Effect of the Welding Speed on the Macrostructure, Microstructure and Mechanical Properties of AA6061-T6 Friction Stir Butt Welds

Abstract

Friction stir welding of aluminum alloys has been progressively used in different industries on the ground of higher welding quality in comparison to fusion welding. In this article, friction stir welding of 6061-T6 aluminum alloy with 9.6 mm thickness was carried out by using three different welding speeds (63, 89 and 110 mm/min). The effect of welding speed on macro-and microstructure, micro hardness, tensile properties and kissing bond was investigated. Results show that the Low Hardness Zone was moved toward the weld center by increasing the welding speed. The average micro hardness in the weld nugget zone increased from 60.1 to 67.6 HV with the raise of welding speed from 63 to 110 mm/min. Thermo Mechanical Affected Zone was clearly revealed using Electron backscatter diffraction (EBSD). The kissing bond was studied by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) mapping. It was proven that the damaging effect of kissing bond was linked to location of this discontinuity, although the growth of kissing bond was linked to higher welding speed. The maximum value of Ultimate Tensile Strength (UTS) (159 MPa) was obtained at 110 mm/min, whereas the Yield Strength (YS) in the sample at 89 and 110 mm/min welding speed exhibit the same trend with 137 MPa and 134 MPa respectively.

A Microstructural Evaluation of Friction Stir Welded 7075 Aluminum Rolled Plate Heat Treated to the Semi-Solid State

“…FSW is defined as a solid state joining process in which the workpieces being welded are not melted [6][7][8]. Continuous improvements to the performance of FSW joints during the process, has been achieved by variations of the process, as for instance, double-sided FSW that offers advantages over conventional FSW methods such as higher transverse speed and even distribution of heat input into the workpieces to be joined [9][10][11].…”

Microstructure and Mechanical Properties of Friction Stir Welded Joint of an Aluminum Alloy Sheet 6005A-T4

“…As a result, the strength of NZ was correspondingly enhanced. However, for 6xxx aluminum alloy, most research were focused on the T6 heat treatment status [7,22,[28][29][30][31][32][33][34][35][36] and few reports on the other status can be referred. According to our pre-research, the aluminum 6005A-T4 presented favorable performance with protentional application to automobile and rail transmit field but the welding routines and corresponding parameters remained to be unknown and need further investigation.…”

Post-Weld Heat Treatment Effects on Mechanical Properties and Microstructure of AA6061-T6 Butt Joints Made by Friction Stir Welding at Right Angle (RAFSW)

“…Friction stir welding (FSW) has attracted an increasing interest among researchers and industrial sectors over the past two decades [1]. Compared to the common fusion-welding techniques, like MIG welding, FSW provides users with many advantages such as better mechanical and fatigue properties of the weld, the ability to weld dissimilar alloys and non-weldable alloys by fusion welding techniques, less energy-consumption, and environmental friendliness [1][2][3][4][5][6][7]. However, there are some obstacles to its prevalent use such as the need for CNC equipment, the large forces involved, the need to use sturdy fixtures, and, generally, the equipment costs and royalties [2,3,8].…”

“…Therefore, it is essential to shed light on the impact of various PWHT processes on the optimized welded samples by the RAFSW technique to make it reliable for potential industrial users. Various parameters affect the physical and mechanical properties of FSW joints such as microstructure, tensile properties, and the micro-hardness distribution of the weld area [6,18,19]. Tool design is one of the influential parameters since the mixing and stirring mechanisms within the weld area are in control of that [20].…”