Study on mechanical, micro-, and macrostructural characteristics of dissimilar friction stir welding of AA6061-T6 and AA7075-T6

Abstract

This research presents the effect of welding speed on dissimilar joints of AA7075-T6 and AA6061-T6 alloys. The weld quality was evaluated through observations of the macrostructure. The mechanical properties of the welds, including the ultimate strength, the percentage of elongation, and the microhardness variations, were determined for different welding speeds. Also the effect of the positions of the two alloys on the mechanical properties was investigated. In addition, during the friction stir welding (FSW) process, the peak temperatures were measured in order to indicate the relation between the peak temperature and the hardness distribution at the heat-affected zone (HAZ). Accordingly, the influence of the welding speed on the developed grain size was elucidated by the microstructural analysis.

Effect of Forced Air Cooling on the Microstructures, Tensile Strength, and Hardness Distribution of Dissimilar Friction Stir Welded AA5A06-AA6061 Joints

“…The recrystallisation caused by the temperature rising during FSW can readily destroy the hardened state and significantly weaken the mechanical properties. In addition, precipitation hardening is one of the strengthening mechanisms for heat-treatable AA6061 [29,30], and grain size also plays an important role according to the Hall-Petch relationship [31]. For AA6061, the main strengthening phase is the needle-shaped β″ phase.…”

Effect of process parameters on mechanical properties of friction stir welded dissimilar 7075-T651 and 5083-H111 aluminum alloys

“…Since recent publications do not give definitive direction as to the optimal weld configuration (i.e., the placement of the alloy on the retreating or advancing side), the examined joints were produced in two configurations. Some researchers [10,14,28,29] reported that when the weaker alloy is placed on the retreating side, the produced weld becomes weaker compared to the opposite configuration. However, according to other investigations [12,13,30], the more efficient mixing of materials and better properties can be achieved with the softer alloy on the advancing side and the harder alloy on the retreating side.…”

Development of Fatigue Life Improvement Technology of Butt Joints Using Friction Stir Processing

“…Peening [14] is a cold working technique which replaces the tensile residual stresses produced by the welding process at the weld region with favorable compressive residual stresses, which effectively introduce a substantial initiation period in the fatigue life of the welded components [15,16]. In this study, a new postweld treatment method, friction stir processing (FSP) [17][18][19], is proposed to extend fatigue life by improving the weld bead shape and the metal structure at the weld zone. For that, first of all, an adequate pin shape and process conditions for FSP were developed through experimentation.…”