Mechanical and microstructure analysis of AA6061 and Ti6AI4V fiber laser butt weld

Dissimilar metal welding involves the joining of two or more different pure metals or alloys, usually by melting and mixing and often with the addition of filler metal. There are several types of dissimilar metal welds including stainless steel, either as base metal or as filler metals. Dissimilar metal joints have distinctive features because of differences in the chemical composition of base metal and filler material. Their alloying elements will diffuse intensely during welding. The structures near the fusion line are very complex. Despite of great potentiality in aircraft and automotive industries, dissimilar joining of hybrid Al-Ti structures is often challenging because of the unavoidable formation of brittle intermetallic compounds, mixing of molten phases, and significant differences in material properties. In this work, dissimilar 2 mm thickness AA6000 and Ti6Al4V butt joints were produced by shifting an Yb fiber laser beam on the upper surface of the Ti sheet. Neither filler wire nor groove preparation was adopted. Different working conditions and seam shapes were assessed. The welds were characterized in terms of metallurgical and mechanical behaviors

Analysis of microstructure and defects in 17-4 PH stainless steel sample manufactured by Selective Laser Melting

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Hybrid welding of AA5754 annealed alloy: Role of post weld heat treatment on microstructure and mechanical properties

In this paper hybrid welding of the annealed AA5754 alloy was studied and the role of post weld heat treatment (PWHT) on microstructure and mechanical properties was investigated. The microstructure and hardness of the base material and welds were analyzed. Due to the segregation, the lowest microhardness value was observed at the welding centerline. High microhardness was registered in a narrow zone at the interface between the fusion zone and the heat affected zone where the welding cycle promotes both the strengthening by Mg solid solution and the lowest grain size. The hardness of the heat affected zone was higher than that of the base material due to dissolution of soluble particles (Mg2Si and Mg2Al3). PWHT at 350 °C increased the microhardness in the fusion zone and the tensile strength with respect to the untreated joint, whereas the strain at fracture was similar showing that the fracture was promoted mainly by the presence of porosity, coarse grain size and insoluble segregated second phases

Ultrasonic spot welding of carbon fiber reinforced epoxy composites to aluminum: mechanical and electrochemical characterization

The mechanical and electrochemical behavior of ultrasonic spot welded hybrid joints, made of AA5754 aluminum and carbon fiber reinforced epoxy with a co-cured thermoplastic surface layer, was studied. The effect of the welding parameters (energy and force) and the thickness of a thermoplastic film, applied as an upper ply in the composite lay-up, on the development of adhesion strength, was investigated. The best mechanical results were obtained when the welding parameters were able to achieve a large bonding area of mechanical interlocking between naked carbon fibers and aluminum and a better load distribution. The electrochemical results excluded the possibility of galvanic corrosion between aluminum and composite adherends thanks to the insulating action provided by the thermoplastic fil