T HE aim of the present work is to study the effect of rotation and welding speeds as well as the T4 and T6 post-weld heat treatments (PWHT) on the corrosion behavior of AA6061-O aluminum plates joined using friction stir welding (FSW). The corrosion properties of welded joints were studied by Potentiodynamic polarization and Immersion tests. The results showed that both T4 and T6 PWHT improves the corrosion resistance of stirred zones compared to base alloy. However, joints of T4 showed lower corrosion resistance compared to T6. Increasing welding speed or reducing rotation speed increased the corrosion resistance of joints.
In the present work, titanium alloy with a composition of Ti-6.5Al-3Mo-1.9Nb-2.2Sn-2.2Zr-1.5Cr (TC21) was subjected to plastic deformation and aging processes. A Plastic deformation at room temperature with 2%, 3% and 4% stroke strain was applied on the studied samples. Then, the samples aged at 575˚C for 4 hr. By applying different plastic deformation ratios, the structure revealed an elongated and thin β-phase embedded in an α-phase. Secondary α-platelets were precipitated in the residual β-phase.Maximum hardness (HV440) was obtained for 4% deformed + aged samples. Minimum hardness (HV320) was recorded for the as-cast samples without deformation. The highest ultimate tensile strength of 1311 MPa was obtained for 4% deformed + aged samples due to presence of high amount of dislocation density as well as precipitation of secondary α-platelets in the residual β-phase. The lowest ultimate tensile strength of 1020 MPa was reported for as-cast samples. Maximum elongation of 14% was registered for 4% deformed + aged samples and minimum one of 3% was obtained for as-cast samples. Hence, strain hardening + aging can enhance considerably the elongation of TC21 Ti-alloy up to 366% and 133% in case of applying 4% deformation + aged compared to as-cast and aged samples without applying plastic deformation, respectively.
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