Equation of State of 6061-T6 Aluminum at Low Pressures

Abstract

The Hugoniot equation of state of 6061‐T6 aluminum was determined in the pressure range from 0 to 31 kbars from measurements of velocities of plane waves induced by plate impact. Below the Hugoniot yield point of 6.4±0.7 kbars, only an elastic wave was observed, while above both elastic and plastic waves were observed. The measuredwavevelocities corresponded closely to values predicted from elastic parameters for the material determined in static tests. Above the elastic limit, the free‐surface velocity was less than the interface velocity by an amount slightly greater than predicted by theory, and appeared to be a function of target thickness. The measured Hugoniot was found to correspond well with elementary elastic‐plastic theory, in which the yield stress is assumed to be a constant, and the change in compressibility with compression is predicted by second order elastictheory. It was found that the measured Hugoniot yield stress corresponded to the static yield stress obtained in simple tension tests, and that the Hugoniot joined smoothly onto an extrapolation of the high pressure Hugoniot data of Walsh and Al'Tshuler.