Factors Contributing to the Excellent Corrosion Resistance of Elektron 21 (EV31a)

I. Syed, Magnesium Elektron, Manchester (UK) 
 
Elektron 21 (ASTM Designation EV31a) is a Mg-RE-Zn-Zr sand casting alloy targeted to fulfil the needs of applications where a good package of castability, mechanical properties and corrosion performance are required. Designed for Aerospace and Speciality Applications, the alloy is capable of operating up to approximately 200°C (400F).

While some existing Mg-Zn-RE-Zr alloys, which offer adequate mechanical properties, suffer from poor corrosion resistance, Elektron 21 was developed taking into consideration various factors that optimised corrosion resistance, without compromising mechanical properties or castability.

This paper discusses various factors, which influence the excellent corrosion performance of the alloy, including the effect of Zn and Gd levels and surface cleaning. By controlling the chemistry of the alloy and eliminating sand cast surface effects, Elektron 21 achieves corrosion rates within the range 10-30mpy (0.1-0.4mcd).

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