Key Engineering Materials Vol. 822

Abstract: The article presents the results of the study of the additive technology of direct growing from aluminum wire using various energy sources - laser, arc and combined laser-arc, as well as their influence on the microstructure of walls grown from aluminum alloy AlMg6Zr. Keywords: high power laser, laser cladding, microstructure aluminum based alloys

Abstract: Additive technologies, in particular, wire-feed laser deposition, can significantly reduce the production cycle of manufacturing large-sized parts or parts of complex shape due to partial or complete elimination of technological operations such as casting, machining and welding. The aim of the work is to develop an analytical model of heating and melting of the filler wire during wire-feed laser deposition. The heat conduction problem was solved by the functional-analytical methods. The practical effectiveness of the functional-analytical methods with respect to computational time is several orders of magnitude higher than numerical ones. Obtained analytical solution made it possible to determine the temperature field for heat flux arbitrarily distributed on the filler wire surface. It is established that at a higher feed rate, the wire tip is completely melted at a greater distance from the laser axis. The shape of the melting surface also depends on the feed rate. At a slow feed rate, a more uniform heating of the wire over the cross section occurs. The melting surface has a small angle of inclination.

Abstract: A solution for new phase inclusion growth is suggested for the case of the Ni-based alloys. This solution takes into account a chemical composition of the alloy and conditions of the laser treatment process. A method for calculation of the chemical reaction rate constant is also suggested for the Ni₃Al formation in the Ni-Al alloy. Modeling is fulfilled for the laser cladding process. Time dependences for the reacting component concentration is obtained as well as for intermetallic inclusion growth and thermal cycle.

Abstract: The laser metal deposition is an advanced manufacturing technology enabling the production of large-sized parts and partially or completely elimination of machining and welding. The process is characterised by a non-uniform local heating of the buildup leading to a stress distribution, which may exceed the yield strength of the material and leads to loss of dimensional accuracy. The interlayer dwell time has a strong influence on the temperature field. The effect of the interlayer dwell time on the distortion and the stress distribution during laser metal deposition of a single-pass wall on the edge of 2 mm thick plate was studied experimentally and numerically. The deposited material was IN625 and the substrate material was AISI 316. A decrease of the residual displacement, due to a uniform shrinkage after the deposition of the last layer and a lower level of the residual compressive longitudinal plastic strain, has been observed in the studies without a dwell time. The peak increment of the free edge displacement corresponds to the first layer and hence the subsequent layers will be deposited on the already plastically deformed buildup. The tensile residual longitudinal stress near the top of the buildup and transverse stress near the edges of the buildup is higher than yield strength in the studies with dwell time.

Abstract: An article presents a review of current standards and guidelines in the field welding fabrication requirements for wind energy structures in arctic conditions. Extreme climatic conditions, such as Arctic, have a strong influence on the requirements for wind turbines structural characteristics, materials and fabrication methods. Special attention has to be paid for selecting steels with suitable mechanical properties, processing methods and delivery conditions. Additionally, it is highly important to select proper welding process and welding parameters, so that the structural integrity and reliable operation can be achieved.

Abstract: Analysis of modern tendencies in digitalization of economics prove the increasing interest of industrial enterprises towards new digital manufacturing technologies. Industrial laser technologies are developing really fast in various branches of industry. Perspectives of hybrid laser welding industrial application particularly in shipbuilding are rather interesting. Introduction of hybrid laser arc welding in shipbuilding increases strongly economic efficiency of the production process. Each project needs preliminary assessment. Feasibility study of replacing the automatic welding equipment by modern hybrid laser arc welding technology at a shipbuilding yard shows its relevance and importance.

Abstract: In this article has carried out X-ray phase analysis of the samples obtained using direct laser deposition. Two groups of samples were studied: the first one was obtained with oscillation of laser radiation, the second one – without. The investigations have shown that in the process of direct laser deposition, the α+β phase is formed from a Ti-6Al-4V titanium alloy with oscillation of laser radiation.

Abstract: Ti-6Al-4V powders from two different vendors and two different fraction were compared with respect to their microstructures, size-distributions, chemistries, surface appearances. In addition, the influence of these powders on the structure and properties of products manufactured by an additive direct laser deposition method were established. The main parameters that have a significant impact on the structure and properties of Ti-6Al-4V deposited parts were established.

Abstract: The article shows the results of multilayer laser cladding of heat-resistant single crystal nickel-based alloy ZhS32-VI (CSMX-4 analogue). The influence of the main technological parameters on geometry and microstructure formation of deposited beads was investigated. Based on obtained dependencies, the regression equations are compiled for describing the shape of bead and the ratio of directional and equiaxial crystallized sections. The obtained dependencies of regime parameters nomination allow restoring the gas-turbine blades by the method of laser cladding.

Abstract: The article discusses the manufacturing technology of the impeller of a high-pressure centrifugal fan using high-speed direct laser spraying. The outer diameter of the part is 1200 mm, the total weight is 100 kg. The material used is metal powder stainless steel 316L. Features of the manufactured products were researched, including possible thermal deformations and methods for dealing with them.