Analysis of Friction Stir Welding Tool Offset on the Bonding and Properties of Al–Mg–Si Alloy T-Joints

Abstract

Research on T-configuration aluminum constructions effectively decreases fuel consumption, increases strength, and develops aerial structures. In this research, the effects of friction stir welding (FSW) tool offset (TO) on Al–Mg–Si alloy mixing and bonding in T-configurations is studied. The process is simulated by the computational fluid dynamic (CFD) technique to better understand the material mixing flow and the bonding between the skin and flange during FSW. According to the results, the best material flow can be only achieved at an appropriate TO. The appropriate TO generates enough material to fill the joint line and results in formation of the highest participation of the flange in the stir zone (SZ) area. The results show that, in the T-configuration, FSW joints provide raw materials from the retreating side (RS) of the flange that play a primary role in producing a sound mixing flow. The selected parameters were related to the geometric limitations of the raw sheets considered in this study. The failure point of all tensile samples was located on the flange. Surface tunneling is the primary defect in these joints, which is produced at high TOs. Among the analyzed cases, the most robust joint was made at +0.2 mm TO on the advancing side (AS), resulting in more than 60% strength of the base aluminum alloy being retained.

Effects of FSW Tool Plunge Depth on Properties of an Al-Mg-Si Alloy T-Joint: Thermomechanical Modeling and Experimental Evaluation

“…The chemical composition and mechanical properties of AA6068 aluminum alloy used in this study are presented in Table 1 and Table 2 . Determination of the chemical composition was performed by emission spectroscopy (Hitachi, Japan) according to the ASTM E415 [ 13 ]. For the micrographic analysis of joint surface flow, an optical camera (Canon, Huntington, NY, USA) was used.…”

“…The test was repeated three times for each welding condition, and their average values were reported. For the use of flow stress of the base metal at different temperatures in the simulation procedure, uniaxial tension tests were performed on AA6068 aluminum alloy from 25 °C up to 500 °C according to ASTM E21 [ 13 ]. Thermal conductivity and specific heat of AA6068 aluminum alloy were measured according to ASTM E1461 and the results used in the simulation procedure [ 13 ].…”

“…T-shape joints consist of two structural parts called skin and stringer (flange). The skin is placed horizontally, and the flange is added vertically to the skin [ 13 ]. One of the most effective solid-state joining technologies is friction stir welding (FSW), which can improve the final properties of the welded joint compared to traditional joining techniques [ 14 ].…”

“…During the joining process of T-configuration structures, the most critical factor is the optimal mixing of the skin and flange without defects [ 16 ]. Internal voids and material explosions are common defects that directly affect the strength of FSW T-joints [ 13 ]. In comparison with other configuration joints, it was found that the final properties of T-configuration joints have a higher sensitivity to FSW parameters.…”

Investigation of Mechanical and Microstructural Properties of Welded Specimens of AA6061-T6 Alloy with Friction Stir Welding and Parallel-Friction Stir Welding Methods

“…By changing the condition of each of the parameters, the heat and material flow distribution in the process change, which ultimately leads to a change in the mechanical quality of the joint [8][9][10][11][12][13]. The most important factors influencing the FSW process are the temperature and the material flow distribution patterns in the welding zone [14][15][16][17][18]. The heat and flow of materials created in the process derive from two factors: welding geometry and tool geometry.…”