The work presents an analysis of selected magnesium alloys as structural materials to be used in production of aircraft parts as well as their technological parameters in some manufacturing processes. Upsetting test, backward extrusion and Kobo extrusion of complex cross-sectional profiles and forging process were realized using magnesium alloys AZ31, AZ61, AZ80, WE 43 and Mg alloy with Li for production of thin -walled aircraft profiles and forged aviation parts. The range of temperatures and extrusion rate for the manufacturing these profiles were determined. Tests also covered the analysis of microstructure of Mg alloys in the initial state as well as after the extrusion process. It has been proved that the proper choice of parameters in the case of a specific profile extruded from magnesium alloys allows the manufacturing of products of complex cross-sections and the quality required in aerospace industry. This has been demonstrated on the examples of complex cross-sectional profiles using elements of varied wall thickness and examples of forged aviation parts: aircraft wheel hub and helicopter lever for control system.

Influence of the methodology of mathematical processing of experimental data on the calculated value of the activation energy in hot forming was evaluated for three very different alloys: iron aluminide, low-alloyed steel and magnesium alloy. Application of the mean strain rates is appropriate but calculations with use of nominal strain rates of the plastometric tests do not give significantly different results. Calculations based on the processing of the simplified power dependence between strain rate and peak stress can give the results differing very substantially from those that were gained by the solution of the complex hyperbolic relationship. This has negative impacts, particularly at prediction of the maximum flow stress in the broad range of forming conditions, represented by the Zener-Hollomon parameter.

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The paper presents analysis of plasticity characteristics and microstructure of magnesium alloys for hot plastic treatment with different aluminium content (3÷8%). Tests were conducted for assessment of susceptibility of tested alloys to hot plastic deformation. A tensile test was run in temperature from 250 to 450• C. Based on the results, ultimate tensile strength (UTS) and reduction of area (Z) were determined for samples. Conducted compression tests allowed to specify the flow stress and microstructure changes after deformation. The activation energy in hot forming was determined for investigated alloys. The parameters of the process where flow is significantly influenced by twin formation in microstructure were determined. A varied plasticity of tested alloys was found depending on aluminium content. Test results will be useful in development of forging technology of selected construction elements which serve as light substitutes for currently used materials.Keywords: magnesium alloy, research of plasticity, microstructure, dynamic recrystallization, activation energy W pracy analizowano charakterystyki plastyczności i mikrostrukturę stopów magnezu przeznaczonych do przeróbki plastycznej na gorąco ze zróżnicowaną zawartością aluminium (3÷8%). Badania prowadzono dla oceny podatności badanych stopów do kształtowania plastycznego w warunkach przeróbki plastycznej na gorąco. Przeprowadzono próbę rozciągania w temperaturze od 250 do 450• C, na podstawie której określono wytrzymałość na rozciąganie i przewężenie badanych próbek. Wykonane próby ściskania pozwoliły na wyznaczenie naprężenia uplastyczniającego i zmian mikrostruktury po odkształceniu. Dla badanych stopów wyznaczono energię aktywacji odkształcenia plastycznego na gorąco. Określono parametry procesu, dla których na przebieg plastycznego płynięcia wpływa istotnie bliźniakowanie w mikrostrukturze. Wykazano zróżnicowaną plastyczność badanych stopów w zależności od zawartości aluminium. Wyniki badań będą pomocne do opracowania technologii kucia wybranych elementów konstrukcyjnych stanowiących lekkie zamienniki stosowanych obecnie materiałów.

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