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Dimensionless parameters and scaling laws that describe the geometric dimensions of a cermet weld bead formed during direct metal deposition are determined. A Ti64 titanium alloy and ceramics (silicon carbide, SiC) with different volume fractions are used as a powder mixture. A model for estimating the thermophysical parameters of a heterogeneous material is proposed. It is shown that, regardless of the volume fraction of ceramics, the dimensionless geometric parameters of a single track (depth, width, and height) depend on two dimensionless parameters: normalized enthalpy and the Peclet number. Also, these dependences can be approximated by algebraic expressions. [ABSTRACT FROM AUTHOR]

An overview of laser welding methods and additive manufacturing technologies used in modern mechanical engineering is given, and the main trends and aspects of these technologies are discussed. Laser welding processes of thermally hardened aluminum alloys and problems of obtaining high-strength welded joints are considered. The additive growth of heterogeneous materials is analyzed taking into account the dimensionless parameters determining the structure of materials fabricated by additive manufacturing. [ABSTRACT FROM AUTHOR]

Results of a series of experiments aimed at studying laser cladding of individual tracks with the use of the B4C–Ti–6Al–4V cermet powder mixture are reported. The influence of laser cladding parameters (radiation power, beam motion velocity, and focus position) on the characteristics of tracks being formed (geometric sizes, microhardness, and elemental composition) is studied. It is shown that an increase in the concentration of reinforcing particles in the initial powder mixture alters the character of mass transfer inside the melt pool, leading to changes in the shape of the single track. It is found that a complex heterogeneous structure is formed in the melt pool, including secondary phase compounds formed in chemical reactions due to in-situ synthesis. The microhardness values at various points of the single track are observed to differ by more than a factor of 2 (in the interval HV0.3 = 548–1415). [ABSTRACT FROM AUTHOR]

The influence of the laser beam parameters (power, motion velocity, and focus position) on the characteristics of the track being formed (size, elemental composition, and microhardness) is studied. If the difference in the laser radiation absorption coefficients in the heat conduction and keyhole regimes is taken into account, then the track sizes can be determined by a unified dependence on the energy parameter. The effect of the laser beam on the chemical composition and microhardness of cermet (WC-NiCrBSi) tracks is studied. Regardless of the track formation regime, these parameters are determined by a dimensionless parameter, which describes the degree of dilution of chemical substances. It is found that a track with the maximum mass fraction of tungsten and the greatest value of microhardness is formed at small values of the dimensionless parameter, which corresponds to the heat conduction regime. The microhardness of the deposited cermet structure is observed to be 4–5 times higher than the microhardness of the substrate material. [ABSTRACT FROM AUTHOR]

The energy balance of laser cutting of low-carbon and stainless steel sheets with the minimum roughness of the cut surface is experimentally studied. Experimental data obtained in wide ranges of cutting parameters are generalized with the use of dimensionless parameters (Peclet number and absorbed laser energy). It is discovered for the first time that the minimum roughness is ensured at a certain value of energy per unit volume of the melt (approximately 26 J/mm), regardless of the gas type (oxygen or nitrogen) and laser type (fiber laser with a wavelength of 1.07 μm or CO laser with a wavelength of 10.6 μm). [ABSTRACT FROM AUTHOR]