In many industrial cases it is possible to avoid the microstructure preparation requiring complicated processing steps and use the material in as received condition. This possibility is discussed by Woo et al. (1997). They investigated Al-Mg alloys containing 5.3, 7 and 11 wt.% of Mg in the temperature range of 300–550 ◦C and strain rate range 0.5*10−4 to 10−1. Steady state stress—strain
rate curves are presented and it is noted than they can be fitted by Backofen equation with the m value equal to 0.3 for each temperature and chemical composition if the strain rate is less than 10−2. The elongations reached at the temperature of 400 ◦C and the
strain rates of 10−3 and 10−2 are in the range of 200–275%. Lower
temperatures and higher strain rates leads to abrupt decreasing of tensile ductility.
Due to the initial industrial restrictions, the forming temperature was chosen at 415 ◦C. Two series of tensile and free bulging tests were performed at this temperature on hot rolled sheets of a 0.92 mm mean initial thickness. In both cases the specimens were annealed during 20 min before the deformation and then deformed in argon atmosphere. Microstructure analysis showed that average grain size was 9.5 ± 0.7 m before and 10.5 ± 0.7 m after the annealing.