scholarly journals Crack Sensitivity Control of Nickel-Based Laser Coating Based on Genetic Algorithm and Neural Network

Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 728 ◽  
Author(s):  
Yu ◽  
Sun ◽  
Huang ◽  
Wang ◽  
Wang ◽  
...  
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Laser Cladding ◽  
Process Parameters ◽  
Feed Rate ◽  
Crack Density ◽  
Scanning Speed ◽  
Powder Feed Rate ◽  
Powder Feed ◽  
Overlap Rate

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.

scholarly journals Study on the Deformation Control and Microstructures of Thin-Walled Parts Repaired by Laser Cladding

Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 369 ◽  
Author(s):  
Jiangtong Yu ◽  
Wenlei Sun ◽  
Haibo Huang ◽  
Yong Huang
Keyword(s):  
Laser Cladding ◽  
Feed Rate ◽  
Laser Power ◽  
Visual Analysis ◽  
Scanning Speed ◽  
Powder Feed Rate ◽  
Dendritic Crystal ◽  
Powder Feed ◽  
Minimum Deformation ◽  
Thin Walled

To reduce the deformation and improve the quality of thin-walled parts repaired by laser cladding, a three-factor, three-level orthogonal experimental scheme was employed to clad Ni60 powder on thin-walled parts with a thickness of 3.5 mm. To measure the deformation of the thin-walled parts, a method of combining the meshing of the backs of the thin-walled parts and fixing one end of the parts during cladding was used. The effects of the powder feed rate, laser power, and scanning speed on the deformation of the thin-walled parts were studied via visual analysis and analysis of variance, and the process parameters that resulted in the minimum deformation were determined. The deformation process of the thin-walled parts and the causes of cladding stress were also studied, and the microstructure of the cladding layer with the minimum deformation was analyzed via scanning electron microscopy (SEM). The results reveal that the deformation of the thin-walled parts increased with the increase of laser power. The increases of the scanning speed and powder feed rate were found to reduce the deformation of thin-walled parts; the laser power was found to have a significant effect, and the powder feed rate was found to have no significant effect, on the deformation of thin-walled parts. The order of the influence of factors on the deformation of thin-walled parts from greatest to least was determined to be as follows: laser power > scanning speed > powder feed rate. The optimal parameters to obtain the minimum deformation and good metallurgical bonding of thin-walled parts were found to be a powder feed rate of 1.4 r/min, a laser power of 1100 W, and a scanning speed of 8 mm/s. From the bottom to the top, the crystal structure of the coating with the minimum deformation was found to be coarse dendrite, dendritic crystal, and equiaxed crystal.

Parametric investigation and characterization on SS316 built by laser-assisted directed energy deposition

2019 ◽  
Vol 234 (3) ◽  
pp. 452-466 ◽  
Author(s):  
K Benarji ◽  
Y Ravi Kumar ◽  
CP Paul ◽  
AN Jinoop ◽  
KS Bindra
Keyword(s):  
Deposition Rate ◽  
Process Parameters ◽  
Feed Rate ◽  
Laser Power ◽  
Energy Deposition ◽  
Scanning Speed ◽  
Powder Feed Rate ◽  
Parametric Investigation ◽  
Powder Feed ◽  
Directed Energy

In the present work, parametric investigation and characterization of stainless steel 316 (SS316) built by laser-assisted directed energy deposition (L-DED) is performed. Single-track L-DED experiments are carried by varying laser power, scanning speed, and powder feed rate using full factorial experimental design. The effect of L-DED process parameters on the track geometry, deposition rate, and microhardness is investigated, and three different combinations of process parameters yielding maximum deposition rate and hardness are identified for bulk investigation. The identified process parameters are laser power of 1000 W, powder feed rate of 8 g/min, and scanning speed of 0.4 m/min, 0.5 m/min, and 0.6 m/min. The austenitic phase [Formula: see text] is detected at all the conditions. However, ferrite [Formula: see text] peak is observed at 0.6 m/min due to microsegregation and thermal gradients. The minimum crystallite size is estimated to be 24.88 nm at 0.6 m/min. The porosity and microstructure analysis is carried out by optical microscopic images. The fine columnar dendritic structure is observed in L-DED samples at all conditions. An average microhardness of 317.4 HV0.98 N is obtained at 0.4 m/min, and it is observed that microhardness reduces with an increase in scanning speed mainly due to increase in lack of fusion and porosity. Tribology studies are carried out at different values of normal load and sliding velocity. The minimum specific wear rate of 0.02497 × 10−4 mm3/Nm is observed at scanning speed of 0.4 m/min. Scanning electron microscope of the wear tracks analysis shows abrasive wear as the major wear mechanism. This study provides a path for building SS316 components for various engineering applications.

Processing parameter, microstructure and hardness of Ni base intermetallic alloy coating fabricated by laser cladding

MRS Advances ◽  
2017 ◽  
Vol 2 (26) ◽  
pp. 1381-1386 ◽  
Author(s):  
Takeshi Okuno ◽  
Yasuyuki Kaneno ◽  
Takuto Yamaguchi ◽  
Takayuki Takasugi ◽  
Satoshi Semboshi ◽  
...  
Keyword(s):  
Laser Cladding ◽  
Feed Rate ◽  
Laser Power ◽  
Alloy Coating ◽  
Intermetallic Alloy ◽  
Ingot Metallurgy ◽  
Processing Parameter ◽  
Powder Feed Rate ◽  
Cladding Layer ◽  
Powder Feed

ABSTRACTNi base intermetallic alloy coating was fabricated by laser cladding, controlling the laser power and powder feed rate. Atomized powder of the Ni base intermetallic alloy was laser-cladded on the substrate of stainless steel 304. The hardness and microstructure of the clad layers were investigated by Vickers hardness test, SEM, XRD and TEM observations. The hardness of the cladding layer was affected by the dilution with the substrate; it increased with decreasing laser power and increasing powder feed rate. By optimizing the dilution with the substrate, the cladding layer with an almost identical hardness level to that of the Ni base intermetallic alloy fabricated by ingot metallurgy was obtained. The TEM observations revealed that a very fine-sized microstructure composed of Ni3Al and Ni3V was partially formed even in the as-cladded state. After annealing, the two-phase microstructure composed of Ni3Al and Ni3V was developed in the cladding layer, resulting in enhanced hardness in the cladding layers fabricated in the majority of cladding conditions.

Modeling of Transport Phenomena in the Laser Multilayered Cladding

2009 ◽  
Author(s):  
Fanrong Kong ◽  
Radovan Kovacevic
Keyword(s):  
Feed Rate ◽  
Molten Pool ◽  
Laser Power ◽  
Steel Powder ◽  
Mass Transfer Process ◽  
Scanning Speed ◽  
Heat Radiation ◽  
Powder Feed Rate ◽  
Transient Model ◽  
Powder Feed

The present work studies the heat and mass transfer process in the laser multilayered cladding of H13 tool steel powder by numerical modeling and experimental validation. A solid-liquid-gas unified transient model was developed to investigate the evolution of temperature distribution and flow velocity of the liquid phase in the molten pool. In this model, an enthalpy-porosity approach was applied to deal with the solidification and melting occurring in the clad, and a level-set method was used to track the evolution of the molten pool free surface. Moreover, heat loss due to forced convection and heat radiation and laser heat input occurring on the top surface of deposited layer and substrate have been incorporated into the source term of governing equations. The effects of laser power, scanning speed, and powder feed rate on the dilution and height of the multilayered clad are investigated based on the numerical model and experimental measurement. The results show that increasing the laser power and powder feed rate, or reducing the scanning speed, can increase the clad height and directly influence the remelted depth of each layer of deposition. The numerical results have a qualitative agreement with the experimental measurements.

scholarly journals Optimizing the Characteristics of the Laser Hardfacing Process Parameters to Maximize the Wear Resistance of Ni-Based Hard-Faced Deposits Using the RSM Technique

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
S. Gnanasekaran ◽  
Samson Jerold Samuel Chelladurai ◽  
T. Ramakrishnan ◽  
S Sivananthan ◽  
G. Padmanaban ◽  
...  
Keyword(s):  
Weight Loss ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Process Parameters ◽  
Feed Rate ◽  
Laser Power ◽  
Travel Speed ◽  
Powder Feed Rate ◽  
Powder Feed ◽  
Rsm Technique

The nickel-based Colmonoy-5 hardfacing alloy is used to hard-face 316LN austenitic stainless steel components in fast reactors. The nominal composition (in wt%) was listed as follows: 0.01 C, 0.49 Si, 0.87 Mn, 17.09 Cr, 14.04 Ni, 2.56 Mo, 0.14 N, and balance Fe. Hardfacing is a technique of applying hard and wear-resistant materials to substrates that need abrasion resistance. The thickness of hardfacing deposit varies between 0.8 mm and 2 mm based on parameter combinations. In this study, laser hardfacing process parameters including laser power, powder feed rate, travel speed, and defocusing distance were optimized to reduce weight loss of laser hard-faced Ni-based deposit. The tribological characteristics of reactor-grade NiCr-B hard-faced deposits were investigated. The RSM technique was used to identify the most important control variables resulting in the least weight loss of the nickel-based alloy placed on AISI 316LN austenitic stainless steel. Statistical techniques like DoE and ANOVA are utilized. Changing the laser settings may efficiently track the weight loss of laser hard-faced nickel alloy surfaces. These are created using the response surface technique. The deposit produced with a laser power of 1314 W, powder feed rate of 9 g/min, travel speed of 366 mm/min, and defocusing distance of 32 mm had the lowest weight loss of 16.4 mg. Based on the F value, the powder feed rate is the major influencing factor to predict the hardness followed by power, travel speed, and defocusing distance.

The Influence of Process Parameters on Structure of Ceramic Coatings Deposited by PS-PVD Method

2017 ◽  
Vol 267 ◽  
pp. 243-247 ◽  
Author(s):  
Marek Góral ◽  
Tadeusz Kubaszek
Keyword(s):  
Process Parameters ◽  
Feed Rate ◽  
Ceramic Powder ◽  
Turbine Blades ◽  
Oxide Coating ◽  
Ceramic Coatings ◽  
Columnar Structure ◽  
Powder Feed Rate ◽  
Influence Of Process Parameters ◽  
Powder Feed

Thermal Barrier Coatings (TBC) is the most advanced system for protection of turbine blades and vanes against high temperature, and oxidation. They are used in most advanced jet engines. In present article the new Plasma Spray Physical Vapour Deposition Technology was used to obtain yttria stabilized zirconia oxide coating with columnar structure. In research the different process parameters were changed. It was observed that powder feed rate had big influence on coating thickness. The large amount of Ar in plasma gasses combined with high powder feed rate resulted in partial evaporation of ceramic powder and splat-type structure. The same effect was observed when the power current was decreased form 2400 to 1600 A as well as pressure was increased to 200 Pa when the powder feed rate was 30 g/min. The obtained results showed that full evaporation of ceramic powder requires very low feed rate of ceramic material (2 g/min), high power current and high He content into plasma.

Effect of Process Parameters on Laser Directed Energy Deposition of Copper

2019 ◽  
Author(s):  
Sunil Yadav ◽  
Christ P. Paul ◽  
Arackal N. Jinoop ◽  
Saurav K. Nayak ◽  
Arun K. Rai ◽  
...  
Keyword(s):  
Process Parameters ◽  
Feed Rate ◽  
Laser Power ◽  
Energy Deposition ◽  
Process Conditions ◽  
Powder Feed Rate ◽  
Track Geometry ◽  
Powder Feed ◽  
Directed Energy Deposition ◽  
Directed Energy

Abstract Laser Additive Manufacturing (LAM) is an advanced manufacturing processes for fabricating engineering components directly from CAD Model by depositing material in a layer by layer fashion using lasers. LAM is being widely deployed in various sectors such as power, aerospace, automotive etc. for fabricating complex shaped and customized components. One of the most commonly used LAM process is Directed Energy Deposition (LAM-DED) which is used for manufacturing near net shaped components with tailored microstructure, multi-materials (direct and graded) and complex geometry. This paper reports experimental investigation of LAM of Copper (Cu) tracks on Stainless Steel 304 L (SS 304L) using an indigenously developed LAM-DED system. Cu-SS304L joints find wider applications in tooling, automotive and aerospace sectors due to its combination of higher strength, thermal conductivity and corrosion resistance. However, laying Cu layers on SS304L is not trivial due to large difference in the thermo-physical properties. Thus, a comprehensive experiments using full factorial design are carried out and a number of Cu tracks were laid on SS304L substrate by varying laser power, scan speed and powder feed rate. The laid tracks are characterized for track geometry and porosity and the quality of the tracks are analyzed. Lower values of laser power and higher powder feed rate results in discontinuous deposition, while higher laser power and lower powder feed rate results in cracked deposits. Porosity is observed to vary from 6–45 % at different process conditions. Analysis of Variance (ANOVA) of deposition rate and track geometry is performed to estimate the major contributing process parameters. This study paves a way to understand effect of process parameters on LAM-DED for fabricating bimetallic joints and graded structures of Copper and SS304L.

Optimization Research of Process Parameters for Laser Cladding Valve Parts Based on Genetic Algorithm

2012 ◽  
Vol 229-231 ◽  
pp. 382-386
Author(s):  
Jian Bin Wang ◽  
Ji Shu Yin
Keyword(s):  
Genetic Algorithm ◽  
Laser Cladding ◽  
Process Parameters ◽  
Fitness Function ◽  
Quantitative Relationship ◽  
Scanning Speed ◽  
Optimum Process ◽  
Control Parameters ◽  
Group Setting ◽  
Optimization Of Process Parameters

The optimization research of process parameters for big power Laser cladding valve parts, is a research focus of modern surface hardening technology. The article discussed in detail for solving the optimum process parameters of Laser cladding for the selection approach of strategy of genetic algorithm, the quantitative relationship model was established between process parameters and the valve parts property using neural network method , which process parameters are laser power (P), scanning speed (V), powder feeding rate (G), scan spacing (D) and thickness ( ) etc., the best configuration program of Genetic Algorithm control parameters has been obtain by means of the parameters encoding、initial group setting、fitness function design,genetic operation design and algorithm control parameters setting. The optimization of process parameters is obtained to fit the Laser cladding technology by using genetic algorithm toolbox in the MATLAB environment, and the optimization goal of the valve parts property has also been achieved. Practice has proved that the optimal process parameters are correct by the genetic algorithm , and has a very good production practice guide.

Laser Clad Geometry: Experimental Observation and Geometric Modeling

2010 ◽  
Vol 148-149 ◽  
pp. 628-632 ◽  
Author(s):  
Zhi Jian Wang ◽  
Shi Yun Dong ◽  
Bin Shi Xu ◽  
Wei Xia
Keyword(s):  
Feed Rate ◽  
Geometric Modeling ◽  
Mass Conservation ◽  
Scanning Speed ◽  
Optical Microscope ◽  
Powder Feed Rate ◽  
Powder Feed ◽  
Simulation Based ◽  
Geometric Simulation ◽  
Theoretical Results

In this paper, a new analytical method of laser clad geometric simulation was developed. The effects of laser process parameters such as laser power, scanning speed, and powder feed rate on estimating clad geometry were investigated in this approach. A series of cladding was prepared by 1 kW diode pumping solid-state laser, to characterize the cross-section image of the clad by optical microscope. The clad profile was fitted by pitch arc and line in AutoCAD, with results displaying the arc-like upper profile of the clad. The theoretical results are discussed and compared with experimental data. The simulation based on the mass conservation is capable of predicting the clad width and depth with reasonable accuracy at medium powder feed rate.

Laser Cladding of Micro-Fluidic Channel Mold

2011 ◽  
Vol 216 ◽  
pp. 424-429
Author(s):  
Xu Yue Wang ◽  
H.R. Guo ◽  
Yong Bo Wu ◽  
Wen Ji Xu ◽  
D.M. Guo
Keyword(s):  
Laser Cladding ◽  
Feed Rate ◽  
Laser Power ◽  
Powder Feed Rate ◽  
Fluidic Channel ◽  
Powder Feed ◽  
Technical Requirements ◽  
Clad Layer ◽  
Cad Cam ◽  
Geometrical Dimensions

Laser cladding of micro-fluidic channels mold was performed using Nd:YAG laser and synchronous powder feeder. Influences of laser power and powder feed rate on clad layer geometrical dimensions and qualities were investigated. Results show that powder feed rate 1.5-2.5 g/min used obtains micro clad layers which meet geometrical dimensions’ requirement of micro-fluidic channels mold and combination of parameters laser power 400 W and powder feed rate 2.0 g/min achieves micro clad layer with better clad quality. Scanning paths of micro-fluidic channels mold was planned through CAD-CAM software. Using optimum parameters combination, multilayer laser cladding experiment was carried out and a sample of micro-fluidic channels mold was fabricated with expectative structure and hardness. A little milling and polishing makes the sample meet technical requirements, 0.2mm in height and 0.3mm in width. Fabricating a mold takes 15-20 min totally.

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