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HANBin LIUXiang-hua WANGGluo-dong SHEGuang-fu 《钢铁研究学报(英文版)》2005,12(1):12-16
Therearethreemajordifferencesbetweenthenewlydevelopedhotstripcoolingsystemandthecon ventionalsystem .Firstly ,newtemperaturemathemat icalmodelisdevelopedwithmoreaccurateconsidera tionsontemperaturedependenceoftheheattransfercoefficient,phasetransformation… 相似文献
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在实验室用真空感应炉冶炼复相钢和马氏体钢,锻坯、控轧成3 mm厚的板材后采用不同冷却模式进行控制冷却.研究了成分、冷却工艺对组织与力学性能的影响.结果表明:卷取温度降低,钢的强度上升,伸长率下降,组织由铁素体 珠光体向贝氏体、马氏体转变;低温卷取时钢的强度主要取决于碳含量,硅含量的提高使钢的强度和塑性均有所提高;分段冷却对组织与性能的影响较复杂.通过不同的控制冷却工艺实现了用相同的成分获得不同强度等级要求的汽车用先进高强度钢. 相似文献
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A mathematical model to predict steel bar thermal behaviour during continuous quenching after the finishing mill has been developed. The model includes process variables, such as finishing rolling speed, finishing temperature, rod size and chemical composition, water flowrate and mechanical design of the cooling device. It was found that empirical correlations for the heat-transfer coefficient belonging to water spray systems are suitable to simulate fast cooling employing submerged water-cooling tubes. Martensite depth is strongly influenced by the bar diameter and water velocity inside the submerged tube. Mist spray systems are not as effective as submerged tubes for cooling steel bars, although, the initial cooling rates are higher. The % volume of martensite is a direct function of the self-tempering temperature, and independent of the fast cooling device. 相似文献
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《Baosteel Technical Research》2010,(Z1):56
Hot-rolled wide strip for production of large diameter,heavy gauged(up to 19 mm) helical line pipe grade X80 was a priority development over the last three years.Microstructure,texture and mechanical properties of strips have been characterised.Also the welding conditions have been simulated.The favourable microstructure is achieved by the proper selection of an appropriate chemical composition of low carbon content and increased niobium micro alloying in combination with suitable strictly controlled hot-rolling parameters.The addition of niobium in combination with the adjustment of other alloying elements increases the recrystallisation stop temperature and thus makes it possible to apply a high temperature processing(HTP) concept.The homogeneous bainitic microstructure across the strip gauge is then formed during accelerated cooling on the run-out table of the hot-rolling mill.All results indicated excellent properties of these hot strips which make it suitable for spiral pipes of grade X80 for example 18.9mm×Φ1 220 mm at dimension. 相似文献
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The need for accurate prediction and control of cooling profiles of steel strips on runout tables has led to the development of a mathematical model that is able to predict coiler temperatures under any given condition with an accuracy of ± 14 °C as well as calculating the entire temperature profile of a steel strip with sufficient accuracy. Comparisons with online strip temperature data at various locations of the runout table, which were obtained by a new experimental procedure, show that the effect of single cooling headers on the thermal response of a steel strip can be predicted. The model takes into account all relevant thermodynamic effects by means of a statistical approach. Heat transfer to the environment, steel thermophysical properties and phase transformation are modelled using B‐splines. Model adaptation is realised by fitting calculated and measured coiler temperatures of approximately 40000 strips with a least square method in order to gain optimal base values for the B‐spline functions. During model development special attention was paid to the model's capability of being re‐adjustable to a large variety of conditions as well as its local behaviour. Therefore, concepts like temperature‐dependent heat transfer coefficients, which are applicable only to one specific plant, have been avoided in favour of a more generalised formulation of the model that helps to gain insight into the physics of the processes involved, i.e. heat transfer of subcooled jet impingement boiling and film boiling. It was found that both cooling water and steel surface temperature have a large influence on heat transfer whereas the influence of strip speed can be neglected. 相似文献
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介绍了SPHC产品的化学成分和力学性能标准,针对SPHC钢带镰刀弯、边部黑线等问题,从工艺优化、改善钢带力学性能方面进行了理论分析,制定实施了相应技术措施.对实物质量进行了检测,产品的屈服强度和抗拉强度分别提高20 MPa和10 MPa,伸长率基本不变,产品质量大幅度提高. 相似文献
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To gain insight into the effects of various parameters controlling the thermal behaviour of a quenched steel strip during the process of accelerated cooling by an array of planar water jets, a parametric study has been performed using a previously developed and validated mathematical model. The behaviour of the strip was characterized by its coiling temperature, top and bottom surface temperature variations and heat extraction in the jet impingement region, top surface heat extraction in the film boiling region, and top and bottom surface thermal penetration depths. Parametric variations included cooling system design conditions, such as the top and bottom nozzle widths, and operating conditions such as the top nozzle discharge velocity, the cooling water temperature, and the ratio of volumetric water flow rates applied at the top and bottom surfaces. The effects of steel strip parameters such as strip thickness and strip velocity were also considered. 相似文献
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LIUZheng-dong DQJin IVSamarasekera JKBrimacombe 《钢铁研究学报(英文版)》2005,12(2):37-44
Aconventionalhotstripmillconsistsmainlyof areheatingfurnace,descalingunits,roughing stands,finishingstands,runouttableanddowncoil ers.Metallurgicalprocessesofsteelstripassociated withhotrollingareausteniterecoveryandrecrystal lizationinrollingstands,pha… 相似文献
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《钢铁冶炼》2013,40(1):93-96
AbstractShape defects are found in hot rolled steel strip when unwrapping tightly wound coils. This problem is particularly acute in thin strips that were considered to be defect free while processing. A model developed to predict the occurrence and magnitude of such defects in hot rolled low carbon steel strip is described in the present paper. The model assumes that the strip is free of shape defects as it exits the last stand of a continuous mill, but, as a result of processing conditions, thermal and microstructural gradients are present across the width of the strip. It is considered that the variation of ferrite and austenite mixture is caused by the chemical composition of the steel and the actual temperature of the strip. On cooling to room temperature, the distribution of both temperature and microstructure will cause variation in the local contraction that the steel is subjected to, and will promote shape defects. 相似文献
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用于生产热轧不锈带钢的1780mm热连轧机设备功能强,工艺技术先进。该轧机的建成投产标志中国不锈热轧带钢装备达到国际先进水平。通过热轧工艺的研究,在达到轧机设计能力的同时,使热轧不锈带钢性能不断提高。实际生产表明1780mm热连轧机在生产不锈带钢方面正在发挥越来越重要的作用。 相似文献
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This study explores the reasons underlying the frequent appearance of “marking problem”during the production of double-walled copper-brazed steel tubes.To this end,we compared two types of copper-coated steel strips,of which one has almost no problem during production,whereas the other has higher number of incidences of“marking problem”.We analyzed the chemical composition,mechanical properties,the cross-sectional metallographs, and surface quality of the trimmed edge in both types of specimen.After the roll forming process,the bonding condition between the steel layers of the tubes before and after brazing process has also been examined.Results indicate that the chemical composition and mechanical properties of the two kinds of strips are similar;however,the edge quality of the trimmed strips is significantly different.It is believed that the irregular shape of the edge portions in the strips will be more pronounced during the bevel treatment.Consequently,smooth and tight seams cannot be guaranteed by such uneven beveled edges,which lead to higher number of incidences of “marking problem”during production. 相似文献
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冷却控制策略的好坏对带钢的力学性能至关重要,对冷却控制策略的评价是一个值得研究的问题。在对带钢冷却实际过程进行分析的基础上提出了一个带钢冷却控制过程的仿真方案。该仿真方案能再现生产过程中温度控制的实时数据和控制效果,为带钢冷却控制程序模块的运行情况提供了一种离线的调试和分析手段,对研究冷却控制策略、改进冷却控制系统有着重要意义。 相似文献
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《钢铁冶炼》2013,40(8):618-627
AbstractTraditionally, mechanical property estimation is carried out by destructive testing, which is costly and time consuming. Sometimes, the time schedule in the mill is so tight that coils are dispatched, while the samples are still under investigation; thus, knowledge of the strip quality immediately after rolling without mechanical testing can save a lot of time and money. As the rolling process is complex and final mechanical properties of steel depend on many parameters, it is almost impossible to develop an accurate first principle based mathematical model, so an artificial neural network based model to predict the mechanical properties of hot rolled steel strip has been developed. This paper describes the neural network based online system that helps in predicting mechanical properties of interstitial free (IF) steel strip and also elaborates how this models can help in capturing various metallurgical phenomena during rolling. 相似文献
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固定化学成分和其他工艺参数,研究了紧凑式带钢生产卷取温度变化(625和579℃对Ti微合金化高强钢组织和力学性能的影响。热轧带钢的力学性能测试表明,卷取温度降低后,屈服强度降低205 MPa,而-20℃冲击功由11.7J增加到47 J。采用光学金相、电子显微术等手段分析了钢中组织和析出物,625℃卷取带钢为铁素体组织,579℃卷取带钢组织更为细小,贝氏体特征明显;而卷取温度降低后纳米尺寸碳化物的数量显著减少,由此降低了沉淀强化效果,造成强度大幅下降,并与组织细化一起改善材料的韧性。卷取温度是Ti微合金化高强钢生产中重要的工艺参数,需要严格控制。 相似文献