For a long time, aluminium wrought alloys have been interesting materials for the sheet metal processing industry due to their low density and high affinity for passivation which results in corrosion resistance in many environments [1]. Despite the advantages aluminium alloys cannot compete with modern steel sheet alloys due to their low strength and low formability. Even when the microstructure of the aluminium alloys is modified, steel remains the first choice. Aluminium wrought alloys with the designation EN AW-5xxx and EN AW-6xxx show similar yield strength values compared with bake-hardening steels; although the fracture elongation differs by around 50% in favour of the steels (Fig. 1). Yield strength values from non-heat-treatable, and therefore only strain-hardenable, aluminium alloys of the EN AW-5xxx group are slightly higher when present in a highly strain-hardened condition (e.g. H18). But their fracture elongation values in an annealed condition are equivalent to those exhibited by the EN AW-6xxx group, which are precipitation hardenable. So, ways of enhancing the fracture elongation of wrought aluminium alloys to levels that are at least comparable with those of deep-drawing steels and additionally possess corresponding strength values are sought. Forming aluminium alloys below room temperature would be an approach, where strain hardening losses and precipitation processes are not an issue. In this regard there is no danger of a reduction in strength through the mechanism of recovery, recrystallization and aging which is in most cases induced by forming at higher temperatures. Furthermore, in previous investigations during tensile testing it was observed that in certain aluminium alloys, which were present in various heat treatmentconditions, the Lüders and the Portevin-LeChatelier (PLC) effect occurs at room temperature [2] [3]. This PLC effect not only causes a bad surface quality on sheet metals, but also creates a reduction of the uniform elongation and fracture elongation [2]. It is expected that in tensile testing at low temperatures the negative impact caused by the PLC effect can be reduced and therefore the values of uniform elongation and fracture elongation can be increased.
Mechanical behaviour of automobile relewant aluminium wrought alloys at low temperatures
International Aluminium Journal ; 88 , 9 ; 77-82
2012
6 Seiten, 10 Bilder, 2 Tabellen, 17 Quellen
Article (Journal)
English
Aluminiumlegierung , Streckgrenze , Schmiedelegierung , Niedertemperatur , Korrosionsbeständigkeit , Härtungsbedingung , Kaltverfestigen , Passivierung , Mikrostruktur , Zugprüfung , Raumtemperatur , Hochtemperatur , Oberflächenqualität , mechanische Eigenschaft , Automobilindustrie , Blechstahl , Al-Mg-Legierung
Machining wrought aluminium alloys
British Library Conference Proceedings | 1998
|Wrought Alloys of Aluminium in Aircraft
Emerald Group Publishing | 1929
|Use of wrought aluminum alloys in automobile construction
Engineering Index Backfile | 1921
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