Application of Steady Magnetic Field for Refining Solidification Structure and Enhancing Mechanical Properties of 25Cr-20Ni-Fe-C Alloy in Centrifugal Casting.

Abstract

Electromagnetic centrifugal casting technique based on magnetohydrodynamic principles has beenapplied to improve the solidification structure and mechanical properties of a 25Cr-20Ni-Fe-C alloy. Theexperimental results show that the solidification structure can be controlled by electromagnetic centrifugal casting. As the magnetic flux density increases, the solidification macrostructure changesfrom coarse columnar grains to a mixed structure consisting of fine curved columnar and equiaxed grains, and finally, into fine equiaxed grains. The columnar-equiaxed transition is achieved through the fracture of growing dendrites, and the size of equiaxed grains is also affected by the magnetic flux density. The al]oy with equiaxed grain structure produced by electromagnetic centrifugal casting shows both better tensile strength at room and higher temperatures, and longer stress-rupture life comparedwith the same alloy with columnar grain structure produced by conventional centrifugal casting under the same stress.