于粒状贝氏体,粒状贝氏体具有比板条贝氏体更好的塑性。     

贝氏体形态对细晶铁素体/贝氏体双相钢室温力学性能的影响

基于过冷奥氏体动态相变的思想,通过两道次压缩变形结合控制冷却的热模拟轧制工艺,获得不同贝氏体含量及形态的细晶铁素体贝氏体双相钢。通过显微组织观察及力学性能测试,考察了第二相贝氏体特征对双相钢室温拉伸变形行为的影响。研究结果表明,形变后快速冷却可获得无碳板条状贝氏体,较慢的冷速或在贝氏体转变区保温处理可获得粒状贝氏体。贝氏体体积分数大于20%左右的细晶铁素体/贝氏体双相钢具有低的屈服强度,高的抗拉强度,高的伸长率,低屈强比以及连续屈服特性。屈服强度既与铁素体晶粒尺寸相关,也与贝氏体形态和数量相关。板条贝氏体引起的屈服强度提高大于粒状贝氏体,粒状贝氏体具有比板条贝氏体更好的塑性。     

Efferent and afferent connections of the nucleus lateralis posterior thalami ("pulvinar") in the albino rats (author's transl)

The efferent and afferent connections of the lateral posterior nucleus (LP) of the albino rat were investigated light microscopically with the silver-degeneration-methods and the HRP-methods as well. The results are: 1. The main projection region of the LP is the area of 18a of the peristriate visual cortex. Most degenerating axons terminate in layer IV. A few fibers pass layers III and II and terminate in layer I. It is not sure if there are also terminating fibers in layer IV. We could not find a topistic relation between LP and area 18 a. 2. We observed a small number of degenerating fibers in area 17, too. 3. A part of the degenerating fibers runs to the temporal cortex end enters area 20. 4. There is no evidence for a projection of the LP to both the subcortical regions and to the superior colliculus. 5. The majority of the LP's afferent fibers originates - on the subcortical level - from the superior colliculus. Especially the lamina III (Str. opticum) of the ipsilateral and of the contralateral side is here the source of fibers terminating in the LP. 6. Other subcortical sources of fibers terminating in the LP are: the pretectal region, the ventral part of the LGN, the Zona incerta, the thalamic reticular formation, and the dorsal raphe nucleus. 7. There exists a fiber projection of the area 17 to the LP. The axons originate mainly from pyramidal cells in layer V. It is discussed whether the area-17-fibers terminating in the LP are collaterals of the fibers terminating in the superior colliculus. The projection of the area 18a to the LP is of greater importance. The axons of this area originate mainly from cells of the layer VI. It becomes obvious that the thalamic relay-station of the second visual pathway seems to project nearly exclusively to the neocortex. In contrast to the dorsal LGN, however, the LP is not only a simple relay-station for visual information as also non-visual information arrives here. The morphological basis for these inputs has not yet been clarified completely. We have to take into consideration as well as the connections with the superior colliculus and the pretectal region and the cortical connections. It is remarkable that there exists also a projection of LP-fibers to a region outside the classical visual cortex. In mammals of higher evolution that kind of projection extends increasingly. It is discussed if - under comparative-anatomical aspect - the morphological changes in the pulvinar region are an expression of the neocorticalization, whereas the morphological changes in the dorsal LGN reflect mainly the functional specialization of the visual system.     

Ecology of flea groups of the species conformis (Siphonaptera: Pulicidae: Xenopsylla) of the fauna of Russia and adjacent countries (review)

Within the boundaries of the former USSR, the northern part of the conformis group distribution is located. It spreads over the arid regions of the Trans-Cacucasus, Pricaspijckaja lowland, Kazakhstan and Middle Asia. In this area 10 species and subspecies occur. They are mainly parasites of gerbillins. Unlike many other Siphonaptera the conformis fleas, when in the host's home, do not concentrate in the nest but inhabit the passages of burrow and food chambers throughout the year. On this reason the preimaginal development and existence of the adults take place not at the temperature of the habitable nest, which is heated by the host body, but at the temperature of the soil at a depth of burrow. The temperature threshold for preimaginal development of conformis fleas is reported to be 10-12 degrees. Temperature below the threshold is fatal for all immature instars. On the contrary the imago can survive at freezing temperature. The annual cycle of the conformis fleas is characterized by the presence of adults throughout the year. They breed in the warmer season and overwinter in the state of reproductive diapause. In this state the fleas are able to attack the host and to feed but do not deposit eggs. In the north deserts the reproduction begins at the early April and terminates at the early September. Southern, the reproductive period is longer. Furthermore, the complete interruption of the reproduction in the autumn-winter time may be absent as it was observed in X. gerbilli gerbilli and X. hirtipes in the south of the Middle Asia. On the other hand it is noted that in southern deserts the rate of oviposition falls in the most hot time. The number of generation per year in the conformis fleas varies from 2-3 in north deserts to 6-7 in south ones. The flea populations peak in late autumn when the insects cease to bread. The high abundance is maintained until springtime. After the diapause is ceased and the fleas begin breeding their abundance declines. In the late spring and early summer the emergence of adults begins and the populations increase. In a mild of summer the second fall takes place and then the fall is replaced by the autumnal peak. On their main hosts the conformis fleas prevail over all other species of Siphonaptera especially for warmer time when their quota among other fleas does not descend as a rule below 90% but more oftently it approaches to 100%. The fleas of this group and especially species parasitizing Rhombomys opimus are remarkable for the high level of their abundance. In the northern deserts in the periods of the most high abundance (late autumn, winter and early spring) the number of fleas per burrow occupied by family of Rh. opimus exceeds usually 1000 specimens and sometimes it can reach several thousands. In the southern deserts the abundance of the fleas is lower but the period of their active parasitizing is longer. In the species parasitizing Rh. opimus it is shown that in a complex burrow only some part of fleas has the possibility to feed regularly. In the spring and summer the percentage of fleas daily attacking the host varied from 17 to 86% and from 10 to 150 ectoparasites feed daily on one animal depending on the quantity of fleas and of hosts in the burrow. The number of attacking fleas is regulated by behaviour of the hosts, which change the used parts of burrow when the fleas are crowded there.     

A transient precursor of the HIV-1 protease. Isolation, characterization, and kinetics of maturation

Recently, the mechanism of autoprocessing of the protease (PR) of the human immunodeficiency virus type 1 from the model polyprotein, MBP-DeltaTF-PR-DeltaPol, which contains the protease linked to short native flanking sequences (DeltaTF and DeltaPol) fused to the maltose binding protein (MBP) of Escherichia coli, was reported (Louis, J. M., Nashed, N. T., Parris, K. D., Kimmel, A. R., and Jerina, D. M. (1994) Proc. Natl. Acad. Sci. U. S. A. 91, 7970-7974). According to this mechanism, intramolecular cleavage of the N-terminal strands of the dimeric MBP-DeltaTF-PR-DeltaPol protein leads to the formation of the PR-DeltaPol intermediate, which is subsequently converted to the mature protease by cleavage of the C-terminal strands. We now report the purification and characterization of the PR-DeltaPol intermediate and the kinetics of its processing to the mature protease. Unlike the MBP-DeltaTF-PR-DeltaPol precursor, PR-DeltaPol has proteolytic activity similar to that of the mature enzyme at pH 5.0. The pH rate profile for kcat/Km is similar to that of the mature protease above pH 4.0. Although the PR-DeltaPol is more sensitive than the mature protease toward denaturing reagents, both the enzymatic activity and the intrinsic fluorescence of PR-DeltaPol are linearly dependent on the protein concentration, indicating that the protein is largely in its dimeric form above 10 nM. In contrast to the first-order kinetics observed for the proteolytic reaction at the N terminus of the protease, the proteolytic reaction at the C terminus of the protease is second order in protein concentration. These results are discussed in terms of a mechanism in which the C-terminally located DeltaPol peptide chains are cleaved intermolecularly to release the mature protease.     

Luders Deformation in Weld Joints

The elastoplastic transition in welded low-carbon steel samples is considered. Two methods of manual arc welding of floating-electrode type are employed: a traditional steady arc; and pulsed welding with controlled heat consumption. In terms of the structural characteristics and mechanical properties of the welded metal, the methods are identical. In both cases, extended elastoplastic transition by the nucleation and propagation of Luders bands is observed. However, the underlying process is different. In the traditional steady arc, the Luders bands are formed in the applied metal initially as diffuse regions where the deformation is localized. These regions fill the seam and convert it to the plastically deformed state. The moving fronts of the bands are finally shaped in the thermal-influence zones and pass to the basic metal. The velocity and morphology of the fronts match those of fronts in uniform objects of the same steel. When using a pulsed arc, Luders bands appear some distance from the weld seam, at the clamps of the loading device. Up to the thermal- influence zones, the velocity and morphology of the fronts correspond to those for the basic metal. At the fusion boundary, the front stops and forms the nucleus of a new band, which expands in the seam metal. This new band first transforms the applied metal to the deformed state and then creates a moving front in the opposite thermal-influence zone. The velocity of the front differs by an order of magnitude in the applied metal and the basic metal. The weld seam determines the nucleation of Luders bands. An explanation is offered for the different origins of the elastoplastic transition in the two welding methods. In traditional welding with a steady arc, the local long-range stress is considerably higher in the thermal-influence zones than in the basic metal. Therefore, the nucleation of Luders bands is a relaxational process in this case. In pulsed arc welding, the local long-range stress is higher in the basic metal, where the Luders bands appear. The results may be used in selecting the test conditions for power-system equipment.     

基于驻极体静电俘能器的优化设计与实验测试

针对环境中的低频振动能量,建立了一种双端固支梁振动式驻极体静电俘能器理论模型.利用Matlab/Simulink数值仿真对静电俘能器的各项关键参数进行了优化.分别研究了静电俘能器的输出功率、谐振频率、半功率带宽与驻极体表面电位、空气间隙以及负载电阻的关系.在研究中,外部激励加速度幅值及驻极体尺寸保持恒定.数值分析结果如下:(1)存在一个最佳表面电位使得静电俘能器的输出功率达到最大值,随着表面电位的增加,软弹簧效应逐渐增强使得俘能器谐振频率发生偏移,半功率带宽逐渐增大.(2)当表面电位一定时,存在一个最佳初始空气间隙使得功率达到最大,随着间隙的增大,半功率带宽随之减小.(3)当表面电位和空气间隙保持一定时,存在一个最佳负载使得功率达到最大,随着负载的减小,谐振频率发生偏移.(4)当空气间隙一定时,存在一个最佳负载使得带宽达到最大,且表面电位越大,相同负载下的带宽越大.实验测试了不同负载电阻下俘能器的输出特性:输出功率及半功率带宽都随着负载电阻的增大,先增大而后减小.当负载电阻为90MΩ时,对应的最大输出功率为0.188 mW;当负载电阻为330 MΩ时,对应的半功率带宽达到最大值为4.7 Hz.      

Rolling of metal balls

The rolling of balls (diameter 93 and 125 mm) of precise mass in helical grooves is simulated by means of QForm-3D and DEFORM-3D software. A model of a virtual rolling mill is created. Analysis of the stress state at characteristic points along the rolling axis focuses on the effective stress, the components of the stress tensor, and the mean normal stress. The mass of balls rolled on new and worn rollers is measured. The quality of internal metal layers is verified, and the hardness of rolled balls over the vertical and horizontal symmetry axes is measured. Modeling of ball rolling shows that the hot blank (a rod of hot-rolled steel) is satisfactorily captured by the rollers. Rolling is stable, without slipping. The blank completely fills the grooves; no gaps are observed between the metal and the walls. The crosslinks between the balls are completely eliminated within the rollers. The crosslinks are cut by the rim of the rollers and pressed into the body of the ball. The individual balls continue to roll along the finishing section of the groove; the stubs of the crosslinks are smoothed; and a completely shaped ball with a smooth surface emerges from the rollers. In modeling the stress–strain state, all the components of the stress tensor are negative. In other words, all the components of the stress tensor are compressive in rolling of the balls. Statistical analysis of the data from weighing of the rolled balls (diameter 93 and 125 mm) shows that the mass deviates from the required value by no more than 1%. Measurement of the hardness over the diametric cross section of the balls shows that there is no decline in hardness in the internal layers. That indicates high quality of the ball core.     

Phlebotomines (Diptera: Psychodidae) focusing visceral leishmaniasis in the State of Mato Grosso do Sul, Brazil

INTRODUCTION: In the Americas, Lutzomyia longipalpis has been incriminated as the vector of visceral leishmaniasis in almost all the areas in which this disease has been reported. The notification of human cases of visceral leishmaniasis and the presence of dogs with an appearance suggestive of the disease in the country of Corumbá, Mato Grosso do Sul State, Brazil, led us to undertake an entomological investigation in this area, for the purpose of identifying the phlebotomine vector. MATERIAL AND METHOD: The county of Corumbá is located in the Pantanal region and its urban area is situated at 18 degrees 59' 44" South and 57 degrees 39' 16" West. The research project was carried out in peri and intradomiciliary environments, in three urban districts, one of which was central and the other two on the outskirts, and in a cave situated outside the urban perimeter. Most of the captures were made weekly with light automatic traps, in the period from February 1984 to December 1986. Meteorological data for this period were obtained from the city's meteorological station and those for the period from 1925 to 1982 from the literature. RESULTS: The urban phlebotomine fauna consisted of eight species and was similar to that of the cave, except that in the latter the species were more abundant. Lutzomyia cruzi was predominant in the peri and intradomiciliary environments. Its prevalence in the central district was of 90.3% and lower in the outskirts. Lu. forattinii presented considerable prevalence (39.0%) in one of the outlying districts too. In the cave, Lu. corumbaensis was the predominant species, followed by Lu. sordellii, Lu. forattinii, Lu. peresi and Lu. cruzi. The impact of the climatic condition and the action of insecticides in the urban area on the frequency of the species, as well as the use of the cave as a breeding ground by the phlebotomines, in view of the changes in the sex rate, are commented. Data on anthropophily and captures of Lu. forattinii using dog bait have been added. CONCLUSION: The predominance of Lu. cruzi in the urban area; the great prevalence of Lu. forattinii in most of the outlying areas studied and the anthropophily of this latter species, as well as the strong affinity of these species with Lu. longipalpis, the main vector of visceral leishmaniais in other areas of the Americas, suggest the participation of both in the transmission of the disease in Corumbá.     

热轧精轧侧导板控制方法的改进

1750热轧线在生产薄规格时经常由于轧烂,破坏轧制稳定性,严重影响产品质量。究其原因都是由于带钢尾部在机架内跑偏、甩尾等原因造成轧烂。介绍了通过对控制方法优化的改进,将侧导板开口度按带钢头部、中部、尾部分段设定,实现侧导板开口度多次摆位控制方法,保证了带钢沿轧制中心线稳态运行。     

频率域激电法在广西某金矿区的找矿应用

广西某金矿区内广泛分布炭质岩,使得矿区整体电阻率偏低,加大了异常体的分布范围,对区分矿致异常及进一步缩小找矿靶区产生了干扰。为了满足深部找矿的勘探要求,在该矿区开展了激电中梯扫面和激电测深等一系列双频激电工作。通过重点把握中、高极化的激电异常区,再结合低阻构造带进行找矿靶区的初步圈定,最后对主要异常区和构造带开展激电测深验证。根据视幅频率和视电阻率确定了4个激电异常区并划分了5条构造带,验证结果表明：1、2号异常区分别与1、2号构造带吻合较好,推测异常是由断裂带或破碎带周边的炭质地层和金属硫化物引起的;3号异常区位于3号构造带与5号构造带相交处,且有向北延伸的趋势,推测异常主要由炭质地层所引起;4号异常区内没有相应构造带的控制,难以对异常源进行合理推断。根据上述勘探结果,圈定了3个地球物理找矿靶区,通过与激电测深反演以及后期的钻探资料进行比较,验证了双频激电法对本金矿区找矿的指导意义,为进一步地质勘探工作提供了科学依据,也为今后开展相关的电法工作提供了思路。