Abstract
	In this paper, the influence of chemical composition of aluminium alloy 5251 (Al-2Mg) on mechanical properties and structure of cold rolled strips was determined. Especially the alloys with different contents of magnesium were tested. Final stage of strips production consists of cold rolling from 4.5 mm initial thickness to 1.0 mm final thickness and recrystallization annealing, in order to partly or completely remove the strain hardening. The specimens taken from strips with magnesium content 1.8 % and 2.2 %, close to the limiting values, were subjected to mechanical testing, hardness measurements and cupping tests. On the base of hardness, yield and tensile strength measurements and material structure observation, the influence of magnesium content in aluminium alloy 5251 on mechanical properties was carried out. The special emphasis was put on the determination of annealing parameters, which allow to obtain the final strip corresponding with only one state of strain hardening. Finally, the suitable heat treatment process was established for alloys with different chemical composition, allowing for obtaining mechanical properties in a given range. It was found, that the range of magnesium content in aluminium alloy 5251 is too wide  to achieve mechanical properties, belonging to the same state of strain hardening, performing identical technological process.