Refill Friction Stir Spot Welding Of Dissimilar Alloys

Lightweight alloy materials such as magnesium and aluminum alloys are frequently employed in the automotive and manufacturing industry in order to improve vehicle fuel economy. This creates a pressing need for joining of these materials to each other, as well as to steels. Given the drastic difference in thermal and mechanical properties of these materials and the limited solubility of aluminum or magnesium in steel, dissimilar alloy fusion welding is exceptionally difficult. Refill friction stir spot welding (RFSSW) is a solid-state joining technology which connects two materials together with minimal heat input or distortion. The RFSSW process involves a three-piece non-consumable tool with independently controlled sleeve and pin components, which rotate simultaneously at a constant speed with the sleeve penetrating into only the top sheet. Joining of Al 5754 alloy and DP 600 plate using friction stir seam welding is investigated. Two travel speeds of the shoulder are used to compare the mechanical and microstructural properties of the two kinds of welds made. Scanning electron microscopy (SEM) and optical microscopy are utilized to characterize the microstructure. Mechanical properties are evaluated using tensile testing. Joining of Al 6063-T6 and Zn coated DP 600 steel using RFSSW is studied. Spot welds could reach a maximum overlap shear load of 3.7 kN when using a tool speed of 2100 RPM, a 2.5 s welding time and 1.1 mm of penetration into the upper Al 6063 sheet. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were conducted to characterize the interface, which revealed that zinc layer was displaced into the interface and upper sheet, which may facilitate the bonding between the two sheets. Microhardness measurements reveal that the fracture path propagates through the soft heat affected zone of the Al alloy during overlap shear testing. Joining of Mg alloys ZEK with Zn coated DP 600 steel sheets by RFSSW is also studied here. In joints between ZEK 100 and DP 600, the maximum overlap shear fracture load is 4.7 kN, when a 1800 RPM tool speed, 3.0 s welding time and 1.5 mm penetration into the upper ZEK 100 sheet is applied. SEM and transmission electron microscopy (TEM) revealed that a continuous layer of FeAl2 particles accommodate bonding of the ZEK 100 and DP 600 sheets, which appears to have originated from the galvanized coating on the DP 600. If the zinc layer is removed then the maximum overlap shear fracture load is 3.1 kN. X-ray diffraction analysis of the interface between the Mg alloy and the DP 600 steel on the Mg side also revealed that intermetallic (IMCs) such as FeAl2 existed as an interfacial layer between the two sheets. It can be revealed from the displacement curve that the absorbed energy of the weld made under the condition of 1800 RPM, 3.5s, and 1.5mm of plunge depth in tensile testing up to failure point is approximately 2.73J

Process Modelling Applied to Aluminium-Steel Butt Welding by Hybrid Metal Extrusion and Bonding (HYB)

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Off-line path programming for three-dimensional robotic friction stir welding based on Bézier curves

Robotic friction stir welding (RFSW) is an innovative process which enables solid-state welding of aluminum parts using robots. A major drawback of this process is that the robot joints undergo elastic deformation during the welding, because of the high forces induced by the process. This leads to tool deviation and incorrect orientation. There is currently no computer-aided manufacturing/computer-aided design (CAD) software for generating off-line paths which integrates robot deflections, and the main purpose of this study is to propose an off-line methodology to plan a path for RFSW with the integration of the deflections

Friction Stir Welding and processing in alloy manufacturing

This MDPI book is the printed copy edition of the Special Issue (SI) 'Friction Stir Welding and Processing in Alloy Manufacturing' that was previously published online in the open access journal Metals. The book collects 10 papers with the latest developments in the fields of FSW, friction stir spot welding (FSSW), and friction stir processing (FSP), written by well-known researchers who have contributed significantly to advances in computational modeling, numerical simulation, and material characterization in the field. Each contribution has been subjected to peer review by three experts in the field in order to monitor the research quality of the outcome.Peer ReviewedPostprint (published version