The aim of this study was to develop a new manufacturing process for bimetallic materials by combining laser treatment with traditional casting methods. This process involves laser-treating nickel alloy-grade UNS 6230 plates to create a regular macro-relief on their surface. These treated plates are then placed in a sand mold, and molten non-alloy steel (S235JRG2) is poured into the mold to create bimetallic layered castings. The experimental procedure focuses on optimizing the melt-to-solid phase ratios and pouring temperatures to achieve a uniform microstructure and strong mechanical properties in the bimetals. The produced bimetallic castings are suitable for applications in the oil refining and chemical industries and heavy machinery sector. The quantitative results indicate that the optimized process parameters lead to a high-quality transition zone with minimal defects, characterized by the diffusion of alloying elements from the nickel alloy to the steel. The microstructure, chemical, and phase compositions were evaluated using XRD and SEM with EDS, confirming the formation of a robust metallurgical bond. Key findings include a significant improvement in the hardness and strength of the transition layer, with the optimal pouring temperature being 1600 °C. The resulting bimetallic materials demonstrate an improved performance in demanding industrial environments.

The problem of the article is designed to reveal the proposed, developed and researched new method of improving the adhesion strength of plasma wear-resistant coatings on the outer surfaces of weapons made of high-alloy, heat-resistant steels, using additional cyclic (3-4) times their heating by laser radiation to temperatures of 0.6 – 0.8Tpl for a few milliseconds. The purpose of increasing the resource of use and the quality of the appearance of the weapon by applying wear-resistant coatings with increased adhesion strength to the base using plasma gas-thermal spraying followed by laser thermal cycling. Determination of the main factors and parameters of the process of laser thermocycling of plasma coatings, their interrelationships, development of an algorithm for determining the conditions of laser thermocycling, establishment of the rational range of their values by mathematical modeling and experimental research. The results of mathematical modeling of laser cyclic heating of plasma coatings of HTN of different thicknesses are presented, which allows determining the irradiation parameters that ensure their heating to temperatures at the "coating-substrate" boundary ≤1000ºС, on the surface - to Т< Тpl, at maximum cooling rates. It has been proven that laser thermocycling provides an increase in the adhesion strength of coatings to the base from 14–18 to 90–110 MPa, a decrease in porosity from 10–12% to 7–8%, which is due to the redistribution of alloying components at the “coating–base” interface, with the formation of elements of the metallurgical connection, contributes to a significant increase in wear resistance and a decrease in the coefficient of friction due to the formation of secondary ultradispersed film structures. We consider laser thermocycling of plasma coatings is an effective method of improving their quality and strength of adhesion to the base.

В статті наведено результати програмного моделювання температурного поля, зумовленого впливом рухомого джерела енергії в процесі синтезу інструментального шару абразивного інструмента на основі надтвердих матеріалів (НТМ), яке було реалізовано методами скінчених різниць та Ньютона для розв’язання систем нелінійних рівнянь, а для знаходження значень температури на межі середовищ використано рівняння теплового балансу. Доведено, що застосований комплекс методів є дійсно дієвим і дозволяє достатньо коректно згенерувати характер змін температурного поля досліджуваного зразка. Виявлено, що розрідження вузлів адаптивної сітки на незмінних за температурою ділянках, є недостатнім, і це обумовлено неоднорідністю матеріалу покриття. На основі результатів моделювання здійснено обробку абразивних НТМ і доведено доцільність використання лазерного випромінювання для формування робочого шару абразивного інструменту. Дослідження в основному зосереджено на опроміненні зерен абразивів лазером з довжиною хвилі λ = 10,6 мкм. Статичну міцність зерен абразивних матеріалів вимірювали до та після лазерного опромінення за допомогою вимірювальної установки DA-2 за стандартною методикою. Як сполучний матеріал використовували порошки бронзи та нікелю. Їх змішували з зернами абразивного матеріалу і наносили на сталеві опорні пластини з наступним лазерним опроміненням сформованого шару. Для дослідження мікроструктури зразків поряд з локальним та інтегральним рентгенівським елементним аналізом використовували скануючу електронну мікроскопію (РЕМ). Детально досліджено взаємодію лазерного променю та зерен абразивних матеріалів та встановлено взаємозв’язки між основними технологічними параметрами та якістю композитів (довговічністю зерен, зносостійкістю та міцністю зв’язку). Запропоновану технологію може бути використано для виготовлення абразивних інструментів для обробки матеріалів, які широко використовуються в поліграфічній промисловості (сталі, сплави, композитні матеріали, кераміка), а також в інших галузях — авіа-, судно- та машинобудуванні.

An analysis of the existing methods of sintering diamond-containing composites is presented. On the basis of mathematical modeling and experimental studies, the conditions of the laser liquid-phase sintering of diamond-containing composites under which they retain their strength are determined. The energy and technological parameters of the laser irradiation process are characterized, which determine the range of laser processing modes within which no oxidation and crack formation occur, and a high-quality composite with specified geometrical parameters is formed. It has been proven that composites consisting of synthetic diamond grains and a metal bond do not lose strength under the condition that the temperature during laser heating does not exceed 1600 °C and the exposure time is 0.3 s. Electron microscopy and X-ray diffractometry were used for experimental studies of the microstructure and phase composition of the sintered layers. A new design and manufacturing method for a drum-type abrasive tool with replaceable diamond inserts for grinding large-sized aircraft and shipbuilding products are proposed. Components of a laser technological complex for the implementation of the process of sintering the diamond-containing layer of the abrasive inserts of the drum have been developed.

The main drawback of existing studies of gas laser cutting of low-carbon steels of various thicknesses is the lack of a unified methodology for establishing a clear dependency between cutting parameters and the achievement of maximum productivity with proper processing quality. In this regard, this paper analyzes the effect of key factors, in particular the range of thicknesses of the workpieces being processed, the conditions of focusing and defocusing the laser beam, as well as the type and pressure of the process gas, on the achievement of optimal cutting speeds for low-carbon steel sheets. The right choice of laser beam defocusing parameters—both in value and direction—is one of the key things when working with powerful laser radiation. Thanks to the accumulated defocusing conditions, it was possible to systemize the selection of effective cutting modes for low-carbon steels and determine the dependence of the optimal cutting speed on the metal thickness for a wide range of these thicknesses. It has also been determined that cutting thin-gauge metals gives better results when using compressed air, while for cutting thick workpieces it is preferable to use oxygen. The research results made it possible to formulate general recommendations for selecting the optimal gas laser cutting modes for low-carbon steels using 20 kW laser radiation for different workpiece thicknesses. As a result, a nomogram and a table with recommendations for selection of the necessary cutting parameters were created, which complements this nomogram, which together make it possible to set the optimal cutting speeds and significantly facilitate the selection of the relevant technological parameters for gas laser cutting of low-carbon steels within the thickness range from 5 to 80 mm.

Laser forming (LF) of sheet material is a progressive treatment process and have some benefits. Laser forming is a flexible process and need no heavy metal-intensive equipment and tools. Materials with high rigidity, brittle, elastic materials can be treated by laser forming. Therefore, the investigation of LF is important task. An important point to study is repeatability of multipass laser forming of sheet materials and explore of the possibilities of stabilizing process parameters. Actually, this research is aimed at these issues. Methods and results of experimental investigation of repeatability of multipass laser forming of sheet materials on parallel and multidirectional passes are described. A methodical approach of using the VisualWeld software package for modeling the process of multi-pass laser forming has been developed. The mentioned software package was used for modeling as an alternative to a physical experiment to predict sample deformations and determine treating parameters. It has been experimentally established that the repeatability in laser forming is quite high, the difference in the amount of deformation preferably did not exceed 5%. In addition, it is shown that by varying the direction of irradiation trajectories, their step and the number of passes on each trajectory, it is possible to obtain a complex spatial configuration of the product.