1st ICAI 2020

International Conference on Automotive Industry 2020

Mladá Boleslav, Czech Republic

Table 1: Nominal composition and typical tensile properties of selected cast magnesium alloys

Tensile properties

Designation (acc. To ASTM)

Nominal Composition [wt%] Condition

0.2% Proof Stress [MPa]

Tensile Strength [MPa]

Elongation [%]

Sand cast

75

180 230 140 220 135 230 200 170 215 215 200 135 225 170 240

4 3 3 5 2 4 3 2 5 2 7

AZ63 Al 6, Zn 3, Mn 0.3

T6

110

Sand cast

80 80 95 80

Al 8, Zn 0.5, Mn 0.3

AZ81

T4

Sand cast

T4 T6

120 100

Al 9.5, Zn 0.5, Mn 0.3

AZ91

Chill cast

T4 T6

80

120 125 105 135 110 145

AM50 AM20

Al 5, Mn 0.3 Al 2, Mn 0,5

Diecast Diecast

10

AS41 AS21

Al 6, Mn 0.3, Si 1 Diecast Al 2, Mn 0.4, Si 1 Diecast

4.5

4 5

ZC63 Zn 6, Mn 0.5, Cu 3

T6

Source: POLMEAR, I. Light Alloys – From Traditional Alloys to Nanocrystals 2.1.2 Wrought magnesium alloys – basic overview

Major effort to apply wrought magnesium alloys concerns both about their specific strength (super light and high strength on the other hand) and their ductility. Historically, first tendency to use wrought magnesium alloys appeared in the military aircraft in the 1940s. Nowadays, main interest in the development new wrought products can be observed in the automotive. Basic feature, which influences the formability of magnesium, arises from its hexagonal lattice (see Figure 2). At low temperatures, there is not active sufficient number of slip systems and that is why deformation occurs by slip on the basal planes in the close-packed directions and by twinning on the pyramidal planes. At temperatures over c. 250° C become active also additional pyramidal slip systems, which results in higher formability of magnesium products (Polmear, 2006). That is why forming temperature is very important at processing magnesium sheets and truly very limited cold forming can be performed in the case of magnesium sheets. Wrought magnesium materials are mainly produced by rolling, extrusion and forging. From the rolling point of view, magnesium sheets can be produced by reversing, multi-stage hot rolling of cast slabs (that can be taken as “conventional” production technology) or by so-called twin roll casting, which enables the production of magnesium strips in an economic way as well. This technology uses

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