Aluminum based alloys of the 5xxx series are identified by a high magnesium content (4÷4.9%) which through its compounds can induce special properties of mechanical strength and resistance to various forms of corrosion. The use of 5083 aluminum alloy is especially intended for pressure vessels, products that work in special conditions of temperature and environment with increased aggressiveness, which requires the request in specifications of special properties, especially in the test of resilience. This paper aims to define the best combination of heat treatments, either homogenization or homogenization and artificial aging, in order to obtain the best mechanical and structural characteristics. Two homogenizations were carried out on the cast products (at 350°C and 450° C, respectively), each followed by artificial aging (180°C or 140°C), with different maintenance times, respectively 1h, 12h and 24h). Finally, structural correlations could be made between the values of mechanical properties (yield strength, hardness, tensile strength, elongation, microhardness and resilience) and the grain size corresponding to each structural condition.

Aluminum based alloys are widely used as applications for heat exchangers, especially for car radiators. The main alloy used is 3003 (in according with ISO6361), which is usually plated with a 4000 series alloy (which has a lower melting point). The present paper gives a comparative analysis of the mechanical characteristics values of the 3003 alloy plated sheets, in different states (state O and state H24), and different sheet thicknesses (0.5 mm, 0.97 mm, and 2 mm respectively). Statistical comparative analysis shows that the considered processes are stable (in control) in the sense of control chart (X chart and R chart values) are within the control limits and there are no specific trends. The stability of the processes was highlighted by the use of performance indices. Thus, the CPK performance index in all the analyzed situations is much higher than 1.33, which means that the processes are stable with a normal distribution of values. Instead, the PPK capability index values are much lower than CPK. The distribution of elongation values (in state O, at a thickness of 0.97 mm - with the value of the PPK capability index 1.95 and in state O 2.5 mm thickness - with the value of the PPK capacity index 2.25 mm) has a value greater than 1.67, which indicates that this characteristic is in a state of statistical control (ie PPK ≥ 1.67 and CPK ≥ 1.33). The fact that for the other characteristics the value of the PPK ≤ 1.67 capability index, and yet the process is stable, means that there must be process improvements through various corrective measures until continuous stability is achieved. The complete statistical analysis, performed on the values of the mechanical characteristics, of the 3003 alloy plated sheets, in different delivery states and different thicknesses, showed, finally, that the applied technological processes led to obtaining appropriate mechanical characteristics, without deviating from outside the limits of tolerance, with high reproducibility and stability.