Clad Height Research Articles

Machine learning-based prediction of single clad characteristics and non-destructive characterization of multi-layer deposited FeCoNiCrMo HEA on EN24 via laser cladding

The prediction of the proper metallurgical bonding and bead morphology in a laser cladding is very crucial to get a best profile of multi-clad layer. This work explores the laser cladding performance of FeCoCrNiMo high entropy alloy (HEA) on EN24 by analyzing the bead morphology with various process parameters. Machine learning (ML) technique is applied for two set of data where feasibility of the metallurgical bond is predicted and tested. From second set of data mainly three ML models, Support vector machine (SVM) radial kernels, K-Nearest neighbor (KNN), and multilayer perceptron (MLP) were applied to predict the outcomes. Sequential Minimal Optimization (SMO) algorithm is applied to identify the proper bonding between the substrate and cladded materials, which is classification-based ML model. The KNN model consistently attained the highest predictive accuracy across all response variables. It achieved perfect R² values and exhibited the lowest error metrics for clad width (w), clad height (h), clad depth (d), heat affected zone (HAZ), and Microhardness, establishing it as the most reliable and accurate model among the three applied ML model. To minimize the HAZ, the best conditions are lower laser powers, higher scanning speeds, and lower powder feed rate which is observed by contour plot. This reduces thermal diffusion into the substrate, maintaining material properties. Also, a non-destructive approach is used to characterize the multi-layer cladded before and after the deposition. The cladding process has significantly altered the microstructural and magnetic properties of the EN24 substrate, resulting in more refined grain structure and increased microhardness in the cladded region.

The effect of productive and quality deposition strategies on residual stress for Directed Energy Deposition (DED) process

In the Directed Energy Deposition (DED) realm, challenges persist concerning process stability and mechanical properties in as-built components. Facts like inconsistent laser head feed rate and accumulated heat during multi-layer deposition result in variations in melt pool energy, causing variant clad widths and heights. Moreover, significant residual stress in as-built DED parts can induce excessive distortions and cracking. To tackle these challenges, offline energy control systems that adjust laser power or feed rate have been implemented to manage melt pool energy and improve productivity. Additionally, an innovative online clad height compensation system has been developed to achieve global height geometry, further boosting productivity. However, the impact of these productive and quality control systems on the mechanical properties of austenitic stainless-steel parts, specifically residual stress, remains unexplored. In this research, residual stress measurements in as-built DED thin wall parts fabricated with energy and/or height control strategies using neutron diffraction have been investigated. The control of three key DED parameters influencing residual stress distribution and magnitude has been identified and discussed. Measurements indicate that neither offline energy control nor online height control adversely affects the quality of the thin wall parts and offline LP-based energy control can reduce residual stress magnitude and its variation. Additionally, the height control results in compressive residual stress with elevated magnitudes. Furthermore, aggressive DED parameters hold the potential for further improvement by pairing with an energy control strategy. This study establishes a foundation for further developing comprehensive control strategies designed to enhance the productivity and quality of DED systems.

Determination of process parameters for additive manufacturing with Inconel 718 powder

Abstract In this study, the additive manufacturing (AM) of Inconel 718 was investigated, and the processing parameters can affect the mechanical properties of the product. The five-axis laser cladding composite processing machine Tongtai AMH-630 is used, and the laser power is set to 800W based on the thermal impact of the laser on the base plate. However, the laser scanning speed (600-1200mm/min) and powder feed rate (3~15g/min) are not arbitrary combinations. It is recommended to present the feed per unit length in g/mm, which seems to be more clearly expressed. Regardless of changes in laser scanning speed and wheel speed, it is a reasonable decision to control the combination of the two at about 0.01-0.013g/mm. Through single-pass cladding experiments, we select different combinations of laser scanning speed and powder feed rate with a cladding aspect ratio in the range of 3:1 to 4:1. In the multi-pass cladding experiment, an overlap rate of 30% was used as the plane cladding spacing; a spacing of 80% of the cladding height was used as the stacking height. This study uses scanning speeds of 600, 700, 800, 1000 and 1200mm/min to clad a rectangular body. Tensile test specimens were processed using a CNC lathe, and tensile tests were conducted to obtain variations in tensile strength and elongation at different scanning speeds. The mechanical properties of both will decrease as the scanning speed increases. At a scanning speed of 600mm/min, its tensile strength is comparable to that of Inconel 718 standard materials; but its elongation is 61% of that of standard materials. If Hot Isostatic Pressing (HIP) is applied after cladding, it seems that a higher scanning speed can achieve a performance closer to that of standard materials.

Parametric investigation on surface responses of TIG cladded medium carbon steel substrate with TiO2–SiC powder

The present research work consists of surface modification of a medium-carbon steel substrate with TiO2–SiC powder of the same weight percentage. A Taguchi L9 orthogonal array was used for the design of experiments. Different input process parameters, such as current (A), scan speed (mm/s) and gas flow rate (L/min), have played a significant role in controlling geometrical surface responses. The relationship between different input parameters and response surfaces (clad height, clad width) was plotted and discussed. Diagrams have been utilized to demonstrate the combined impacts of any two process factors on clad height and clad width, such as TIG current–scan speed, TIG current–gas flow rate and gas flow rate–scan speed. Experimental observations revealed that cladding input parameters have a significant influence on response surfaces. TIG current has the maximum impact on clad height. Observations showed that with the increment of current up to a certain amount clad height increased. It was also observed that with an increment of current, clad width increases. Observations revealed that as the gas flow rate rises, clad height decreases but clad width increases. It was further noted that with an increase in scan speed, clad height and clad width follow a downward trend.

Statistical modeling and optimization of clad geometry in laser cladding of Amdry 365 on Hastelloy X superalloy with response surface methodology

The aim of this study is to statistically investigate and optimize the laser cladding process of Hastelloy X superalloy using NiCoCrAlY powder (Amdry 365). In this study, response surface methodology was used to investigate the influence of laser input variables such as scanning velocity, laser power, and duty cycle on the clad geometry (including height, width, and angle) and dilution ratio. The results indicate that with increasing duty cycle and laser power, the clad width increases significantly, while the clad height increases slowly. However, increasing the scanning velocity leads to a decrease in the width and height of the clad. Furthermore, the clad angle and dilution ratio increase with increasing input parameters. The results of variance analysis shows that laser scanning velocity had the most significant impact on clad height, angle and dilution ratio, while laser power had the greatest influence on clad width. The laser power of 321.3 W, the scanning velocity of 6.3 mm/s and the duty cycle of 76 % proved to be the optimal input parameters. An experimental test was carried out to validate the optimal conditions based on the optimization responses. The validation results show that the developed models are able to describe the responses with an accuracy of less than 9 % error. The EDS analysis performed in the cladding zone of the optimum specimen showed the presence of the β phase in the dendritic region and the γ phase in the interdendritic region.

Multi-targeting optimization of cladding process parameters based on NSGA-II algorithm and entropy weight method

Abstract Laser cladding is a new technology that can be used in the field of manufacturing and surface modification. The parameters of cladding 316L powder on 45 steel are studied by designing orthogonal experiments. Three optimal variables including laser power, scanning speed and cladding height are established. The mathematical model of target response with coating width, height and cladding area as indexes is constructed. Based on the Pareto set of NSGA-II, the optimal process parameters are found. The optimal solution on the Pareto front is obtained by the entropy weight method and data normalization. According to the results, when the laser power is 1607.0079 W, the scanning speed is 6.0033 mm/min, and the cladding height is 11.9961 mm, the optimized predicted cladding width is 1.3776 mm, the cladding height is 0.1847 mm, and the cladding area is 2.2907 mm2.

A multi-sensor based online monitoring system for laser hot-wire surface cladding process

A multi-sensor online monitoring system, including a high-speed camera, a spectrometer, and an infrared camera, was developed to enhance the laser hot wire cladding process. This innovative process feeds a preheated wire, using a hot-wire power supply, into a shallow molten pool formed on the substrate surface by a rectangular diode laser beam. This study assesses the capability of the monitoring system to detect variations in cladding process conditions that significantly influence the geometry and quality of the clad layer. Specifically, the study involved four sets of laser hot-wire cladding experiments, altering substrate surface conditions, substrate thicknesses, laser powers, and scanning speeds. The real-time data from the three sensors were synchronized and analyzed in depth, focusing on the morphology and microhardness of the clad layers. A laser vision sensor was employed to examine the surface profile and roughness of the clads. The findings indicated that the crucial role of surface preparation in influencing the dynamics of the molten pool, subsequently affecting the geometry, dilution depth, and microhardness of the clads. The sensors demonstrated increased sensitivity to changes in surface conditions compared to variations in other conditions like substrate thickness, laser power, and scanning speed. A significant correlation was found between the dilution depth, clad height, surface roughness, and microhardness of the clad layer. These correlations are in response to adjustments in laser power, scanning speed, and surface preparation and can be reliably and rapidly detected by the multi-sensor system.

Statistical modeling and optimization of clad geometry in laser cladding of Amdry 961 on Inconel 713LC superalloy with response surface methodology

In this study, Inconel 713LC superalloy was laser-clad with Amdry 961 powder using a 1 kW fiber laser. Response surface methodology was used to investigate the effect of laser power, duty cycle, and scanning speed on the deposited bead's geometry (width, height, and clad angle) and the dilution ratio. Interestingly, higher laser power and duty cycle increased bead width, clad angle, and dilution ratio but decreased bead height, while the opposite effect was observed for scanning speed. The process optimization was performed by a simultaneous optimization technique. This technique identified the ideal parameters: a laser power of 840 W, a duty cycle of 79.5%, and a scanning speed of 4.38 mm/s. These settings effectively optimized clad properties, with mean absolute errors of 7.96% for clad width, 14.74% for clad height, 16.71% for clad angle, and 5.166% for dilution ratio. These values demonstrate the precision of optimized parameter settings.

EXPLORING EPITAXIAL GRAIN GROWTH AND MARANGONI-INDUCED CONVERSION IN COLUMNAR DENDRITES: A STUDY OF INCONEL 718 ADDITIVE MANUFACTURING VIA DIRECT LASER ENERGY DEPOSITION

This study characterizes the microstructure changes of Inconel 718 (IN718) by laser cladding (LC). Well-bonded pore-free, crack-free, single-layer, and multi-layer (overlapped) LC was done on IN718 with the same powder. The basic microstructure illustrates the presence of [Formula: see text], [Formula: see text], and [Formula: see text] -phases. The precipitation of an irregularly shaped laves phase was observed with dendritic grains in the top and bottom regions of the single-track LC. Further, the epitaxial grain growth of columnar dendrites was observed in the interdendritic region along the laves phase. High leveraging of quick-dissolving behaviors of the laves phase in multi-track LC enhances the high-temperature mechanical performance. Modified grain morphology of the multi-track LC in terms of size, shape, and orientation is reported. Columnar dendrites (short and long) are the most common grains, with varied sizes and orientations reported in line with the Marangoni effect. The microhardness at the top layer of single and multi-track exhibited a higher value of 490.6[Formula: see text]HV and 500.7[Formula: see text]HV, respectively, which is comparatively lower than the bottom layer of single and multi-track samples. The influencing process parameter over clad width is scan speed, and over clad height is powder feed. The nonlinear mathematical model is proposed with a reliability of 99.22% and 99.52% for clad width and height, respectively.

Multi-track, multi-layer cladding layers of YCF102: An analytical and predictive investigation of geometric characteristics

This paper proposes a prediction method of the geometric characteristic parameters of cladding layers with multi-track and multi-layer. YCF102 cladding layers with different number of tracks and layers were laser cladded on the AISI 1045 steel substrate. The changing trend of the geometric characteristic parameters was analyzed by a laser microscope, and the prediction method of clad height, clad width and melt pool depth with the different number of tracks and layers under various processing parameters were proposed respectively. The results show that the increase of the number of tracks and layers lead to the increase of clad height, clad width and melt pool depth. When cladding the sixth layer, the clad width and melt pool depth still show an increasing trend, but the increase rate of melt pool depth slows down. The average residual values between the calculated and measured values of clad height, clad width and melt pool depth are 280.01 μm, 158.90 μm and 8.00 μm respectively, which are only 5.69%, 4.01% and 1.72% of the corresponding measured values. It is indicated that the prediction method is reasonable. The proposed prediction method can be used to predict the geometric characteristic parameters of multi-track and multi-layer cladding layers. The application of the method can effectively save the processing time and cost of the laser cladding repair of machine parts.

Forming characteristics analysis of variable-process alternated overlapping strategy based on contour description for laser melting deposition

To predict the geometric characteristics and improve the forming quality and macro-micro defects of multi-track overlapping cladding layer effectively, the experimental research of laser melting deposition single-track Co-based alloy on 42CrMo substrate was carried out. The influence trends of laser process parameters on the single-track cladding height and cladding width were analyzed, and the regression prediction models were established. A variable-process alternated overlapping strategy was proposed using the geometric functions to fit the single-track profile. The surface forming quality and macro-micro defect of different overlapping cladding layers were compared and evaluated. The results showed that the cladding height and cladding width regression models established by an improved optimization algorithm had an excellent prediction effect. The variable-process alternated overlapping cladding layer prepared by the parabolic function had a flat surface, and the fluctuation distance was 81.56 μm, which was significantly improved compared with other overlapping strategies. The surface flatness of the continuous overlapping cladding layer was the worst and the spheroidization defect was the most unsatisfied. The internal defects of the constant-process alternated overlapping cladding layer were the most terrible, with more non-fusion and cracks caused by oxides. The variable-process alternated overlapping strategy proposed in this study can effectively prepare a multi-track cladding layer with a smooth surface and dense interior, which provides essential theoretical guidance for the near-net forming of component surface deposition and repair.

Scaling laws and numerical modelling of the laser direct energy deposition

A computational framework that can be easily implemented into a two-phase flow model has been developed for DED (direction energy deposition) process. The information on the in-flight powder stream is treated by an analytical model and regarded as input to the cladding model. The cladding model utilizes Computational Fluid Dynamics (CFD) technique with the volume of fraction (VOF) method, which considers interfacial dynamics and interaction with the powder stream.Furthermore, we have applied Buckingham π theorem to develop scaling laws for the geometry of the final track. In contrast with the dimensional empirical models proposed in the previous studies, the dimensionless laws in this study can largely match the trends of measured data with noticeable variations of working conditions collected from several different studies. The dimensionless cladding width is dominated by the dimensionless laser power with a positive correlation. The increase in dimensionless laser power and powder mass flow rate usually results in a greater value of the dimensionless cladding height, but this trend could become opposite when the values of catchment and energy efficiencies are close to 100%. A threshold that dilution suddenly goes up has also been provided and validated based on the dimensionless parameters. This study provides a reliable numerical model and scaling laws with sufficient generality. The processing window has also been carried out with constraints of dilution and contact angle, bringing design guidelines to the related industries.

Effect of temperature step on selection strategy of deposition head lift height and manufacturing stability during the direct laser deposition process

Based on the layer by layer cladding characteristics of the direct laser deposition (DLD), the optimal selection strategy of deposition head lift height is one of the effective methods to maintain the manufacturing process stability, improve product quality, and reduce complex post-process. However, owing to the temperature step caused by changeable layer residual temperature, the selection of deposition head lift height becomes extremely complex. In this paper, to clearly analyze the effect of temperature step on selection strategy of deposition head lift height for the DLD multilayer deposition process with a 1.85 kW fiber laser and a coupled coaxial four-channel nozzle, a semi-theoretical model considering the main physical phenomena involved in DLD process is proposed, validated, and applied. Here, working plane position, deposition head lift height, and step of residual and preheating temperature are considered as input process variables while manufacturing stability and error are determined as process responses. Results show that without considering the temperature influence, the final manufacturing stability can be achieved by ensuring that the distance between the deposition head and the initial working plane is less than the maximum relative distance corresponding to the selected deposition head lift height. When the layer residual temperature is considered, the single-layer cladding height steps positively, which makes the extreme working plane position positively migrated, and the manufacturing stability is also further enhanced. However, due to the migration of the finally stable working plane position, the manufacturing errors are also conditionally changed. Finally, in order to obtain an optimal manufacturing process, for any DLD process where the initial working plane position has been determined, the deposition head lift height should be selected slightly smaller than the single-layer height corresponding to that determined plane under residual temperature condition (hTr,Si), otherwise the manufacturing process will gradually lose stability and lead to fabrication failure.

Laser Cladding of Alloy 82 Powder for Corrosion Protection in Small Modular Reactors

There has been an increased demand for surface modification technologies to enhance corrosionresistance and wear-resistance. Among the representative surface coating technologies, laser cladding has attracted great attention because of its multiple advantages including low heat input, low dilution ratio, controllable clad height, etc. Recently, laser cladding has been considered as a surface coating technology for the next-generation small modular reactor, although submerged arc welding was utilized for the 3rd generation nuclear reactor. Cobalt-free materials are required as cladding materials in the nuclear reactor because cobalt has a long half-life. In this work, nickel based cobalt-free Alloy 82 powder was utilized. The main experimental parameters for laser cladding were intensively investigated by varying laser power, scan speed, powder supply, carrier and shield gas, overlap ratio, etc. Additionally, cross-sectional area calculation and EPMA analysis were carried out to examine the dilution ratio. Mechanical properties were also evaluated using microhardness tests and wear tests at high temperatures. Finally, corrosion tests were performed to compare a laser clad surface with an uncoated carbon steel surface. Our study indicates that the laser cladding using Alloy 82 powder is feasible for corrosion protection in next-generation small modular reactors.

Z-Increments Online Supervisory System Based on Machine Vision for Laser Solid Forming.

An improper Z-increment in laser solid forming can result in fluctuations in the off-focus amount during the manufacturing procedure, thereby exerting an influence on the precision and quality of the fabricated component. To solve this problem, this study proposes a closed-loop control system for a Z-increment based on machine vision monitoring. Real-time monitoring of the precise cladding height is accomplished by constructing a paraxial monitoring system, utilizing edge detection technology and an inverse perspective transformation model. This system enables the continuous assessment of the cladding height, which serves as a control signal for the regulation of the Z-increments in real-time. This ensures the maintenance of a constant off-focus amount throughout the manufacturing process. The experimental findings indicate that the proposed approach yields a maximum relative error of 1.664% in determining the cladding layer height, thereby enabling accurate detection of this parameter. Moreover, the real-time adjustment of the Z-increment quantities results in reduced standard deviations of individual cladding layer heights, and the height of the cladding layer increases. This proactive adjustment significantly enhances the stability of the manufacturing process and improves the utilization of powder material. This study can, therefore, provide effective guidance for process control and product optimization in laser solid forming.

Experimental and Analytical Investigation of the Re-Melting Effect in the Manufacturing of 316L by Direct Energy Deposition (DED) Method

In this study, the effects of the laser power (2000 W, 2250 W, 2500 W), scanning speed (0.6, 0.8, 1 m/min), and powder feed rate (10, 12.5, 15 g/min) on material structures and their mechanical properties were investigated in the production of 316L stainless steels through Direct Energy Deposition (DED). In addition, changes in the microstructure caused by the re-melting process were also investigated. Optimized process parameters were modeled using the CFD software (FLOW 3D V3.0). In order to see the effects on the density and mechanical properties, the sample production was repeated as a build and by applying the re-melting process between the layers. When the energy density and powder feed rate are considered together, it has been determined that the deposition rate increases in direct proportion to the energy density and tends to decrease inversely with the powder feed rate. When the experimental and analysis results of the single clad height are compared, it is seen that the values obtained are very approximate. It has been observed that the most important parameters affecting the formation of porosity are the energy density and powder feed density. Re-melting slightly affects the microstructure of the material and causes grain growth. Changes in the impact strength of the re-melted samples were observed depending on the energy density.

Multi-objective optimization of process parameters of laser cladding 15-5PH alloy powder based on gray-fuzzy taguchi approach

Laser cladding is a new surface treatment technology that is widely used for surface modification of metal parts, and the high quality of the surface geometry of the cladding layer can save a lot of resources for the company. To obtain high quality of the clad layer, the L25 Taguchi experiment of laser cladding process parameters was designed to laser-clad a single 15-5PH layer on the surface of 45# steel; the effect of process parameters on the surface morphology and dilution rate of the coating was determined by ANOVA; the optimal combination of process parameters was obtained by combining gray correlation and fuzzy inference system method. The ANOVA results show that the scanning speed among the laser cladding process parameters plays a key role in obtaining the best superposition of the four geometrical features of the cladding layer simultaneously; With the optimization objectives of larger clad width and height, smaller clad depth, and 30% dilution rate, the optimal combination of process parameters, (P: 600W, V: 500 mm min−1, F −1 : 1.3 r min−1), obtained based on the Gray-fuzzy Taguchi Approach, was compared and analyzed to find a significant improvement in the geometric quality characteristics of the optimized clad layer. The analysis of microstructure, physical phase, hardness, wear resistance and corrosion resistance showed that the 15-5PH clad layer was able to effectively enhance the surface properties of the 12Cr13 substrate. The optimization method proposed in this study can solve the problem of parameter optimization in the industrial multi-parameter and multi-response processes.

Analysis and prediction of Cu-Sn-Ti alloy deposited on 316 L steel by coaxial laser cladding

Cu-Sn-Ti has the advantages of excellent properties and low cost, which makes it suitable to be used as a bonding agent for CBN grinding wheels. In this paper, laser cladding was used to obtain Cu-Sn-Ti clad layers on the surface of 316 L steel substrate, and the effects of process parameters (laser power, scanning speed and powder feeding rate) on the clad height, melting pool width, melting pool depth and dilution rate were investigated. Then, the extent of the effect of different process parameters on the clad layer morphology and the reasons for it were analyzed in terms of laser energy as well as absorbed energy. Finally, the numerical prediction models of the morphological characteristic parameters of the clad layer were established and the microhardness of the clad layer was measured. The results showed that the coefficients of determination of the numerical prediction models for clad height, melting pool width, and melting pool depth were 0.9723, 0.9688, and 0.9840, respectively. The maximum relative error of dilution rate was 3.6%. The microhardness of the clad layer reached 310.6–366.2 HV0.5. The results provided theoretical support for the deposition of Cu-Sn-Ti bonding layers with outstanding morphology on the surface of 316 L substrates.

Optimization and wear behaviors of 316L stainless steel laser cladding on rail material

Laser cladding is a potential technology for repairing the rail with side wear. The laser processing parameters should be optimized and the wear behaviors of clads should be analyzed before its application. Therefore, single-pass and multi-pass laser cladding experiments of 316L stainless steel powder with different laser powers, scan speeds, scan modes (directions), and numbers of layers are conducted on the U71Mn rail to optimize the processing parameters. After that, sliding wear tests are conducted on different depths in clad to explore the wear behaviors. The results show that with the increase in laser power, the clad width is increased, the height is increased first and then decreased. With the increase in scan speed, both the clad height and width are decreased. Scan mode 1# produces the thinnest clads, the mode 3 produces the thickest ones. The microstructure of clad is composed of dendritic grains. With the increase in depth in clad, the grain size decreases and the hardness increases. The grain size is increased with laser power and decreased with scan speed, and the hardness is increased with the power and speed. Smallest grains and highest hardness are produced using mode 1#, and largest grains and lowest hardness using mode 3#. The Cr and Ni elements from clad permeate into the heat affected zone of U71Mn rail material. Wear depth of clad has a positive relationship with the grain size and a negative relationship with the post hardness. A wear resistance coefficient, Xphv2.55/Xgs1.56,where Xphv refers to the post hardness and Xgs refers to the grain size, is proposed to characterize the inherent anti-wear property of 316L stainless steel clad on U71Mn rail.

Research on Geometrical Features of FGH95 Nickel-based Superalloy by Coaxial Single Track Laser Cladding

FGH95 nickel-base superalloy powders were coated on GH4169 nickel-base superalloy by coaxial single-track laser cladding. The effects of process parameters on cladding width and cladding height were studied based on the three-factor and three-level orthogonal experiment. The experimental results are nonlinearly fitted by MATLAB software, and the mathematical model between the geometrical features and the process parameters is set up. The results show that the effect factor on the clad width is in the order of first power, followed by feeding rate, and scanning speed. However, the influence on the clad height is in the order of first scanning speed, followed by laser power, and feeding rate. The average prediction error of cladding width and height is less than 7%. The model can accurately forecast the geometrical features of the cladding coating and can offer some references for the optimization of laser cladding.