Modern methods and technologies for the creation and processing of materials provide great opportunities for research. This work is devoted to the study of the causes of hot cracks, as well as the application of an analytical method for assessing the occurrence of hot cracks in high-temperature nickel alloys ZhS32, ZhS6U, ZhS6K, Rene 80, Rene 41, processed by laser powder cladding. In the course of the work, the process of the influence of a heat source on samples was modeled, an analysis of thermal fields and isotherms was performed, on the basis of which an analytical method was developed for finding the criterion for the pressure drop along the crystallization front in different modes and grades of alloys, to assess the tendency to form hot cracks in high-temperature nickel alloys.

In modern production, direct laser deposition technologies are used to shorten the time of production of a new product at the design and manufacturing stages. The development of technology follows the path of introducing new powder materials and determining rational technological regimes for the formation of a surface layer of specified quality. This work is about study of samples from a cermet composite material (CCM) by direct laser deposition. Technological parameters for defect-free build-up of full-size small-sized parts of gas turbine engines (GTE) are determined. Structures were studied and tests were conducted to determine the mechanical properties of deposited laboratory samples. The technology of full-size small GTE parts manufacturing has been worked out.

BACKGROUND: A state-of-the-art aircraft gas turbine engine is an advanced technology consisting of a compressor, combustion chamber, turbine, nozzle, and other components. It includes the axial compressor with multistage rotor and stator blades important for the reliable operation of the gas turbine engine. All these components are subject to static, dynamic, and cyclic loads causing fatigue cracking, thermally induced stress, and mechanical damage. To increase the service life of gas turbine engines and reduce maintenance costs, technologies are used to restore worn or damaged moving blade surfaces. AIM: To restore worn surfaces of moving blades of DR-59L high-pressure turbine by laser cladding. MATERIALS AND METHODS: Prior to repairing the blades, we tested a range of laser cladding parameters on a check test piece to determine a defect-free structure. Stellite-21 cobalt alloy powder was used as a filler. To evaluate the structure and mechanical properties of the claded test pieces, we conducted metallographic studies and mechanical tests. RESULTS: By modeling the blade airfoil restoration process, we determined the operational conditions of the laser cladding process. No defects were detected during the capillary test of the restored surfaces. The uniaxial tensile test of the restored blade airfoil showed increased tensile strength and elongation. CONCLUSIONS: Laser cladding technology allowed to restore the worn surfaces of moving blades of DR-59L high-pressure turbine; thereby increasing the service life of the engine unit.

BACKGROUND: Various types of coatings are used for corrosion and wear protection of structural materials and thermal insulation. Coatings that are used in high-temperature conditions, e.g. aircraft and industrial gas turbine engines, have the most complex structure. They are used to isolate the turbine components from the hot gas flow, increasing the durability and energy efficiency of engines [1]. Thermal barrier coatings have three main requirements, including low thermal conductivity, stability at high temperatures, and high durability, and they are fairly difficult to remove. AIM: To solve the problem of removing thermal barrier coating from moving blades of gas turbine engines subjected to intensive wear in tough operating conditions. Laser cleaning technology is proposed as the most effective cleaning method. It is an advanced technology that allows finding solutions to reduce production costs and increase the performance and quality of processes [2]. The paper discusses the importance of preserving the basic blade material during thermal barrier coating removal for its subsequent use (new coating). The aim is to remove the thermal barrier coating without damaging the basic metal and to determine the optimal conditions for such works. METHODS: To achieve the aim, the blade made of CS70-VI alloy was cut into several parts along the length of the airfoil; one part was selected as a check test piece that was not cleaned. The remaining test pieces were tested during laboratory experiments aimed at studying the influence of input laser cleaning parameters on the removal of the thermal barrier coating. All samples were then subjected to metallographic tests to determine the material structure, microhardness, and thickness of the thermal barrier coating. RESULTS: The paper presents metallographic analysis of microhardness and thickness of thermal barrier coating after testing confirming the effectiveness of laser cleaning to ensure the durability and reliability of moving blades for gas turbine engines. CONCLUSION: The study involved a literature review of papers related to laser cleaning. Next, we selected the variation ranges of the main processing parameters and conducted a series of experiments followed by the metallographic analysis of test pieces. Metallographic analysis allowed to determine the conditions ensuring complete removal of the thermal barrier coating and the relationship between the thickness of the thermal barrier coating and the radiation power.

The study of the formation of microstructural features of low-alloy bainite-martensitic steel 09CrNi2MoCu are of particular interest in additive technologies. In this paper, we present a study of cold-rolled samples after direct laser deposition (DLD). We investigated deposited samples after cold plastic deformation with different degrees of deformation compression (50, 60 and 70%) of samples from steel 09CrNi2MoCu. The microstructure and mechanical properties of samples in the initial state and after heat treatment (HT) were analyzed and compared with the samples obtained after cold rolling. The effect on static tensile strength and impact toughness at −40 °C in the initial state and after cold rolling was investigated. The mechanical properties and characteristics of fracture in different directions were determined. Optimal modes and the degree of cold rolling deformation compression required to obtain balanced mechanical properties of samples obtained by additive method were determined. The influence of structural components and martensitic-austenitic phase on the microhardness and mechanical properties of the obtained samples was determined.