Investigation on Yield Behavior of 7075-T6 Aluminum Alloy at Elevated Temperatures

Abstract

Aluminum alloys have drawn considerable attention in the area of automotive lightweight. High strength aluminum alloys are usually deformed at elevated temperatures due to their poor formability at room temperature. In this work, the yield behavior of 7075 aluminum alloy in T6 temper (AA7075-T6) within the temperature ranging from 25 °C to 230 °C was investigated. Uniaxial and biaxial tensile tests with the aid of induction heating system were performed to determine the stress vs. strain curves and the yield loci of AA7075-T6 at elevated temperatures, respectively. Von Mises, Hill48 and Yld2000-2d yield criteria were applied to predicting yield loci which were compared with experimentally measured yield loci of the AA7075-T6. Results show that yield stress corresponding to the same equivalent plastic strain decreases with increasing temperature within the investigated temperature range and the shape of yield loci evolves nearly negligibly. The experimental yield locus expands with an increase of equivalent plastic strain at the same temperature and the work hardening rate of AA7075-T6 exhibits obvious stress-state-dependency. The non-quadratic Yld2000-2d yield criterion describes the yield surfaces of AA7075-T6 more accurately than the quadratic von Mises and Hill48 yield criteria, and an exponent of 14 in the Yld2000-2d yield function gives the optimal predictions for the AA7075-T6 at all investigated temperatures.

A Materials Science-Based Approach to Finite Element Simulation of Warm-Forming of Al-Mg-Zn Alloys

“…However, we believe that the procedure presented here is viable because failure in deep-drawing often occurs in the plane strain condition, which is covered by the notched tensile tests. Nevertheless, further research could focus on adding equi-biaxial tensile experiments with inductive heating and digital image correlation (DIC), as demonstrated by Lin et al [12], for studying the underaged sheet warm-forming process.…”

Effects of Aging under Stress on Mechanical Properties and Microstructure of EN AW 7075 Alloy

“…Stress values were selected in order to have different conditions namely, conventionally aged (0 MPa), stress-aged under low (50 MPa) and stress-aged under high (200 MPa) stresses. Whereas the lower stress level of 50 MPa is clearly below yield strength of 7075 T6 even at 200 • C, the higher stress level of 200 MPa approaches yield strength at 200 • C [35,36]. A thermocouple was attached to every sample by springs to measure temperature during experiments.…”

KNN-Entwicklung in der Halbwarmumformung/ANN development in semi-hot forming

“…Durch ihr geringeres Gewicht weisen 7xxx-er Aluminiumlegierungen bei ähnlicher Festigkeit im Vergleich zu Stahl ein hohes Leichtbaupotenzial auf [1]. Aufgrund der hohen Festigkeit und geringen Duktilität ist die Umformbarkeit solcher Legierungen bei Raumtemperatur (RT) jedoch begrenzt.…”