Electromagnetic Stirring Technology Research Articles

Beneficial Utilization of Electromagnetic Stirring Technology in Al-Ce Alloys

Beneficial Utilization of Electromagnetic Stirring Technology in Al-Ce Alloys

Influence of the presence of a “shelf” on the outer surface of the submerged nozzle and the electromagnetic effect within its length on the qualitative distribution of metal flows during continuous casting of steel

Continuous casting of steel has many ways to control the quality of the billets. The possibilities offered by electromagnetic stirring are far superior to physical eff ects, but combining these two quality control methods can be extremely effective. Research have shown the possibility of a qualitative effect on the flow of the liquid in the mold with implementation of electromagnetic stirring technology and the “skirt” is used in the form of a “shelf” on the nozzle, which is immersed in the mold. In addition, implementation of this shelf increase the possibilities of using direct-flow nozzles with the slope of the inner wall, where in each case it gives advantages, both with an expanding channel, and with a narrowing one. The design of the shelf also does not affect the implementation of electromagnetic stirring in the process of continuous casting, since it is below the level of the mold meniscus and above the level of the effect of the electromagnetic stirrer in the mold. The results of the research show that when using a “shelf” in the middle of the immersion nozzle depth, the casting process is accompanied by the control of most of the flows that are created when the jet enters into the mold and effect of EMS. It also affects the formation of vertex on the meniscus. And the implementation of a “shelf” at the outlet of the submersible nozzle completely changes the nature of the flow of the incoming jet.

Optimization of an Electromagnetic Technology in ArcelorMittal Gent for Improving Products Quality in Steel Industry

AbstractA multi-mode electromagnetic stirring technology (MM-EMS) delivered by Danieli–Rotelec Company has been implemented in ArcelorMittal Gent CC2. This solution is able to control the liquid steel flows in CC mould by braking, accelerating or stirring them through the use of three different modes: EMLS, EMLA and EMRS. This paper presents the methodology followed in order to optimize the working of this new technology for improving the quality of products in terms of slivers defects. Different tools were developed and used by ArcelorMittal Maizières R&D to reach this objective: Numerical simulation with MagnetoHydroDynamics (MHD) tool to simulate the fluid flows in mould under the influence of magnetic fields, Submeniscus Velocity Control (SVC) tool to directly measure the liquid steel flows in the mould and finally some quality investigation tool like Automatic Surface Inspection System to detect defects directly on coils and qualify quality of products. Numerical and experimental approaches were associated to finally deliver to ArcelorMittal Gent steelplant an optimized actuator efficient for reducing defects in slabs and improving the final quality of products.

Analysis of the Cool Bending Fracture of HRB400

The tests were conducted on 400MPa hot-rolled ribbed bar (HRB400). The cool bending fracture appeared frequently in the production was analyzed. The research result showed that the cool bending fracture of rebar were caused by element segregation of C, Mn, inclusions, the existence of banded structure, widmannstatten structure and bainite structure in the center and edge of rebar. The inclusions are the root cause of internal crack and one of the reasons to fracture. Reasonable cooling rate can refine grain size, while the overquick cooling speed could result in the formation of widmannstatten structure in acicular or plume, increased the brittleness of steel and reduce its cold bending properties. On this basis, some improvement opinions were put forward: using the raw material with low Mn, S and P; reducing the S content with pretreatment of hot metal; controlling the content of C and Mn respectively in C: 0.18 ~ 0.23%, Mn:1.20~1.30%; extending argon blowing time at argon flushing station, using electromagnetic stirring technology; controlling the cooling rate at 15 °C/s.

Applications Analysis of the Technology of Mold Electromagnetic Stirring in a Steel Mill

This article mainly analyzes that some steels select mold electromagnetic stirring technique in billet continuous casting production, improve the slab quality effectively in all directions,analyzes how to refine crystal axis with electromagnetic stirring technology, improve the rate of equiaxed crystal, make less bubbles on the slab surface and subsurface, reduce the non-metallic inclusions ,reduce the crack on the surface of the production, reduce the central segregation and make the solidified shell uniform, and etc in detail according to the relevant data. It also put forward some corresponding solutions in accordance with the problems in the production of electromagnetic stirring with billet caster mold in this factory.

Mold Electromagnetic Stirring for Horizontal Continuous Casting of CuCrZr Alloys with Composite Properties

The authors investigated the mold electromagnetic stirring technology of horizontal continuous casting for CuCrZr alloys. Due to the oxidizability of the zirconium, the CuCrZr alloys are difficult to produce by continuous casting process. A short process for CuCrZr alloys material engineering is urgently needed. The mold electromagnetic field improved the surface of CuCrZr wire rod. The cast structure was also refined. With the help of mold electromagnetic stirring technology, CuCrZr wire rods were horizontal continuous cast. By using a set of suitable parameters, big weight wire rods with an excellent surface were cast. The CuCrZr wire rod possessed an average grain size of 1.5mm, and the columnar crystal proportion was less than 10%.

Continuous casting: make better steel and more of it!

An impressive number of papers are published each year that report on continuously-cast steel quality issues and new machine equipment; few of them (if any) discuss productivity and cost issues as they should be addressed by plant management, caster operators, and scientists. At Management & Quality Control meetings in steel plants, much time is spent discussing tenth of percent rejections at the end of the processing line. But, little time is devoted to discuss slab direct-application ratios where rejections are several percents and penalty on the overall scheduling and organization of the steel production line very serious. At IPC & SOP review meetings (Integrated Process Control & Standard Operating Practices review meetings), much time is spent discussing upper and lower statistical (6-sigma) control-limit diagrams. However, no mention is made that such diagrams only prove process capability (process repeatability and reproducibility) and not product quality. There should be no comfort if center line is at 10% slab abnormality code month after month! It is the goal of the author to draw from an approach that combines 30+ years of research and plant experience. The result is the opportunity to “connect the dots” and a wide breadth of in-situ process understanding. The paper looks at continuous casting machines as tools for maximizing corporate earnings. It is about making good steel on the first attempt. Very systematically and practically, the paper discusses disturbing steelmaking defects, their causes, and how Electro-Magnetic Stirring technology can be used to eliminate them. It draws the attention to academics looking to validate or invalidate what they know or don’t know, and provides in-depth, concise, practical explanations and guidelines to plant operators who are less interested or do not have the time to assimilate highly-technical presentations and publications.

Study on Slag Entrapment of Molten Steel in Mold with Electromagnetic Stirring Technology

Considering the process conditions of the continuous billet casting, this paper has studied the slag entrapment behavior of molten steel in mold by using of a water model, and analyzed the influence rules of the submerged nozzle immersion depth, the electromagnetic stirring intensity and the mould flux viscosity on the slag entrapment in mold. The results show that the surface velocity in meniscus gradually increases with the stirring intensity increasing and the submerged nozzle immersion depth decreasing. When the submerged nozzle immersion depth is shallower, the mould flux viscosity is lower, and the stirring intensity is high, the interface turbulence of the liquid steel and slag is more severe, slag entrapment may occur in the extreme state. In order to avoid the slag entrapment in the working condition, it is necessary to increase the submerged nozzle immersion depth and decrease stirring intensity mildly.

Preparation of semi-solid AlSi7Mg alloy slurry

In this article, semi-solid AlSi7Mg alloy slurry was prepared by low superheat pouring and weak electromagnetic stirring. The effects of pouring temperature and stirring power on the microstructure of the AlSi7Mg alloy slurry were studied. The results showed that the semi-solid AlSi7Mg alloy slurry, 127 mm in diameter, could be prepared by using the low superheat pouring and weak electromagnetic stirring technology and this new technology could save energy and make the pouring process convenient. When the liquid AlSi7Mg alloy was poured at 650°C or 630°C, the solidified microstructure of the AlSi7Mg alloy slurry, prepared by weak electromagnetic stirring, was remarkably improved when compared with that of the slurry prepared without stirring. The primary α-Al grains appeared rosette-like or spherical. When the pouring temperature was decreased, the shape of the primary α-Al grains gradually changed from dendritic-like grains to spherical grains. When the pouring temperature was appropriately increased, that is, raised to a certain superheat, the pouring process became easier and an ideal spherical microstructure of the AlSi7Mg alloy slurry, prepared by weak electromagnetic stirring, could also be obtained. In this experiment, when the stirring power was 0.36 kW, the optimized pouring temperature parameter was 630°C. When the AlSi7Mg alloy slurry was prepared by low superheat pouring and weak electromagnetic stirring, the pouring temperature was 630°C. Increasing the stirring power appropriately could gain better spherical primary α-Al grains, but if the stirring power was increased to a certain value, the shape of the primary α-Al grains did not improve further. In this experiment, the optimized stirring power parameter was 0.36 kW.