Abstract: The difference of room temperature mechanical properties between the columnar crystal and the center equiaxial crystal of large round bloom solidification structures obtained by the different current intensity of mold electromagnetic stirring (MEMS) was investigated. Moreover, the difference of porosity degree，tensile strength and tensile elongation between the columnar crystal and the center equiaxial crystal was studied by original position analysis (OPA) method and tensile tests at room temperature. And then the reason for the results was analyzed qualitatively. The results show that the porosity degrees of columnar crystal and center equiaxial crystal are both reduced, the tensile strengths are increased, and the tensile elongations are roughly decreased with the increase of the current of MEMS. The porosity degree of columnar crystal is better than center equiaxial crystal under the same current of MEMS. The tensile strengths along different directions of center equiaxial crystal are almost same, but in columnar crystal the tensile strengths along the radial direction of columnar crystal are higher than the vertical to radial direction. Besides, the tensile strengths of center equiaxial crystal are obviously higher than those of columnar crystal. The difference between tensile elongations along different directions of center equiaxial crystal is smaller than that of columnar crystal.

Key words: large round bloom , mold electromagnetic stirring, porosity degree , tensile strength, tensile elongation