Heat affected zone in the laser-assisted milling of Inconel 718

Pan, Zhipeng; Feng, Yixuan; Hung, Tsung-Pin; Jiang, Yun-Chen; Hsu, Fu-Chuan; Wu, Lung-Tien; Lin, Chiu-Feng; Lu, Yingcheng; Liang, Steven Y.

doi:10.1016/j.jmapro.2017.09.021

Cited by 56 publications

(21 citation statements)

References 25 publications

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“…Firstly, it is usually difficult to heat up the cutting volume in a homogeneous manner. Secondly, the maximum cutting width or depth in LAMill are constrained by the laser spot diameter, which becomes a very significant impediment when the width of cut is bigger than the laser spot size; hence, not surprisingly, LAMill has usually been demonstrated only for small cutting widths [29][30][31][32] comparable with the spot size of the laser. In addition, the optics system has to be changed to adapt to different cutting widths or depths, which is always time consuming.…”

Section: Introductionmentioning

confidence: 99%

On modelling of laser assisted machining: Forward and inverse problems for heat placement control

Shang

Liao

Sarasua

et al. 2019

International Journal of Machine Tools and Manufacture

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Laser assisted machining (LAM) is one of the most efficient ways to improve the machinability of difficultto-cut materials (e.g. Nickel-based superalloys). In the conventional LAM process, the laser beam is focused ahead of the cutting area at a fixed location, which leads to a series of restrictions, e.g. small heating area and non-uniform heat distribution due to the limitation of beam size and energy distribution. In this paper, a novel spatially and temporally (S&T) controlled laser heating method was proposed, in which a large area can be heated up with a small laser spot by controlling the beam scanning, i.e., laser power, path and speed of scanning. The laser configuration for the prescribed HAZ (heat affected zone) was achieved by solving the inverse problem where the laser power together with either laser path or laser speed were optimised to achieve a particular temperature distribution in the chip to be removed by the following milling cutter. The proposed S&T laser heating method was thoroughly validated both for the forward and, the more important, inverse heating models by performing extensive temperature experiments by both infrared thermal camera and thermocouple array and further verified by laser assisted milling (LAMill) tests of Inconel 718 for large widths of cuts. The results showed that by applying path-optimised LAMill based on the inverse solution of the thermal problem, the peak and mean principal cutting forces were reduced by 55% and 47.8% respectively compared with the conventional dry milling process while the surface roughness improved by at least 14%. Moreover, after controlling the HAZ using the inverse thermal problem, a microstructure analysis of the machined surface showed that the proposed laser heating method avoids overheating of the workpiece below the planned depth of cut for the milling operation.

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Section: Introductionmentioning

confidence: 99%

On modelling of laser assisted machining: Forward and inverse problems for heat placement control

Shang

Liao

Sarasua

et al. 2019

International Journal of Machine Tools and Manufacture

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“…Apart from the experimental studies, during the last decades, studies including the finite element (FE) modeling of LAM processes were presented, focusing mainly on laser-assisted milling and laser-assisted turning with a view to act complementary to the experimental studies towards the study of fundamental thermo-mechanical phenomena and the optimization of LAM process. The majority of the presented models are related to laser-assisted milling and especially the effect of laser heating on the substrate, e.g., [26,49], whereas fewer works deal with the coupled thermo-mechanical problem, e.g., [21,50].…”

Section: Introductionmentioning

confidence: 99%

“…In their model they calculated emissivity and absorptivity based on experimental data and managed to predict HAZ under various process conditions. Although laser scanning is usually performed in a linear path in laser-assisted milling simulations, Pan et al [26] simulated a rotating laser scanning path for the laser scanning and absorption ratio was approximated based on the melting area prediction. In the work of Liu and Shi [21] the effect of laser beam preheating was calculated analytically and then considered as an initial temperature boundary condition for the machining process which was solved sequentially with the temperature field inserted in the cutting model after some time intervals.…”

Section: Introductionmentioning

confidence: 99%

Thermo-mechanical aspects of cutting forces and tool wear in the laser-assisted turning of Ti-6Al-4V titanium alloy using AlTiN coated cutting tools

Habrat

Krupa

Markopoulos

et al. 2020

Int J Adv Manuf Technol

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Machining of hard-to-cut materials with conventional processes is still considered as a challenge, as the special properties of these materials often lead to rapid tool wear and reduced surface integrity. For that reason, it is preferable to combine conventional machining processes with other technologies in order to overcome the problems of machining these materials. In the present work, laser-assisted turning experiments on a Ti-6Al-4V workpiece were conducted using AlTiN coated cutting tools in order to investigate the effect of laser heating on cutting forces, cutting temperature, tool wear and microstructure alterations. Two series of experiments were performed under varying cutting speed, laser spot diameter and workpiece diameter values; the first series involved only laser heating of the workpiece and the second both laser heating and cutting. The findings revealed the effect of process parameters on cutting forces and temperature determining the importance of workpiece diameter size, indicated the formation of martensite phase at the top of the heat-affected zone of the workpiece and also showed that high temperatures can lead to intensive tool wear, instead of having a beneficial effect for the cutting tool. Finally, finite element (FE) simulations were carried out in order to study the time evolution of the temperature field and calculate the heating and cooling rates during the process. From the FE results, relatively high heating and cooling rates were observed for smaller workpiece diameters and lower cutting speed, whereas the high magnitude of these rates justified the creation of the martensite phase through a diffusionless transformation.

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“…The overall forward problem methodology of the residual stress prediction considering laser effect is summarized in Fig.1. The heat source is calculated according to the size of laser spot and the laser power, and temperature field after laser preheating is calculated based on the conduction within workpiece [13,14]. The geometry of milling tool is simplified as in orthogonal cutting at each instance, in order to predict the flow stress dependent on micro-structure evolution [15,16], followed by cutting forces [17] and machining temperature [18] predictions.…”

Section: Introductionmentioning

confidence: 99%

Inverse Analysis of the Residual Stress in Laser–Assisted Milling

Feng¹,

Hung²,

Lu³

et al. 2019

Preprint

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In laser-assisted milling, higher temperature in shear zone softens the material potentially resulting in a shift of mean residual stress, which significantly affects the damage tolerance and fatigue performance of product. In order to guide the selection of laser and cutting parameters based on the preferred mean residual stress, inverse analysis is conducted by predicting residual stress based on guessed process parameters, which is defined as the forward problem, and applying iterative gradient search to find process parameters for next iteration, which is defined as the inverse problem. An analytical inverse analysis is therefore proposed for the mean residual stress in laser-assisted milling. The forward problem is solved by analytical prediction of mean residual stress after laser-assisted milling. The residual stress profile is predicted through the calculation of thermal stress, by treating laser beam as heat source, and plastic stress by first assuming pure elastic stress in loading process, then obtaining true stress with kinematic hardening followed by the stress relaxation. The variance-based recursive method is applied to solve inverse problem by updating process parameters to match the measured mean residual stress. Three cutting parameters including depth of cut, feed per tooth, and cutting speed, and two laser parameters including laser-tool distance and laser power, are updated with respected to the minimization of resulting residual stress and measurement in each iteration. Experimental measurements are referred on the laser-assisted milling of Ti-6Al-4V grade 5 and ELI. The percentage difference between experiments and predictions is less than 5% for both materials, and the selection is completed within 50 loops.

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Heat affected zone in the laser-assisted milling of Inconel 718

Cited by 56 publications

References 25 publications

On modelling of laser assisted machining: Forward and inverse problems for heat placement control

On modelling of laser assisted machining: Forward and inverse problems for heat placement control

Thermo-mechanical aspects of cutting forces and tool wear in the laser-assisted turning of Ti-6Al-4V titanium alloy using AlTiN coated cutting tools

Inverse Analysis of the Residual Stress in Laser–Assisted Milling

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Heat affected zone in the laser-assisted milling of Inconel 718

Cited by 56 publications

References 25 publications

On modelling of laser assisted machining: Forward and inverse problems for heat placement control

On modelling of laser assisted machining: Forward and inverse problems for heat placement control

Thermo-mechanical aspects of cutting forces and tool wear in the laser-assisted turning of Ti-6Al-4V titanium alloy using AlTiN coated cutting tools

Inverse Analysis of the Residual Stress in Laser&ndash;Assisted Milling

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Inverse Analysis of the Residual Stress in Laser–Assisted Milling