Changes in Hardness and Structure of Cold Drawn Pure Aluminum Bi-Crystals

Abstract

To know the influence of grain boundaries on the structure and hardness of cold-drawn aluminum bi-crystals, the present study was performed on an aluminum bi-crystal bar which was prepared from a 99.999% purity aluminum ingot by Bridgeman’s method. Specimens were cold-drawn successively to about 98%. Shape, structure and hardness changes were investigated at various working degrees. The main experimental results obtained were as follows: Work-hardening and structure changes depend on the orientation of grains in the cold-drawn specimen. Softening of grains which depends on orientations occurs during cold-drawing. The new grain growth is different from that of the primary recrystallization. The new grains are formed the grain boundary of deformation bands and at the grain boundary of the bi-crystal.