The study investigates the effects of pre-strain on the bake hardenability and precipitation behavior of Al-Mg-Si automotive body sheets. The scanning electron microscopy, transmission electron microscopy, tensile test, Vickers hardness test, and differential scanning calorimetry were conducted for the purpose. It was found that the pre-strain treatment partially inhibits the natural aging hardening effect but cannot completely eliminate it. The pre-straining significantly enhances the bake hardening effect, with the 5% pre-strain sample showing the highest increase in yield strength and hardness. The formation of fine β" precipitates and dislocation structures contribute to the observed strengthening. Additionally, the study highlights the importance of optimizing pre-strain levels to achieve the best balance between strength and ductility in bake-hardened aluminum alloys.
References
[1]
Lu, G., Wang, J., Liu, Y. and Liu, C. (2020) Effect of Heating Rate during Solution Treatment on the Bendability of Al-Mg-Si Al-loys. Materials Science and Engineering: A, 791, Article ID: 139604. https://doi.org/10.1016/j.msea.2020.139604
[2]
Wang, D., Shu, X., Wang, R. and Xu, S. (2020) Mechanism of Necking Defect of 6082 Aluminium Alloy Rolled by Cross-Wedge Rolling Method Based on Material Thermal Properties. Journal of Central South University, 27, 3721-3732.
https://doi.org/10.1007/s11771-020-4572-y
[3]
Birol, Y. (2005) Pre-Straining to Improve the Bake Hardening Response of a Twin-Roll Cast Al-Mg-Si Alloy. Scripta Materialia, 52, 169-173.
https://doi.org/10.1016/j.scriptamat.2004.10.001
[4]
Ding, L., Jia, Z., Liu, Y., Weng, Y. and Liu, Q. (2016) The Influence of Cu Addition and Pre-Straining on the Natural Aging and Bake Hardening Response of Al-Mg-Si Alloys. Journal of Alloys and Compounds, 688, 362-367.
https://doi.org/10.1016/j.jallcom.2016.07.066
[5]
Kwon, Y., Lee, Y.S. and Lee, J.H. (2007) Deformation Behavior of Al-Mg-Si Alloy at the Elevated Temperature. Journal of Materials Processing Technology, 187, 533-536.
https://doi.org/10.1016/j.jmatprotec.2006.11.207
[6]
Carreño-Morelli, E., Ghilarducci, A.A. and Urreta, S.E. (1999) Dislocation Pinning in a Low-Dose Neutron Irradiated Al-Mg-Si Industrial Alloy. Philosophical Magazine A, 79, 293-304. https://doi.org/10.1080/01418619908210298
[7]
Misumi, K., Kaneko, K., Nishiyama, T., Maeda, T., Yamada, K., Ikeda, K., et al. (2014) Three-Dimensional Characterization of Interaction between Β Precipitate and Dislocation in Al-Mg-Si Alloy. Journal of Alloys and Compounds, 600, 29-33.
https://doi.org/10.1016/j.jallcom.2014.02.059
[8]
Cottrell, A.H. (1953) LXXXVI. A Note on the Portevin-Le Chatelier Effect. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 44, 829-832. https://doi.org/10.1080/14786440808520347
[9]
Brindley, B.J. and Worthington, P.J. (1970) Yield-Point Phenomena in Substitutional Alloys. Metallurgical Reviews, 15, 101-114.
https://doi.org/10.1179/mtlr.1970.15.1.101
[10]
Serizawa, A., Hirosawa, S. and Sato, T. (2008) Three-Dimensional Atom Probe Characterization of Nanoclusters Responsible for Multistep Aging Behavior of an Al-Mg-Si Alloy. Metallurgical and Materials Transactions A, 39, 243-251.
https://doi.org/10.1007/s11661-007-9438-5
[11]
Wang, Y., Zhao, Y., Xu, X., Pan, D., Jiang, W., Yang, X., et al. (2018) Superior Mechanical Properties Induced by the Interaction between Dislocations and Precipitates in the Electro-Pulsing Treated Al-Mg-Si Alloys. Materials Science and Engineering: A, 735, 154-161. https://doi.org/10.1016/j.msea.2018.08.029
[12]
Teichmann, K., Marioara, C.D., Andersen, S.J., Pedersen, K.O., Gulbrandsen-Dahl, S., Kolar, M., et al. (2011) HRTEM Study of the Effect of Deformation on the Early Precipitation Behaviour in an AA6060 Al-Mg-Si Alloy. Philosophical Magazine, 91, 3744-3754. https://doi.org/10.1080/14786435.2011.593577
