Fundamental understanding of the interaction of continuous wave laser with aluminium

Coroado, Júlio; Meco, Sónia; Williams, Stewart; Ganguly, Saibal; Suder, Wojciech; Quintino, L.; Assunção, Eurico

doi:10.1007/s00170-017-0702-6

Cited by 16 publications

(11 citation statements)

References 23 publications

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“…High power density and high applied energy guarantee high vaporisation rate, and consequently, high aspect-ratio welds, whereas long laser-material interaction time creates large weld pools [27]. A specific penetration depth can be achieved through a trade-off between both parameters, which is the working base of the power factor model in CW mode [26].…”

Section: Experimental Study Rationalementioning

confidence: 99%

“…The q p, peak needed to achieve a particular penetration decreases quadratically with E SP, pulse . This means that similarly to CW welding [26], there is also a trade-off between both parameters through a constant rate of material vaporisation [33] in PW micro-seam welding. Since both t i and q p have a direct influence on the maximum temperature of the thermal cycle [34], when E SP, pulse increases through an increase in t i for a constant q p, peak (Eq.…”

Section: Effect Of Beam Diametermentioning

confidence: 99%

“…The laser user typically wants to control the depth of penetration, weld width and distortion, and avoid defect formation. The power factor model, previously developed for low carbon steel [25] and then extended for aluminium [26], can select the optimum laser parameter settings for laser power and welding speed for a given beam diameter, to obtain a specific weld profile in CW macro laser welding. This study focuses on redefining the original formula to fit the characteristics of PW lasers.…”

Section: Introductionmentioning

confidence: 99%

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Selection of parameters in nanosecond pulsed wave laser micro-welding

Coroado

Ganguly

Suder

et al. 2021

Int J Adv Manuf Technol

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The digital control of the latest nanosecond pulsed wave (PW) fibre lasers allows very high flexibility in controlling the application of the total energy to a workpiece, which brings several advantages to the joining process. By choosing different pulse shapes in different spatial profiles, it is possible to apply low energy per pulse with high precision and accuracy resulting in lower heat input. Since the energy of each pulse is insufficient to generate melting, these lasers operate at very high pulse repetition frequencies near continuous wave (CW) regime. Nevertheless, the peak powers of PW lasers are much higher than CW. In this research, the effect of peak power, pulse energy, pulse width, pulse repetition frequency and duty cycle has been studied. The experimental work was conducted in bead on plate of austenitic stainless steel to investigate the effect of laser on the weld geometry, i.e. depth of penetration and width. An empirical model, previously established for CW mode, which enables the achievement of a particular penetration depth independent of the beam diameter, was redesigned and tested for PW mode. The “pulse power factor model” allows the laser user to select a weld profile that meets certain quality and productivity requirements independent of the laser system. It was shown that identical depth of penetration but different weld metal profile can be obtained for a specific beam diameter for a range of different system parameters by keeping a constant trade-off between pulse power factor and interaction time.

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Section: Experimental Study Rationalementioning

confidence: 99%

Section: Effect Of Beam Diametermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Selection of parameters in nanosecond pulsed wave laser micro-welding

Coroado

Ganguly

Suder

et al. 2021

Int J Adv Manuf Technol

Self Cite

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“…Concerning the assembly of aluminum alloy components, laser beam welding has become an established solution in the industry. Indeed, the high energy intensity of the laser beam allows to deliver a low overall heat input fulfilling the welding operation with reduced thermal damage to the surrounding material [6]. This allows the achievement of a fine weld seam with narrow heat affected zone and limited thermal distortion with respect to alternative processes like tungsten inert gas (TIG) or metal inert gas (MIG) welding.…”

Section: Introductionmentioning

confidence: 99%

Fiber laser welding of AA 5754 in the double lap-joint configuration: process development, mechanical characterization, and monitoring

Garavaglia

Demir

Zarini³

et al. 2020

Int J Adv Manuf Technol

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Aluminum alloys are widely spread in many industrial sectors due to their desirable characteristics as low density, good formability, high specific strength, and good resistance to corrosion. Autogenous laser welding is a technology that enables the use of these materials in the industrial process due to its high repeatability, reliability, and ease of automatization. In particular, in automotive applications, Al-alloys are welded in lap-joint configurations with more than 2 layers of material. The welding condition should be monitored in order to detect the complete penetration, hence guaranteeing the appropriate weld resistance. The use of non-invasive and coaxial monitoring solutions is highly desirable for the identification of weld defects during the process. This study investigates an autogenous laser welding process and monitoring in the double lap-joint configuration of sheets of AA 5754. First, the process parameters are investigated to identify the geometrical and mechanical characteristics of the resultant welding seams at different process conditions. The employed high-brilliance 3 kW fiber laser provided the possibility of reading the back-reflected light signal from an internal photodiode. The capability of this signal to be used as a non-invasive, coaxial, and remote monitoring system in order to predict the process outcome was tested. In the experiments the back-reflected light intensity could be correlated to the weld seam width at the second interface, as well as the strength of the joint to shear. Finally, the monitoring signal behavior was demonstrated under simulated weld defect conditions. The results show that weld anomalies such as lack of penetration, misalignment, and gap formation can be sensed through the monitoring approach.

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“…Nowadays, high-brilliance fiber lasers represent a key tool for industrial manufacturing in terms of wavelength and available power in continuous wave. 7,8 Welding in the keyhole regime 9 can be easily achieved, and it has the advantage to create a weld seam with high aspect ratio (depth over width), limited heat affected zone, higher penetration, and good mechanical properties. On the other hand, the generated keyhole cavity is affected by instability which can lead to various defects like spatter 10,11 and pore formation.…”

Section: Introductionmentioning

confidence: 99%

Process development and coaxial sensing in fiber laser welding of 5754 Al-alloy

Garavaglia

Demir

Zarini³

et al. 2019

Journal of Laser Applications

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The use of Al-alloys is increasing in the automotive industry due to the pressing necessity to reduce weight and fuel consumption. Several parts concerning the car body are assembled through welding, where a high-quality seam is a key requirement. For this purpose, laser welding stands as an appealing option. On the other hand, laser welding of Al-alloys is a complex process due to the high reflectivity, reactivity, and crack susceptibility of these materials. In many cases, such issues limit the applicability of the autogeneous welding, which is an advantageous feature of laser welding. High-brilliance fiber lasers have been an enabling technology for improving the weldability of Al-alloys. However, laser welding of Al-alloys, especially in a lap-joint configuration, requires robust processing conditions able to maintain seam quality for each weld in high volumes even with part tolerances and tooling variability. Accordingly, this work discusses the process development and monitoring in laser welding of 5754 Al-alloy. In particular, the process was carried out in a double lap-joint configuration with 1 mm sheets, commonly used in automotive applications. A 3 kW fiber laser with in-source integrated monitoring capability was employed as the light source. The process feasibility zone was investigated as a function of laser power and welding speed, while the effect of focal position was investigated for the weld robustness. Weld seam types and defects were identified, as well as the monitoring signals associated light back-reflected from the process.

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Fundamental understanding of the interaction of continuous wave laser with aluminium

Cited by 16 publications

References 23 publications

Selection of parameters in nanosecond pulsed wave laser micro-welding

Selection of parameters in nanosecond pulsed wave laser micro-welding

Fiber laser welding of AA 5754 in the double lap-joint configuration: process development, mechanical characterization, and monitoring

Process development and coaxial sensing in fiber laser welding of 5754 Al-alloy

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