The aluminum ingot produced by hot top casting has uniform structure and good mechanical properties. In order to obtain such a casting structure, aluminum ingot hot top casting is used for round ingot casting.
The quality of aluminum alloy ingots has an important impact on the subsequent processing procedures and the quality of aluminum products. Common defects in ingots include cracks, pores, porosity, slag inclusion, segregation, cold separation, etc. There are many reasons for these defects in actual production, including the structure of the casting mold and the properties of the alloy, the degree of melt purification and grain refinement, casting process parameters, etc.
Ingot quality includes ingot structure and surface quality. It is now agreed that the uniform fine grain structure on the ingot section is the best structure for ingot. In order to obtain this kind of casting structure, round ingot casting adopts hot top casting.
Advantages of Ingot Hot Top Casting
(1) The ingot produced by hot top casting has a uniform structure and good mechanical properties. This is because the effective crystallization height of the hot top mold is very small, the cooling rate of the ingot is increased, the liquid cavity of the ingot becomes shallower, and the transition zone is narrowed, so the compactness of the ingot is improved.
(2) The hot top casting eliminates the funnel and realizes lateral flow. The metal liquid level in the hot top and distribution launder is kept at the same level, realizing stable short mold casting and same level casting. The oxide film on the liquid surface in the crystallizer is stable and does not cause agitation, thus effectively preventing the secondary pollution of the melt and improving the purity of the metal.
(3) The surface of the ingot is smooth, and the degree and depth of the inverse segregation around the ingot are greatly reduced. Because in hot top casting, the countercurrent cooling effect of the secondary cooling water is relatively sufficient, which effectively prevents the secondary remelting of the condensate, thereby inhibiting the formation of segregation tumors. At the same time, during the casting process, the head of the ingot always maintains a stable liquid column, which reduces the solidification position of the melt in the mold, effectively prevents the premature cooling of the metal liquid level, and makes the meniscus become Stable and effectively inhibit the formation of cold barriers.