Laser Cladding Process Parameters Research Articles

Evaluation of solidification and microstructure in laser cladding Inconel 718 superalloy

The development of directional or completely equiaxed microstructures by the laser cladding process can determine the final properties and applications of Inconel 718 alloys. The main purpose of this study is to investigate the effect of laser cladding process parameters on the solidification and final microstructure of Inconel 718 alloy. In this study, Inconel 718 powder was cladded on the Inconel 718 substrate by Nd: YAG laser using laser power of 150–300 W, scanning rate of 4–6 mm/s and powder feeding rates of 150, 200, 250, 300 and 400 mg/s and the effect of them on the solidified microstructure at three zones of the interface, middle and surface of coating was studied. The dendritic secondary arms spacing was calculated and the cooling rate was determined in each zone. The structural defects including cracks, porosity and segregation and finally phase analysis were examined. The results showed that with increasing laser power from 150 to 300 W and also laser scanning rate from 4 to 6 mm/s due to decrease in the G/R ratio, so that the more part of microstructure was equiaxed. In addition, by taking distance from the interface, the dendrite secondary arms spacing decreased from 1.08 to 0.98 and the cooling rate increased from 2.3649 × 104 k/s to 3.2641 × 104 k/s. With increase in the powder feeding rate the equiaxed zone increases. However, the effect of the powder feeding rate cannot be directly and specifically determined. The all samples were free crack but, the small amount of porosity was observed in cladding sample. Results showed that between the laser parameters and the percent of porosities were not exist of the clear relation.

Optimizing Processing Parameters for Multi-Track Laser Cladding Utilizing Multi-Response Grey Relational Analysis

Multi-track laser cladding is the primary technology used in industrial applications for surface reinforcement and remanufacturing of broken parts. In this study, the influence of processing parameters on multi-track laser cladding was investigated using a Taguchi orthogonal experimental design. A multi-response grey relational analysis (GRA) was employed to identify laser cladding processing parameters that simultaneously optimize the flatness ratio of the coating and the cladding efficiency. The optimal parameters setting found by GRA were validated experimentally. Results showed that the flatness ratio and cladding efficiency were closely correlated to the overlap rate and laser power, where the overlap rate shows the most significant impact on the flatness ratio and the laser power shows the most significant impact on cladding efficiency. Results from the validation experiment were within one percent (0.97% error) of the predicted value. This demonstrates the benefits of utilizing GRA in laser cladding process optimization. The methods presented in this paper can be used to identify ideal processing parameters for multi-response multi-track laser cladding processes or other industrial applications.

Laser Cladding Ti Coated CBN/CuSnTi Alloy on Steel for Grinding Tools of Ocean Ship

ABSTRACT Zhao, X.; Yu, T.; Zhao, Y.; Zhang, Y.; Yang, L.; Jiang, S., and Wang, W., 2018. Laser cladding Ti coated CBN/CuSnTi alloy on steel for grinding tools of ocean ship. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 571–578. Coconut Creek (Florida), ISSN 0749-0208. In this study, laser cladding CBN/CuSnTi alloy mixed powder on the AISI 1045 steel substrate for grinding tools of ocean ship was investigated. Various laser cladding processing parameters were conducted to find the appropriate laser cladding parameters to fabricate grinding tools of ocean ship in the continuous fiber laser beam with coaxial powder nozzle. The morphology of the laser cladding layer was analyzed by laser scanning confocal microscopy (LSCM) and the CBN grits with specific laser process parameters was observed by scanning electron microscopy (SEM). The interface conditions among the CBN grit/alloy matrix/substrate were detected by SEM...

Influence of Laser Cladding Process Parameters on Morphology of Cladding Layer and Its Optimization

Influence of Laser Cladding Process Parameters on Morphology of Cladding Layer and Its Optimization

Laser cladding of nanoparticle TiC ceramic powder: Effects of process parameters on the quality characteristics of the coatings and its prediction model

In laser cladding process, the quality characteristics of the coatings are directly affected by laser cladding process parameters. In this work, in order to investigate the effects of the process parameters on the quality characteristics of the ceramic coatings on Ti6Al4V substrates, which were prepared by laser cladding using nanoparticle TiC powder as pre-placed material, five single factors (laser power, scanning speed, pre-placed powder thickness, laser spot diameter and multi-track overlapping ratio) and four interactions related to laser power were selected as influencing factors, and then multi-track cladding experiments with L27(313) orthogonal array designed by Taguchi method were carried out to obtain the geometric characteristics (coating thickness, coating width and height difference) and mechanical property (micro-hardness) of the coatings. Based on experimental results, the influence extents of all factors on quality characteristics were ranked by signal-to-noise (S/N) ratio, and the significances of all factors on quality characteristics were evaluated by using P-value from the analysis of variance (ANOVA). Then the effects of the significance factors on quality characteristic were analyzed in detail, and the optimal process parameters were selected. Finally, a prediction model based on support vector machine (SVM) was developed for the quality characteristics of the cladding coatings. The results showed that the pre-placed powder thickness, laser spot diameter and laser power were the most crucial process parameters. The prediction model based on SVM method can correctly describe the relations between cladding process parameters (input variables) and quality characteristics of coatings (output characteristics), with the correlation coefficient CC > 0.94. This research work gives a guideline for the selection of appropriate process parameters for laser cladding of high-quality coatings using nanoparticle TiC ceramic powder as starting material.

Computational and Experimental Investigation of Micro-Hardness and Wear Resistance of Ni-Based Alloy and TiC Composite Coating Obtained by Laser Cladding.

The influence of processing parameters on the micro-hardness and wear resistance of a Ni-based alloy and titanium carbide (TiC) composite cladding layer was studied. Mathematical models were developed to predict the micro-hardness and wear resistance of the cladding layer by controlling the laser cladding processing parameters. Key processing parameters were the laser power, scanning speed, gas flow, and TiC powder ratio. The models were validated by analysis of variance and parameter optimization. Results show that the micro-hardness is positively correlated with laser power and TiC powder ratio, where the TiC powder ratio shows the most significant impact. The wear volume decreased with an increasing TiC powder ratio. The targets for the processing parameter optimization were set to 62 HRC for micro-hardness and a minimal volume wear. The difference between the model prediction value and experimental validation result for micro-hardness and wear volume were 1.87% and 6.33%, respectively. These models provide guidance to optimize the processing parameters to achieve a desired micro-hardness and maximize wear resistance in a composite cladding layer.

Optimization of Process Parameters, Microstructure, and Properties of Laser Cladding Fe-Based Alloy on 42CrMo Steel Roller.

The mould foot roller is a key component of a continuous casting machine. In order to investigate the possibility of using laser cladding to repair mould foot roller, Fe-based powders and 42CrMo steel are used in this work. The laser cladding process parameters were optimized by orthogonal experiments. The chemical compositions, microstructure, properties of the cladding layer under the optimum process parameters, and substrate were systematically investigated by using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), microhardness test, wear test, and salt spray corrosion test. The results indicate that the primary factor affecting the width and depth of the cladding layer is laser power. The scanning speed also has a significant effect on the height of the cladding layer. The optimum process parameters for repairing the mould foot roller are 2 kW laser power, 4 mm/s scanning speed, and 15 g/min feeding rate of powder. Along the depth direction of the cladding layer, the microstructure of the coating gradually transforms from plane crystal, cell grains, or dendrites to equiaxed grains. The matrix is mainly martensite with retained austenite; the eutectic phase is composed of netlike M2B, particulate M23(C,B)6, and M7(C,B)3 phase. The hardness of the cladding layer is significantly improved, about three times that of the substrate. The weight loss of the cladding layer is just half that of the substrate. Its wear resistance and corrosion resistance have been significantly improved. The work period of the laser cladding-repaired foot roller is much longer than for the surfacing welding-repaired one. In summary, laser cladding technology can increase the life of mould foot rollers.

MoFeCrTiWAlNb refractory high-entropy alloy coating fabricated by rectangular-spot laser cladding

In order to improve the wear resistance of M2 tool steel, a MoFeCrTiWAlNb high-entropy alloy (HEA) coating has been successfully fabricated by the rectangular-spot laser-cladding technique. The phase structures, microstructure, hardness, and wear resistance of HEA coatings were carefully investigated. The final laser-cladding process parameters are P = 3.0 kW, v = 4 mm/s, and a rectangular spot of 10 × 2 mm. The phase composition of the coating consists of body-centered-cubic solid solution and (Nb,Ti)C carbides plus small amounts of hexagonal-close-packed Fe2Nb phases. The coating metallurgically bonds to the substrate. Al2O3 formed by oxidization of Al atoms was a heterogenous nuclear center for (Nb,Ti)C. The highest average microhardness value of HEA coatings reached 1050 HV0.2, which is far higher than that of the substrate (approximately 330 HV0.2). Furthermore, compared with the substrate, the HEA coating exhibits prominent wear resistance with lower friction coefficient, fewer wear volumes, and smoother worn surface under the same conditions.

Analysis of laser cladding process parameter influence on the clad bead geometry

In the present study, fiber laser has been used in laser cladding with an off-axis powder injection. The aim of this study is to analyze the effects of the laser cladding process parameters on the clad layer geometry. The parameters studied were laser power, cladding speed, and powder feeding rate. This study was conducted by using single-pass clad layers. The powder material used was stainless steel AISI 316L and the substrate material used was structural steel S355. The relationship between the laser cladding process parameters and the clad layer geometry was established by using statistical analysis. Analysis of the cladding results concluded that the laser power and cladding speed are the main parameters that control the clad layer width. The majority of the variations were in the clad height, but the clad bead side angle was also dependent on the powder feed rate and cladding speed. This study successfully established the relationship between the laser cladding process parameters and the clad geometry.

Multiresponse Optimization of Laser Cladding Steel + VC Using Grey Relational Analysis in the Taguchi Method

Laser cladding of metal matrix composite coatings (MMCs) has become an effective and economic method to improve the wear resistance of mechanical components. The clad quality characteristics such as clad height, carbide fraction, carbide dissolution, and matrix hardness in MMCs determine the wear resistance of the coatings. These clad quality characteristics are influenced greatly by the laser cladding processing parameters. In this study, American Iron and Steel Institute (AISI) 420 + 20% vanadium carbide (VC) was deposited on mild steel with a high powder direct diode laser. The Taguchi-based Grey relational method was used to optimize the laser cladding processing parameters (laser power, scanning speed, and powder feed rate) with the consideration of multiple clad characteristics related to wear resistance (clad height, carbide volume fraction, and Fe-matrix hardness). A Taguchi L9 orthogonal array was designed to study the effects of processing parameters on each response. The contribution and significance of each processing parameter on each clad characteristic were investigated by the analysis of variance (ANOVA). The Grey relational grade acquired from Grey relational analysis was used as the performance characteristic to obtain the optimal combination of processing parameters. Based on the optimal processing parameters, the phases and microstructure of the laser-cladded coating were characterized by using x-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS).

Possibility of Multi-material Laser Cladding Fabrication of Nickel Alloy and Stainless Steel

There are some applications in the industry for multi-material components, including device engineering and multifunctional surface engineering, having to eliminate a brazing or welding technological step. This study investigates the laser cladding process parameters, related single track geometry and quality of multi-material samples. The optimal process parameters for steel were found of 0.21-0.26 J/mm2 and 0.25 10-2 g/mm under the scanning velocity of 1400-1700 mm/min and powder feeding of 4.2-4.5 g/min. The bimetal thin walls, cylinders and cubes were manufactured within the optimal conditions. The requirements of steel and nickel joining were explored. For the examination, the optical microscopy, SEM, EDX microelement analysis and hardness analysis were involved.

Technology of pulsed laser surface coating in pressing tool repair

A pressing tool is a rarther complicated device operated in the conditions of loading of hundreds of tons, periodic temperature gradients of hundreds of degrees, and subject to the influence of corrosives. The paper describes the operation of restoring the geometry of the tool by pulsed laser surface coating with filler metal feed. Laser cladding is carried out on a process installation including a pulse solid-state laser on YAG: Nd with the emission wavelength of 1.06 μm. An algorithm of optimizing the design process is proposed. Using this technique makes it possible to significantly reduce the time of technological preparation of production, as well as the proportion of pilot studies. On the basis of the developed optimization techniques process parameters of laser cladding are selected. Macro- and micro- analysis of the surface under investigation is also carried out. Microhardness of the cross section of the basic material and surface coating is measured for the comparison and evaluation of their properties. The values of hardness (HRC) are chosen according to Rockwell hardness scale taking into account suitable ratios obtained according to Vickers (HV). Measurements of the material hardness are required to identify the ability to resist elastic and plastic deformation or fracture in the case of introducing a harder metal solid that does not take permanent set in the surface layer of the material.

Analysis and optimization of process parameters in Al–SiCp laser cladding

The laser cladding process parameters have great effect on the clad geometry and on dilution in the single and multi-pass aluminum matrix composite reinforced with SiC particles (Al/SiCp) coatings on ZE41 magnesium alloys deposited using a high-power diode laser (HPLD). The influence of the laser power (500–700W), scan speed (3–17mm/s) and laser beam focal position (focus, positive and negative defocus) on the shape factor, cladding-bead geometry, cladding-bead microstructure (including the presence of pores and cracks), and hardness has been evaluated. The correlation of these process parameters and their influence on the properties and ultimately, on the feasibility of the cladding process, is demonstrated. The importance of focal position is demonstrated. The different energy distribution of the laser beam cross section in focus plane or in positive and negative defocus plane affect on the cladding-bead properties.

Effect of process parameters in laser cladding on substrate melted areas and the substrate melted shape

In the present study, the application of fiber laser cladding by off-axis powder injection is studied as a surface treatment or coating process. The aim of this study is to analyze the effect of laser power, powder feeding rate, and cladding speed to melt the pool shape. The effects of change in process parameters on clad bead substrate melted areas are also studied. The influence of the laser beam's energy input into the melt pool is also discussed in this paper. This study is based on single pass clad layers, the additive material used was 316L stainless steel and S355 structural steel worked as the substrate material. By systematic change in the main laser cladding process parameters (cladding speed, laser power, and powder feeding rate), the process parameters' effect on the clad bead shape was studied. The process parameters were studied by using the design of experiment methodology. This multilevel full-factorial method experimentally (by use of preliminary test results) optimized the test matrix. Through statistical analysis of the results, it was observed that the laser power and powder feed rate were the main factors controlling the substrate melted area. This study successfully established the relationship between the main laser cladding process variables and the substrate melting area and substrate melted shape. The analysis concluded that low powder feeding rates and cladding speeds melt the substrate material thus increasing the dilution. However, it was also observed that in some cases there was less penetration in the side of the clad bead than in the middle. In addition, the asymmetrical substrate melted shape was observed when the powder feed rate was increased.

Technology of pulsed laser surface coating in pressing tool repair

A pressing tool is a rarther complicated device operated in the conditions of loading of hundreds of tons, periodic temperature gradients of hundreds of degrees, and subject to the influence of corrosives. The paper describes the operation of restoring the geometry of the tool by pulsed laser surface coating with filler metal feed. Laser cladding is carried out on a process installation including a pulse solid-state laser on YAG: Nd with the emission wavelength of 1.06 μm. An algorithm of optimizing the design process is proposed. Using this technique makes it possible to significantly reduce the time of technological preparation of production, as well as the proportion of pilot studies. On the basis of the developed optimization techniques process parameters of laser cladding are selected. Macro- and micro- analysis of the surface under investigation is also carried out. Microhardness of the cross section of the basic material and surface coating is measured for the comparison and evaluation of their properties. The values of hardness (HRC) are chosen according to Rockwell hardness scale taking into account suitable ratios obtained according to Vickers (HV). Measurements of the material hardness are required to identify the ability to resist elastic and plastic deformation or fracture in the case of introducing a harder metal solid that does not take permanent set in the surface layer of the material.

Dry metal forming of high alloy steel using laser generated aluminum bronze tools

Regarding the optimization of forming technology in economic and environmental aspects, avoiding lubricants is an approach to realize the vision of a new green technology. The resulting direct contact between the tool and the sheet in non-lubricated deep drawing causes higher stress and depends mainly on the material combination. The tribological system in dry sliding has to be assessed by means on the one hand of the resulting friction coefficient and on the other hand of the wear of the tool and sheet material. The potential to generate tailored tribological systems for dry metal forming could be shown within the investigations by using different material combinations and by applying different laser cladding process parameters. Furthermore, the feasibility of additive manufacturing of a deep drawing tool was demonstrated. The tool was successfully applied to form circular cups in a dry metal forming process.

Effects of Laser Cladding Process on Cladding Layer Qualities of Nickel-Base Alloy

Nickel-base alloy powder is widely applied to strengthen the surface of products through laser processing. This paper presents the experiments on laser cladding of Ni45 alloy powder on substrates of 45 steel. The experimental results show that the laser cladding processing parameters such as laser power, scanning speed, powder feed rate and overlap ratio have great effects on the qualities of the cladding layer. Optimizing the processing parameters is an effective way to improve the layer qualities and obtain desired cladding layers.

Microstructure and Wear Resistance of Laser Clad Cobalt-based Composite Coating on TA15 Surface

Abstract The cobalt-based composite coating reinforced with in-situ synthesized multiple particles was fabricated on TA15 titanium alloy surface by transverse flow CO2 laser adopting the optimizing laser cladding process parameters to improve wear resistance and hardness in surface. X-ray diffraction (XRD), metallurgical microscope, scanning electron microscope (SEM), hardness tester and wear testing machine were used to analyze the coating. The results show that the microstructures of the coating are mainly composed of γ-Co, α-Ti solid solution and in-situ synthesized TiB2, Cr5Si3, TiC, WB, SiC, Co3Ti and NiC particles. And these multiple granular reinforced phases are dispersively distributed among the fine dendritic structures in the cladding layer. The microhardness of the cladding layer compared with that of the substrate, has been improved a lot, HV reaching about 10000 MPa which is around three times higher than that of the substrate. Compared to titanium alloy, the wear resistance of the cladding layer has been distinctly improved, and the wear rate of the cladding layer is about 1/12 of the titanium alloy. The wear mechanism of the cladding layer is a mixed type of adhesion and abrasion.

Study on Laser Transmittance in Coaxial Laser Cladding

The research of mechanism of laser passing through powder stream in coaxial laser cladding is of great significance for optimization of laser cladding process parameters and detective controls in the manufacturing process. The paper is focused in theoretical model of concentration field for powder stream from coaxial nozzle. Based on the model, the distributions of concentration of powder stream along central axis are simulated, geometric parameters of the nozzle are optimized. Theoretical model of laser passing through powder stream in coaxial laser cladding has been presented from Beer-Lambert law. The influence of powder flow rate on the laser transmittance has been discussed in view of the model. The system used for testing the power of the laser that has passed through powder stream in coaxial laser cladding is developed. It is shown that the geometric shape is fine while the width of the powder outlet is 0.4 mm and the angle of the outer powder cavity is 18°. It can be found that laser powder attenuation by powder stream tends to increase with increasing powder flow rate when the structure parameters of the nozzle are fixed. The results of the experiment shows that the deviation between theoretical values is consistent with experimental values while the laser power is 200 W, 300 W, 400 W and powder flow is choose in the range of from 0 to 50 mg/s.

The Prediction of Coating Geometry from Main Processing Parameters in Laser Cladding

Based on a recently published recursive model describing the geometry of laser clad coatings and on experimental track characteristics we propose specific functions to describe the geometry of laser clad coatings formed by overlap of individual tracks depending on the processing parameters. The recursive model provides a very good description ofthe whole geometry of the coating from the Height H and width w of a single laser track for any overlap ratio OR. We have shown in the past that the height and width of a single track are well correlated with the main laser cladding processing parameters for both coaxial and side cladding set-ups. Combining these two approaches leads to prediction of the complete geometry of laser clad coatings from basic processing parameters. These parameters are: Feeding rate F, Laser beam scanning speed S and overlap ratio OR. The character of the functions that describe the height and waviness of the final coating is the same for both coaxial and side cladding set-ups.