Surface inclusions and their evolution on strip rolled on CSP line and in following cold rolling process

Abstract

Hot and cold rolled strip samples with surface defects such as black pockmark, sliver and central cracking were collected from a compact strip production line followed by cold rolling. Microstructures and chemical compositions of the strip with defects were studied by scanning electronic microscopy and energy dispersive X-ray spectroscopy. Four typical types of defects on strip including surface spherical mould powder entrapment, centre spherical mould powder entrapment, surface linear mould powder entrapment and centre linear mould powder entrapment were studied by hot and cold rolling experiment in laboratory. It was observed that spherical mould powder entrapment was transformed into the surface black pockmark after the hot rolling and cold rolling process. Centre spherical mould powder entrapment led to central fracture in the hot and cold rolling process. Surface linear mould powder entrapment resulted in sliver and centre linear mould powder entrapment led to severe sliver.     

Effects of powder material and process parameters on the roll compaction,sintering and cold rolling of titanium sponge

ABSTRACT

Roll compaction is a powder metallurgy process that has the potential for cost reduction in the production of titanium parts. In this study, experiments were carried out to investigate the effects of powder type and size on the roll compaction and subsequent sintering and cold rolling behaviour of titanium powder. Powders used ranged in upper sieve sizes from 0.15 to 3?mm. Strip density was found to increase with decreasing powder size while thickness decreased. Following sintering in the range of 800–1200°C, cold rolling was performed with various levels of thickness reduction. Average (across the width) densities of up to 88% were achieved, with higher density regions in the middle of the strips reaching up to 99%. Roll force was measured during cold rolling and found to increase with increasing final (post-cold rolling) density and also with increasing roll gap reduction amounts.     

大功率陶瓷发射管栅极用TZM薄板工艺研究

进行了烧结、轧制工艺对比试验,研究了合金粉末粒度、烧结温度、中间热处理工艺对TZM合金微观组织、性能以及轧制过程的影响,探讨了影响大功率陶瓷发射管用TZM薄板表面质量的主要因素。结果表明：减小TiH2和ZrH2粉末粒度和适当提高烧结温度,可生产适合轧制TZM薄板的板坯,在后续冷轧过程中可明显减少起皮缺陷的产生;TZM烧结板坯于1350—1450℃开坯可保证轧制正常进行;轧制总加工率达到70％,板材厚度约8mm时,进行1550℃退火处理,可避免后续冷轧过程中分层现象的产生;按上述工艺生产的大功率陶瓷发射管栅极用TZM薄板室温和高温力学性能满足要求。     

Hot rolling of blanks from copper and nickel powders

Summary The authors investigated the hot rolling of preformed blanks from electrolytic copper and carbonyl nickel powders. The blanks were prepared by cold pressing, cold rolling, wedge pressing, and sintering loosely poured powder. The hot rolling was carried out in a special mill, in a hydrogen atmosphere. The investigation showed that at high rates of deformation, a rolling temperature of 0.8–0.9 T_melt, and a reduction of 50% the hot rolling of preformed copper and nickel blanks in one pass can yield strip with a relative density of 100%, a fine-grained structure, and mechanical properties which are not inferior to those of materials obtained by sintering powder compacts or cold-rolled strip.Translated from Poroshkovaya Metallurgiya, No. 6 (66), pp. 25–28, June, 1968.     

Method of calculating the power and force parameters of the cold rolling of porous materials with the aid of a computer

Conclusions On the basis of a comparative analysis of results of numerical experiments carried out by various methods, it is shown that the method proposed by the authors is well suited for practical calculations, with the aid of a computer, of the power and force parameters of the cold rolling of strip. In the present stage of development of cold rolling as a process for the manufacture of powder metallurgy strip, the method could be used for providing starting data in the design of the mechanical units of metal powder rolling mills.Translated from Poroshkovaya Metallurgiya, No. 7(151), pp. 11–21, July, 1975.     

利用热镀锌渣制备超细锌粉的试验研究

利用冷轧厂热镀锌渣为原料,采用蒸发-冷凝法直接制备出超细锌粉。采用新型蒸发装置、冷却装置,考察了最大蒸发温度、恒温时间、保护气体通入量、蒸发物料量、冷却强度等对锌粉收得率及粒度分布的影响。对所得超细锌粉的化学成分、粒度分布、XRD和微观结构进行测试,并讨论了锌粉团聚的原因及对策。     

粉末冶金马氏体-奥氏体复合钢的组织与性能研究

近年来，汽车、建筑等领域对高强度-高塑性金属材料的需求日益增长，为了获得高强度-高塑性的金属材料，粉末冶金技术发挥着越来越重要的作用。通过放电等离子烧结技术（SPS）烧结质量比为2:1的马氏体钢和奥氏体钢混合金属粉末，复合钢的奥氏体相均匀分布于马氏体相当中，试样致密度高达95.5%，并通过后续的热轧处理，提高复合钢的烧结质量，致密度提高至98.9%。热轧后复合钢的屈服强度、抗拉强度、均匀伸长率和总伸长率分别为960 MPa、1 529 MPa、6.7%和6.7%。在热轧的基础上引入冷轧+短时间高温回火处理，粉末冶金复合钢性能进一步提高。其中冷轧30%/500℃回火5 min的复合钢，屈服强度、抗拉强度、均匀伸长率和总伸长率分别为1 899 MPa、1 964 MPa、9.2%和10.0%。     

Texture of Cold Rolled Strip of Fe-3Si Steel Produced by Thin Slab Casting and Rolling

 The hot rolled strip of Fe-3Si steel was experimentally produced by thin slab casting and rolling (TSCR) process in the laboratory. The texture evolution rule was investigated during hot rolling and cold rolling. The texture distribution of cold rolled strips with four kinds of cold rolling reduction schedules was observed through X-ray diffraction method, and the orientation density variation of 1/16 layer, 1/8 layer, 1/4 layer, and 1/2 layer in thickness was analyzed. The cold rolled texture of steel A with four kinds of cold rolling reduction schedules was mainly composed of α and γ fibers. Cold rolling reduction ratio of 70% was more beneficial for obtaining more γ fibers. The γ fiber texture orientation density of {111}<011> and {111}<1 12> was the largest on the 1/8 layer and 1/4 layer and the least on the 1/16 layer and 1/2 layer for steel B. The texture orientation density of {001}-{223}<110> in the α fibers for steel C was increased, but the texture orientation density of {332}-{110}<110> was low.     

轧制方式对SUS430铁素体不锈钢组织和性能的影响

 采用X射线衍射技术和光学显微分析等方法,研究了同步和异步冷轧方式对SUS430铁素体不锈钢微观组织、织构演变以及力学和成形性能的影响。结果表明,与同步冷轧相比,由于异步轧制剪切变形的引入,可使异步冷轧板材的平均晶粒尺寸减小。在同步冷轧过程中,其二次冷轧再结晶织构为完整的γ纤维织构,导致铁素体不锈钢的最终性能优于同步一次冷轧;而在异步冷轧过程中,异步一次冷轧再结晶织构为强点{111}<[1][1]2>的γ纤维织构,异步二次冷轧再结晶织构属于随机取向织构,其结果是异步一次冷轧板材的性能优于异步二次冷轧。综合分析表明,与异步二次冷轧方式相比,同步二次冷轧方式有利于铁素体不锈钢性能的提高。     

酸再生提高氧化铁粉质量浅析

介绍了邯钢冷轧厂所引进的ANDRITZ酸再生生产工艺;结合该厂酸再生运行情况,分析了影响酸再生副产氧化铁粉质量的因素;并提出了提高氧化铁粉质量的方法且加以实施,使氧化铁粉质量达到生产软磁用粉标准。     

Manufacture of steel-aluminum wire by the powder metallurgy method

Summary This investigation showed that it is possible to produce bimetallic steel-aluminum wire by the hot rolling of aluminum powder onto a steel wire followed by cold compacting rolling and drawing.The mechanical and technological properties of a wire made by this method satisfy the requirements of the cable industry.The conductance of the cermet aluminum part of the wire is the same as that of aluminum rolled from ingots.A special mill has been developed for rolling bimetallic steel-aluminum cermet wire.The investigation being described was initiated by A. G. Makarov, Chief Scientific Officer of the State Committee on Electrical Engineering at the State Planning Commission of the USSR, and was carried out under the supervision of I. M. Fedorenko, Academician of the Academy of Sciences, UkrSSR.     

冷轧锯片钢喷粉起泡问题分析及解决措施

为了研究冷轧锯片钢65Mn在客户使用过程中出现喷粉后起泡现象的原因,通过扫描电镜对起泡位置及基板表面进行观察,起泡位置表层存在针眼状孔洞,基板表面存在密集分布的微小裂纹。通过光学显微镜及荧光分析对基板组织及表层成分进行分析,基板表层存在5~10μm的脱碳层,其深度与裂纹深度相当。分析表明,在客户酸洗锯片钢过程中酸液在微裂纹内部残留,在喷粉过程中与基板反应生成气体,是造成65Mn喷粉起泡的主要原因。控制热轧加热温度及保温时间改善脱碳现象,配合冷轧过程加入一次罩式退火可改善带钢表面微裂纹,能有效控制喷粉起泡问题的发生。     

在酸再生机组提升氧化铁粉质量的探索与实践

介绍了宝钢不锈钢冷轧厂ANDRITZ酸再生生产工艺.结合酸再生机组生产氧化铁粉的过程,分析了影响氧化铁粉质量的因素,通过探索和改进,氧化铁粉质量得以有效提升,达到了生产软磁用铁粉的标准.     

基于组织均匀性的690合金管冷轧及退火工艺优化

针对国产690合金成品管晶粒组织均匀性控制差的问题,引入不均匀因子Z评定组织均匀性,设计单、双道次冷轧和退火实验.实验结果表明:690合金荒管经变形量50%的单道次冷轧,在1100℃下保温5 min的中间退火处理后晶粒组织最均匀;荒管经一二道次变形量依次为50%、70%的双道次冷轧,两道冷轧工序之间采用1100℃保温时间5 min的中间退火,最后在1060℃下保温5 min或者1100℃保温3 min进行固溶处理获得的组织均匀性最好.      

五机架冷连轧机的负荷分配计算

针对八辊五机架全连续冷连轧机在轧制过程中的特点,在综合考虑了轧机产量和产品质量的前提下,用多目标优化问题的求解方法对多辊冷连轧机的轧制策略进行优化,确定各机架的负荷和待轧带钢的目标厚度,并开发了河北中钢1 250 mm八辊五机架全连续冷连轧机的负荷分配计算程序。通过现场实例证明,该方法精度高、速度快,可满足在线控制需求,是一种适合多辊全连续冷连轧机的负荷分配方法。     

5+1型轧机高强钢五道次模式轧制规程优化

 某钢厂新建主要用于轧制超高强钢5+1型冷连轧机组,其第4机架采用小辊径轧机,其他机架采用普通轧机。在实际生产中,该机组同时负责其他钢种的轧制,为了避免出现轧制能力过剩等问题,基于能耗节约与稳定轧制的综合考虑,针对高强钢的轧制,5+1型冷连轧机组采用5道次模式进行轧制。在减少1个道次的情况下,为保证产品质量和轧制稳定,对机组的轧制规程提出了更高的要求。综合出口板形质量、总压下量、机组轧制过程稳定性等因素考虑,结合小辊径轧机的特点,对5+1型冷连轧机组5道次高强钢模式下的机组进行了取舍。基于出口板形分布对压下规程进行分配,在此基础上,利用两种轧机机型的特点对压下规程进行精调。张力制度的优化目标以保证小辊径轧机轧制稳定性为主,其次通过优化张力调节各个机架的出口板形,令其与压下规程优化的结果共同作用,对整体机架轧制的稳定及出口板形的优化形成互补,从而开发了5+1型冷连轧机组高强钢5道次轧制模式下的轧制规程综合优化设定技术。在轧制模式减少了1道次的情况下,优化了机组轧制高强钢的出口板形,提高了产品的质量,在减少小辊径机组打滑、振动趋势的同时,最大程度上保证了轧制的整体稳定性,大大提高了整个机组的经济效应,具有进一步推广应用的价值。     

基于改进混洗蛙跳算法的冷连轧轧制规程优化

 轧制规程优化是使轧制过程达到最佳状态的重要保证。综合考虑影响冷连轧轧制过程的多种因素,以等功率裕度和克服划痕为目标函数,建立了轧制规程多目标优化模型,并采用自适应混沌变异蛙跳算法对轧制规程进行优化设计。该算法是在基本蛙跳算法中,加入自适应混沌变异操作,具有较好的寻优精度和收敛速度。对某钢厂1370mm冷连轧机轧制规程进行优化的结果表明,优化后的规程较好地实现了各机架等功率负荷分配,降低了划痕出现的概率和程度,大大地提高了产品质量,增加了经济效益。     

Human infection with Trypanosoma cruzi induces parasite antigen-specific cytotoxic T lymphocyte responses

Experimental models of Chagas' disease, an infection caused by the intracellular protozoan Trypanosoma cruzi, have demonstrated the crucial immunoprotective role played by CD8(+) T lymphocytes. These cells dominate inflammatory foci in parasitized tissues and their elimination from mice leads to uncontrolled parasite replication and subsequent death of the infected host. A trypomastigote surface antigen, TSA-1, and two amastigote surface molecules, ASP-1 and ASP-2, were recently identified as targets of CD8(+) cytotoxic T lymphocytes (CTL) in T. cruzi-infected mice. Until now, however, there was no evidence for the development of parasite-specific CTL in T. cruzi-infected humans. In this study, human CTL specific for TSA-1-, ASP-1-, and ASP-2-derived peptides were detected in the peripheral blood mononuclear cells from 21 of 24 HLA-A2(+) T. cruzi-infected patients. CTL recognition was antigen specific, A2-restricted, and CD8(+) T cell-dependent. Demonstration of human CTL against T. cruzi and against target molecules identified using the murine model provides important information for the optimal design and evaluation of vaccines to prevent or ameliorate Chagas' disease.     

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The general cold rolling mill cannot dynamical display and quantitative control the section properties of strip due to lack of profile gaugemeter. To this problem, through a large number of field trials and theoretical studies, taking the general four-roll cold rolling unit as research object, comprehensive considered the equipment and process characteristics in tandem cold rolling process, based on the strip thickness distribution mechanism model of tandem cold rolling, a whole set of design method for the virtual profile gaugemeter and the feedback control technology for section properties was put forward. It make full use of incoming materia??s section configuration data which come from the profile gaugemeter of hot rolling unit, and the real-time rolling process parameters, such as rolling force, tension, roll bending force and roll tilt amount, which come from the level 1 of tandem cold rolling unit. It can not only dynamical display the section configuration of cold rolled product and dynamic forecast the wedge quantity and plate crown, but also feedback control the section properties of strip. The section quality of cold rolled steel strip product was greatly improved. This technology should be used widely.     

冷连轧升降速过程板形变化及其张力补偿技术

 针对冷连轧升降速过程中轧制压力的波动造成冷连轧机组升降速阶段轧制不稳定和板形质量不佳等问题,为了减小轧制力波动,获得优质板形,在结合冷连轧机组的设备及工艺特点的前提下,充分考虑到乳化液流量充足与不足两种情况下轧制速度的波动对轧制压力变化的影响,分析了冷连轧升降速过程中板形演变机理。在此基础上,以冷连轧机组升降速过程中整体轧制压力波动最小为目标函数,开发了一套相应的张力补偿模型,并将其应用到某1 800五机架冷连轧机组的生产实践,取得了良好的使用效果,有效提升了轧制稳定性与板形质量,具有进一步推广应用的价值。