W artykule zaprezentowano wyniki badań dotyczących wpływu parametrów odkształcenia na zmianę naprężenia uplastyczniającego oraz mikrostrukturę stopu magnezu AZ61 (oznaczenie wg norm ASTM). Próby jednoosiowego ściskania na gorąco przeprowadzono w zakresie temperatury od 250 do 400 [stopni] C i prędkości odkształcenia od 0,01 do 1 s-1. Analiza wyników badań plastometrycznych oraz obserwacja mikrostruktury w pozwoliły ustalić, który mechanizm odkształcenia plastycznego - poślizg czy bliźniakowanie - dominuje w określonych warunkach kształtowania stopu AZ61. Otrzymane wyniki porównano z rezultatami prowadzonymi wcześniej dla stopu typu AZ31 o mniejszej zawartości aluminium.
The current trends in the automotive and aircraft focus first and foremost on a reduction of the vehicle weight and saving energy, thereby protecting the environment. Such a set of technical, economical and ecological aspects arouses a considerable interest of the industry in light alloys. Owing to a number of their advantageous mechanical properties including, first of all, low density (1.74 g/cm3), magnesium alloys are more and more frequently used as an engineering material. There is a regular increase visible in the number of components made of magnesium alloys in the car structure. However, for the production of components from magnesium alloys, casting processes are still most often applied. Alloys used for plastic working are less popular compared to those processed via casting and therefore, the number of their grades is much smaller. The number of alloying components in cast magnesium alloys is always higher than in alloys subject to plastic working. Alloys from the group Mg?Al?Zn?Mn have the best set of properties, for they contain as much as 8 % Al with an addition of Mn (up to 2 %) and Zn (up to 1.5 %). From among elements subjected to plastic working, sheet metal deserves special attention, for it can be applied for the construction of light vehicles. In connection with the complexity of the phenomena which take place in the microstructure, a number of studies in the field of Mg-Al-Zn alloys subjected to plastic working are focused on detecting the mechanisms of deformation and structure reconstruction during deformation. There are two main mechanisms of deformation of magnesium alloy - slip and twinning. Magnesium alloys crystallize with hexagonal close pack (HCP) structure and they have very limited number of slip systems. The paper presents the research results on the effect of deformation parameters on flow stress and microstructure of AZ61 magnesium alloy. Hot compression tests were conducted at the temperature range of 250 to 400 [degrees] C and at the strain rate range of 0.01 to 10 s-1. Analysis of the plastometric tests results as well as examination of microstructure at different deformation phases allowed to determine what kind of deformation mechanism - slip or twinning - dominates in the specific conditions of AZ61 alloy forming. The results were compared to the ones obtained for AZ31 magnesium alloy.