A new friction stir welding based technique for corner fillet joints: experimental and numerical study

Abstract

Friction stir welding (FSW) is an energy efficient and environmentally "friendly" (no fumes, noise, or sparks) welding process, during which the sheets are welded together in a solid-state joining process. FSW is mature for simple configurations but a significant lack of knowledge is found when dealing with different designs such as T-sections, corner welds and box sections. The present work explores the feasibility of producing corner fillet geometries using FSW. Although such a kind of geometry has traditionally been considered unfeasible for the process, it seems to have a great potential to be used for T-joint configurations, a recurrent design pattern in transport applications. A specific tool has been developed and a set of welds has been produced with it. The process has been analysed by both micro and macro observations and a dedicated numerical model tuned by comparison of the thermal histories experimentally measured by embedded thermocouples. According to the obtained results, the proposed model is able to represent a useful design tool for the process. Main problem pending to be solved is how to avoid the formation of a tunnel defect in the weld centre line due to a suck effect of the tool on the stirred material.