Abstract
Creep-ageing behaviour of aluminium alloy 7B04-T651 at 115 °C under a range of tensile stress levels has been experimentally investigated and numerically modelled for creep-age forming (CAF) applications. Creep strain, yield strength evolution and precipitate growth of creep-aged specimens were investigated. The alloy was modelled using a set of unified constitutive equations, which captures its creep deformation and takes into account yield strength contributions from three creep-age hardening mechanisms. Applications of the present work are demonstrated by implementing the determined material model into a commercial finite element analysis solver to analyse CAF operations carried out in a novel flexible CAF tool. Stress relaxation, yield strength, precipitate size and springback were predicted for the creep-age formed plates. The predicted springback were further quantified and compared with experimental measurements and a good agreement of 2.5% deviation was achieved. This material model now enables further investigations of 7B04 under various CAF scenarios to be conducted inexpensively via computational modelling.
Highlights
Creep-age forming (CAF) is a metal forming technique that utilises the collective behaviour of viscoplastic deformation and microstructural change of aluminium alloys under external loading at elevated temperature [1]
Creep-ageing tensile test pieces of geometry and dimensions shown in Figure 1 and plates of dimensions 600 mm · 350 mm · 8.2 mm had been machined from the same bulk material in the longitudinal rolling orientation and provided in T651 temper by Aviation Industry Corporation of China (AVIC) Beijing Aeronautical Manufacturing Technology Research Institute (BAMTRI) (Beijing, PR China)
A material model was presented with its constants determined for creep-age forming of aluminium alloy 7B04-T651
Summary
Creep-age forming (CAF) is a metal forming technique that utilises the collective behaviour of viscoplastic deformation (creep) and microstructural change (ageing) of aluminium alloys under external loading at elevated temperature [1]. Manufacturing using this technique, in addition to better formed part quality and industrial environment, can reduce the number of manufacturing operations to form a part and the associated costs as well [2, 3]. The equation set was employed in finite element analysis to simulate an actual CAF process of the alloy in the form of
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