Paint-bake effect on the plasticity and fracture of pre-strained aluminum 6451 sheets

Abstract

In automotive engineering, sheet metal components are subject to a 20min heat treatment at 180C during paint baking. This process may significantly alter the mechanical properties of 6000-series aluminum alloys through artificial ageing. Here, a comprehensive experimental program is carried out to characterize the anisotropic plasticity and the fracture initiation in prestrained artificially-aged aluminum 6451 sheets. It is found that the combination of pre-straining up to 5% strain and heat treatment mainly changes the material's strain hardening behavior and the stress-state sensitivity of its fracture response. The material parameters of the Yld2000-2d plasticity model with combined Swift-Voce hardening are identified for four distinct materials from uniaxial tension and shear experiments. The corresponding Hosford-Coulomb fracture model parameters are determined from smiley shear, V-bending and punch experiments. As an important byproduct of the research, the Yld2000-2d and Hosford-Coulomb models are successfully validated for all four materials through notched and central hole tension experiments. Simple empirical expressions are also provided to estimate the material properties as a function of the prestrain in engineering practice.

Numerical Analysis of Edge Cracking in High-Silicon Steel during Cold Rolling with 3D Fracture Locus

“…All specimens were machined by electro-discharge. Fracture tests using four-eight specimens with different shapes were performed to construct the 3D fracture loci of steels (DP600 [12,13], aluminum 6451 [14], TRIP780, DP780, and DP590 [15]). Following the previous studies [12][13][14][15], this study constructed a 3D fracture locus of high-silicon steel using five different specimens (Figures 3 and 4a-d).…”

The Influence of Cold Forming and Heat Treatment Processes on the Mechanical and Fracture Properties of AA6016 Aluminum Sheets

“…Constitutive models have been widely used in the study of aluminum alloy formation due to its ability to reflect the relationship between stress and strain during material deformation. Models that simultaneously consider pre-strain and heat treatment include the H-S flow stress model [2,6] and the combination of the YLD2000-2d yield criterion with the Swift-Voce hardening model [7]. These models were calibrated by fitting stress-strain curves obtained under different pre-strain and heat treatment conditions.…”

“…Fracture models, known for effectively describing material fracture behavior under various stress states, are extensively utilized in researching aluminum alloy fracture behavior. Notably, there has been research on the Hosford-Coulomb failure model after pre-strain and heat treatment [7]. By calibrating the parameters of the Hosford-Coulomb failure model using the experimentally obtained force-displacement curves, the pre-strain-and post-heat-treatment Hosford-Coulomb failure model can be obtained.…”

Tensile Behaviors and Mechanical Property Analyses of T-Welded Joint for Thin-Walled Parts in Consideration of Different TIG Welding Currents Using Multiple Damage Models and Fracture Criterions: Numerical Simulation and Experiment Validation

“…What is more, considering the stress triaxiality and size effect on damage evolution under different stress states, the relationship among the material damage and stress-strain damage parameters is also revealed with the Gurson-Tvergaard-Needleman (GTN) model through FE simulation [ 16 , 17 ]. Additionally, Abi-Akl et al analyzed the anisotropic plasticity and the fracture initiation in pre-strained, artificially aged aluminum 6451 sheets and researched the material’s strain hardening behavior and the stress-state sensitivity with the Swift-Voce hardening model [ 18 ]. Cao et al analyzed the working hardening behavior of different metallic alloys with Hollomon, Swift, and Voce models and compared the prediction accuracy of tensile strength for different hardening models [ 19 ].…”