Effect of Welding Parameters on Friction Stir Welded Ti–6Al–4V Joints: Temperature, Microstructure and Mechanical Properties

Abstract

In this study, friction stir welding (FSW) of 2-mm-thick Ti–6Al–4V alloy plates was performed using a newly designed friction tool—and the effect of rotation speed and welding speed on microstructure and mechanical properties of the joints were investigated. A simulation model for FSW temperature field calculation was developed, and the effect of rotation speed and welding speed on the temperature field was investigated by experimental and numeric methods. The results show that the rotation speed has a dominant effect on peak temperature, while welding speed determines the dwell time of the weld exposed to high temperatures. In addition, the influence of process parameters on the microstructure of the joints was investigated using optical and scanning electron microscopy. The results revealed that there was a phase transformation in the stir zone during welding. The final microstructure of the stir zone was fully lamellar (α + β) structure, and the heat affection zone had a bimodal microstructure consisting of prior equiaxed α and lamellar (α + β) structure. Both rotation speed and welding speed affect the grain size of the weld. Lower peak temperature with decreasing spindle speed and/or shorter dwell time with increasing feed rate could produce finer grains in the stir zone of the joints, thereby could lead to higher microhardness value and the tensile strength of the joints.

Simulation of Temperature Field in FSW of 6061T6 Aluminum Alloy IGBT Liquid Cooled Radiator Panel

“…References [8] and [19] in the FSW process parameters indicated that the selected FWS liquid cooled radiator panel material is 6061T6 aluminum alloy under a set of the simulated rotational speed of 1000 r/min, the welding speed of 2 mm/s, and shaft downward pressure of 8000 N. Heat in the entire welding process is mainly concentrated in the weld area [30], and the surface temperature is shown in figure 8. The highest temperature is concentrated in the shoulder area of the stirring tool, and the temperature area spreads in a circular pattern from the shoulder to the surrounding area.…”

Microstructural and Mechanical Characterization of the Dissimilar AA7075 and AA2024 Aluminum Alloys Reinforced with Different Carbide Particles Welded by Friction Stir Welding

“…Using incorrect welding parameters in friction stir welding can affect the quality of the weld and increase the likelihood of cracking. This is the case, for example, if an excessively high welding speed is used, which can increase the probability of thermal cracking [40]. In addition to the above features, the SEM images showed the presence of WC and ZrC particles on the fracture surfaces.…”

Influence of Friction Stir Processing on the Hardness and Tribological Properties of Aluminium-Magnesium Alloys

“…In the present work, only two parameters, i.e., speed and feed, are varied in the study of the properties. Impact of tool speeds on microstructure and mechanical attributes on Ti-6Al-4V joints, and the optimal range is between 400 and 600 rpm, coupled with a feed rate of 75 mm/min [11]. Tool shoulder diameters between 18 to 24 mm will produce defect-free zones in 6 mm thick plates of AZ31B magnesium alloy for different process parameter combinations [12].…”