Induction assisted laser cladding for high deposition rates

This paper provides an overview of the commonly used processes and equipment for laser cladding, including pre-set powder feeding, simultaneous powder feeding, wire feeding cladding, and coaxial cladding nozzles. By comparing the above processes and related nozzles, the coating characteristics are summarized for the selection of appropriate methods and equipment in different working environments. Meanwhile, the morphology and properties of the clad layers of shaft parts processed with different process parameters (e.g. laser power, scanning speed, lap rate, powder feed rate) and the influence of the combined parameters are overviewed. The changes and mechanisms of metals, ceramics, and metal-ceramic composites in terms of hardness, wear resistance, metallurgical bonding, and microstructure are analyzed. In addition, the application of numerical simulation techniques to simulate the temperature and stress fields and to plan the melting trajectory when laser cladding processing is performed on the surface of shaft parts are reviewed. Finally, the problems in the current research on laser cladding of shaft parts are summarized and the development directions are discussed.

Optimization of process parameters for laser cladding Stellite6 cobalt-based alloy

Evaluation of the mechanical properties of Inconel 718 components built by laser cladding

Human body is highly sensitive and repairing often incurs pain and expenses. Strength of the materials degraded by poor joint (either weld or link). New material technology is proposed many biomaterials for repairing bone and tissue and also many bio-implantation applications. Especially bioactive material like bioactive glass is used for biomedical applications for replacement and repairing organs in human body. This research work focuses on suggesting material of S53P4 bioactive glass Nano-coated Zirconium dioxide for manufacturing artificial knee implant for fixing in human body. The substrate of Zirconium dioxide is Nano-coated with S53P4 bioactive glass by means of laser cladding process. The laser cladding process parameters were optimized by Taguchi method to enhance mechanical properties like compressive strength, wear resistance and microhardness of Zirconium dioxide implant material. The key parameters like Laser Power (1 kW, 2 kW, 3 kW and 4 kW), beam diameter (2 mm, 3 mm, 4 mm and 5 mm), powder feed rate (10 g/min, 15 g/min, 20 g/min and 25 g/min) and scanning speed (3 mm/s, 4 mm/s, 5 mm/s and 6 mm/s) were considered. The optimal parameters result the higher compressive strength and microhardness are obtained as 373 MPa and 898.37 HV0.2 and minimum wear volume is attained as 0.148 mm3 in the Nano-coated implant material.

To compute the attenuation of laser power by powder stream and the temperature distribution of the powder particles arriving at different sites on the surface of the workpiece, a three-dimensional analytical model was presented based on Lambert-Beer theorem, Mie’s theory, and heat equilibrium principle. The obtained results revealed that for a given stream spread and speed of powder particles, the laser intensity distribution of laser spot and the temperature distribution of the powder particles reaching the surface of workpiece are both greatly affected by the powder feeding rate and the feeding angle. It was suggested that the presented results should be considered in the laser cladding process in order to control the dynamic processes in laser molten pool.

Laser cladding is one of the emerging additive manufacturing technologies and has been adopted in various industrial fields. In this study, the morphological characteristics of a single clad of Inconel 718 manufactured by coaxial laser cladding with high laser power from 4200 W to 5400 W, powder feeding rate from 25 g/min to 50 g/min, and cladding speed from 20 mm/s to 50 mm/s are studied. The cross-section of the melt pool is analyzed and classified by type into three types: shallow dilution, flat dilution, and fluctuating dilution. Nine parameters are designed to describe the morphological characteristics of the clad, and the corresponding linear regression models are developed to establish a quantitative relationship between the combined process parameters and morphological characteristics. The results indicate that the total area of the cross-section A, the clad area above the substrate Ac, the area of the molten substrate Am, the total height of the cross-section H, the height of the clad above the substrate hc, the penetration depth hm, the clad width W, the dilution ratio D, and the wetting angle θ are determined by complex coupling of energy input and mass accumulation, and they are proportional to PF0.4/V, P0.5F/V, P/F0.2/V0.4, P2F0.6/V, PF0.7/V, P2/F/V0.3, P/V0.8, P/FV0.2, and PF7/V0.8, respectively. The large linear regression coefficients and the analysis residuals indicate the high reliability of the statistical linear regression models. This work aims to provide a comprehensive understanding of the influence of the main processing parameters on the morphological characteristics of the clad, which is of great value in providing a reference and laying a basis for the practical application of laser cladding technology at a high deposition rate.

To further develop the advantages of face gear drives and improve their anti-sticking performance and wear resistance, a novel method using laser cladding as the primary process is proposed; here, grinding processing is used as the secondary process, i.e., achieving tooth surface strengthening of the orthogonal offset face gear using two types of materials to form a material gradient based on a laser cladding technology. Then, grinding processing is performed using a five-axis grinding machining. First, according to the forming principle of the face gear tooth surface, we establish the coordinate system of the orthogonal offset face gear and the gear cutter coordinate system; we also derive the tooth surface equation of the virtual gear cutter and the tooth surface equation of the orthogonal offset face gear. Second, we research the principles of the laser cladding and establish a laser cladding test bed for the orthogonal offset face gear. Based on the analysis of the design of the cladding layer and the process parameters of the face gear, the selection of the scanning path, the heat accumulation during the laser cladding process, and the accuracy control of the scanning position, we perform a laser cladding experiment on the offset orthogonal face gear. Third, we establish the machining coordinate system of the face gear based on the machine tool structure and conduct a grinding experiment for the face gear after the cladding process. Finally, we analyze the morphology and hardness of the face gear after grinding. A bench test verification of the axle face gear transmission system is completed. The results show that the precision and surface hardness of the tooth surface are significantly improved after grinding. Meanwhile, the accuracy and feasibility of the laser cladding surface of the face gear are verified.

The aim of the present work is to establish the relationship between laser cladding (LC) process parameters (power, process speed, and powder feed rate) and AISI D2 tool steel metallurgical transformations, with the objective of optimizing the processing conditions during real reparation. It has been deposited H13 tool steel powder on some steel substrates with different initial metallurgical status (annealed or tempered) using a coaxial LC system. The microstructure of the laser clad layer and substrate heat-affected zone (HAZ) was characterized by optical microscopy, scanning electron microscopy, and electron backscattered diffraction. Results show that the process parameters (power, process speed, feed rate, etc.) determine the dimensions of the clad layer and are related to the microstructure formation. Although it is simple to obtain geometrically acceptable clads (with the right shape and dimensions) in many cases some harmful effects occur, such as carbide dilution and non-equilibrium phase formation, which modify the mechanical properties of the coating. Specifically, the presence of retained austenite in the substrate–coating interface is directly related to the cooling rate and implies a hardness diminution that must be avoided. It has been verified that initial metallurgical state of the substrate has a big influence in the final result of the deposition. Tempered substrates imply higher laser absorption and heat accumulation than the ones in annealed condition. This produces a bigger HAZ. For this reason, it is necessary to optimize the process conditions for each repair in order to improve the working behaviour of the component.

Laser Cladding is one of the leading processes within Additive Manufacturing technologies, which has concentrated a considerable amount of effort on its development. In regard to the latter, the current study aims to summarize the influence of the most relevant process parameters in the laser cladding processing of single and compound volumes (solid forms) made from AISI 316L stainless steel powders and using a coaxial nozzle for their deposition. Process speed, applied laser power and powder flow are considered to be the main variables affecting the laser cladding in single clads, whereas overlap percentage and overlapping strategy also become relevant when dealing with multiple clads. By setting appropriate values for each process parameter, the main goal of this paper is to develop a processing window in which a good metallurgical bond between the delivered powder and the substrate is obtained, trying simultaneously to maintain processing times at their lowest value possible. Conventional metallography techniques were performed on the cross sections of the laser tracks to measure the effective dimensions of clads, height and width, as well as the resulting dilution value. Besides the influence of the overlap between contiguous clads and layers, physical defects such as porosity and cracks were also evaluated. Optimum process parameters to maximize productivity were defined as 13 mm/s, 2500 W, 30% of overlap and a 25 g/min powder feed rate.

In order to achieve the restoration of the sprocket, it is significant to repair or modify the damaged sprocket by using an advanced surface treatment technique, such as the laser cladding process. In this paper, the Taguchi method was applied to conduct the experiment to optimize the process parameters for repairing a sprocket in the laser cladding process. The dilution was chosen to evaluate the quality of the cladding layer and the effect of the process parameters, such as the laser power, scanning speed, and powder feeding rate, with respect to the cladding layer geometry, and the dilution was investigated systematically. Then, using the optimized parameters, the sprocket was remanufactured and its surface profile characteristics, microstructure, and microhardness of the repaired sprocket were analyzed. The results show that the optimal process parameters (1000 W, 2.81 g/min, 1200 mm/min) obtained by the Taguchi method could realize the lower dilution. With the optimal parameters, the repair accuracy of the sprocket could reach 2.973 mm, which offers the machining allowance for machining of the sprocket. A white bright band observed at the interface shows that the metallurgical bonding was realized between the cladding zone and base metal. The microhardness of the cladding zone is higher than that of the heat-affected zone and base metal. Furthermore, the results reveal that the Taguchi method can effectively acquire the optimal combination of process parameters, and the laser cladding process exhibits good feasibility and effectiveness for repairing the machinery components with complex shapes.

Impacts of laser cladding residual stress and material properties of functionally graded layers on titanium alloy sheet

This paper aimed to establish a nonlinear relationship between laser cladding process parameters and the crack density of a high-hardness, nickel-based laser cladding layer, and to control the cracking of the cladding layer via an intelligent algorithm. By using three main process parameters (overlap rate, powder feed rate, and scanning speed), an orthogonal experiment was designed, and the experimental results were used as training and testing datasets for a neural network. A neural network prediction model between the laser cladding process parameters and coating crack density was established, and a genetic algorithm was used to optimize the prediction results. To improve their prediction accuracy, genetic algorithms were used to optimize the weights and thresholds of the neural networks. In addition, the performance of the neural network was tested. The results show that the order of influence on the coating crack sensitivity was as follows: overlap rate > powder feed rate > scanning speed. The relative error between the predicted value and the experimental value of the three-group test genetic algorithm-optimized neural network model was less than 9.8%. The genetic algorithm optimized the predicted results, and the technological parameters that resulted in the smallest crack density were as follows: powder feed rate of 15.0726 g/min, overlap rate of 49.797%, scanning speed of 5.9275 mm/s, crack density of 0.001272 mm/mm2. Therefore, the amount of crack generation was controlled by the optimization of the neural network and genetic algorithm process.

A semi-empirical method for selecting the processing parameter s of laser cladding is proposed. This phenomenological approach uses simple mathematical formulae, derived from a statistical analysis of measured data, to relate the laser cladding parameters with the geometric features of the clad track. Given the prescribed clad height and avai lable laser beam power, the proposed method allows to calculate values of the scanning speed and powder feed rate which are required to obtain low dilution, pore free coatings, fusion bonded to the substra te. To illustrate the application of this method, variable powder feed rate laser cladding e xperiments were carried out with Stellite 6 powder on mild steel substrates. In this technique t he laser beam power and radius and the processing speed are kept constant, while the powder feed rate is varied along a single track length according to a specified linear function. The expressions derive d from the model allowed to plot the experimental data in a coherent manner, revealing the combine d role of the different processing parameters.

Numerical simulation and experimental analysis of thermal conduction and stress in laser cladding repair of thin-walled parts

Over the last decade, researchers have demonstrated interest in tribology and prototyping by the laser cladding process. In-situ laser cladding enables the formation of a uniform clad by melting the powder to form desired composition from pure powder components. Since TiC has desirable properties, such as hardness, wear and corrosion resistance, Ti and Graphite (C) are used as a composite material (i.e., TiC) to increase hardness and wear resistance of AISI 1030 carbon steel.In previous papers, the effect of laser parameters on the clad quality was investigated. In this paper two combined parameters (i.e. the effective energy per unit area (Eeff) and the powder deposition density (PDD) were plotted in order to recognize the high quality clad zone. Afterward a range of clad conditions with constant and variable effective energies in high quality clad zone were conducted to study the role of the effective energy on morphology and distribution of TiC particles.Complete metallurgical bonding between substrate and the clad was observed in all samples.SEM analysis has been used to study the TiC particles’ morphology from the bottom to the top of the clad. Presence of in situ TiC particles in Fe (Ti) solid solution has been confirmed by XRD and EDS analysis.Over the last decade, researchers have demonstrated interest in tribology and prototyping by the laser cladding process. In-situ laser cladding enables the formation of a uniform clad by melting the powder to form desired composition from pure powder components. Since TiC has desirable properties, such as hardness, wear and corrosion resistance, Ti and Graphite (C) are used as a composite material (i.e., TiC) to increase hardness and wear resistance of AISI 1030 carbon steel.In previous papers, the effect of laser parameters on the clad quality was investigated. In this paper two combined parameters (i.e. the effective energy per unit area (Eeff) and the powder deposition density (PDD) were plotted in order to recognize the high quality clad zone. Afterward a range of clad conditions with constant and variable effective energies in high quality clad zone were conducted to study the role of the effective energy on morphology and distribution of TiC particles.Complete metallurgical bonding between substrate...