Strain Rate Effects on Tensile Deformation of 2024-O and 7075-O Aluminum Alloy Sheet

摘要

Coarse- and fine-grained 2024 and 7075 alloy sheets were tensile tested at strain rates ranging from 10~(-3) to 10 /s. Ultimate tensile strengths decreased up to 10~(-1)/s and increased at higher strain rates. Total elongations at failure showed the same behavior with uniform and localized components showing similar dependencies on strain rate. The initial ductility decrease at low strain rates is attributed to thermal gradients associated with a transition from isothermal to adiabatic conditions. At strain rates above 10~(-1)/s, ductility increases as strain rate hardening effects become dominant. Although the fine-grained materials had higher elongations than their coarse-grained counterparts, both variants responded similarly to changes in strain rate. The only difference was a tendency for off-center failures in coarse-grained specimens tested at the slower strain rates.