Investigation of micro structural characteristics of friction stir welded AA6061 joint with different particulate reinforcements addition
Radhika Chada, Naveen Kumar, I. Rajasri Reddy
Abstract
The joining of heat-treated alloys(AA6061-T6) by the Welding process often results in a deterioration of mechanical properties because of the coarsening and dissolution of the strengthening precipitates (Mg2Si, Al3FeSi, Al12FeSi) at the weld nugget. However, it scares the applications of AA6061-T6 alloy. To enhance mechanical properties of Friction stir welded(FSWed) AA6061-T6 alloy and to minimize the loss of T6 condition, butt joints (FSW-SiC, FSW- B4C, FSW- TiB2, and FSW- Al2O3) were fabricated with the addition of more complex reinforcement particles( SiC, B4C, TiB2and Al2O3).In this work, the microstructure, tensile strength, surface properties such as hardness, and wear resistance of reinforced FSWed AA6061-T6 alloy joints were investigated. In contrast, the base metal and the welded joint prepared without reinforcement material were utilized as a reference to control the process. The grain refinement, which had been the reason for improved mechanical properties, was enhanced with reinforced particles in the weld region. Due to the high density of homogeneous dispersion of more complex reinforcement particles and considerably increased grain refinement throughout the welded joints, all the reinforced welded joints improved over the unreinforced joint in yield strength, hardness, and wear resistance. The addition of SiC, B4C, TiB2, and Al2O3 particles increases the hardness and wear resistance by14.5%,26.2%,8.9%, and 19.3%. At the same time, it did not influence much on the tensile properties compared to the unreinforced welded joint. Due to the extremely high hardness value and homogeneous dispersion of B4C particles in the FSW- B4C joint showed the highest percentage of hardness enhancement. Furthermore, the distribution of reinforcement particles improved the wear resistance of reinforced FSWed joints regardless of particle type compare to the base plate and unreinforced joint.