Friction stir welding of dissimilar metal joints

Abstract

Friction stir welding is a solid-state welding technology, which is suitable for joining dissimilar metals such as aluminium and copper. Because the solidus temperature is typically not exceeded, the formation of intermetallic phases can be reduced when compared to fusion welding processes. In friction stir welding, the intermetallic layer thickness, which determines the seam properties, is influenced by the welding temperature and is formed in correspondence with the Arrhenius law. It is typically in the range of a few hundred nanometers thick. In turn, the process temperature is determined by the process parameters, primarily the rotational speed and the feed rate of the machine tool. In this study, a temperature-controlled friction stir welding process has been applied to lap joints of aluminium and copper. Welding experiments with various welding speeds and probe lengths were performed in order to assess the effect of the temperature-time profile near the welding interface. The joints were investigated by tensile shear tests as well as optical microscopy and scanning electron microscopy.Friction stir welding of dissimilar metal joints Materialwiss. Werkstofftech. 2019, 50, 949-957

Estimation of The IMC Layer Thickness of Friction-Stir-Welded Aluminum/Copper Lap Joints By Using Temperature Simulation

“…9 shows the layer thicknesses calculated by the iterative approach. It can be seen, that different feed rates and layer temperatures lead to different thicknesses, which corresponds well to the observations of [31] and [33]. The calculated layer thicknesses for a feed rate of 300 mm/min are very close to the measured ones of [31].…”

“…These temperatures were also applied to the interfacial area due to the high thermal conductivity of aluminum. The calculated temperatures agreed well with the preset and controlled welding temperatures of [31] and [33]. Both studies were based on the same experimental set-up, while [31] used a constant feed rate of 300 mm/min and [33] varied the feed rate (see Table 5).…”

“…-The calculated layer thicknesses are slightly higher than the measured thicknesses of the experimental studies [31,33]. Therefore, the prefactor of diffusion and the activation energy may need to be updated to be used for layer temperatures exported from the described simulation.…”

“…7: Layer thicknesses of experiments no. 1, 3 and 5 using the estimation of [31] and compared with the results of [33] Two aspects have to be pointed out, when comparing the calculated layer thicknesses of this study with the measured ones of the experimental studies:…”

Role of plunge depth on the joint formation and mechanical behavior of Al6063‐AZ91 dissimilar lap joint produced by friction stir welding

“…The interface of Al−Mg 3.2 lap joint and its magnified image shows the formation of a thin intermetallic layer between Al6063 and AZ91 sheets which strengthens the joint, Figure 7a, b. Usually, the formation of intermetallic layer is required to produce strong weld joints while joining dissimilar metals [33, 34]. AZ91 Mg alloy is a supersaturated alloy with 9 % aluminum.…”