Stress relaxation ageing behaviour and constitutive modelling of a 2219 aluminium alloy under the effect of an electric pulse

Experimental investigations of stress-relaxation ageing behaviour of AA6082

“…Additionally, 12 hr stress-free ageing test was carried out for reference. higher initial strain in the elastic region corresponds to a larger initial stress level and a higher percentage of relaxed stress, which is consistent with previous findings for stress-relaxation of AA2219 [10] and AA7050 [19]. In the plastic region, although the initial stress changes only slightly with increasing initial strain levels for AA6082-T6 (from 227.0 to 228.9 MPa when the initial strain level increases from 0.60% to 2.00%), a significantly higher relaxed stress percentage is observed with increasing initial strain levels.…”

“…is generated by loading in the plastic region and will not change during stress-relaxation, hence ̇ = 0. As stress-relaxation mainly results from the creep strain during stress-relaxation ageing tests, creep mechanisms can be applied to explain the stress-relaxation behaviour [10].…”

“…n, the stress exponent in the equation, has been widely used to indicate creep mechanism of metals [31]. For aluminium alloys, there are generally three types of creep mechanisms with associated stress exponent n being 3, 5, and 8 [10,24]. n = 3…”

“…Most of the current investigations on stress-relaxation ageing behaviour has been focused on 2000 and 7000 series aeronautical aluminium alloys. Three stages of stress-relaxation have been reported, including a first stage with a drastic drop of stress, a slow stress-relaxation rate changing stage and a stable stage; and a threshold stress has been proposed due to the interaction between precipitates and dislocations during the concurrent stress-relaxation and ageing [9,10]. The other series of heat treatable aluminium alloys, 6000 series Al-Mg-Si alloys, has been widely used for large panels in trains, ships and automobiles [11].…”

Research on theoretical modeling and numerical simulation of viscoelastic-plastic bending neutral layer in T-welding stiffened panels-based aged stress relaxation forming

“…Zhan et al 3 conducted the comparative study of stress relaxation and creep behavior for 7055 alloy, and found that the trend of creep and stress relaxation behavior was similar. In order to achieve high-strength, high-performance and highprecision collaborative manufacturing of large complex plates, an EPC was further introduced into the CAF process for 2219 Al plate by Zhan et al, 4 to explore the difference between the deformation and phase transformation activation energies in this alloy panel. At the same time, the stress relaxation aging constitutive model considering the effect of EPC was established.…”