On material flow in Friction Stir Welded Al alloys

A Tongne,C Desrayaud,M Jahazi,E Feulvarch

doi:10.1016/j.jmatprotec.2016.08.030

Abstract

AA6082-T6 joints were produced using a trigonal shape pin. The influence of Friction Stir Welding (FSW) process parameters on the formation of banded structures was predicted using numerical modeling and then experimentally validated by optical and electron microscopy. Special attention was paid to the formation and evolution of banded structures observed in the plane of the welded sheets. A finite element (FE) analysis based on the Coupled Eulerian–Lagrangian formulation was developed to predict and quantify the influence of FSW process parameters on the formation and extent of the banded structures. The combination of the experimental and numerical analyses showed that the formation of the banded structures is mainly related to the geometry of the pin whereas the friction conditions have a much smaller effect.

Highlights

Friction Stir Welding (FSW) is a solid state joining process in which a rotational tool moves along the interface of the parts to be welded
Friction stir welds have superior mechanical strengths when compared to conventional welding processes
The comparison shows that FSW welds are the strongest ones both for bending and tensile tests

Summary

Introduction

Friction Stir Welding (FSW) is a solid state joining process in which a rotational tool moves along the interface of the parts to be welded. MIG, TIG and FSW welds of aluminum alloy 5086-H32 have been studied by Taban and Kaluc (2007). Fatigue tests carried out by Ericsson and Sandström (2003) on welds made of aluminum alloy 6082 showed that the fatigue strength of FSW welds is higher than that of MIG and TIG welds. For FSW welds, the material forming the joint undergoes different thermomechanical histories depending on its location in the joint. This gradient in thermomechanical history results in various microstructural features and plays major role in determining the mechanical strength of the joint. The microstructure of the joint exhibits a number of characteristic features such as:

Objectives

Findings

Discussion

Conclusion