On the Elastoplastic Behavior of Friction Stir Welded Tailored Blanks for Single Point Incremental Forming

Abstract

The current market requirements are increasingly pushing the industry towards the manufacturing of highly customized products. Tailored blanks are a class of sheet metals characterized by the local variation of properties, attributable to the presence of different materials, different thickness distribution, and thermal treatments. In the manufacturing of tailored welded blanks, welding and forming processes cover a central role. In this framework, friction stir welding demonstrated to be a suitable candidate technology for the production by joining of tailored blanks. Indeed, sheet metals welded by this solid-state welding process typically exhibit high formability when compared to the conventional welding methods. Due to the improved formability, a good deal of attention has been recently given toward the single point incremental forming (SPIF) process and its integration with FSW. Remarkable efforts have been dedicated to the numerical modeling of the SPIF of metallic alloy sheets jointed by FSW. The main criticisms in these models are related to the definition of the mechanical properties of the materials, which are affected by the structural alteration induced by the FSW. The present work aims to model the local alterations in the mechanical properties and to analyze how these local characteristics affect the formability of the blanks. With this purpose, a 20 mm wide sample collected from a FS welded blank of aluminum alloy AA6082 has been modeled using the mechanical properties variation achieved in a previous work. The influence of this local variation in properties has been assessed using a Finite Element Model Updating strategy.

Calibration of the Elasto-Plastic Properties of Friction Stir Welded Blanks in Aluminum Alloy AA6082

“…The experimental evidence demonstrates that their elastoplastic behavior is sensibly influenced by the tool rotational speed and the advancing velocity adopted during FSW. Single point incremental forming processes of friction stir welded tailored blanks in aluminum alloy in butt joint configuration demonstrated that with a proper choice of the process parameters the welding line presents a better formability than the base material [28,29].…”