Development of a Squeeze Semisolid High-Pressure Die Casting Process for Magnesium Structural Parts

High-pressure die casting is the most common method used to produce magnesium castings, due to the excellent balance of cost and properties for high production volumes with limitations in terms of final mechanical properties. A newly developed process based on employing low injection speeds, in a range slightly over the standard semisolid speeds with a modified die, with thick gates and high die temperatures has been developed. Despite working with speeds that are not in the lamellar flow, the obtained parts present very low porosity, allowing the use thermal treatments to increase the ductility without producing blisters. The demonstration has been performed in a AM60B magnesium body joint produced by the squeeze casting process. Finally, the microstructure and the mechanical properties of as-cast and T4 heat-treated samples were studied. The results indicate the improvement of the mechanical properties in T4 heat-treated parts; specifically, a 40% improved deformation-to-failure, 40-60% improved penetration force and 90% of energy absorption were possible to obtain employing the newly developed SC + T4 process.