Online monitoring of thermo-cycles and its correlation with microstructure in laser cladding of nickel based super alloy

Muvvala, Gopinath; Karmakar, Debapriya Patra; Nath, Ashish Kumar

doi:10.1016/j.optlaseng.2016.08.005

Cited by 124 publications

(29 citation statements)

References 35 publications

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“…Simulation tools are crucial in a competitive environment to prevent a trial-and-error approach to set the optimum processing conditions at a pre-design stage [ 1 ]. Moreover, proper modeling of an industrial process is the key to introduce closed-loop real-time monitoring where signals are managed for the purpose of control [ 2 ], to correct possible deviations of the main factors with respect to the intended, simulated response. Therefore, two issues must be addressed: the building of a reliable model structure and the arranging of effective equipment for real-time monitoring.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Laser Heating of Aluminum and Model Validation via Two-Color Pyrometer and Shape Assessment

Alfieri

2018

Materials

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The modeling of laser-based processes is increasingly addressed in a competitive environment for two main reasons: Preventing a trial-and-error approach to set the optimum processing conditions and non-destructive real-time control. In this frame, a thermal model for laser heating in the form of non-penetrative bead-on-plate welds of aluminum alloy 2024 is proposed in this paper. A super-Gaussian profile is considered for the transverse optical intensity and a number of laws for temperature-dependent material properties have been included aiming to improve the reliability of the model. The output of the simulation in terms of both thermal evolution of the parent metal and geometry of the fusion zone is validated in comparison with the actual response: namely, a two-color pyrometer is used to infer the thermal history on the exposed surface around the scanning path, whereas the shape and size of the fusion zone are assessed in the transverse cross-section. With an average error of 3% and 4%, the model is capable of predicting the peak temperature and the depth of the fusion zone upon laser heating, respectively. The model is intended to offer a comprehensive description of phenomena in laser heating in preparation for a further model for repairing via additive manufacturing.

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Section: Introductionmentioning

confidence: 99%

Simulation of Laser Heating of Aluminum and Model Validation via Two-Color Pyrometer and Shape Assessment

Alfieri

2018

Materials

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“…The mechanical properties of laser cladding coatings are largely determined by the possible development of secondary phase transformations in the solid state [14,15]. A new effect of an increase in the strength and tribological properties of NiCrBSi laser coatings during additional annealing at temperatures of 1000 -1075°C was found in studies [13,16].…”

Section: Fabrication Of Heat-resistant Nicrbsi Coatings By Combined Lmentioning

confidence: 99%

Wear-resistant nickel-based laser clad coatings for high-temperature applications

et al. 2019

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The effect of high-temperature processing on laser clad Ni-based coatings is studied. Annealing at 1025°C forms thermally stable framework structures with large chromium carbides and borides. As a result, improved hardness and wear resistance of the coating are maintained when heated to 1000°C. Stabilizing annealing also increases the frictional thermal resistance of the NiCrBSi coating. Under high-speed (3.1-9.3 m / s) sliding friction, when the surface layer temperature reaches about 500 -1000°С and higher, the wear resistance of the coating increases by 1.7 -3.0 times. The proposed approach to the formation of heat-resistant coatings is promising, in particular, for a hot deformation tool and other components of metallurgical equipment operating under high thermal and mechanical loads. Such products include crystallizer walls of continuous casting machines. For the walls, the development of laser cladding technology for wear-resistant composite coatings on copper alloys is relevant as an alternative to thermal spraying. The cladding of composite NiBSi-WC coatings of 0.6 and 1.6 mm thickness on a Cu-Cr-Zr bronze substrate heated to 200 -250°C with a diode laser is considered. The presence of boron causes the formation of the W(C, B) carboboride phase, whose hardness is higher than that of WC in the initial powder. Depending on the thickness of coatings and, accordingly, on the duration of heating and the subsequent cooling, the process of secondary carboborides precipitation from the solid solution can be suppressed (in the "thin" coating) or activated (in the "thick" coating). This leads to a higher wear resistance under friction sliding 1.6 mm thickness coating.

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“…These are related to laser source, motion of workpiece, powder-substrate material combinations, clad geometry, powder flow dynamics, shrouding gas flow and so on. Significant research efforts are being invested for analytical [4][5][6][7], numerical [2, 9-11] and empirical modelling [12], and in-process monitoring and control [13][14][15][16][17][18][19][20] of laser cladding process. The numerical models are both two dimensional (2D) [2, 11] and three dimensional (3D) [9,10].…”

Section: Introductionmentioning

confidence: 99%

“…Multiple responses such as clad track width, clad height, cladding zone temperature, cooling rate, etc. have been successfully monitored in real time [9,[13][14][15][16][17][18][19][20]. However, practical implementation of real time control have been so far reported for either laser power or scan speed or powder flow rate.…”

Section: Introductionmentioning

confidence: 99%

Estimation of dilution in laser cladding based on energy balance approach using regression analysis

Chakraborty

Dutta

2019

Sādhanā

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Laser cladding is a complex manufacturing process involving more than 19 variables related to laser source, workpiece movement, powder-substrate material combinations, clad geometry, powder flow dynamics, shrouding gas flow and so on. Significant research efforts have been directed to analytical-numericalempirical modelling of laser cladding and also in-process monitoring and control of the process. Still, due to complicated physics there is a dearth of simple analytical model for estimation of dilution in laser cladding. Its experimental measurement requires suitable micrographs of the clad cross section perpendicular to the clad path. This is a time-consuming and destructive way of measurement. Numerical models are time consuming to evaluate and hence not suitable for fast decision making or real-time control implementation. The analytical models available, despite having many approximations, are a little complicated, require fair amount computer programming and often need suitable prior guessing of range of output parameters for adjustment of constant values in the models. This poses some challenges for use and having an intuitive guidance, for a beginner/ unskilled operator. Besides, their complexity may erect barrier in the way of their implementation for real time monitoring and control. This work proposes a simple linear regression model, formed based on energy balance approach, to estimate dilution in laser cladding. After fitting to a set of data, within a suitable process parameterwindow, for a particular clad-substrate material combination, this model can estimate dilution as a function of input/easily measureable parameters, viz. laser power, scan speed, clad width and clad height. The model fitted well to the experimental data taken from literature.

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Online monitoring of thermo-cycles and its correlation with microstructure in laser cladding of nickel based super alloy

Cited by 124 publications

References 35 publications

Simulation of Laser Heating of Aluminum and Model Validation via Two-Color Pyrometer and Shape Assessment

Simulation of Laser Heating of Aluminum and Model Validation via Two-Color Pyrometer and Shape Assessment

Wear-resistant nickel-based laser clad coatings for high-temperature applications

Estimation of dilution in laser cladding based on energy balance approach using regression analysis

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