Influence of magnetic field and inoculation on columnar structure transformation

Purpose: The main aim of investigations was the reduction of grain size and unification of structure for clean metal casting by introduction of small amount of inoculant, with rotate and impulse reverse magnetic field. Design/methodology/approach: Experimental plan was planed on the basis of statistical factor design on two levels for three variables: pulse frequency, current intensity and inoculant quantity. The output parameters: area of equiaxed crystals zone, average area of equiaxed crystal, average area of columnar crystal and most important equiaxed crystals zone content were calculated by computer program Multi Scan Base (program to processing and image analysis) after macroscopic metallographic research. Findings: The results of investigations and their analysis show relationship between area of equiaxial zone and pouring parameters: induction of magnetic field, pulse frequency of magnetic field and quantity of inoculant sort AlTi5B. Research limitations/implications: Towards lack of resolute relations between casting parameters and structure was selected statistical analysis to determine these relations using stepwise regression. In order to obtain accurate results, authors of this paper are going to extend the resarch range and use Zr and V to inoculation. Practical implications: The work presents refinement of structure methods which are particularly important in continuous and semi-continuous casting where products are used for plastic forming. Large columnar crystals zone result in forces extrusion rate reduction and during the ingot rolling delamination of external layers can occur. Thus, in some cases ingot skinning is needed, which rises the production costs. Originality/value: The value of this paper resides in coupling of two fineness of structure methods. The first method is internal factor – inoculation with Ti+B and the second method is external factor – influence of electromagnetic field on crystallization process.