A. N. Cherepanov

Development of a technology for laser welding of the 1424 aluminum alloy with a high strength of the welded joint

Results of an experimental study of properties of joints obtained by using different regimes of laser welding of the 1424 alloy (Al–Mg–Li) are reported. The strength and structure of the welded joints are determined. The influence of various types of welded joint straining on its strength is studied. It is demonstrated that the joint strength increases in the case of plastic straining.

Investigation of the technology of laser welding of aluminum alloy 1424

In this study, certain technological variants of the laser welding of alloy 1424 of the Al–Mg–Li–Zr system are considered with the purpose of obtaining the durability level of the welded joint, which is close to that of the basic metal. It is shown that, in the case of using various types of plastic deformation of the welded joint, its durability can be increased considerably to 0.85–0.95 from that of the basic metal.

Effect of nanoparticles on the structure and properties of an aluminum alloy poured into a mould with the use of a magnetohydrodynamic disk pump

The influence of two nanomodifiers with different compositions during their homogenization in the AL7 aluminum melt and moulding on the properties of the modified aluminum alloy is studied. Experiments are performed with the use of a centrifugal conductive magnetohydrodynamic pump. The melt is poured into a graphite mould with three cylindrical channels 38 mm in diameter and 160 mm long, which are designed for a metal mass of 500 g. Two compositions are used as modifying agents: nano-scale particles of the aluminum nitride powder 40-100 nm in size and metallized carbon nanotubes smaller than 25 nm, which are clad with aluminum to improve wetting of their surface. The analysis of the structure of the experimental and reference samples shows that the use of modifiers leads to refinement of the grain structure of the cast metal. According to the Hall-Petch theory, this effect may result in improvement of mechanical characteristics of the cast metal.

Investigation of the structure and mechanical properties of castings of alloy AlSi7Mg, cast irons GG15 and GG25 and steel GX120Mn12, modified by nanosized powders

The influence of nanopowders on the structure and mechanical properties was investigated in castings of aluminium alloy AlSi7Mg, grey cast irons GG15 and GG25 and steel GX120Mn12. Mixtures of SiC, TiCN and Y2O3 nanopowders were used. These mixtures or nanocompositions were coated with Cu, Cr, Ni and Fe metal protectors in order to improve wetting of the metal melt. Introducing small amounts of nanocompositions (less than 0.1 wt%) into the melt was found to refine the microstructure and improve the mechanical properties of the castings.

Modifying metal with nanopowder in a continuous bar-casting machine

The modification of metal by nanopowder is studied as a means of improving the quality of continuous-cast bar, complex components, and rebar. The introduction of TiCxNy-Fe nanopowder in the tundish of the continuous-casting machine reduces the liquation of the elements over the ingot cross section and the content of nonmetallic inclusions and also increases the structural and chemical uniformity. The use of nanopowder inoculators changes the structure of complex components (angle bar) and rebar, as well as the shape, size, and distribution of the nonmetallic inclusions, and also reduces the grain size and improves the mechanical properties.

Nanopowder modification of metals to improve continuous-cast slab

The influence of nanopowder modification of metal on the quality of continuous-cast slab is investigated. The introduction of powder strip with titanium-carbonitride filler in the tundish of the continuous-casting machine reduces the liquation of chemical elements over the slab cross section, increases the chemical and structural homogeneity, shrinks the region of dendritic structure, curtails the development of macrostructural defects, and enhances the density and mechanical properties of the cast steel.

Melting point of the coating on a refractory nanoparticle

Thermodynamic analysis shows that the melting point of a thin metallic coating on a spherical nanoparticle may considerably exceed that of the corresponding bulk metal if the surface tension between the melt and the refractory nanoparticle exceeds that between the solid coating and the particle. By this means, the stability of exogenous nanoparticles used to modify high-temperature alloys may be increased.