Multilayer Surfacing Research Articles

Process parameters selection for multi-layer friction surfacing of 7075 aluminium alloy

The effect of deposition parameters on the microstructure and mechanical properties are studied in multi-layer friction surfacing of 7075 aluminium alloy. These multi-layer structures were successfully manufactured after a parametric study which allows the generation of a deposition window, including an interface quality comparison. A higher rotational speed leads to a larger grain sizes. The coarse precipitates size and volume fraction decrease along the build direction in correlation with the thermal cycles’ profile. The top layer has a higher hardness after deposition, while bottom layers are in annealed state due to the growth of the strengthening phases. Fracture surface analysis revealed that transversal cracks are due to interlayer decohesion and that voids nucleated on the coarse precipitates.

Investigation of microstructural and mechanical properties in AA2024-T351 multi-layer friction surfacing

This study on multi-layer friction surfacing (MLFS) as a process for additive manufacturing focuses on the influence of process parameters on the resulting microstructural properties for the precipitation-hardenable Al-Cu-Mg alloy AA2024. The energy input, which is determined by the process parameters, is correlated with the process temperature, which has a direct influence on the microstructure and mechanical properties. At higher process temperatures, e.g. at 450.1∘C, larger average grain sizes, i.e. 2.5 μm, were observed in the deposited material compared to lower temperatures, i.e. 1.2 μm at 380.6∘C. At the same time, hardness (109.2 HV0.1 ↔ 115.7 HV0.1) and ultimate tensile strength (360.8 MPa ↔ 423.3 MPa) were lower at higher temperatures, in particular due to a pronounced overaging. In terms of overall mechanical behavior, the interfaces between the first layer and the substrate are the weak points of MLFS, as they exhibit lower tensile strength compared to the interfaces between the layers. Within the MLFS, the interfaces have a slightly higher hardness, which can be attributed to locally smaller grains.

ОБРАБОТКА ОТВЕРСТИЯ ОПОРНОГО РОЛИКА ХОДОВОЙ СИСТЕМЫ ТРАКТОРА ПРОШИВКОЙ

Restoring the surface of the roller treadmill to its nominal value using automatic surfacing technology makes it possible to obtain a significant surfacing layer with a sufficient degree of strength and wear resistance. At the same time, as a result of thermal action, the metal of the roller receives a linear shrinkage, due to which the diameter of the hole for the bearing of the roller axis decreases. In this case, it becomes impossible to install the outer bearing cage. (Research purpose) The research purpose is substantiating the method of processing the seat under the outer bearing cage after surfacing the treadmills of the support roller. (Materials and methods) It was noted that the surfaces of the treadmills of the support rollers wear out quickly as a result of abrasive friction with the track link and the soil. It was clarified that when surfacing in all ways, metal shrinkage occurs and the diameter of the hole for the outer bearing cage decreases. (Results and discussion) It was found that the wear of the treadmills of the support rollers averaged 13.9 millimeters. Restoration of the treadmill surface of the roller to the nominal value, carried out by the method of multilayer automatic surfacing, caused a decrease in the diameter of the roller opening by an average of 0.73 millimeters. We chose from the considered options for calibrating the hole the most preferable from and time-saving one, the firmware processing method. (Conclusions) The appearance of shrinkage of the support roller hole during restoration by automatic surfacing and the method of calibrating the hole using firmware were substantiated. The method provides tension in the coupling of the outer ring of the bearing with the roller within 0.015-0.039 millimeters and surface cleanliness within Ra 1.25-0.63 micrometers. The firmware is simple in design and can be manufactured in a repair shop.

Change in structure and properties of high-speed steel deposited layer after tempering and electron beam processing

The structure and properties of multilayer coatings made of high-speed R18Yu steel formed on a substrate of 30KhGSA steel during multilayer plasma surfacing in a mixture of argon and nitrogen followed by high-temperature tempering and electron beam processing are studied using the methods of light, scanning and transmission electron microscopy. Plasma surfacing forms a layer, the main phases of which are α-Fe and carbides of М6С(Fe3W3C–Fe4W2C) composition, forming a frame mesh. After high-temperature tempering, particles of the carbide phase of globular or faceted shape are identified in the bulk of α-Fe with sizes from 10 to 38 nm. The microhardness of the deposited layer made of R18Yu steel increases after tempering and is 5.3 GPa. Electron beam processing is accompanied by a multiple (3 or more times) reduction in the wear parameter (increased wear resistance of the material); the microhardness of the modified layer does not change and is 5.3 GPa.

Structure and properties of high-speed R2M9YuAT alloy formed by plasma surfacing in nitrogen with flux-cored wire

The structure and properties of the high-speed R2M9YuAT alloy formed by plasma surfacing in nitrogen are studied. The samples are surfaced by a plasma arc at reverse polarity with the supply of non-current-carrying filler flux-cored PP-R2M9YuAT wire, additionally containing nitrided ferrochrome and titanium, into the weld pool. Surfacing of the samples is carried out using a plasma surfacing installation using UD-417D flux-cored wires. After surfacing is completed, the workpiece is cooled in air and subjected to high-temperature tempering at a temperature 560...580 °C, holding time 1 hour, number of temperings 4. The microhardness distribution of the surface layer of the deposited R2M9YuAT alloy in the state after plasma surfacing and after surfacing and high-temperature tempering is studied. Microhardness values vary from a minimum value of 4.68 to 5.93 GPa, and the distribution of microhardness of the deposited layer in the state after plasma surfacing is characterized by significant unevenness, which is explained by the comрlex thermal effect of multilayer plasma surfacing. Quadruple hightemperature tempering leads to the transformation of retained austenite and the precipitation of carbides and carbonitrides. The microhardness of the deposited metal after tempering increases from 6.89 to 7.48 GPa, and its distribution has become more uniform. It is established that the main phases in the deposited metal after high-temperature tempering are a solid solution of α-iron, carbides and carbonitrides based on iron, tungsten, molybdenum, chromium, aluminum and titanium.

Correlation of Microstructure and Local Mechanical Properties Along Build Direction for Multi-layer Friction Surfacing of Aluminum Alloys

The process variant of friction surfacing (FS) depositing multiple layers on top of each other is known as multi-layer friction surfacing (MLFS). Due to the solid-state nature of the process, re-heating is significantly reduced compared to common fusion-based AM techniques. The work gives a detailed and fundamental insight into the microstructure along the MLFS build direction for two different aluminum alloys and different process parameters. Focusing on the grain size distribution and recrystallization ratio, the stacks show a higher degree of recrystallization and finer grains at the interfaces. The observed grain sizes at the interfaces were 2.0 µm (AA5083) and 1.1 µm (AA2024), and 5.8 µm (AA5083) and 3.1 µm (AA2024) at the layer center. For the non-precipitation-hardenable alloy (AA5083), the local microstructural trend could be related to the hardness distribution along the stacks, i.e., a slightly higher hardness at the layer interfaces (95 HV) compared to the layer center (90 HV). The relationship is more complex for precipitation-hardenable alloys (AA2024), which show a rise in hardness between 40 HV0.2 and 45 HV0.2 along the stack height. The effect of subsequent layer depositions on the microstructure and hardness is discussed and a distinctive grain size distribution along the build direction was shown to be a fundamental characteristic.

Development of flux-cored wire of Fe – C – Si – Mn – Cr – W – V system with additives of carbon-fluorine-containing material and titanium

The paper considers research of quality of the electric arc coating obtained using flux-cored wire of the Fe – C – Si – Mn – Cr – W – V system with additives of carbon-fluorine-containing material and titanium. The formation of an electric arc coating was carried out using an automatic arc welding machine ASAW-1250 with a new chromium-containing flux-cored wire on plates made of St3 steel. To exclude mixing of the deposited metal with the substrate steel, multilayer surfacing was conducted. The surfacing mode was calculated and refined experimentally. The authors studied the composition and properties of the surface of the electric arc coating after surfacing. As a substitute for amorphous carbon they used a carbon-fluorine-containing material (dust of gas purification of aluminum production). Surfacing was carried out under a flux made from slag produced by silicomanganese with a high content of sulfur. A regression analysis of influence of the deposited layer’s chemical composition on its hardness and wear rate was carried out and mathematical models of the investigated performance characteristics of the electric arc coating were obtained. With an increase in the content of chromium, tungsten, carbon and silicon, hardness of the deposited metal and its resistance to abrasive wear increase. The results of the conducted research make it possible to develop measures ensuring the required level of performance characteristics of the electric arc coating and can be used to make a forecast of hardness of the deposited layer and its wear resistance when the chemical composition of the metal changes, to predict the operational resistance of rolling rolls deposited with wires of the PP-Np-35V9Kh3SF type. Mathematical models of hardness of the deposited layer and its wear resistance help to clarify the mechanism of hardening and formation of protective properties of the surface layers of rolling rolls by means of electric arc coatings deposited with flux-cored wires.

Hardening technology of metallurgical equipment parts by high-speed nitrogen alloys

The technology for hardening of metallurgical equipment parts by high-speed alloys with high nitrogen content is developed. The manufacturing process of deposited parts includes: machining of the workpiece, plasma surfacing, high-temperature tempering, finishing machining and quality control. To form a coating on 30KhGSA steel, an installation for plasma surfacing of bodies of rotation is used. A method and surfacing materials for multilayer plasma surfacing are developed, which make it possible to obtain deposited layers made of high-speed alloys (type R18Yu), additionally alloyed with nitride ferrochrome and titanium, which allows increasing the nitrogen content from 0.02 to 0.12 %. The surfacing method with low-temperature heating and surfacing materials prevent the formation of cracks during the surfacing process and ensure the hardness of the deposited metal up to 59...60 HRC without additional heat treatment. The hardness of the deposited metal after high-temperature tempering at a temperature of 560...580 °C increases to 62...64 HRC. Multilayer plasma surfacing made it possible to obtain a high-quality surfaced layer without cracks, pores and microstructure defects. The main phases of the deposited layer are a solid solution of α-iron, carbides and carbonitrides based on iron, tungsten, molybdenum, chromium, aluminum and titanium. The wear resistance of the deposited parts of metallurgical equipment (rolls and rollers of crushers) increases by 1.5—2.0 times.

Economically alloyed powder wires and method their multilayer plasma surfacing in nitrogen medium

A method and powder wires are developed for multilayer plasma surfacing with heat-resistant highhardness steels such as R2M9Yu steel additionally alloyed by nitrided ferrochrome and titanium. The surfacing method with low temperature heating and surfacing materials prevent the formation of cracks during the surfacing process and ensure the hardness of the deposited metal up to 59...60 HRC without additional heat treatment. It is established that the main phases in the deposited metal are a solid solution of α-iron, carbides and carbonitrides based on iron, tungsten, chromium, molybdenum, aluminum and titanium.

Computer analysis of plastic strain accumulation in multilayer arc welding and surfacing

Level of plastic deformations is calculated in multilayer acr welding and surfacing. The equations of compatibility of displacements caused by heating of the metal during successive application of rollers are solved. It is revealed that in the case of successive surfacing of beads and a change in the distribution of limiting temperatures, a complex pattern of the stress state of the metal arises in the zone of surfacing. This indicates the need to take into account this phenomenon in multilayer welding and surfacing in engineering practice.

Structure and Mechanical Properties of Al–Mg Alloy Workpieces in Multilayer Surfacing with Interlayer Deformation

Structure and Mechanical Properties of Al–Mg Alloy Workpieces in Multilayer Surfacing with Interlayer Deformation

Experimental Investigation of Efficiency and Deposit Process Temperature during Multi-Layer Friction Surfacing

Multi-layer friction surfacing (MLFS) follows the principle of the friction surfacing (FS) process, which is an established solid state coating technology for similar and dissimilar metallic materials. With this approach, the deposition of a consumable material on a substrate is enabled via friction and severe plastic deformation (SPD), processing the material below its melting temperature. The focus of the present study lies on the investigation of the temperature distribution during MLFS deposition. The measurements show that the temperature within the stack tends to be slightly higher on the advancing side. Additionally, the deposition behavior, i.e. deposition rate and consumable stud consumption rate, was investigated. Along MLFS stack height, deposition efficiency tends to sightly decrease, shown by decreasing layer thickness and increased length of remaining consumable studs. Overall, MLFS is highly repeatable for multiple layers and presents stable deposition conditions. Additionally, the technique has a comparatively low heat input to the substrate and the already deposited material.

Досвід впровадження адитивних технологій при ремонті деталей ГТД зі сплава ЕП 648 ВІ (ХН50ВМТЮБ-ВІ) в умовах серійного виробництва

Technology has been developed for repairing the nozzle assembly (SA) casing in the D-18T engine by additively growing the damaged part by microplasma surfacing with a powder of EP648VI (KhN50VMTYUB-VI) alloy. Traditionally, a part with such damage was rejected. The cost of replacing a damaged part with a new one is about 200 thousand hryvnias. The article discusses the equipment and features of the growing technology using the method of microplasma multilayer surfacing. Additive growth of the cut-damaged part was carried out on a STARWELD 190 H robotic installation for microplasma powder surfacing using EP648 VI alloy powders with a 63–163 micron fraction. After growing, heat treatment (aging at 700 ºС, exposure for 16 hours), mechanical processing, and quality control of the grown part were carried out. To create an evidence base to determine the possibility of installing a repaired part on the engine, a set of studies was carried out, which included the determination of the chemical composition of samples grown using a technology similar to repair, metallographic studies, and mechanical tests. As a result, it was found that the chemical composition of the deposited metal meets the requirements of the technical specifications TU 14-1-3046-97 "Bars made of heat-resistant alloy grade KhN50VMTYUB (EP648), and the microstructure of the deposited metal after heat treatment is a γ - solid solution with the presence of carbides, carbonitrides and a small amount of γ´ phase, which corresponds to the normally heat-treated state of the EP 648 VI (KhN50VMTYUB-VI) alloy and the level of mechanical properties of the grown alloy with subsequent serial heat treatment (aging at 700 ° C, holding for 16 hours) not lower than the level of the forging used at serial production of a part. The economic effect of the introduction of this technology is shown, which is more than 100 thousand hryvnias (about 23% of the cost of a new part).

Anisotropy and Mechanical Properties of Dissimilar Al Additive Manufactured Structures Generated by Multi-Layer Friction Surfacing

Anisotropy and Mechanical Properties of Dissimilar Al Additive Manufactured Structures Generated by Multi-Layer Friction Surfacing

Hardening of surface layer of cold rolls by multilayer plasma surfacing in nitrogen atmosphere

High service properties of cold rolling working rolls can be provided by plasma surfacing in protective-alloying nitrogen atmosphere with heat-resistant alloys (such as steel R18Yu). The distributions of hardness, microhardness and the structure of the surface layer of the deposited working rolls of cold rolling, which have impact on their performance, are studied. It is established that the surfacing technology and the surfacing material make it possible to obtain high-quality surfaced alloy without cracks, pores, slag inclusions and macro- and microstructure defects. Additional contribution to the hardening is made by high-temperature tempering of the deposited metal. The deposited alloy is pearlitic grains, along the boundaries and joints of the grains are carbonitrides based on iron, tungsten, chromium, molybdenum, aluminum (Me6NC and AlN).

Microhardness and Structure Distribution over the Layer of a High-Hardness Heat-Resitant Alloy Formed by Multi-Layer Plasma Surfacing in a Nitrogen Medium

Microhardness and Structure Distribution over the Layer of a High-Hardness Heat-Resitant Alloy Formed by Multi-Layer Plasma Surfacing in a Nitrogen Medium

Improving VT6 Titanium-Alloy Components Produced by Multilayer Surfacing

Improving VT6 Titanium-Alloy Components Produced by Multilayer Surfacing

Оптимизация процесса многослойной центробежной индукционной наплавки покрытий на основе алюминиевых сплавов

As a result of the conducted research, using the methods of mathematical planning of the experiment, the optimization of the process of multilayer centrifugal induction surfacing of antifriction coatings based on aluminum alloys was performed, which made it possible to develop a mathematical model and determine the optimal range of values of technological modes. The dependences of the minimum wear rate of the coating material Iq (mg/m) on the parameters of multilayer induction centrifugal surfacing of aluminum alloy coatings are established. The main factors affecting the wear rate of the coating were the heating temperature of the part T (°C), the time of the isothermal exposure t (min) and the speed of rotation of the part n (rpm). Based on the results of computational and experimental modeling, it is shown that in order to obtain the optimal wear intensity of the aluminum alloy coating material, the parameters of the multilayer centrifugal induction surfacing process should be as follows: the rotation speed of the part n = 1,750–1,875 rpm, the heating temperature of the part T = 775–800 °C, the isothermal exposure time t = 7–8 min.

Исследование влияния термообработки на микроструктуру и механические свойства образцов из алюминиевого магнийсодержащего сплава 1580, полученных способом многослойной наплавки

Исследование влияния термообработки на микроструктуру и механические свойства образцов из алюминиевого магнийсодержащего сплава 1580, полученных способом многослойной наплавки

ИССЛЕДОВАНИЕ ПРОЦЕССА МНОГОСЛОЙНОЙ ЭЛЕКТРОДУГОВОЙ НАПЛАВКИ С ПРИМЕНЕНИЕМ ФЕРРОМАГНИТНОЙ ШИХТЫ ДЛЯ ВОССТАНОВЛЕНИЯ ДЕТАЛЕЙ ХОДОВОЙ ЧАСТИ ЭКСКАВАТОРОВ

The article is devoted to determining the number of deposited layers by the method of electric arc welding using a ferromagnetic charge in the case of eliminating wear on the cam of the drive wheel of the EKG–5A excavator from 35KhML steel. As well as assessing the distribution of hardness and the presence of defects along the layer height during sequential cooling of the deposited rollers and in the absence of cooling before by applying a subsequent roll in multilayer surfacing.