Sen YANG
,
Yunpeng SU
,
Zhenxia LIU
,
Weidong HUANG
,
Yaohe ZHOU
材料科学技术（英文）
Cellular spacing selection of Cu-27.3 wt pct Mn alloy has been investigated by laser surface rapid resolidification experiments. The experimental results show that there exists a wide distribution range in cellular spacing under ultra-high temperature gradient and rapid solidification conditions and the average spacing decrease with increase of the growth rate. The experimental results are compared with the current KGT model for rapid cellular/dendritic growth, and a reasonable agreement is found.
关键词:
Sen YANG
,
Wenjin LIU
,
Minlin ZHONG
,
null
,
null
材料科学技术（英文）
A Ni-base alloy composite coating reinforced with TiC particles of various shapes and sizes on medium carbon steel substrate was produced by multilayer laser cladding. The chemical compositions, microstructures and surface morphology of the cladded layer were analyzed using energy dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), and X-ray diffractometry (XRD). The experimental results showed that an excellent metallurgical bonding between the coating and the substrate was obtained. The microstructure of the coating was mainly composed of γ-Ni dendrites, a small amount of CrB, Ni3B, M23C6 and dispersed TiC particles. Much more and larger TiC particles formed in the overlapping zone, which led to a slightly higher microhardness of this zone. The maximum microhardness of the coating was about HV0.21200. The effects of the laser processing parameters on the microstructures and properties of coating were also investigated.
关键词:
Laser cladding
,
null
,
null
,
null
Sen YANG
,
Yunpeng SU
,
Wenjin LIU
,
Weidong HUANG
,
Yaohe ZHOU
材料科学技术（英文）
The detailed laser surface remelting experiments of Cu-31.4 wt pct Mn and Cu-26.6 wt pct Mn alloys on a 5 kW CO2 laser were carried out to study the effects of processing parameters (scanning velocity, output power of laser) on the growth direction of microstructure in the molten pool and cellular spacing selection under the condition of ultra-high temperature gradient and rapid directional solidification. The experimental results show that the growth direction of microstructure is strongly affected by laser processing parameters. The ultra-high temperature gradient directional solidification can be realized on the surface of samples during laser surface remelting by controlling laser processing parameters, the temperature gradient and growth velocity can reach 106 K/m and 24.1 mm/s, respectively, and the solidification microstructure in the center of the molten pool grows along the laser beam scanning direction. There exists a distribution range of cellular spacings under the laser rapid solidification conditions, and the average spacing decreases with increasing of growth rate. The maximum, λmax, minimum, λmin, and average primary spacing, , as functions of growth rate, Vb, can be given by, λmax=12.54 , λmin=4.47 , =9.09 , respectively. The experimental results are compared with the current Hunt-Lu model for rapid cellular/dendritic growth, and a good agreement is found.
关键词:
Laser surface remelting
,
null
,
null
,
null
WU Su-zhou
,
ZHANG Jiong-ming
,
LI ZHi-zheng
钢铁研究学报(英文版)
The SEN clogging is a long term issue for all the steelmakers. In the current study, the kinetics of SEN clogging during steel continuous casting was established. The dynamic build-up of alumina inclusions to the lining refractory of SEN was analyzed. The fluid flow and inclusions motion are calculated by means of mathematic model. Effect of diameters of inclusions, roughness of nozzle, diameter of nozzle and casting speed on the entrapment probability are estimated.
关键词:
nozzle clogging;mathematic model;inclusion motion
B.W. Li
,
X.Y. Tian
,
E.G. Wang
,
J.C. He
,
null
,
null
,
null
,
null
金属学报(英文版)
In recent years, thin slab continuous casting technology has been widely used to improve the quality of the product and to reduce
the cost. One of the challenges faced by this technology is to design reasonable flow patterns, which strongly affect the surface
and inner properties of the final slab in the mold. With the fixed scales and complex geometrical structures of nozzle and funnel
type mold, a series of numerical simulations are made to analyze the flow patterns in melt steel using finite volume method based
on structured body fitted coordinate grids. The CFD (computational fluid dynamics) package is validated first using one typical case described in previously published studies, and then it is developed to study the effect of operational parameters on fluid
flow in thin slab caster. Two operational parameters, casting speed and SEN depth (submerged entry nozzle), are mainly
considered for numerical analysis. On the basis of present simulations, the reasonable SEN submergence depths corresponding to different casting speeds are suggested according to fluid flow characteristics like, flow jet impingement on the narrow side of
the mold, flow speed of the melt steel beneath the meniscus and the recirculation region. This is the first stage of study on the numerical analysis of the whole thin slab casting process with electromagnetic brake.
关键词:
continuous casting
,
null
,
null
王翠娜 温良英 陈登福 张大江 彭政 靳星
钢铁
针对某钢厂板坯连铸结晶器及浸入式水口(SEN)的结构参数，建立了描述结晶器内钢液流动的三维数学模型，用FLUENT软件对结晶器内钢液的流场和温度场进行耦合计算，分析SEN底部形状对结晶器内流场和温度场的影响。结果表明：凸底水口出口附近钢液的速度较大，对结晶器窄面的冲击深度较大，使结晶器内高温区下移，不利于凝固坯壳的生长；平底水口自由面速度较大、温度较高，有利于保护渣的熔化，但易产生液面裸露现象；凹底自由面速度较小、温度较低，有利于液面稳定。
关键词:
浸入式水口（SEN）;底部形状;结晶器;流场;温度场
王翠娜
,
温良英
,
陈登福
,
张大江
,
彭政
,
靳星
钢铁
针对某钢厂板坯连铸结晶器及浸入式水口(SEN)的结构参数,建立了描述结晶器内钢液流动的三维数学模型,应用FLUENT软件对结晶器内钢液的流场和温度场进行耦合计算,分析SEN底部形状对结晶器内流场和温度场的影响,并利用水模试验对钢液的流动行为进行了验证.结果表明:凸底水口出口附近钢液的速度较大,流股的冲击深度较大,使结晶器内高温区下移,不利于凝固坯壳的生长;平底水口自由面速度较大、温度较高,有利于保护渣的熔化,但易产生液面裸露现象;凹底自由面速度较小、温度较低,有利于液面稳定.
关键词:
浸入式水口
,
底部形状
,
结晶器
,
流场
,
温度场
Y.P.Du
金属学报(英文版)
According to turbulent theory and characteristics of beam blank continuous casting, 3-D model to represent the flow of beam blank mould is established. The predicted results indicate that the exit obliquity of up 15°(+15°) should be adopted, which will benefit the floatation of non-metallic inclusion and purification of the molten steel. When the nozzle angle is 120°, the flow pattern is reasonable. Proper nozzle depth can be 200ram. Turbulent kinetic of meniscus can be reduced by adopting the square nozzle and suitable area of side outlet when casting speed increases. The results are consistent with those of water model experiment, so the model is exact and reasonable. The model can provide important information for design of SEN and defining of immersion depth.
关键词:
SEN parameter
,
null
,
null
