Orthogonal tests of lead-clad tin bimetal continuous casting by air pressure core-filling

To provide theoretical basis and practical guidance for preparing composite rods of external diameter no larger than 12 mm by directly continuous casting, low melting point materials of lead and tin were selected to prepare composite rods of external diameter 12 mm and inner diameter 8 mm with air pressing core filled continuous casting process. The orthogonal tests consisting of three factors and three levels were designed to investigate the parameters of melting lead temperature, continuous casting speed and air pressure that affect the performance of the composite rods. The results show that melting lead temperature is the most important factor that influences the solid/liquid interface location; continuous casting speed is the most important factor that influences the surface quality and lead and tin inter-diffusion amount; air pressure can improve the surface quality obviously and make the rods easily drawn out, but the surface quality cannot get obvious improvement when the air pressure is above 0.03 MPa. The composite rods have excellent surface quality, obvious intermediate layer, even thick clad, and metallurgical bonding interface under the condition of melting lead temperature of 375 °C, continuous casting speed of 10 mm/min, and air pressure of 0.03 MPa.     

4145H钢的电炉连铸工艺生产

4145H钢是石油钻铤用钢,对钢水纯净度、非金属夹杂物含量、钢材的晶粒度、中心碳偏析等指标要求严格。采用电炉连铸工艺开展了4145H钻铤用钢的制备研究。结果表明,化学成分调整合格后,连铸过热度为25—35℃、铸速为0．4～0．6m／min、冷却水量为180m3／h时可以拉出280mm×280mm合格方坯。当加热炉出炉温度1160～1170℃、入轧温度965—975℃、缓冷时间46h、出坑温度100～150℃时,可以获得质量合格的西130的4145H轧制材。     

超宽板坯包晶钢连铸初生坯壳应力的数值模拟

利用商业软件计算了超宽包晶钢连铸过程中初生坯壳所受应力.研究结果表明,由于包晶反应引起的体积收缩,包晶成分钢种的凝固坯壳表面应力显著大于非包晶钢成分钢种,在距铸坯中心约200～400 mm处应力出现极大值;随板坯宽度的增加,坯壳表面应力增大,应力极值点向坯壳中心方向移动;连铸工艺参数直接影响包晶钢表面应力大小,随过热度减小,拉速增加,结晶器冷却强度减弱,坯壳表面应力减小,铸坯表面裂纹发生概率降低.在本研究条件下,对断面为3 200 mm×150 mm的铸坯,适宜的过热度为15～25℃,拉速为1.2 m/min,结晶器宽面冷却强度为5 500 L/min.     

基于有限差分法的单晶热型连铸凝固过程的数值模拟

采用有限差分法对金属单晶热型连铸凝固过程的温度场进行数值模拟,对不同工艺组合下的液固界面曲线进行分析和比较,确定了连铸速度、冷却水流量、冷却距离、铸型温度等主要工艺参数对液固界面位置和形状的影响,其中连铸速度对凝固界面形状的影响不大,但对其位置的影响较大;改变冷却水流量和冷却距离均可调节冷却强度,相比之下,冷却距离对液固界面的影响更大;铸型温度对固液界面位置的影响较大,应进行准确控制。实际操作中可采用较小的冷却距离,同时适当提高连铸速度,保持铸型温度略高于金属熔点。     

Q235小方坯连铸过程中凝固特性的研究

分析了Q235凝固时的结晶特性,柱状晶容易生长.数值计算了小方坯连铸机在2.6 m/min拉速、不同二冷配水下铸坯的温度场和凝固前沿温度梯度.在弱水冷却时,铸坯坯壳凝固前沿温度梯度比较小,得到细小的柱状晶和少量等轴晶.连铸坯中间裂纹主要与二冷水相关,合适的二冷配水可降低或消除中间裂纹.     

连铸结晶器内钢液流场的数值模拟

采用商业软件,针对连铸机结晶器的结构和工艺参数,进行了流动过程的三维数值模拟,分析了浸入式水口的浸入深度、水口侧孔倾角和拉速对结晶器内钢液流动的影响.结果表明,合适的浸入深度、水口侧孔倾角和拉速有利于夹杂物的上浮,减小液面波动.     

Process parameters of manufacturing single crystal copper by heated mold continuous casting

1Introduction Withthedevelopmentofthetechnologyinelectron ics,telecommunicationsandAV,itisnecessarytotrans ferallkindsofsignalswithahighfidelity(Hi Fi)anda super definitioninordertomeettheincreasingrequire mentsoftelecommunicationsandmodernsciencetechnol …     

Investigation of Cast Copper Structure

In this paper, the results of exploration macrostructure and microstructure of continuous cast copper bars are shown. Quantitative parameters of copper cast bars depending on the speed of continuous casting are rated. It is fixed that independent of speed of casting the macrocrystalline columnar structure consisting of four zones is formed. By means of raster electron microscopy, the microstructure of cast copper is studied. It is determined that the accumulations of eutectic Cu-Cu20 in the form of lines and gas pores by size from 2 to 35 microns at the boundaries grain are observed. With the use of the transmission electron microscope, specific dislocation configuration on cast copper sub-boundary grains is determined. It indicates to high-temperature strain of cupper in the course of cast bar solidification. The important finding can be used for the design technology of copper continuous casting and plastic working of cast bars.     

Deformation behavior of Cu-12wt%Al alloy wires with continuous columnar crystals in dieless drawing process

The microstructure and mechanical properties of Cu-12wt%Al alloy wires which are composed of continuous columnar crystals after dieless drawing forming at drawing speed of 1.0―1.4 mm/s and deformation temperature of 600―900℃ were analyzed, and deformation behavior of the alloy during dieless drawing forming was experimentally investigated. The results showed that in the abovemen-tioned conditions, recrystallization phenomenon was not found during dieless drawing forming. When a drawing speed of 1.0 mm/s was...     

奥氏体与马氏体不锈钢板坯在结晶器内收缩规律与结晶器锥度的研究

针对奥氏体和马氏体不锈钢连铸中的质量问题,对太钢第三炼钢厂结晶器的锥度进行了调查分析.根据铸机和不锈钢的钢种特性,分别计算比较了马氏体和奥氏体连铸坯在结晶器内的收缩规律,分析了连铸工艺参数如拉坯速度、过热度对铸坯收缩的影响规律,在此基础上设计了曲线锥度的结晶器,并在生产实践中取得了很好的效果.     

影响亚包晶钢铸坯表面纵裂纹的因素研究

采用金相、扫描电镜、连续测温等方法对亚包晶钢铸坯表面纵裂纹产生原因进行了系统研究,研究结果表明:当钢水过热度35℃和15℃浇铸时,铸坯表面纵裂纹发生率明显提高;随着拉速的增加铸坯纵裂纹发生率呈上升趋势;在同一拉速条件下,铸坯内弧比外弧更易于生成凹陷和裂纹;结晶器铜板热流密度不均是铸坯纵裂纹产生的主要原因,并在二冷区进一步扩展。     

Q345D板坯连铸凝固传热过程数值模拟

基于凝固传热学理论,以300 mm厚Q345D板坯连铸过程为研究对象,建立了板坯二维凝固传热数学模型。利用等效比热法对凝固潜热进行处理,分析了拉速、过热度、二冷区喷水量以及二冷区长度变化对出结晶器坯壳厚度、铸坯表面温度等凝固参数的影响。结果表明,适当提高拉速、降低过热度和增加二冷段长度,可以促进连铸坯凝固,降低板坯缺陷,提高生产效率。     

塑性变形单晶铜线材织构的研究

将单晶连铸技术制备的直径Φ8 mm工业单晶铜线材,在C733-4/ZF型工业拉丝机上按同一方向冷拔至直径分别为Φ4 mm、Φ2 mm和Φ1 mm的铜线材,应用极图分析和织构定量计算的方法研究了变形量与织构的关系.结果表明:变形单晶铜线材中的形变织构主要为<100>丝织构,也有少量<110>丝织构;随着变形量的增加,<100>丝织构的体积百分数先减小后增加,而<110>丝织构先增加后减小.     

大方坯连铸过程中铸坯传热及凝固行为的研究

结晶器和二冷区传热对大方坯产品质量和铸机的生产率有重要影响，本文讨论了包钢引进的全国最大的方坯连铸机在拉坯时结晶器和二冷区传热情况以及坯壳凝固生长，铸坯温度的变化规律。着重讨论了电磁搅拌，过热度和拉速对坯壳凝固和生长规律的影响，指出控制铸坯凝固的主要因素是凝固潜热，影响凝固未端的最主要因素是拉速，而电磁搅拌对其影响区内的传热和坯壳生长和铸坯温度亦有重大影响。     

不锈钢高速连铸中结晶器的热流计算

在高效连铸过程中,结晶器的传热效率起着至关重要的作用。在进行加拿大国家自然科学基金资助的高速连铸的战略性研究项目时,在Ａｔｌａｓ Ｓｔｅｅｌ钢铁公司的方坯连铸机上进行了１次工业试验,目的是研究高速连铸不锈钢时结晶器的热流变化。试验中,结晶器４壁共安装了４２个热电偶。不同工艺条件下的温度信号以１０Ｈｚ的频率记录在计算机中,根据每点的平均温度,针对ＩＨＣＰ（Ｉｎｖｅｒｓｅ Ｈｅａｔ Ｃｏｎｄｕｃｔｉｏ     

宽板坯凝固前沿轻压下率模型的研究

结合连铸坯凝固规律及轻压下技术改善铸坯中心偏析的冶金原理,建立宽板坯轻压下率理论模型。根据某厂连铸宽板坯实际生产条件,以传热模型计算的铸坯凝固温度数据作为轻压下率模型计算条件,分析拉速、浇注温度、坯壳凝固收缩特性对铸坯轻压下率的影响规律。结果表明,在相同的拉速和浇注温度条件下,铸坯轻压下率沿拉坯方向的分布总体呈减小趋势;拉速较高时的起始轻压下率小于拉速较低时对应的起始轻压下率;拉速与平均轻压下率呈线性递减关系：拉速每升高0.1m/min,平均轻压下率减小0.015mm/m;浇注温度越低,轻压下区起始轻压下率的值越高;浇注温度对平均轻压下率的影响较小,浇注温度每升高10℃,平均轻压下率仅减小0.002 5mm/m;铸坯外部凝固坯壳的收缩对整个轻压下区平均轻压下率的贡献量为20.4%～22.3%。     

Effect of SEN structure on the mold level fluctuation and heat transfer for a medium thin slab caster

It is important to select suitable parameters of a submerged entry nozzle （SEN） for optimizing the flow and temperature patterns in a mold. The effect of SEN design on the mould level stability, meniscus steel flow velocity, and heat transfer of the mold of a medium thin slab caster was studied by means of 1：1 water modeling and industrial testing. The advantages of a 2-port SEN compared with a 3-port SEN are the following： more optimal flow patterns with a lower mold level fluctuation and a lower meniscus steel flow velocity; proper powder consumption without slag bears due to a reasonable liquid powder thickness. The argon flow rate can be reduced and the mold average heat flux and temperature near the edges of the copper plate are reduced. At a casting speed of 2.5 m·min^-1, the mold level fluctuation lies within ＋5 mm. In addition, soft cooling of the steel shell in the mold is realized, which is suitable for casting crack susceptible steel grades.     

二冷强度对连铸小方坯凝固过程影响规律的数模研究

针对连铸小方坯的中心疏松等质量缺陷,建立了凝固传热数学模型,以研究二冷强度对连铸小方坯凝固过程的影响规律,优化二冷制度,改善铸坯质量.本文基于射钉和测温实验所建立的小方坯凝固传热模型精细度较高,用此模型深入研究二冷喷嘴的数量和喷射范围对小方坯凝固传热的影响;经验证,模拟结果与实测结果误差在1.7％以内.利用该模型定量分析了二冷强度对铸坯温度,凝固坯壳厚度和凝固终点的影响规律.结果表明,随着二冷强度的增大,二冷区内的铸坯表面中心温度降低,而进入空冷区后则逐渐趋于一致.二冷强度每增加10％,足辊段出口处温度平均降低8℃,二冷一段出口处温度平均降低10.75℃,二冷二段出口处温度平均降低10.75℃,二冷三段出口处温度平均降低9.75℃,铸坯凝固终点缩短约0.168m.     

Nb微合金化钢异型坯连铸工艺的优化

为了减少Nb微合金化钢连铸异型坯表面裂纹缺陷，研究了Nb微合金化钢的高温塑性，并结合工业性试验，对Nb微合金化钢异型坯连铸二冷工艺制度进行了优化；另外对结晶器用保护渣的理化性能进行了改进，大大提高了Nb微合金化钢连铸异型坯表面质量。     

TGG晶体缺陷的研究

TGG晶体是一种具有高菲尔德常数、低吸收系数、高热导率和高激光损伤阈值的磁光晶体。利用固相法和液相法合成多晶原料,采用中频感应加热提拉法,提拉生长TGG磁光晶体。通过对熔体组分、拉速、转速、热效应分析,得出了生长无缺陷晶体的最佳工艺参数。以液相法合成多晶原料,温度梯度为0.02~0.04℃/mm,拉速为1.0~1.2mm/h,转速为10~15r/min生长出无杂质、无开裂的优质TGG磁光晶体。