贾洪海
,
于湛
,
雷作胜
,
邓康
,
陈家昶
,
华文杰
,
任忠鸣
金属学报
在小方坯连铸水口中段安置电磁搅拌器，使水口旋转出流以降低注流钢水的冲击深度并形成上升回流，保证小方坯（特钢）连铸中液面融渣和凝固坯壳及成分的均匀性。本文通过在连铸水口的水力学模型内安置的旋流叶轮来模拟水口电磁搅拌的作用，使模型实验中水口出流呈螺旋状流态，并在此基础上，用超声波多普勒测速仪定量测量结晶器模型内液流的垂直及水平速度，以此检验水口电磁搅拌的效果，分析有效的工艺参数。结果表明，旋流式水口有利于改善结晶器内的流场，有效降低冲击深度，增大液流向弯月面区域的回流和热流上传，使液面形成水平环流，提高了液面的活跃程度，并增强钢水表面融渣的效果。
关键词:
小方坯
,
Continuous casting
,
Swirling flow nozzle
,
Magnetic stirring
,
Water simulation
Beijiang ZHANG
,
Guimin LU
,
Jianzhong CUI
材料科学技术（英）
The relationship between electromagnetic frequency and microstructures of continuous casting aluminum alloys was studied. 7075 aluminum alloy ingot of 100 mm in diameter was produced by electromagnetic continuous casting process, the microstructures of as-cast ingot was examined by scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS). The results showed that electromagnetic frequency greatly influenced segregation and microstructures of as-cast ingot, and product quality can be guaranteed by the application of a proper frequency. Electromagnetic frequency plays a significant role in solute redistribution; low frequency is more efficient for promoting solution of alloying elements.
关键词:
Continuous casting
,
null
,
null
,
null
Kee-Hyeon Cho
,
Byung-Moon Kim
材料科学技术（英）
In the present study, a numerical optimization program has been developed for predicting the optimal secondary cooling patterns in a continuous slab caster. Optimization strategy using Broydon-Fletcher-Goldfarb-Shanno (BFGS) method is carried out by determining the constant heat transfer coefficients in each spray zone, which could satisfy the casting conditions and metallurgical criteria specified by the engineer. From the present results, it is found that even a slight variation in the pouring temperature, allowable surface temperature, and casting speed could give rise to the changes in the cooling pattern throughout the spray zones.
关键词:
Continuous casting
,
null
,
null
Jiuzhou ZHAO
,
L.Ratke
材料科学技术（英）
A numerical model is presented describing the microstructure evolution of an immiscible alloy under the continuous casting conditions. Calculations are carried out to investigate the microstructure evolution in a vertical strip cast sample of Al+5 wt pct Pb alloy. The numerical results show that there exists a peak value for the supersaturation in front of the solid/liquid interface, and the minority phase droplets are nucleated in a region around this peak. Under strip casting conditions the Marangoni migration dominates the motion of droplets. This leads to an accumulation of the minority phase droplets in front of the solid/liquid interface.
关键词:
Immiscible alloy
,
null
,
null
,
null
T.Revaux
,
J.D.Guérin
,
J.P.Bricout
材料科学技术（英）
New generation of steel casting processes allow to increase the production rate but they cause some imperfections instance. The main detrimental defects of metallurgical products generally occur during their solidification and cooling. The thermomechanical loadings undergone by the steel form the liquid state must be consequently considered with care. In this context, it is necessary to design some thermomechanical tests that dedicate to study the defectology products and the hot brittleness of steels. Hot mechanical tests use some notched axisymetric specimens and are able to reproduce the real material history. The analyses mainly allow to generate objectives thermomechanical stresses of the strand casting product and know some sensibility parameters on the failure instance. Contributions are relative to the hot ductility and micro or macrosegregation bonds and effects of strain during solidification on the cracks instances. The present results have been obtained from two types of procedure: tensile strain and contraction tests. These procedures are used to determine behaviour of continuous casting steels and cooling rate effects. Contributions are mainly relative to the hot ductility.
关键词:
Hot ductility
,
null
,
null
,
null
,
null
