模拟”机架空过”对CSP铌微合金钢组织演变的过程

 针对CSP工艺轧制含Nb、V微合金钢时采用的“机架空过”工艺,本文在采用实测轧制数据验证组织演变模型的基础上,模拟了F2和F3机架空过工艺对组织演变和平均流变应力(MFS)的影响。结果表明,对本文模拟的钢种,与常规轧制工艺相比,在不降低道次温度的情况下,采用F2机架空过时,可避免混晶,且各道次平均流变应力波动较小。而采用F3空过时,易产生混晶,平均流变应力波动较大。     

CSP工艺轧制低碳锰钢组织演变模拟

为了选择合适的模型来模拟CSP工艺轧制低碳锰钢的组织变化,首先采用Jonas、Sellars、Saito、Yada等人开发的模型进行模拟,然后采用轧卡试验进行了工业试验验证.轧卡试验和计算结果表明:Jonas模型预测的晶粒尺寸在第一道次较实测值偏小,而在最后几道次较实测值偏大;Yada模型预测值较实测值偏小;Sella...     

CSP工艺冷轧微碳钢组织演变研究

采用CSP热轧板为原料,设计了两个成分的微碳钢,对其生产加工过程中的热轧样、冷硬样、退火样及平整后的样板进行了金相显微镜和扫描电镜观察,研究了各个加工过程中金相组织变化、晶粒度变化及Fe3C的析出演变规律。结果表明:CSP热轧板组织均由铁素体和不连续链状碳化物组成,冷轧退火后链状碳化物逐渐均匀,并成连续链状分布在晶界上;碳含量对组织晶粒度有一定影响。     

EAF CSP流程铌微合金钢混晶的分析及控制

基于传统流程的铌微合金化技术,结合EAF CSP流程的工艺特点,通过光学显微镜分析、化学相分析及热模拟实验研究等方法,分析了EAF CSP流程铌微合金钢混晶组织的形成原因。根据以上研究,调整了EAF CSP流程各生产工艺控制,成功解决铌微合金钢的混晶问题。     

Al-Bi过偏晶合金显微组织演变的数值模拟

基于Al-Bi过偏晶合金凝固通过难混溶区阶段产生的液-液相分解及分离的运动行为,采用两相体积平均法,对质量、动量、能量、组分及液滴密度守恒方程进行数值模拟,计算中考虑了形核、扩散长大、Stokes运动及Marangoni运动等多种复杂物理现象的耦合作用,分析了两相运动速度、第二相尺寸分布、第二相体积分数分布以及液滴密度分布对过偏晶合金凝固的显微组织演变及宏观偏析的影响。结果表明,过偏晶合金凝固过程中显微组织演化在不同阶段的主要影响因素不同:凝固初始阶段主要以形核和扩散长大为主;凝固中期和后期第二相迁移运动行为将逐渐占主导作用。凝固过程中,铸件顶角位置首先获得过冷度驱动形核,并以较快的形核速率达到最大形核密度。随着凝固过程不断地进行,第二相小液滴受到的Marangoni力约为Stokes粘滞阻力的两倍,开始由铸件顶角和边缘低温区向中心高温区聚集。凝固时间为1 s时,铸件顶角和边缘第二相小液滴的生长直径和第二相体积分数大于铸件中心位置,而凝固时间为5和7 s时,第二相小液滴直径随铸件中心距离变化的曲线斜率随凝固过程的进行而逐渐变缓,长大速率逐渐变慢。     

X60管线用钢在CSP直轧过程中组织演变规律的实验研究

与传统轧制相比，铸坯在直轧过程中有其不同的特点，因此对其组织演变规律进行研究，对优化生产工艺、生产合格产品至关重要。通过对现场生产的X60管线钢进行轧卡试验，对铸坯以及各道次变形前后的室温组织进行实验研究，结果表明：铸坯组织由表面快冷形成的细晶区和心部的树枝晶区组成；随着变形道次的进行，组织不断得到细化。特别是在第一、第二道次的大变形条件下，组织细化效果显著，为最终得到细小均匀的成品组织奠定了基础。     

冷却速率对高铌微合金钢组织的影响

 采用热模拟和组织显微分析方法研究了不同冷却速率对高铌微合金钢组织的影响。结果表明，铌含量高有利于在极低的冷却速率下获得针状铁素体组织，提高冷却速率则能进一步促进针状铁素体转变，并使铁素体板条得到细化。同时，固溶铌有利于针状铁素体的形成，而铌的沉淀析出则不利于针状铁素体的获得。     

初次再结晶退火对模拟CSP含Cu Hi-B硅钢组织和织构的影响

在实验室用模拟CSP工艺试制Hi-B高磁感取向硅钢薄板（/%:0.07C,3.02Si,0.13Mn,0.020P,0.006S,0.21Cu,0.025Cr,0.016A1,0.004Sn）,该钢经25kg真空感应炉熔炼,铸成41 mm×120 mm板坯-热轧成2mm板-1 120℃常化-冷轧成0.27mm薄板。研究了830~870℃,3~7min退火对再结晶组织和织构的影响。结果表明,0.27mm含Cu Hi-B高磁感取向硅钢板的合适退火工艺为830℃ 5 min,其平均晶粒尺寸为15.6μm,不利织构{111}〈110〉和{001}〈110〉含量较低,有利织构{111}〈112〉分布合理,有利于在二次再结晶退火过程形成良好的高斯组织。     

基于ANSYS的轧机机架牌坊有限元模拟分析

机架牌坊是轧机的重要部件.采用CREO5.0软件建立100 T轧制力的锌板温轧机操作侧机架牌坊三维模型,基于ANSYS17.0软件完成特定载荷下机架的位移变形、应力分布及各阶模态下的振动特性.结果表明:机架牌坊最大变形发生在立柱中段,最大变形量为0.035 mm,最大应力出现在孔系和连接板处,应力值为14.297 MP...     

Analysis on the Microstructure and Performance Evolvement of Alloyed Tool Steel Hot Rolling Strip Produced by CSP Technology

This thesis determinates the microstructure and inclusions of the alloyed tool steel by CSP processing with the help of SEM.The results show that the slab microstructures are the fine branched crystalline grains and the branch width has little disparity from the surface to the central region.For the product,the grain microstructures are fine pearlites and few ferrites with the pearlite space 0.4μm to 0.2μm.     

轧制工艺对CSP线热轧汽车用高强钢板组织特征的影响

研究了薄板坯连铸连轧(CSP)工艺生产高强度汽车用大梁板的工艺控制参数与力学性能和显微组织间的关系.根据柔性工艺控制的指导思想,在珠钢电炉CSP流程下实现了生产不同级别高强度钢板的柔性轧制工艺.利用扫描电镜和透射电镜研究了其组织和强度差异产生的原因.研究表明,钢板最终组织为多边形铁素体和少量珠光体组成,平均铁素体晶粒尺寸约为3.7~5.6μm;当降低卷取温度,部分渗碳体已破碎成细小的碳化物粒子分布于铁素体基体上,钢板中有少量贝氏体出现.     

CSP辊底式加热炉温度控制分析

分析了CSP辊底式加热炉温度控制的特点,指出影响坯料温度的因素、温度变化状况;对影响板坯加热的主要技术因素进行了初步研究,并介绍了该炉型板坯温度的控制方法与经验。     

Mechanism of Black Strips Generated on Surface of CSP Hot-Rolled Silicon Steel

Because of the effect of silicon on the formation of oxide scale, black strip defect is common on the surface of compact strip production (CSP) hot-rolled silicon steel, which leads to difficulty in pickling process compared with plain carbon steels. Although high-temperature oxidation of Fe-Si alloy has been discussed a lot, few studies have explained the mechanism of black strip defect generated on the surface of hot-rolled silicon steel and proposed means to prevent it effectively. Thermogravimetric analyzer (TGA) is used to simulate oxidation of Fe-2. 2Si alloy for 30 min under air condition, and temperature range is from 1000 to 1150°C. Effect of rolling deformation on scale morphology is also discussed. Electron probe microanalysis (EPMA) is used to analyze cross-sectional morphology and elemental distribution of the oxide scale. Schematic diagram of formation of black strip defect is obtained, which helps to provide theoretic basis for proposing of solutions for the problem. It is proposed that lowering furnace temperature and shortening time to stay at high temperature condition after rolling will be helpful to relieve the black strip problem.     

CSP生产Ti微合金化高强钢中纳米碳化物

采用光学金相、电子显微术和化学相分析的方法并结合热力学计算,分析了紧凑式带钢生产(CSP)的Ti微合金化高强钢中的析出物及其析出规律.研究发现:高强钢中存在微米尺寸的立方TiN析出和大量纳米尺寸的析出物粒子;钢中MX相(M=Ti,Mo,Cr;X=C,N)的质量分数为0.0927%,其中10 nm以下的析出物占26.9%;均热之前和均热过程TiN已基本全部析出,连轧前TiC不具备析出的热力学条件;降低钢中N和S含量、严格控制卷取温度可增加TiC的体积分数,降低γ→α相变温度可以阻止细小碳化物长大.结果表明,析出物总的沉淀强化效果约为156 MPa,并能通过化学成分和工艺的控制进一步增强.     

Mathematical Modelling on the Microstructure Evolution of X60 Line Pipe Steel during CSP Hot Rolling

 An integrated process modelling system for simulating the microstructure evolution of Nb-microalloyed HSLA steel produced in CSP hot rolling process has been developed on the basis of the microstructure simulation and mechanical properties prediction technology. Thermo-mechanical coupled finite element models for simulating hot strip rolling have been developed and the distribution of equivalent plastic strain through the thickness direction in the rolled material of CSP rolling was carried out. Thus the distribution of temperature, strain and strain rate through the thickness of the steel stocks, as well as the microstructure evolution during hot rolling of X60 line pipe steel strip have been investigated by using the developed integrated process modelling system. In addition the determination and optimization of controllable process parameters during CSP hot strip rolling for the Nb-microalloyed X60 line pipe steel have been implemented, and control strategies such as adopting larger pass reduction in the first stand, and arranging appropriate pass interval times and proper rolling speed, to reduce or eliminate mixed-grains microstructure of Nb microalloyed strip in CSP processing have been proposed.     

CSP流程中B对低碳Al镇静钢组织及力学性能的影响

研究了B元素对CSP流程生产的低碳Al镇静钢热轧钢带的组织及力学性能的影响,探讨了B元素在CSP流程中的析出规律及对AlN和MnS析出行为的影响.试验结果表明:B元素能够起到使钢带组织软化的作用.在连铸过程中B与N结合形成粗大的BN粒子,减少了钢中固溶氮的质量分数,抑制AlN细微颗粒的析出,减少了铁素体组织细晶强化及AlN析出强化的作用,从而降低了材料的强度.     

Analysis on Microstructure Characteristics and Precipitation Behavior of Automobile Beam Steels Produced by Compact Strip Production

 The microstructure characteristics and precipitation behavior of automobile beam steels produced by Compact Strip Production (CSP) were investigated by use of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy. The result shows that the final microstructure is mainly of polygonal ferrite and small amount of pearlite, the average ferrite grain size is about 3～6μm. Small amount addition Ti to aluminium-killed steel can help to refine the microstructure and improve the mechanical properties. A large number of fine precipitates have been observed in automobile beam steels. The mean particle size is about 10～30nm. Remarkable strengthening and grain refinement can be obtained by these nano-particles.