Effects of electromagnetic stirring on fluid flow and temperature distribution in billet continuous casting mould and solidification structure of 55SiCr

2017 ◽  
Vol 115 (1) ◽  
pp. 103 ◽  
Author(s):  
Hanghang An ◽  
Yanping Bao ◽  
Min Wang ◽  
Lihua Zhao

The optimal combination of current intensity and frequency of mould electromagnetic stirring (M-EMS) in continuous casting billet was a crucial compromise for improving inner quality of cast billet such as reduction in center segregation and porosity of medium-high carbon steel. In the present study, a decoupled three-dimensional mathematic model of electromagnetic field, fluid flow and heat transfer in continue casting billet mould with EMS has been developed, and the effects of current intensity and frequency on the system were also discussed. In addition, the industrial trials were carried out to investigate the magnetic field characteristics in the mould with M-EMS and the influence of M-EMS on the solidification structure of 55SiCr. According to the calculations and analysis, the optimal combination range of current intensity and frequency was 300–320 A and 3–4 Hz, respectively. The results showed that inner quality in as-cast billet of 55SiCr has been improved significantly with optimal parameter of 320 A and 3 Hz. For instance, central equiaxed zone increased from 19% to 33%, the center carbon segregation ratio decreased from 1.13 to 1.05 as well as center porosity has nearly disappeared.

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 516
Author(s):  
Lianwang Zhang ◽  
Changjun Xu ◽  
Jiazheng Zhang ◽  
Tao Wang ◽  
Jing Li ◽  
...  

The electromagnetic model of a large-bloom continuous casting was established to simulate the magnetic field. The model 3600 digital, high-precision, three-dimensional Gaussian meter was used to measure the internal magnetic field of mold electromagnetic stirring (M-EMS). The distribution of simulated magnetic field was basically consistent with that of the measured magnetic field; the accuracy of electromagnetic stirring model was verified. With the increase of current frequency, the electromagnetic force first increases and then decreases; when the current frequency is 9 Hz, the electromagnetic force reaches its maximum value. A bipolar electromagnetic stirring model is proposed; the influence of current intensity and distance were investigated. With the increase of current intensity of lower mold electromagnetic stirring (M-EMSB), the internal magnetic intensity of upper mold electromagnetic stirring (M-EMSA) gradually increases, and the middle region is gradually filled by magnetic field. With the increase of the distance, the range of the low-intensity magnetic field expands. When the current intensity of the M-EMSB is 320 A, and the distance is 400 mm, an 8 mT uniform magnetic field in the range of 1.2 m is formed. Compared with the traditional continuous casting electromagnetic agitator, the center equiaxial crystal of bipolar electromagnetic agitator increases from 30.3% to 49.5%.


Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 66 ◽  
Author(s):  
Wenjie Zhang ◽  
Sen Luo ◽  
Yao Chen ◽  
Weiling Wang ◽  
Miaoyong Zhu

Electromagnetic stirring in mold (M-EMS) has been widely used in continuous casting process to improve the solidification quality of the steel strand. In the present study, a 3D multi-physical-field mathematical model was developed to predict the macro transport phenomena in continuous casting mold with M-EMS using ANSYS commercial software, and was adopted to investigate the effect of current intensity (0, 150, 200, and 240 A) on the heat, momentum, and species transports in the billet continuous casting mold with a size of 160 mm × 160 mm. The results show that when the M-EMS is on, the horizontal swirling flow appears and shifts the high-temperature zone upward. With the increase of current intensity, two swirling flows form on the longitudinal section of continuous casting mold and become more intensive, and the flow velocity of the molten steel at the solidification front increases. Thus, the wash effects of the fluid flow on the initial solidified shell become intensive, resulting in a thinner shell thickness at the mold exit and a significant negative segregation of carbon at the billet subsurface.


2017 ◽  
Vol 36 (4) ◽  
pp. 347-357 ◽  
Author(s):  
Yang Li ◽  
Jing Wang ◽  
Jiaquan Zhang ◽  
Changgui Cheng ◽  
Zhi Zeng

AbstractThe surface quality of slabs is closely related with the initial solidification at very first seconds of molten steel near meniscus in mold during continuous casting. The solidification, structure, and free deformation for given steels have been investigated in droplet experiments by aid of Laser Scanning Confocal Microscope. It is observed that the appearances of solidified shells for high carbon steels and some hyper-peritectic steels with high carbon content show lamellar, while that for other steels show spherical. Convex is formed along the chilling direction for most steels, besides some occasions that concave is formed for high carbon steel at times. The deformation degree decreases gradually in order of hypo-peritectic steel, ultra-low carbon steel, hyper-peritectic steel, low carbon steel, and high carbon steel, which is consistent with the solidification shrinkage in macroscope during continuous casting. Additionally, the microstructure of solidified shell of hypo-peritectic steel is bainite, while that of hyper-peritectic steel is martensite.


2012 ◽  
Vol 482-484 ◽  
pp. 1699-1702
Author(s):  
Chun Liu ◽  
Bai Gang Jin

Application experiments have been done to research the strand quality of high carbon steel 65Mn under the condition of electromagnetic stirring. The experimental results show that the effect of electromagnetic stirring with stirring rollers in side-side disposition mode is better than that in face-face disposition mode. The effect of electromagnetic stirring is also increased with the increasing of current intensity, and the continuous stirring is better than alternating stirring. Thus, conclusion could be arrived that the strand inner quality is improved obviously by the adoption of electromagnetic stirring due to 32% increase of equiaxed zone ratio in the strand and the decrease from B0.5 to C1.0 of the center segregation grade.


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