Geometric Misorientation Changes in Aluminium Subjected to Strain Path Change Test

Abstract

Specimens of commercial purity aluminum were subjected to a strain path change test during high temperature deformation. Specimens were deformed at 4000 C and strain rate of 0.1 s-1 up to various strains of 0.2, 0.5, and 1. Then in a strain path change test, specimens were first deformed to a strain of 0.5, and subsequently deformed to strains of 0.2 and 0. In order to further the understanding of the deformation mechanisms in aluminum, the subgrain sizes and misorientations were characterized in detail by comparative studies using optical microscopy in polarized light (POM), orientation imaging microscopy (OIM/SEM) and transmission electron microscopy (TEM). The analysis revealed that while subgrain size is relatively insensitive to strain, overall misorientations increased with increasing strain. These analyses confirmed a strong bimodal distribution of boundaries during deformation coupled with a low fraction of medium angle boundaries. The results contribute to the understanding that dynamic recovery in aluminum maintains subboundaries with low misorientation but as grains elongate and more subgrain become adjacent to grain boundaries the fraction of high angle boundaries rises.