Three Point Bend Performance of Solutionized, Die Quenched and Heat Treated AA7075 Beam Members

Abstract:

To overcome the low room temperature formability of AA7075-T6 aluminum sheet, without sacrificing the high strength properties of this alloy, a hat section beam member was formed and quenched within a cold die immediately after a 20 minute solutionizing treatment. Natural aging for 24 hours followed the forming process which was then followed by various heat treatments that included a typical precipitation hardening (PH) and industrial paint bake (PB) temperature-time treatment. Tensile specimens were extracted from the beams to evaluate their mechanical properties. When compared to the as-received AA7075-T6 mechanical properties, the beams heat treated with the PH, PHPB and PB treatment resulted in a 5%, 13% and 20% reduction in ultimate tensile strength respectively. A similar trend was shown for the yield strength measurements. There was little effect of the heat treatments on the total elongation, with the PH condition showing a slight improvement. A backing plate was riveted to the beams and a quasi-static 3 point bend test was conducted to evaluate the crush performance. The peak load for the PH, PHPB and PB beams was 9.2, 8.5 and 7.3 kN respectively, but the calculated energy-displacement (or energy absorption) curves were similar for the PH and PHPB parts due to a more ductile fracture behavior for the PHPB material condition.

• Periodical: Materials Science Forum (Volumes 794-796)
• Pages: 431-436
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.794-796.431
• Online since: June 2014
• Authors: Alexander Bardelcik*, Alexandre Bouhier, Michael J. Worswick
• Keywords: 3 Point Bend, AA7075, Die Quenching, Heat Treatment, Warm Forming

References

[1] N. Sotirov, P. Simon, C. Chimani, D. Uffelmann, C. Melzer, Warm deep drawability of peak-aged 7075 aluminium alloy, Key Eng. Mater. 504-506 (2012) 955-960.

DOI: 10.4028/www.scientific.net/kem.504-506.955

[2] P. Dreessen, Effect of Temperature during Warm Forming on the Strength of AA7075-T6 B-Pillars, University of Waterloo, Internal Report (2013).

[3] J. Beland, G. D'Amours, Hot forming of 7075 aluminium alloy tubes to produce complex and strong components, SAE 2012 World Congress, paper 2012-01-0539 (2012).

DOI: 10.4271/2012-01-0539

[4] H. Wang, Y.B. Luo, P. Friedman, M.H. Chen, L. Gao, Warm forming behavior of high strength aluminum alloy AA7075, Trans. Nonferrous Met. Soc. China 22 (2012) 1-7.

DOI: 10.1016/s1003-6326(11)61131-x

[5] R.P. Garrett, J. Lin, T.A. Dean, Solution heat treatment and cold die quenching in forming AA 6xxx sheet components: feasibility study, Adv. Mater. Res. 6-7 (2005) 673-680.

[6] Alcoa Incorporated: Alloy 7075 - Plat and Sheet, http: /www. alcoa. com/mill_products/catalog/pdf/alloy7075techsheet. pdf, accessed Jan. 16, (2014).

[7] J.E. Hatch, Artificial aging of 7XXX alloys, in: Aluminum: Properties and Physical, American Society for Metals, Ohio, 1984, pp.184-194.

[8] K. Dehghani, A. Nekahi, M.A.M. Mirzaie, Optimizing the bake hardening behavior of Al7075 using response surface methodology, Mater Des. 31 (2010) 1768-1775.

DOI: 10.1016/j.matdes.2009.11.014