Grain Structure, Crystallographic Texture, and Hardening Behavior of Dissimilar Friction Stir Welded AA5083-O and AA5754-H14

Abstract

This work investigated the effect of friction stir welding (FSW) tool rotation rate and welding speed on the grain structure evolution in the nugget zone through the thickness of the 10 mm thick AA5083/AA5754 weldments. Three joints were produced at different combinations of FSW parameters. The grain structure and texture were investigated using electron backscattering diffraction (EBSD). In addition, both the hardness and tensile properties were investigated. It was found that the grain size varied through the thickness in the nugget (NG), which was reduced from the top to the base in all welds. Reducing the rotation rate from 600 rpm to 400 rpm at a constant welding speed of 60 mm/min reduced the average grain size from 33 µm to 25 µm at the top and from 19 µm to 12 µm at the base. On the other hand, the increase of the welding speed from 20 mm/min to 60 mm/min had no obvious effect on the average grain size. This implied that the rotation rate was more effective in grain size reduction than the welding speed. The texture was the mainly simple shear texture that required some rotations to obtain the ideal simple shear texture. The hardness distribution, mapped for the nugget zone, and the parent alloys indicated a diffused softened welding zone. The heating effect of the pressure and rotation of the pin shoulder and the heat input parameter (ω/v) on the hardness value of the nugget zone were dominating. Tensile stress-strain curves of the base alloys and that of the FSWed joints were evaluated and presented. Moreover, the true stress-true strain curves were determined and described by the empirical formula after Ludwik, and then the materials strengthening parameters were determined. The tensile specimens of the welded joint at a revolution speed of 400 rpm and travel speed of 60 mm/min possessed the highest strain hardening parameter (n = 0.494).

The Effect of Temper Condition and Feeding Speed on the Additive Manufacturing of AA2011 Parts Using Friction Stir Deposition

“…FSW and FSP generate localized grain refinement in the whole nugget zone (NZ) behind the rotating pin tool. The FSD material is analogous to the NZ in FSW and FSP [ 17 , 36 ]. It was found that the presence of a refined, equiaxed grain structure engaged with the formation of high-angle grain boundaries is an indication of the dynamic recrystallization in FSW of AA2219-T8 [ 9 ] and FSP of AA2024/Al 2 O 3 nanocomposite [ 28 ].…”

“…Low porosity and low residual stress are the main privileges of the as-deposited part; this will make post-processing heat treatment unnecessary in many cases. However, surface finishing will usually be required [ 15 , 16 , 17 ]. Boeing and Airbus companies are considered the first use of additive manufacturing (AM) based on FSW principles [ 10 , 18 , 19 ].…”

The Applicability of Die Cast A356 Alloy to Additive Friction Stir Deposition at Various Feeding Speeds

“…These microstructure features confirmed the data obtained by OM. The AFS-D has a thermomechanical zone like the stir zone in FSP [45,46]. SEM investigation by Choi et al [47] showed that the plate-like Si particles were broken into slightly finer particles by the action of tool stirring during the FSP for A356.…”

The Development of WC-Based Composite Tools for Friction Stir Welding of High-Softening-Temperature Materials

“…Friction stir welding (FSW) is a solid-state welding process [43][44][45][46] that has been used at the laboratory scale for welding both low-softening-temperature materials (Al, Cu, Mg) [45][46][47][48] and high-softening-temperature materials (Ti, Ni, steel alloys) [49][50][51]. However, in terms of industrial applications, only low-softening-temperature materials find their way into a large number of applications, such as shipbuilding, railway, aerospace and automotive [44].…”