In this work, cold spray shot peening was used to treat interstitial-free (IF) steel. Different numbers of impact passes were evaluated and the microstructure and hardness evolution in IF steel were analyzed. Based on the experimental results, the potential of CSSP to achieve surface strengthening and properties enhancement in metallic materials is demonstrated.

This paper presents the development of a modified tool steel (X30CrMnMoN13-3-1) specifically designed for defect-free processing via laser powder bed fusion (LPBF) without requiring complex machine modifications. The research addresses the dual challenge of carbon-containing tool steels in additive manufacturing: maintaining wear resistance while preventing cracking. Through optimization of the alloying system—particularly with carbon, nitrogen, chromium, molybdenum, and manganese—and the use of moderate preheating (150 °C), the authors achieved crack-free components with hardness levels up to 57 HRC after appropriate heat treatment.

This paper aims to develop a multiparameter-based three-dimensional simulation tool for cold spray, designed to predict material deposition behavior in real-world processes under varying process parameters and workpiece geometries.

Additive brazing is a highly advanced process for producing functional and highly durable coatings. By creating a material bond between components through diffusion without the use of flux, dense, wear-resistant, and crack-free layers are formed, which are particularly useful in areas such as wear protection and the reclamation of components. The ability to adjust the coating thickness and hardness makes the process extremely flexible, allowing it to meet the specific requirements of a wide range of applications. Particularly innovative is the ability to precisely and locally braze using laser energy, further enhancing the efficiency and precision of the process. This paper provides an overview of the process, properties of brazed coatings, and applications.

Thermal spray coatings are typically applied to grit-blasted, rough surfaces, though coating models generally assume smooth substrates. This research involved simulating nickel coating formation on rough stainless-steel substrates in an atmospheric plasma spray process. The researchers evaluated coating topography, porosity, thickness, and roughness using a Monte-Carlo stochastic algorithm. The temperature differential between coating and substrate creates residual thermal stresses, which were analyzed using NIST's Object Oriented Finite element software (OOF). Results indicate that substrate roughness increases coating roughness and creates non-uniform stress distribution with concentration points at the coating-substrate interface.

This study evaluates the surface protection of a waste-to-energy boiler wall using the Eutronic Arc Spray Gun 4 HFH. The test involved coating a 3.2 m² section of the boiler membrane wall with four materials: BTW 58 (FeCr-based), METCO 8294 (NiCrMo alloy), TAFALOY 71T (Inconel 625), and Metcoloy 4 (FeCr steel). Before spraying, the surface was grit-blasted to SA 3 finish with a roughness of 75–100 μm. Coatings were applied both with and without a Metco 8450 bonding layer. Additionally, two high-temperature ceramic coatings—Fireside and Tubearmor—were tested. The wear tests were conducted on-site in the boiler's third pass. After one year of exposure, samples were evaluated for condition, wear, and scale formation. BTW 58 and TAFALOY 71T, particularly when combined with Fireside ceramic coating, provided the most effective protection.

The objective of this study was to quantitatively investigate the build-up of residual stresses in selective laser-melted 316L stainless steel samples and identify the nature of the stresses. In addition, the effectiveness of stress relief heat treatment in reducing residual stresses or changing their characteristics was examined. The results were compared against those obtained from conventionally hot-rolled 316L samples.

In this study, a high-entropy alloy (HEA) powder containing boron (NiCrCuMoB) was developed for atmospheric plasma spraying to produce coatings with minimal oxide formation in the molten droplets. The in-situ deoxidizing effect of boron during flight was investigated by analyzing collected HEA particles. The oxidation behavior of individual splats deposited on polished stainless-steel substrates was also examined. The resulting coating microstructure and mechanical properties were characterized. The results demonstrate that the addition of boron effectively suppresses in-flight oxidation of the molten particles, leading to the production of HEA particles with low oxide content. Consequently, bulk-like HEA coatings exhibiting strong metallurgical bonding and a reduced oxide content were achieved due to the deoxidizing action of boron.

In this paper, we evaluate the potential of ultrasonic atomization as a new feedstock manufacturing technique for cold spray by comparing the cold spray performance of an experimental stainless steel 316L powder obtained from ultrasonic atomization with a commercial stainless steel 316L powder produced through gas atomization.

In this paper, oxidation behavior of three hardmetal coating compositions with different Cr 3 C 2 content deposited on 1.4828 (AISI 309) or 2.4856 (Alloy 625) substrates was investigated. Heat treatment was performed in a tube furnace in a slight air flow (2 l/h) in the temperature range 500-900 °C for 2–32 days.

Cold spraying mixed metal-ceramic powders creates metallic matrix composites, but typically achieves low hard phase content in deposits. We investigated this challenge using various hard phases (SiC, diamond, WC, W) with Al and Cu metal matrices. Our results reveal that density difference—not hardness—between components primarily determines deposition efficiency. When using Al with similarly dense materials (diamond, SiC), deposit compositions remained comparable despite hardness variations. However, mixing Al with 50 vol.% of WC or W produced deposits containing 57.9 vol.% and 79.8 vol.% hard phases, respectively. Based on these findings, we established a ballistic theory-based criterion for effective hard particle deposition.

Extreme High -Speed Laser Cladding (EHLA) is a new process category of laser cladding. In this study, EH-LA layer was characterized by comparing with conventional laser cladding (LC) layer. Basic SUS316L layers, as well as WC-reinforced SUS316L layers, were formed on SUS304 substrates using both LC and EHLA processes. The macroscopic morphology, microstructure, microhardness, wear resistance, and residual stress of the four types of layers were evaluated. As a result, EHLA layers exhibited slightly higher micro-hardness and less wear loss than that of LC layers, despite the presence of more micropores. This can be due to their finer dendritic structures. Furthermore, residual stress of EHLA layer was lower than that of LC layer due to those micropores. Additionally, EHLA can add up to 45 wt.% WC into SUS316L layer without crack formation, resulting in higher wear resistance than that of LC where crack formation occurred at 25 wt.% WC. This enhanced crack resistance in EHLA is believed to be due to the less heat input during deposition.

In Laser Cladding, a differentiation must be made between cladding by brazing and cladding by welding regarding process parameters and the resulting material properties. Results of investigations of bronze cladding on steel parts produced by Laser Deposition Brazing will be presented. This means that a strong metallurgical bond is realized by diffusion processes by Laser Deposition Brazing, but the steel base material is not molten. The coatings were characterized by hardness distribution measurements from the bronze cladding to the steel substrate, by measuring the size of the heat-affected zone and by porosity measurements. This combination of a steel substrate and a local bronze coating is used industrially in many tribological applications, such as plain bearings or hydraulic pumps etc. The bronze offers excellent tribological properties. In some cases, the bronze is used as a complete solid part. However, applying the bronze locally to a steel base body instead of using a complete solid bronze component, offers the advantage of the higher modulus of elasticity of the steel, which provides greater stability of shape with regard to possible elastic deformations as these coated parts are exposed to high mechanical loads, it is essential that a high coating quality is achieved by laser cladding and that the properties are extensively and purposefully characterized. The production technology, the characterization and the industrial applications of such bronze coated steel parts are presented and explained in this contribution.

Restoring the damaged shaft parts to extend their service life is an economical and environmentally friendly solution. In recent years, the laser metal deposition (LMD) process has received increasing attention in component restoration. However, the residual stress and deformation inevitably occur due to the heat input, leading to the deflection of the repaired shafts. Therefore, this study aims to minimize the deflection of LMD-repaired shaft parts through parameter optimization. The width and height of the LMD deposit as a function of the laser power and traverse speed were achieved by fitting a series of one-pass experimental results. Based on it, the finite element analysis was conducted to clarify the effect of the repairing conditions (e.g., laser power, traverse speed, and initial substrate temperature) on the deflection and residual stress distribution of the shaft parts after LMD repairing. A 304 stainless steel round bar with a diameter of 6 mm was served as the component to be repaired. The deposit was 316L stainless steel, whose deposition process was realized by the element birth and death technique. The results indicated that the free-end of the specimen experienced complicated deformation during the LMD and cooling process. After cooling off, the substrate presents a residual compressive stress along the axial direction. Moreover, the substrate deflection can be reduced by improving the initial substrate temperature. This study provided an important reference for optimizing the process parameters in repairing the shaft parts.

Erosion-corrosion is a severe problem observed in the coal fired thermal power plant boilers which lead to premature failure of boiler tubes. Thermal spray coatings have been applied successfully to check the erosion-corrosion of boiler tubes. In the present research work NiCrTiCRe coating powders were successfully deposited on T22 boiler steel by two different coating processes i.e. high velocity oxy-fuel (HVOF) and cold spray process. The performance of the coatings in actual power plant boiler were investigated and compared. The uncoated and coated T22 boiler steels were subjected the superheater zone of the coal fired boiler for a total of 15 consequent cycles. The thickness loss data and weight change analysis were used to establish kinetics of the erosion-corrosion. X-ray diffraction, surface field emission scanning electron microscope/energy dispersive spectroscopy (FE-SEM/EDS) techniques were used in the present work for the analysis. The results of thickness loss data indicated that the cold sprayed coating performed better in thermal power plant boiler environment.

This work focuses on the laser cladding process and the behavior or interaction between the powder particles and the laser beam, specifically examining how various process parameters might affect the creation of melt pool formations. The experiment focused on examining the influence of laser intensity and other important factors on the amount of metal in the substrate of 316L stainless steel, particularly while utilizing Inconel 625 powder. The study was conducted by utilizing cross-sectional images and quantifying the ratio of areas of the melted substrate material across a sliced cross-sectional area. The study also investigated the influence of recirculation patterns resulting from the Marangoni convection force on the formation of the melt region. The study's results indicate that a low powder feed rate is preferable, which in this study was 5 g/min, and provides better results with a symmetrical and profound melt profile. The melt shifts to asymmetrical profiles when the feed rate increases significantly over this value. The primary cause of this phenomenon is attributed to the Marangoni forces and the momentum transfer generated by the powder jets. The investigation also emphasizes the complex interplay among the process factors and highlights the crucial role of laser source power in triggering a fast escalation in the volume of melted material. In addition, the study supports the idea that maintaining the laser energy input as a constant helps to create a consistency in the total melt area even when the cladding speed is increased.

Light alloys are being investigated as an alternative to ferrous-based engineering components. The manufacturing of such components requires a surface modification step necessary to eliminate the top surface's poor wear and corrosion response for improved functionality. Thermally sprayed cermet coatings offer improved surface resistance to wear and/or corrosion. This work presents a customized composition of WC-CoCr feedstock cut in fine and coarse powder size distribution (PSD) to fabricate different coatings on aluminium alloy and steel substrates using two high velocity spray techniques. The WC-CoCr coatings sprayed using the high velocity air-fuel (HVAF) technique at varied parameters consist of six different coatings (four thick, ~ 200 μm and two thin ones, 60-80 μm) to investigate the relationship between processing conditions, microstructure, and performance. Using scanning electron microscopy (SEM) and electro-dispersive X-ray spectroscopy (EDX) offered a comprehensive characterization of the respective coatings. Micro indentation, dry sliding wear, dry sand abrasion, and cavitation erosion tests conducted on the samples show the performance of the coatings based on the processing techniques and spray conditions. However, despite the similarities in the microstructural makeup of the coatings and the measured micro indentation hardness of the coatings (1000-1300 HV0.1), their respective specific wear rate (SWR) varied based on spray processing techniques and the substrate on which the coatings were deposited. Three of the HVAF coatings showed ~ 60 % more wear on the aluminium alloy substrate compared to the same coating deposited on a steel substrate. However, irrespective of the substrate used the HVAF coatings showed better wear resistance than the HVOF coating. The dry sand abrasion wear results of the two thick HVAF coatings show them superior to the HVOF coating in the three-body wear experiment conducted. The cavitation erosion resistance of the coatings varied based on the processing conditions and the driving mechanisms but the best two were the AF-2 and AF-6 samples.

High-pressure die casting (HPDC) is a well-established manufacturing process used in the automotive sector to make high-precision components. The necessity to reduce fuel consumption increases the use of low-density components in the automotive industry. Corrosion induced by molten metal is one of many failure modes for dies, changing the die's geometry and surface roughness. All combined wear changes the dimensional precision of the manufactured parts but also the surface quality of the components. Many additive deposition methods are applied to decrease wear and recover the surface. Thermally sprayed coatings can improve the surface properties and recover the geometry of the die caused by the aluminum attack. The main objective of this work is to observe the behavior of the H13, Cr3C2-25NiCr, and WC10Co4Cr coatings deposited by HVOF and HVAF, tested against Aluminum corrosion and Die-soldering tests. After dissolution, the chromium carbide reacts with the aluminum, creating a tough intermetallic interface, and raising the extraction tensile stress. After Aluminum corrosion tests, it was observed that the WC 10Co 4Cr HVAF coating presented low adhesion to the aluminum with no observed coating failure due to the formation of intermetallic. Die soldering tests indicated that the WC 10Co 4Cr protects the substrate, resulting in lower extraction tensile stress than H13 base material and other HVOF coatings. It was possible to observe that WC 10Co 4Cr HVAF coating showed results comparable to AlCrN PVD coating.

Sensors to measure gas velocities in high temperature flows need to be robust, low-profile so that they do not obstruct the flow, and easy to apply on metal surfaces. Thermal spray offers a method of making low-cost sensors that can be applied on large areas. Plasma spray was used to deposit an electrically insulating layer of alumina on a 316 stainless steel block. A 17 mm diameter heater coil was deposited on top of the alumina layer by spraying Nichrome from a twin wire arc spray system through a 3D printed polymer mask. A thermocouple junction was built next to the heater by inserting an insulated Constantan wire through a vertical hole drilled in the steel block and spraying steel on the top of the hole to close it and form an electrical connection between the wire and the surrounding substrate. The junction of the wire and the steel formed a thermocouple whose output voltage was calibrated. A flow loop was built to calibrate the sensor by passing air over it at velocities of up to 5 m/s. A series of 2 min long voltage pulses were applied to the heater, increasing its temperature by approximately 5°-10°C each time, before letting it cool. A calibration curve was developed of the air velocity as a function of the time constant for cooling of the sensor.

The properties of the coating depend, among other things, on the preparation of the substrate surface and the spray parameters. One of the key properties of the coating is its adhesion to the substrate. Suitable preparation of the substrate surface has a great influence on the adhesion of the thermal spray coating. This work aims to study the influence of surface preparation on roughness of substrate and the resulting surface adhesion of coating. Another aim was to compare the effect of the chosen adhesion measurement method. A series of measurements of the roughness of the samples after grit blasting was performed. The effect of using new and used corundum was also taken into account. The selected coating for testing was TWAS (twin Wire Arc Spray) sprayed Zn15Al. The substrate material was low carbon steel 1.0570. The following adhesion measurement methods were chosen for the experiment - adhesion tensile test according to ASTM C633 - 79 standard, method using a special sample holder based on the ASTM C633 - 79 standard. In addition, a series of measurements were performed using Elcometer 510 Model T.