Dependence of the Joint Strength on Different Forming Steps and Geometry in Hybrid Compound Forging of Bulk Aluminum Parts and Steel Sheets

Abstract

Hybrid compound forging of aluminum bulk parts and steel sheet metals is a combination of material lightweight design and structural lightweight design. During this process, an aluminum bulk part and a steel sheet metal are combined and formed simultaneously. A material joint is generated by deforming, using zinc as solder material. This prevents the generation of brittle intermetallic Fe-Al-Phases as well as contact corrosion. The zinc layer is applied to the aluminum bulk part by hot dipping. To create a material locking connection by forming, suitable parameters such as the forming temperature are identified in first experimental trials. Microsections showed that the zinc layer is still intact after forming. In this paper the investigation of the effects of different steps of forming and different geometries of the aluminum bulk part surface on the joint strength are described. The forming tests show that a further forming of the aluminum part, resulting in a bigger deformation, leads to a stronger connection between both joining partners. But there is a limit to the forming since the applied forces can transfer to the steel sheet leading to an unintended deformation. The generated hybrid parts are tested for their ability for further forming. Therefore, the joined hybrid parts are undertaken a deep drawing process to see if the joint withstands further forming of the hybrid part.