Aging Behavior of Aluminum Alloy 6082 Subjected to Friction Stir Processing

Abstract

The present work examined the effect of artificial aging on the microstructure, texture, and hardness homogeneity in aluminum alloy AA6082 subjected to friction stir processing (FSP). Aging was applied to FSP samples at three different temperatures (150 °C, 175 °C, and 200 °C) for a period of 1 h, 6 h, and 12 h. Microstructure analysis using optical Microscopy (OM) and Electron Back-Scattered Diffraction (EBSD) indicated that FSP produced fine equiaxed grains, with an average grain size of 6.5 μm, in the stir zone (SZ) due to dynamic recrystallization. Aging was shown to result in additional grain refinement in the SZ due to the occurrence of recovery and recrystallization with either increasing aging temperature and/or aging time. An optimum average grain size of 3–4 μm was obtained in the SZ by applying aging at 175 °C. This was accompanied by an increase in the fraction of high-angle grain boundaries. FSP provided a simple shear texture with a major component of B fiber. Increasing aging temperature and/or time resulted in the formation of recrystallization texture of a Cube orientation. In addition, Vickers microhardness was evaluated for the FSP sample, indicating a softening in the SZ due to the dissolution of the hardening precipitates. Compared to other aging temperatures, aging at 175 °C resulted in maximum hardness recovery (90 Hv) to the initial value of base metal (92.5 Hv). The hardness recovery is most likely attributed to the uniform distribution of fine hardening precipitates in the SZ when increasing the aging time to 12 h.

Optimizing the mechanical properties of Al-4.5Cu-xSi alloys through multi-pass friction stir processing and post-process aging

“…Ma et al [20] showed that post-FSP aging leads to the dissolution of Mg 2 Si particles in the microstructure of A356 alloy. Similar results have been also reported for AZ31 [57], AA7075 [31,58], and AA 6082 alloys [33]. It seems that the intense plastic deformation and material mixing during FSP facilitate the precipitates dissolution at a lower temperature within shorter time as reported by Feng et al [59] and Ma et al [60].…”

“…In addition to the above, due to the severe deformation and material mixing, FSP accelerates the diffusion rate and shortens the diffusion paths of solutes causing a substantial improvement in dissolution/precipitation kinetics at the temperatures below 300 °C [30]. Therefore, investigating the effect of post-FSP heat treatment has attracted the interest of researchers such as Deore et al [31], John Baruch et al [32], Al-Fadhalah [33], and Cao et al [34] and its positive impact on the mechanical properties of Al-based alloys has been proved. In the present work, an attempt was made to optimize the microstructure and mechanical properties of Al-4.5Cu-xSi (x = 1, 2, 3, and 5 wt.% Si) alloys by applying FSP and post-process artificial aging treatment.…”

Surface Modification of 6xxx Series Aluminum Alloys

“…Fadhalah and Asi [81] explored the effect of FSP on the microstructure, aging kinetics, and microhardness behavior of the AA6082 alloy. They noted that the stirred zone undergoes dynamic recrystallization, leading to refined grains.…”

“…However, these composites exhibit low ductility and toughness, reducing their prospect of applications. In applications such as wear and fatigue, where surface properties are essential, an appropriate alternative would be to convert the material at the surface as a composite by adding the reinforcement particles [71][72][73][74][75][76][77][78][79][80][81][82][83][84][85]. Figure 11 presents a micrograph of the commercial Al alloy with the surface-modified SiC-reinforced composite, using the FSP process.…”

Embrittlement Due to Excess Heat Input into Friction Stir Processed 7075 Alloy

“…Chegeni et al [20] investigated the effects of friction stir welding (FSW) on the microstructural and mechanical properties of 7075 aluminum rolled plates in addition to post welding heat treatment (PWHT) in the semi-solid region. Al-Fadhalah et al [21] examined the effect of artificial aging on the microstructure, texture and hardness homogeneity of 6082 aluminum alloy via FSP. Barbini et al [22] also examined the correlation between heat generation, microstructure and mechanical properties of dissimilar AA2024/AA7050 FSW joints.…”