Advanced forming techniques for Magnesium alloys

Abstract

A new approach (Cotd Hydrostatic Forging) towards an improvement of the forming behaviour of
magnesium alloys has been investigated with the alloys AZ9l (Mg-Al-Zn) and ZK30 (Mg-Zn-Zr).
The idea of the project was to use a sunounding ductile shell in order to provide a hydrostatic
compressive stress state within the magnesium alloy samples during Cold Forging.
The steel Ckl5 has been used as surrounding material during upsetting tests and the aluminum alloy
AA6082 for the forward extrusion experiments. High logarithmic strains up to E = 1.2 (forward
extrusion) could be obtained without the appearance of any cracks for the ZK30 alloy and just of some
small ones.for the AZ91 alloy and o.f course none in the surrounding shell. Mechanical tests showed a
significant increase of the yield strength, ultimate tensile strength and hardness. At the same time, a
notable reducíion of elongation to failure occurred.