Characteristics of Plasticity and Microstructure of Hot Forming Magnesium Alloys Mg-Al-Zn Type / Charakterystyki Plastycznosci I Mikrostruktura Odkształcanych Na Goraco Stopów Magnezu Typu Mg-Al-Zn

Abstract

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.

Metal Forming of Lightweight Magnesium Alloys for Aviation Applications

“…3). Flow stress-strain curves of alloy AZ31 are characteristic for alloy in which during deformation a mechanism of plastic strain called twinning occurs [10]. As it can be observed, the decrease of deformation temperature, below 250°C changes the shape of flow curve for tested alloys with 4.0% and 7,5% lithium.…”

Drawability Studies of Magnesium Alloy Sheets at Elevated Temperature / Badania Tłoczności Blach Ze Stopów Magnezu W Podwyższonej Temperaturze

“…It is a typical feature in the examined alloy that there is the grain growth together with the temperature growth. There are also twinned zones in the form of lenses in Az31 alloy microstructure which seem to be quite characteristic [7][8][9][10][11] and they can be clearly seen in the samples taken after forming at the temperature of 300°C (Mg 300 sample). The microstructure of Az31 alloy after the forming process at the temperature of 250°C has been dominated by twinning whereas the microstructure of Az31 alloy after forming at 350°C has been dominated by numerous slip bands.…”

“…At temperatures above 225°C the additional slipping systems are activated and this guarantees very good formability. Alloy additives provide very good cold formability by changing crystal lattice or fine grain [7][8][9][10].…”

Structure and Properties of Az31 Magnesium Alloy After Combination of Hot Extrusion and Ecap

“…Evaluation of elongation shows an influence of recrystallization (DRX /MDX), as was confirmed by light optical microscopy and transmission electron microscopy. It can be said that recrystallization has an eminent role in grain refinement formation of Mg based alloys [6,[8][9][10]. It is well know that grain size has an impact on the strength properties increasing.…”