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The influence of thermal conditions and some technological methods (intermediate inserts of monolithic metal, nanomodifying additives) on the quality of the permanent joint of porous titanium obtained by laser welding is studied experimentally. It has been established that, to obtain a high-quality defect-free weld, it is necessary to use an intermediate insert made of compact metal placed butt-to-butt between the ends of the butt-welded plates. The position of the focal spot should be set at a depth equal to the thickness of the plate, i.e. on its bottom surface. The use of modifying additives based on titanium nitride increases the dispersion and uniformity of the weld structure and the heat-affected zone, and this positively affects the mechanical characteristics of the metal. [ABSTRACT FROM AUTHOR]

The results of experimental study of laser welding of alloys based on aluminum and titanium using an intermediate composite Al+Ti insert obtained by explosion, with nanopowder additives and plastic deformation of the aluminum seam, are presented. Morphologically high-quality welds have been obtained in the welding of both the aluminum plate and the titanium one with the corresponding parts of the insert. It was found that the collapse of the joint in the tensile test occurred along the aluminum part of the insert, which had a lower tensile strength than that of the titanium one. The use of a nanomodifier without plastic deformation increases the strength of the welded joint by about 10% compared to the unmodified compound. The use of nanomodifying and strain hardening can significantly increase the tensile strength, the value of which is more than 97% of the strength of the AD1 alloy. The experiments on laser butt welding of plates made of aluminum alloy 1424 followed by their plastic deformation confirm the effectiveness of strain hardening of welded joints of aluminum alloys. [ABSTRACT FROM AUTHOR]

The paper concerns the possibility of obtaining a lasting permanent joint of dissimilar metals: technically pure titanium and stainless steel using laser welding and an intermediate composite insert. The insert was a four-layer composition of plates of steel, copper, niobium, and titanium welded by explosion. The material layers used in the insert prevented the molten steel and titanium from mixing, which excluded the formation of brittle intermetallic compounds, such as FeTi and Fe2Ti. The optimization of explosion welding parameters provided a high quality of the four-layer composition and the absence of defects in the area of the joint of insert plates. The results of strength tests showed that values of the ultimate strength and yield of the permanent joint with the composite insert welded by explosion are comparable to the strength characteristics of titanium. [ABSTRACT FROM AUTHOR]