Electromagnetic metallurgy technology on steel making application

The mechanism of electromagnetic stirring for continuous casting is to strengthen the movement of residual molten steel in the strand by means of the electromagnetic force generated by the electromagnetic stirrer, which can change the flow, heat transfer and material migration process during the solidification process of the molten steel, so as to improve the quality of the strand.

A large number of metallurgical and industrial operation practices have proved that the reasonable use of electromagnetic stirring can effectively improve the internal structure of the slab as well as surface quality. Besides, center segregation and center porosity can be decreased, the center shrinkage and cracks can be eliminated, the ratio of equiaxed grain can be increased. In addition, the casting speed and the output will be improved.

The metallurgical effect of electromagnetic stirring is closely related to the continuous casting process conditions. Therefore, the control of metallurgical quality needs to combine with metallurgical process and metallurgical theory. However, with the application of electromagnetic stirring, the range for metallurgical process can be improved.

Here is the content:

l Principle

l Metallurgy principle

l Metallurgical effect

Principle

With the low frequency electromagnetic fields on the mold, the secondary cooling zone or final stage of solidification, using electromagnetic stirring to improve molten steel flow, heat transfer and the migration during the solidification process, improve the equiaxed grain ratio, reduce composition segregation, eliminate center porosity, to increase the steel grades.

Metallurgy principle

Modern theory think that electromagnetic stirring can improve strand organization structure, which is mainly based on the following three points:

1. Changing the dynamics conditions during the solidification process (i.e., mechanical model theory);

2. Changing thermodynamics condition during the solidification process of (i.e., thermal model theory);

3. Improving material migration conditions during the solidification process (to make the components uniform).

The strong electromagnetic stirring force enable the un-solidified molten steel flush the end of the solidification, cut off and corrode the crystal arm of columnar crystal, forming a large number of dendrite fragments as crystal nucleus of equiaxed grain, making the grain multiplied grown, so as to inhibit the growth of dendrites.  

The effects of electromagnetic stirring on the crystal structure of casting strand

Make the components uniform – improving material migration conditions during the solidification process.

Metallurgical effect

Metallurgical effect of electromagnetic stirring for billet continuous casting

Metallurgical effect of electromagnetic stirring for bloom continuous casting

Metallurgical effect of electromagnetic stirring for slab continuous casting