Influence of Alloys Position, Rolling and Welding Directions on Properties of AA2024/AA7050 Dissimilar Butt Weld Obtained by Friction Stir Welding

Abstract

Friction stir welding (FSW) was carried out for the butt joining of dissimilar AA2024-T3 and AA7050-T7651 aluminium alloys with 2-mm thicknesses. A comparison between the position and orientation of different materials was performed by varying the welding speed while keeping the rotational speed constant. Through an analysis of the force and torque produced during welding and a simple analytical model, the results indicate that the heat input was reduced when the AA7050 alloy was located in the advancing side (AS) of the joint. The different material positions influenced the material transportation and the interface in the centre of the stir zone (SZ). The microhardness of both materials was lower when they were in the AS of the joint. The differences in the hardness values were reduced at higher welding speeds when the heat input was decreased. The mechanical performance increased when the lower strength alloy was located in the AS. The material orientation exhibited a small influence when the AA7050 alloy was in the AS and in general on the resulting microhardness for all the cases analysed. The tensile strength values were very similar for both orientations, but an increase in the yield strength could be measured when the materials were oriented in the transverse direction.

Friction Stir Welding of Dissimilar Aluminum Alloy Combinations: State-of-the-Art

“…The placement of the alloy affects material flow as it strongly influences material stirring and mixing. This can be crucial in the final joint microstructure when the BM combination selected have significant differences in mechanical properties [69,70]. As the material flow during FSW is quite complex on its own, the placement of materials becomes an important parameter in welding, similar to the importance of the rotation and the welding speeds (see Table 1).…”

Advances in FSW and FSSW of dissimilar Al-alloy plates

“…The positioning of the two base metals during FSW of dissimilar materials welding is very influential in terms of material flow as it strongly determines material stirring and mixing [3,4]. This can particularly be crucial in the final joint microstructure when the materials combination selected have significantly different mechanical properties [5][6][7][8][9]. Thus, the positioning of base materials becomes an important parameter in welding, similar to the importance of the rotation and the welding speeds.…”

Modeling and optimization of process parameters for friction stir welding of dissimilar aerospace alloys AA2014 and AA7075

“…Localized stress concentration was reported as the main cause of low strength and ductility of welded joints. Barbini et al [31] examined the experimental effects of varying WS at fixed RS and alloys positions in dissimilar FSW of AA2024 and AA7050. High strength was obtained when low strength alloy was placed at the advancing side because of the better material flow and at lower WS.…”