Dissimilar welding of aluminium (Al) and copper (Cu) has many applications in the electric power, electronic and piping industries. The weldments in these applications are highly valued for their corrosion resistance, heat and electricity conducting properties. The Al-Cu joints are lighter, cheaper and have conductivity equal to that of copper alloys. Much research has investigated dissimilar welding of Al-Cu by solid-state welding and fusion welding processes with the aim of optimising the properties and strength of such dissimilar joints. The main aim of the study is to critically review the factors influencing the properties of the Al-Cu joint. The study mainly discusses about the effects of intermetallic compounds (IMC) on the properties of Al-Cu joint and their effect while in service. The effects of joining aluminium alloy 1060 with pure copper by laser welding, friction stir welding and brazing have been reviewed and compared. The review shows that the various intermetallic compound formations in the joint have both beneficial and detrimental effects. The characteristics of these intermetallic compounds vary according to the location of the phase formed. Comparison of processes and parameters for welding of Al 1060 with pure Cu shows that the formation of the intermetallic compounds and their effects on the weld properties are mainly influenced by the welding speed, heat input, the thermal properties of the base metals and the filler metal as well as the dilution between the base metal and filler metal.

To reduce environmental impacts and ensure competitiveness, the fabrication and construction sectors focus on minimizing energy and material usage, which leads to design requirements for complex structures by joining of similar and dissimilar materials. Meeting these industrial demands requires compatible materials with improved properties such as good weight-to-strength ratios, where aluminum (Al) and its alloys are competing candidates for various complex applications. However, joining Al with fusion welding processes leads to joint deterioration. Friction stir welding (FSW) produces joints at temperatures below the melting temperature, thus avoiding flaws associated with high heat input, yet requires improvement in the resultant joint properties. Recent studies have shown that nanoparticle reinforcement in FSW joints can improve weld properties. The main focus of this study is to critically review similar and dissimilar friction stir welding of AA5083 and AA6082 with carbide and oxide nanoparticle reinforcement. The study also discusses the effect of welding parameters on reinforcement particles and the effect of nanoparticle reinforcement on weld microstructure and properties, as well as development trends using nanoparticles in FSW. Analysis shows that friction stir welding parameters have a significant influence on the dispersion of the reinforcement nanoparticles, which contributes to determining the joint properties. Moreover, the distributed nanoparticles aid in grain refinement and improve joint properties. The type, amount and size of reinforcement nanoparticles together with the welding parameters significantly influence the joint properties and microstructures in similar and dissimilar Al welds. However, research is still required to determine the strengthening mechanism used by nanoparticles and to assess other nanoparticle additions in FSW of Al alloys.

High-strength steel S960 is one of a number of advanced steels able to meet the demands of the shipbuilding, offshore, and construction industries for a favorable good high strength/weight ratio. Gas metal arc welding (GMAW) is commonly used in all structural steel fabrication, and developments in GMAW have removed previous limitations regarding high heat input and have reduced flaws. One solution for controlled heat input while ensuring a stable arc is alloying the welding wire. Usage of nanoparticles as an alloying element in welding wire have shown significant improvements in weld properties. This study investigates an S960QC joint welded with a welding wire having Lanthanum (La) nanoparticles as a coating and examines the influence of La on the welding parameters, arc stability, microstructure formation, and mechanical properties. The results are compared with a weld formed with conventional Union X96 welding wire. The microstructures observed in the weld region were martensite and tempered martensite for both wires. In the heat-affected zone, microstructures of upper bainite, martensite, tempered martensite, and globular bainite were found. The La nanoparticle-coated wire provided a stable arc during welding. However, due to the increase in wire thickness, manual wire feeding was required. The impact toughness was lower in the joint formed with the nanoparticle-coated wire. Additionally, the hardness at the fusion region was higher in the joint welded with the nanoparticle-coated wire.

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