Mechanical Testing of Extruded Magnesium for the Development of Automobile Seat Frame Structures

Abstract

To validate a novel structural concept in magnesium lightweighting in early development stages, a magnesium alloy of type MgMnCe is characterized at coupon level and validated at profile level. The feasibility of friction stir welding is confirmed to integrate the alloy into the structure. Specimens are extracted from or set up on basis of generic profiles. For characterization amongst others, miniature tensile specimens in extrusion and transverse direction are utilized. Tensile results show the orthotropic material character of the ME21 alloy used. In transverse direction stiffness as well as strength increases, while elongation at break decreases. The material shows a strongly nonlinear, irreversible material behavior starting at small loads and a moderate strain-rate dependency. On profile level, closed rectangular profiles in four-point bending are used for validation at high impact velocities. These tests reveal large deformation without local failure. This deformation makes the use of closed rectangular profiles promising for the application in seat backrest structures.