Hot damage evolution in a high strength aluminum alloy during hot forming: a study using the Gurson–Tvergaard–Needleman model

• Main Authors: Xiangji Li, Meng Xu, Zhiqiang Zhang
• Format: Article
• Language: English
• Published: Elsevier 2021-09-01
• Series: Journal of Materials Research and Technology
• Subjects: Gurson–Tvergaard–Needleman (GTN) model; Damage evolution; Response surface method (RSM); 7075-T6 aluminum alloy
• Online Access: http://www.sciencedirect.com/science/article/pii/S2238785421007298

The investigation on the formability of 7075-T6 aluminum alloy at elevated temperatures is significant due to its low plasticity at room temperature. Meso-Damage mechanics suggests that the growth and accumulation of micro-voids is an important factor that leads to material damage, fracture, and affects its formability. In this work, the Gurson–Tvergaard–Needleman (GTN) model was used to investigate the damage evolution of the 7075-T6 aluminum alloy during the hot forming process. The effects of different temperatures and strain rates on the formability were investigated through uniaxial hot tensile tests. The parameters of the Gurson–Tvergaard–Needleman (GTN) model were inverse-calibrated using the Central Composite Design (CCD)-Response Surface Method (RSM)-Genetic Algorithm (GA). Control variable method was used to explore the effect of each damage parameter on the fracture initiation and evolution. The results showed that the calibrated Gurson–Tvergaard–Needleman (GTN) model well predicted the high-temperature damage of the 7075-T6 aluminum alloy at 300–450 °C. Predicted necking and fracture volume fractions of voids were less than 3% error from experimental results. Initial void volume fraction (f0) had little effect on damage. Increasing void nucleation volume fraction (fN) significantly advanced the necking and fracture of the material. An increase in the critical void volume fraction (fC) and fracture void volume fraction (fF) resulted in higher peak stresses and fracture strains.