Friction stir welding/processing of metals and alloys: A comprehensive review on microstructural evolution

Recent progress on control strategies for inherent issues in friction stir welding

Friction stir welding (FSW), a highly efficient solid-state joining technique, has been termed as “green” technology due to its energy efficiency and environment friendliness. It is an enabling technology for joining metallic materials, in particular lightweight high-strength aluminum and magnesium alloys which were classified as unweldable by traditional fusion welding. It is thus considered to be the most significant development in the area of material joining over the past two decades. Friction stir processing (FSP) was later developed based on the basic principles of FSW. FSP has been proven to be an effective and versatile metal-working technique for modifying and fabricating metallic materials. FSW/FSP of aluminum alloys has prompted considerable scientific and technological interest since it has a potential for revolutionizing the manufacturing process in the aerospace, defense, marine, automotive, and railway industries. To promote widespread applications of FSW/FSP technology and ensure t...

Recent Advances in Friction Stir Welding/Processing of Aluminum Alloys: Microstructural Evolution and Mechanical Properties

Copper and aluminum materials are extensively used in different industries because of its great conductivities and corrosion resistant nature. It is important to join dissimilar materials such as c...

A Review on Dissimilar Friction Stir Welding of Copper to Aluminum: Process, Properties, and Variants

Microstructural evolution and mechanical properties of dissimilar Al–Cu joints produced by friction stir welding

Good appearance and defect free friction stir welded joints of aluminium alloy to copper were obtained in a narrow range of welding conditions. The weld nugget (WN) consisted mainly of Cu(Al) solid solution, Al and several intermetallic compounds (IMCs), including CuAl2, CuAl, Cu9Al4 and Cu3Al although the maximum peak temperature measured in the weld was 422°C. Intercalation was a typical structure distributed widely in the WN and consisted of many parallel alternate lamellae. At the WN/Cu interface, the intercalations were characterised by flat or bended feature and composed of CuAl+Cu9Al4, Al+CuAl2+Cu(Al) and Cu(Al) laminae. The formation mechanisms for these intercalation structures and IMCs were attributed to the intense stirring action of the tool pin and the short circuit diffusion caused by extreme deformation respectively. The fracture surface exhibited some IMCs, including Cu9Al4 and CuAl2, which should be responsible for the limited tensile strength. The hardness profiles were consisten...

Microstructural characterisation and mechanical properties of friction stir welded joints of aluminium alloy to copper

Al/steel dissimilar welds were obtained by friction stir lap welding (FSLW) with an Al interlayer, which was fabricated by friction surfacing (FS). In present study, the tool pin was totally plunged into the Al plate and interlayer without stirring steel, which avoided the tool wear. The Al plate and interlayer were remarkably intermixed as pin length increased. A diffusion layer, instead of the intermetallic layer, was found at the Al/steel interface, indicating the enhanced atomic migration and related interfacial bonding. The maximum failure load of the joints of 2.8 kN was reached when the 2.5 mm pin tool was used. The heterogeneous microstructure, which was caused by the intermixing, was responsible for the fracture, according to the fracture profiles. Necking and dimples were depicted from the fractographies, indicating that the joints were failed by plastic fracture.

Microstructure and mechanical properties of Al/steel dissimilar welds fabricated by friction surfacing assisted friction stir lap welding

Interfacial microstructure and mechanical properties of Al/Ti dissimilar joints fabricated via friction stir welding

Microstructure and mechanical properties of laser welded-brazed Mg/Ti joints with AZ91 Mg based filler

A new technique of self-refilling friction stir welding (SRFSW) relying on non-consumable joining tool has been developed to repair the keyhole left at the end of 316L stainless steel friction stir welding/friction stir processing (FSW/FSP) seam. The conventional FSW process was transformed by adopting a series of non-consumable tools with gradual change in geometry to create a solid state refilled joint step by step. Using the combined plastic deformation and flow of the material around the keyhole, the SRFSW process is able to repair the keyhole with both metallurgical and mechanical bonding characteristics, and the FSW/FSP seam can be achieved without keyhole or other obvious macro defects. Microstructural observation results showed that the grains in the refilled zone were significantly refined by the tool. Tensile test results showed the refilled joint fractured at the base metal side, and the relative tensile strength and elongation are 112 and 82% of the base metal respectively. Moreover, n...

Li Zhou

Papers

Microstructural characterisation and mechanical properties of friction stir welded joints of aluminium alloy to copper

Microstructure and mechanical properties of Al/steel dissimilar welds fabricated by friction surfacing assisted friction stir lap welding

Interfacial microstructure and mechanical properties of Al/Ti dissimilar joints fabricated via friction stir welding

Microstructure and mechanical properties of laser welded-brazed Mg/Ti joints with AZ91 Mg based filler

New technique of self-refilling friction stir welding to repair keyhole