No abstract

No abstract

Due to the high-strength to weigh ratio, corrosion resistance, good workability and weldability characteristics, aluminium alloys are increasingly used in many sectors. Researches on formability of aluminium alloy sheets have always been a hot topic these last years while very few works taking into both temperature and strain rate effects on formability limits can be found in the literature. In this study, the formability of sheet metal AA5086 is investigated at different temperatures (20, 150 and 200°C) and strain rates (0.02, 0.2 and 2 s −1) through a Marciniak test setup. Experimental results show that the formability of AA5086 increases with temperature and decreases with forming speed. Based on the analytical M-K theory, a Finite Element (FE) M-K model is proposed to predict the Forming Limit Curves (FLCs). A modified Ludwick hardening law with temperature and strain rate functions is proposed to describe the thermo-elasto-viscoplastic behavior of the material. The influence of the initial imperfection (f 0) sensitivity in the FE M-K model is discussed and a strategy to calibrate f 0 is proposed. The agreement

No abstract

No abstract

No abstract

The effect of pulse current on the mechanical properties of AZ31 alloy is investigated through uniaxial tensile test at different temperatures. The electroplastic effect is evaluated by the change of ultimate strength. During tensile test, both microstructure evolution and fracture behaviour are sensitive to the applied deformation conditions. In this work, the influence of pulse current is discussed from the point of view of microstructure evolution and fracture characteristics. The experimental results show that the dynamic recrystallisation temperature of AZ31 is reduced by the pulse current and continuous dynamic recrystallisation is found at 100°C for tensile test with current. The data also indicate that the pulse current accelerates the precipitation and dissolved of the second phase particles in AZ31 alloy.

International audienceThis paper proposes a method to investigate the effects of temperature and strain rate on the forming limit curves (FLCs) by combining a modified Voce constitutive model (Lin-Voce model) with the numerical simulation of Marciniak test. The tensile tests are firstly carried out at different forming temperatures (20, 230 and 290°C) and strain rates (2.5, 120 and 150s-1) for AA5086 sheet. A modified Voce constitutive model (named Lin-Voce model) is proposed to describe the deformation behavior of AA5086 and its material parameters are identified by inverse analysis technique. Then, the proposed constitutive model is verified by comparing numerical and experimental results obtained by tensile tests and Marciniak test, respectively. Finally, the numerical simulation of Marciniak test is carried out at different temperatures (100, 200 and 300°C) and strain rates (2.5, 120 and 150s-1), and the effects of temperature and strain rate on the FLCs of AA5086 are investigated and discussed