Yield Surfaces of Pure Aluminum at Elevated Temperatures

Results of experiments are presented in which thin-walled tubes of pure aluminum are loaded in combined tension and torsion, in the plastic range, at room temperature and at elevated temperatures to 325°F. Yield surfaces in stress-space are obtained at several temperatures for the virgin material and for the material prestrained in torsion to three different levels of prestraining. It is shown that no cross effect exists at all tested temperatures and levels of prestressing. It is also shown that the yield surfaces do not pass through the prestressing point. The paper ends with an analytical evaluation of the experimental results.