This paper mainly studies the behavior of the laser deep-penetration welding melt pool. A laser deep-penetration welding melt pool model under adaptive combined heat sources was established using numerical simulation software. This model can automatically find the keyhole radius and keyhole bottom during the welding process so that all the heat source energy acts on the keyhole wall. The results show that deep and narrow keyholes are more prone to bubble formation; the free surface descends, and the melt pool flow velocity slows down as the keyhole becomes shallower, eventually resulting in a wavy weld seam; once a hump forms on the keyhole wall, there is a spontaneous tendency for the keyhole to close under the action of forces in the melt pool.

The objective of this study is to investigate the formation of the structure and stress–strain state in the joints of AISI 304 stainless steel with a thickness of 2 mm and produced by welding with laser and plasma energy sources. It is established that the microhardness and parameters of the grain and subgrain structures of the welded joint material differ with respect to the dimensions of crystallites, grains, and subgrains according to the welding process. It is shown that, in terms of structure formation, including substructural features, the most favorable structures of 2 mm AISI 304 welded joints are formed by laser–plasma welding. It is predicted that the residual stressed state is less localized with the application of laser–plasma welding than laser welding, and it is characterized by a lower level of residual stresses compared to plasma welding. In all the cases, the maximal stress values are concentrated in the HAZ, and the value obtained using laser–plasma welding is in an intermediate position (431.7 MPa) between those of the laser (443 MPa) and plasma (413.7 MPa) processes. With laser–plasma and laser welding, displacements (deformations) are minimal and close to 0.2 mm. The method of electron speckle interferometry was used, and the results reveal that the error between the calculated and experimental values of equivalent stresses is no more than 6%, which is acceptable. The results of mechanical testing show that, under uniaxial tension, the strength of the welded joints made of AISI 304 steel using laser–plasma and laser welding is the highest and equal to 97% of that of the base metal.

The objective of this study was the additive microplasma powder deposition of 3D metal products. The regularities of the influence of technological parameters of additive microplasma deposition of spatial objects using the powder filler material of a Fe–Cr–Ni–B–Si system on the formation of the microstructure and stress–strain state of 3D product material were studied in this work. Product walls with a layered metal structure with a deposited layer height of about 650 µm and 3.0–3.5 mm thickness were formed as a result of additive microplasma deposition of the HYF–103 powder of a Fe–Cr–Ni–B–Si system. The deposited metal ensured a high ultimate strength (above 600 MPa). The finite element method was used to derive the solution of the thermomechanical problem of additive deposition of 3D prototypes («cylinder», «triangular prism», «square prism», «reverse cone», «straight cone») with HYF–103 powder. The equivalent stresses of the highest magnitude (565 MPa) were predicted in the model sample of the “reverse cone” type, and the lowest stresses (552 MPa) were present in the sample of the “straight cone” type. For all the models, the maximal values of radial movements corresponded to the range of 0.22–0.28 mm. The respective technological mode of deposition was selected to minimize the stress–strain state of the produced 3D objects.

This work demonstrates the possibility of producing spherical Ti-6Al-4V Grade 5 alloy powders with superior technological properties compared to those obtained through conventional industrial gas atomization methods for additive manufacturing, by utilizing plasma atomization of a 1.0 mm diameter...

The possibility of producing spherical powder from Inconel 625 nickel-based superalloy using plasma-arc wire atomization technology in both non-transferred and transferred arc modes has been experimentally confirmed. Particle size distribution analysis showed that using the non-transferred arc...

The design of rare earth (RE) bearing steels requires a thorough understanding of the formation tendency of RE involved phases in steels, while searching for binary and ternary compounds with a wide variety of composition and permutation need a remarkable amount of experimentation which is nearly infeasible. In the present work, we perform a thorough search for the RE-contained compounds in steels by a data-driven high-throughput computational approach. The search results indicate that RE may react with O and N to form a large amounts of oxide and nitride inclusions, while only Y participate in the formation of sulfide inclusion Y₂MnS₄ and Y₂CaS₄. For the case of ternary compounds in Fe-based solid solution, it is found that RE prefers to form ternary phases with the non-metallic elements, i.e., B, C, O, P and Si, and only Y is found to combine with metal Cr to form YCr₄Fe₈. Finally, our screen suggests that RE can participate in the formation of the nano-scale precipitates of κ-carbides, L1₂ precipitates and B2 precipitates, but MC and M₂C carbides.