Use of Cooling Slope in Semisolid Billet Casting

Abstract

Presently, the traditional techniques accessible for large scale generation of semisolid slurry are mechanical stirring, electromagnetic stirring, etc. These encounter from disadvantages such as complicated design, high cost, structural inhomogeneity and low efficiency. The cooling slope is taken to be a simple but effective technique owing to its simple design and easy control of process parameters, low equipment and running costs, high production efficiency and reduced inhomogeneity. With this standpoint, the main aim of the current research is to investigate experimentally the solidification on a cooling slope, in addition to the study of final microstructure of the semisolid cast billets. In utmost casting uses, dendritic microstructure morphology is not preferred because it results in poor mechanical properties. Forced convection producing adequate shearing in the mushy zone of the partially solidified melt is one of the means to suppress this dendritic growth. The dendrites formed at the solid-liquid interface are detached and carried away due to strong fluid flow to form slurry. This slurry, comprising of rosette or globular particles, offers less resistance to flow even at a high solid fraction and can effortlessly fill the die-cavity. The said principle is the foundation of a novel production technique t called “semi-solid forming” (SSF), in which metal alloys are cast in the semi-solid state. This technology has several advantages over other usual commercial casting processes, like decrease of macrosegregation, decrease of porosity along with less forming efforts as well.