Computational and experimental modeling of new forging ingots with a directional solidification: the relative heights of 1.1

Abstract

The work’s purpose is to increase the forging ingot’s quality. A crystallization mechanism of shortened ingots has been investigated. The shortened ingots allow changing a direction of the metal solidification. The rational geometry of the ingot (a ratio of height to diameter and a value of taper) needs to be determined. The special technique of the theoretical and experimental investigations has been developed. The theoretical investigations have been carried out by finite element method. An adequacy test of the theoretical results has been carried out by experimental investigations on transparent and metallic models (pure aluminum) of the ingots. The macrostructure investigations of the shortened ingots with directional solidification have been produced. A hardness distribution on the longitudinal section has been investigated. It was found that for the ingot with the ratio of H/D = 1.1 the most part of the ingot’s body (60–70%) has a dense, homogeneous and small-grained structure. The small grain, which provides a dense structure, forms at the bottom and in the corners from the bottom side. The distribution of the grain dimensions along the ingot radius at different height levels allows to conclude that the bottom and middle parts along the height have the same small-grained structure. The high and uniform hardness values are characteristic for the ingot with H/D = 1.1. The middle and hot-top layers of the ingot have commensurate hardness, which have a difference from the bottom part maximum on the 5%. The ingot with the reverse taper of 7% allows to make a most dense and homogeneous structure. Thus, the improvement in the large forged quality ingots is possible by providing the directional solidification and reverse taper.