Materials Characterization of Cast EV31A-T6 Magnesium for Rotorcraft Applications

EV31A-T6 is the latest generation magnesium casting alloy developed to provide the best value for use in rotorcraft transmission cases. This alloy is a potential replacement because of its improved strength and corrosion resistance compared to ZE41A-T5 (ZE41A), and reduced cost and improved castability compared to WE43B-T6 (WE43). Bell Helicopter conducted a multi-year project involving several foundries to verify the mechanical properties of sand cast EV31A-T6, as well as the impact of welding on tensile and fatigue strength. The tests included tensile and axial fatigue testing, fracture surface analyses, and microscopy. A demonstration EV31A-T6 component was cast using an existing tool for a ZE41A casting. Additional testing was performed to compare the difference in properties between air and hot water quenched material. This paper details the work performed and recommendations for further investigations.