Predicting Lap Shear Strength for Friction Stir Scribe Joining of Dissimilar Materials

Abstract

Friction stir scribe technology has been developed to join materials with vastly different properties, most importantly different melting regimes. Specifically lighter, lower temperature materials such as aluminum or magnesium can be joined to higher temperature materials such as steel and titanium. The scribe portion of the modified friction stir welding pin tool creates in situ mechanical interlocks at the material interface. This mechanical interlocking, or hook-like interface morphology, has shown promising joint strength. However, this morphology can vary along a weld length and is sensitive to joining and tooling parameters. The current work seeks to determine the sensitivity of joint strength to the morphology of the hook interface and predict joint strength based on key morphology parameters. Key morphology features of the hooks extracted from joined samples are varied to quantify their impact on simulated lap shear strength. Predictable joint strength is key to wide spread use of this technique.