The effect of process parameters on keyhole welding with a 400 W Nd : YAG pulsed laser

Torkamany, M.J.; Hamedi, M.; Malek, F.; Sabbaghzadeh, J.

doi:10.1088/0022-3727/39/21/009

Cited by 77 publications

(50 citation statements)

References 11 publications

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“…Then, decreasing the contribution of single pulses by increasing the pulse repetition rate is expected and in accordance with the pervious experimental reports [13]. An important parameter that has considerable effects on the target surface condition and the resultant amount of ablation rate [13,14], as shown in Figure 4, is the overlapping factor (O f ) that is calculated as [15] …”

Section: Production Ratesupporting

confidence: 86%

Optimisation of GaAs nanocrystals synthesis by laser ablation in water

Sharifi

Dorranian

Torkamany

2013

Journal of Experimental Nanoscience

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Laser ablation of a gallium arsenide (GaAs) wafer immersed in distilled water was carried out using the fundamental wavelength of a high frequency Nd:YAG laser with 240 ns pulse duration. Rate of nanoparticles generation through laser ablation for various amounts of laser pulse energies (0.4-0.94 mJ) and repetition rates (400-2000 Hz) were studied and a maximum ablation rate of 19.6 mgr/s was obtained. Formation of the pure GaAs nanocrystals (NCs) is confirmed using TEM micrograph and X-ray diffraction analysis. Band-gap energy of generated GaAs NCs is calculated by Tauc method to be between 2.48 and 2.60 eV which is larger than the band-gap energy of bulk GaAs. The band-gap energy of NCs is increased by increasing the energy of laser pulses and is decreased by increasing the pulse repetition rate.

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Section: Production Ratesupporting

confidence: 86%

Optimisation of GaAs nanocrystals synthesis by laser ablation in water

Sharifi

Dorranian

Torkamany

2013

Journal of Experimental Nanoscience

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“…This is due to the deep penetration induced by the keyhole phenomenon, in which a hole is opened up, so that the laser energy can be penetrated and absorbed deeply into the specimen. In other words, the change in welding mode from conduction to keyhole provides 4-5 times increase in laser power coupling efficiency (Torkamany et al, 2006).…”

Section: Resultsmentioning

confidence: 99%

Experimental Investigation on Micro-Welding of Thin Stainless Steel Sheet by Fiber Laser

Ismail¹,

Okamoto²,

Okada³

et al. 2011

American Journal of Engineering and Applied Sciences

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Problem statement:The miniaturization of components plays an important role for manufacturing in electrical and electronic industries. The joining technology of thin metal sheets has been strongly required. Laser welding with micro-beam and high-speed scanning is a promising solution in micro-welding, because it has high-potential advantages in welding heat sensitive components with precise control of heat input and minimal thermal distortion. Approach: In this study, the characteristics of laser micro-welding of thin stainless steel sheets by using a single-mode CW fiber laser with high-speed scanning system were experimentally investigated. Results: It was clarified that the welding bead width and depth increased with increasing the scanning velocity under a constant energy density condition and high efficient welding was expected by using high-speed laser scanning with Galvano scanner. The utilization of shielding gas was very effective to obtain smooth fusion bead and the combination of micro beam spot and high-speed laser scanning made it possible to obtain good overlap welding of ultra-thin stainless steel sheets. Conclusion: A faster and high quality welding could be achieved by using a single-mode fiber laser with micro-beam and high-speed scanning.

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“…Although these models are valid for conduction mode welding but, when the laser power density is increased to a level sufficient to evaporate a thin layer of material and the second kind of laser welding mode known as keyhole welding occurs they are not able to evaluate the composition change. By keyhole formation, a deep hole is created inside the weld pool, which is an effective trap for the laser beam [6]. Therefore, creation of keyhole will increase the laser energy coupling to the material.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Composition Change in Pulsed Nd:YAG Laser Welding

Torkamany¹,

Parvin²,

Jandaghi³

et al. 2010

Laser Welding

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Abstract:A numerical model based on the kinetic theory of gases and the thermodynamic laws is developed for keyhole formation in pulsed laser welding. For a single incoming pulse the spatial profile of the created keyhole was simulated as a function of time using this model. Since undesirable loss of the volatile elements affects on the weld metal composition and properties we have focused in our model to find the process conditions that minimum of these losses take place during pulsed laser welding. The major laser welding process parameters including pulse properties have been examined formerly in this model. The power density and pulse duration were the main investigated variables. The model predicts that loss of alloying elements increase at higher peak powers and longer pulse durations. The model was used for two different kinds of metals, one from the ferrous compoundsStainless Steel 316-and the other an aluminum alloy-5754 Aluminum alloy-. By running the model for SS316 it was found that concentrations of the Fe base and Nickel were increased in the weld metal region while concentrations of the chromium and manganese were decreased. Pulsed laser welding of stainless steel 316 in keyhole mode was experimentally studied too. The welding work piece was 2 mm thick SS316 sheet metal. After welding experiments, samples were cut and weld cross sections were analyzed. The concentrations of iron, chromium, nickel and manganese were determined in the weld pool by means of the Proton-Induced X-ray Emission (PIXE) and Energy Dispersive X-ray/Wavelength Dispersive X-ray (EDX/WDX) analysis. It was shown that the composition alteration, predicted by the model due to varying of the laser parameters is in well accordance to the corresponding experimental data. Al5754 was the second material used for laser welding experiments. Weld metal composition change of this alloy in keyhole mode welding, using a long pulsed Nd:YAG laser was investigated by use of the developed numerical model and supported with experimental measurements. During laser welding process, the significant variables were laser pulse duration and power density. It was predicted in the model and concurred experimentally that, the concentration of magnesium in the weld metal decreases by increasing the laser pulse duration, while the aluminum concentration increases. Moreover, the concentrations of aluminum and magnesium elements, in the weld metal were 9 www.intechopen.com Laser Welding 194determined by laser induced breakdown spectroscopy (LIBS) for different welding conditions.

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The effect of process parameters on keyhole welding with a 400 W Nd : YAG pulsed laser

Cited by 77 publications

References 11 publications

Optimisation of GaAs nanocrystals synthesis by laser ablation in water

Optimisation of GaAs nanocrystals synthesis by laser ablation in water

Experimental Investigation on Micro-Welding of Thin Stainless Steel Sheet by Fiber Laser

Estimation of Composition Change in Pulsed Nd:YAG Laser Welding

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