Effects of axial static magnetic field on columnar to equiaxed transition in directionally solidified low carbon steel

ABSTRACT

The effects of axial static magnetic field (ASMF) on the columnar-to-equiaxed transition (CET) in directionally solidified low carbon steel including peritectic reactions were investigated. Experimental results show that the dendrite morphology of this peritectic steel can be modified under ASMF. The increases of the magnetic field intensity and temperature gradient and the decrease of the growth speed can promote the CET. The columnar dendrites become equiaxed dendrites at a low growth speed. According to numerical simulations, a thermoelectric magnetic convection in the melts and a thermoelectric magnetic force acting on the secondary dendrite neck are induced by the interaction between a thermoelectric current and ASMF. The influence of ASMF on the CET covers the formation of the thermoelectric magnetic convection, transport of the fragments in the melts and detachment of dendritic side arms. In addition, the application of ASMF can extend the process window of equiaxed grains formed.

KEYWORDS:

• Low carbon steel
• axial static magnetic field
• columnar to equiaxed transition
• thermoelectric magnetic force

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Jianbo Yu http://orcid.org/0000-0003-3204-2486

Additional information

Funding

This work was financially supported by the Joint Funds of the National Natural Science Foundation of China (Nos. U1560202, 51604171 and 51690162), the Shanghai Municipal Science and Technology Commission Grant (No. 17JC1400602).