Relationships between the surface quality of a single crystal copper ingot and the process parameters of a heated mould continuous casting method

The relationships between the surface quality of a single crystal copper ingot and the process parameters of heated mould continuous casting method were studied experimentally using our own design of horizontal heated mould continuous casting apparatus, and the mechanism by which process parameters affect the surface quality of a single crystal copper ingot is analyzed in the present paper. The results show that the process parameters affect the surface quality of a pure copper ingot by affecting the position of the liquid-solid interface in the mould. The position of the liquid-solid interface in the mould must be controlled carefully within an appropriate range, which is determined through a series of experiments,in order to gain a single crystal copper ingot with good surface quality.     

锌铝合金热型连铸的工艺方法

就热型连铸工艺条件下对具有共晶、包晶和共析转变的5种典型锌铝合金的连续定向凝固进行了研究,找出了各种合金的最佳工艺参数配合范围.研究表明引锭操作是热型连铸工艺的关键环节,型口温度、拉铸速度、冷却条件、合金成分和液位压头对铸锭表面质量有直接影响,型口位置的固液区存在着热和力的平衡.只有通过调节工艺参数,维持固液界面的良好位置,才能拉铸出表面光滑的线材.     

热型连铸Ag-Cu-Zn合金工艺及其组织

在自制的水平式热型连铸设备上,选用合适的工艺参数制备出了表面质量良好、内部组织沿轴向均匀分布的Ag-Cu-Zn合金铸棒.     

热型连铸锌铝合金定向凝固线材的组织分析

对热型连铸锌铝合金定向凝固线材的铸态及热处理组织进行了观察、分析和讨论。结果表明：热型连铸锌铝合金线材的显微组织为定向生长的平行柱状枝晶组织;共晶合金ZA5的枝状芥是的每个枝晶都由多层片状共晶β和η两相构成,过共晶合金的组织为初生树枝晶和枝晶间共晶组织,其中ZA8,ZA12初生相为β相,ZA22和ZA27的初生相是α相。     

热型连铸锌铝合金的缺陷形成与机理

对5种典型锌铝合金在热型连铸工艺条件下的连续定向凝固进行了研究, 探讨该工艺下锌铝合金线材表面缺陷的产生机理, 并对部分缺陷的组织结构进行了显微分析. 结果表明 只有金属液压头、型口温度、拉铸速度和冷却条件诸工艺参数在一定范围内的协调配合, 才能拉铸出表面光滑的锌铝合金线材. 不合理的工艺参数将导致热裂、表面粗糙、糊状型口和拉漏等缺陷. 固液两相区的形状和位置对上述缺陷的形成有重要影响, 当固液两相区位于型口或型内时, 凝固界面将向型内凸入, 如果剩余液体不能抵消凝固收缩, 就会出现表面粗糙; 若凝固界面深入型内较多, 则使型内凝固的铸锭摩擦力过大, 形成热裂; 固液两相区移至型外, 凝固界面将变成平面, 容易发生拉漏.     

凝固模拟技术应用于PUMA主盖的铸造工艺设计

应用华中科技大学开发的InteCast铸造凝固模拟软件,对PUMA发动机的主轴承盖工艺进行了模拟,比较了两种工艺的铸造缺陷,并以此作为模具设计的参考依据,开发了适合生产的工艺和模具。     

热型连铸单晶铜的性能

利用自制的热型连铸设备生产了单晶铜棒材，对其铸态、冷加工态、退火态的力学性能与电学性能进行了系统的测试与研究。结果表明：和多晶铜相比，单晶铜在铸态时具有良好的塑性和较低的电阻率，并具有优异的室温延展性，其延伸率可达6100％以上；冷拉拔加工后单晶铜表现出更大的加工硬化现象，但采用合理的退火工艺可使其加工硬化得到缓解。     

热型连铸单晶铜工艺参数对铸棒表面质量的影响

在自行设计，制造的横引式热型连铸设备上对影响连铸过程的各工艺参数进行试验，并就各工艺参数对铸件表面质量的影响机理进行了分析。结果表明，各工艺参数主要是通过影响固液界面在型口中的位置来影响铸棒的表面质量，只有对各工艺参数进行合理匹配，才能得到表面光滑的铸棒，此外，液位高度变化即液位波动，也会对铸棒的表面质量产生 一定影响。     

铁型覆砂铸造前悬架的凝固模拟及工艺优化

采用铁型覆砂铸造方法生产前悬架铸件.通过制定其铸造工艺、凝固模拟技术分析及优化,生产实践结果表明,应用铁型覆砂铸造工艺生产前悬架铸件可以提高该铸件的综合质量,降低生产成本,具有显著的经济效益和竞争优势.     

消失模铸造工艺在阳极钢爪铸造中的应用

介绍了消失模铸造工艺特点，以及在钢爪铸造过程中的特殊要求。丹江铝业公司四期技改工程中阳极钢爪的铸造全部采用消失模铸造工艺，这在铝行业的阳极钢爪铸造技术上属新工艺。     

电工圆铝杆铸坯结晶组织不良的原因与对策

通过对包头铝业股份公司电解一公司普罗佩兹电工圆铝杆生产线的铸坯结晶组织不良原因进行分析和试验，找到了冷却带的调整和氟硼酸钾的添加量的优化组合，获得了比较理想的铸坯结晶组织，确保了向国外出口电工圆铝杆的顺利生产，满足了用户对高品质产品的需求。     

用石膏型精密铸造工艺制作塑料制品用锌合金模具

介绍一种用于制造塑料制品生产用锌合金模具的石膏型精密铸造工艺。首先以塑料制品样品作为原始模型，翻制石膏阴凹模，后者用来制作锌合金凸模。然后用此锌合金凸模浇注塑料制品生产用的锌合金铸型。采用这种工艺可以缩短模具生产周期，并可以降低模具的生产成本。     

定向凝固水平连铸多晶铜的动态本构方程

以带有同步组装技术的分离式Hopkinson压杆装置作为热模拟装置，采用基于MTS（Mechanical Threshold Stress）模型建立的FCC晶体结构的动态本构方程，确定了定向凝固水平连铸多晶铜动态本构方程参数，研究了其动态冲击特性，获得高温段（685K-1085K）的理论应力-应变曲线与实验曲线相当吻合，而在低温段（低于685K）的理论曲线与实验曲线出入较大。结果也表明定向凝固水平连铸多晶铜在485K和685K之间有一温度能使其回复能达到阀值。     

Construction and analysis of dynamic solidification curves for non-equilibrium solidification process in lost-foam casting hypoeutectic gray cast iron

Most lost-foam casting processes involve non-equilibrium solidification dominated by kinetic factors, while construction of a common dynamic solidification curve is based on pure thermodynamics, not applicable for analyses and research of non-equilibrium macro-solidification processes, and the construction mode can not be applied to nonequilibrium solidification process. In this study, the construction of the dynamic solidification curve (DSC) for the nonequilibrium macro-solidification process included: a modified method to determine the start temperature of primary austenite precipitation (TAL) and the start temperature of eutectic solidification (TES); double curves method to determine the temperature of the dendrite coherency point of primary austenite (TAC) and the temperature of eutectic cells collision point (TEC); the "technical solidus" method to determine the end temperature of eutectic reaction (TEN). For this purpose,a comparative testing of the non-equilibrium solidification temperature fields in lost-foam casting and green sand mold casting hypoeutectic gray iron was carried out. The thermal analysis results were used to construct the DSCs of both these casting methods under non-equilibrium solidification conditions. The results show that the transformation rate of non-equilibrium solidification in hypoeutectic gray cast iron is greater than that of equilibrium solidification. The eutectic solidification region presents a typical mushy solidification mode. The results also indicate that the primary austenite precipitation zone of lost-foam casting is slightly larger than that of green sand casting. At the same time, the solid fraction (fs) of the dendrite coherency points in lost-foam casting is greater than that in the green sand casting.Therefore, from these two points, lost-foam casting is more preferable for reduction of shrinkage and mechanical burntin sand tendency of the hypoeutectic gray cast iron. Due to the fact that the solidification process (from the surface to center) at primary austenite growth area in the lost-foam cylinder sample lags behind that in the green sand casting,the mushy solidification tendency of lost-foam casting is greater and the solidification time is longer.     

Solute distribution in columnar crystal zone of continuous casting billets

1　ＩＮＴＲＯＤＵＣＴＩＯＮＫｕｓａｎｏｅｔａｌ[1] ｆｏｕｎｄｔｈａｔｕｎｄｅｒｔｈｅｃｏｍｂｉｎｉｎｇａｃｔｉｏｎｏｆｔｈｅｒｏｌｌｅｒｓｕｐｐｏｒｔｉｎｇｆｏｒｃｅａｎｄｔｈｅｐｒｅｓｓｕｒｅｏｆｍｏｌｔｅｎｍｅｔａｌ,ｔｈｅｍｏｖｉｎｇｔｒａｃｋｏｆｌｉｑｕｉｄ/ｓｏｌｉｄｉｎ ｔｅｒｆａｃｅｉｎｔｈｅｄｉｒｅｃｔｉｏｎｏｆｃａｓｔｉｎｇｉｓａｓｉｎｅｗａｖｅｗｈｉｃｈｉｓｆｏｒｍｅｄｂｙｔｈｅｐｅｒｉｏｄｉｃｂｅｎｄｉｎｇｄｅｆｏｒｍａｔｉｏｎｏｆｂｉｌｌｅｔｓｈｅｌｌ.Ａｎｄｔｈｉｓａｆｆ…     

基于ANSYS的磨球金属型铸造工艺优化设计

利用UG软件对磨球金属型铸造工艺及模具进行三维建模、利用parasolid接口将模型数据导入ANSYS进行有限元分析和工艺的优化设计,得到了模具的三维温度场,并获得模具的最优结构参数。采用该参数的铸造工艺使砂套尺寸明显减小,磨球质量和收得率显著提高。     

热型连铸Cu-Cr合金铸态下的组织与性能

用热型连铸法制备过共晶Cu-Cr合金线．探讨了其在铸态下的微观组织形态、力学性能和导电性能。结果表明：随着含Cr量的增加，Cu-Cr合金的抗拉强度增加，拉铸速度增加，Cu-Cr合金的导电性增加。     

Refinement of primary carbides in AISI DC 53 cold work tool steel by thin section copper permanent mould casting and water atomization

In this study, as alternative methods to conventional production methods involving thin section copper permanent mould casting (fast solidification) and water atomization (rapid solidification) of AISI DC 53 cold work tool steel have been investigated. Thin slabs obtained by copper mould casting was homogenized at 1150 °C for one hour and then hot rolling was be applied. After hot rolling, conventional heat treatment have been applied to thin slabs. The same heat treatment procedure have been performed for a commercially available AISI DC 53 which is manufactured by thick section ingot casting and rolling. In order to investigate also the effect of rapid solidification on AISI DC 53 tool steel, steel powder was produced by water atomization technique. Experiments have revealed that thin steel slabs in permanent copper mould and rapidly solidified tool steel powder by water atomization have a more refined primary M₇C₃ carbides than commercially available steel.     

Study on traveling magnetic field casting of sheet components

The distribution of a magnetic field over an inductor used for sheet castings has been investigated experimentally. With an increase in height from the surface, the magnetic field density decreases according to the exponential law. In the transverse direction, the magnetic field density is approximately uniform except near the edges. The magnetic field density is direct proportional to the number of turns multiplied by the current in amperes. Ferromagnetic material in the upper mould can enhance the magnetic field density. Under the electromagnetic force, the mould-filling process of sheet casings has been studied by physical simulation method. The difference in filling capability between gravity casting and travelling magnetic field casting has been studied. The electromagnetic force can enhance the filling process, but it also brings a problem. With an increase in the magnetic field density, the surface quality of the aluminum alloy sheet castings becomes poor. The reason is discussed.     

Design and evaluation of an enhanced constrained rod casting mould for experimental characterisation of hot tearing in aluminium casting alloys

The most popular mould configuration for hot tearing evaluation of aluminium alloys, the Constrained Rod Casting (CRC) design, was evaluated via computer modelling. Filling patterns, heat flows, and shrinkage areas were assessed using the existing published design, and improvements in the design were generated. A mould of the improved design or Enhanced Constrained Rod Casting (ECRC) was fabricated and successfully used to evaluate the hot tearing tendencies of A206.2 and A380 die casting alloys. The ECRC mould reduced fill time and increased uniform filling of the constrained rods, which resulted in more uniform solidification rates for all the constrained rods. The ECRC mould and novel measurement technique predicted hot tearing in real time of A206.2 and A380 die casting alloys at initial pouring temperatures of 700, 760, and 800 °C. The A206.2 alloy exhibited hot tearing characteristics at the measurement rod while A380 did not show any hot cracking defects.