Special Issue "Modelling of Laser Welding"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Optics and Lasers".

Deadline for manuscript submissions: closed (15 April 2021) | Viewed by 3489

Special Issue Editor

Prof. Dr. Jean-Pierre Bergmann
E-Mail Website
Guest Editor
Department of Production Technology, Technische Universitaet Ilmenau, 98693 Ilmenau, Germany
Interests: laser welding; joining; US-welding; friction-stir welding; digitalization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The development of new high-intensity laser sources with lower wavelengths presents new challenges and phenomena for the welding pool and key hole, especially for steel and aluminum. High-intensity IR lasers produce a large amount of spatter at high speed before the pre-humping regime, while green lasers exhibit different behaviors during the transition from heat conduction to key-hole welding. This Special Issue will focus on models resulting from experimental investigation as well as modeling and simulation approaches that can help us to understand the melt flow conditions around the key hole and can be used to evaluate key hole dynamics. In addition, papers correlating spatter formation with the manipulation of the melt pool and key hole dynamics are welcome.

Prof. Dr. Jean-Pierre Bergmann
Guest Editor

Manuscript Submission Information

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Keywords

  • key hole dynamics
  • spatter formation
  • green laser
  • humping
  • pressure in the key hole
  • melt pool dynamics

Published Papers (4 papers)

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Research

Article
Effect of Micro Solidification Crack on Mechanical Performance of Remote Laser Welded AA6063-T6 Fillet Lap Joint in Automotive Battery Tray Construction
Appl. Sci. 2021, 11(10), 4522; https://doi.org/10.3390/app11104522 - 15 May 2021
Cited by 2 | Viewed by 849
Abstract
Remote laser welding (RLW) has shown a number of benefits of joining 6xxx aluminium alloys such as high processing speed and process flexibility. However, the crack susceptibility of 6xxx aluminium alloys during RLW process is still an open problem. This paper experimentally assesses [...] Read more.
Remote laser welding (RLW) has shown a number of benefits of joining 6xxx aluminium alloys such as high processing speed and process flexibility. However, the crack susceptibility of 6xxx aluminium alloys during RLW process is still an open problem. This paper experimentally assesses the impact of transverse micro cracks on joint strength and fatigue durability in remote laser welding of extruded AA6063-T6 fillet lap joints. Distribution and morphology of transverse micro cracks were acquired by scanning electron microscope (SEM) on cross-sections. Grain morphology in the weld zone was determined by electron backscatter diffraction (EBSD) while static tensile and dynamic fatigue tests were carried out to evaluate weld mechanical performance. Results revealed that increasing welding speed from 2 m/min to 6 m/min did not introduce additional transverse micro cracks. Additionally, welding at 2 m/min resulted in tensile strength improvement by 30% compared to 6 m/min due to the expansion of fusion zone, measured by the throat thickness, and refinement of columnar grains near fusion lines. Furthermore, the weld fatigue durability is significantly higher when fracture occurs in weld root instead of fusion zone. This can be achieved by increasing weld root angle with optimum weld fatigue durability at around 55°. Full article
(This article belongs to the Special Issue Modelling of Laser Welding)
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Article
Investigations of the Absorption Front in High-Speed Laser Processing Up to 600 m/min
Appl. Sci. 2021, 11(9), 4015; https://doi.org/10.3390/app11094015 - 28 Apr 2021
Viewed by 504
Abstract
High processing speeds enormously enlarge the number of possible fields of application for laser processes. For example, material removal for sheet cutting using multiple passes or precise mass corrections can be achieved by means of spatter formation. For a better understanding of spatter [...] Read more.
High processing speeds enormously enlarge the number of possible fields of application for laser processes. For example, material removal for sheet cutting using multiple passes or precise mass corrections can be achieved by means of spatter formation. For a better understanding of spatter formation at processing speeds of several hundred meters per minute, characterizations of the processing zone are required. For this purpose, a 400 W single-mode fiber laser was used in this study to process stainless steel AISI 304 (1.4301/X5CrNi18-10) with speeds of up to 600 m/min. A setup was developed that enabled a lateral high-speed observation of the processing zone by means of a glass plate flanking. This approach allowed for the measurement of several dimensions, such as the penetration depth, spatter formation, and especially, the inclination angle of the absorption front. It was shown that the loss of mass started to significantly increase when the absorption front was inclined at about 60°. In combination with precise weighings, metallographic examinations, and further external process observations, these findings provided an illustration of four empirical process models for different processing speeds. Full article
(This article belongs to the Special Issue Modelling of Laser Welding)
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Article
OCT Capillary Depth Measurement in Copper Micro Welding Using Green Lasers
Appl. Sci. 2021, 11(6), 2655; https://doi.org/10.3390/app11062655 - 16 Mar 2021
Cited by 3 | Viewed by 905
Abstract
The transition of the powertrain from combustion to electric systems increases the demand for reliable copper connections. For such applications, laser welding has become a key technology. Due to the complexity of laser welding, especially at micro welding with small weld seam dimensions [...] Read more.
The transition of the powertrain from combustion to electric systems increases the demand for reliable copper connections. For such applications, laser welding has become a key technology. Due to the complexity of laser welding, especially at micro welding with small weld seam dimensions and short process times, reliable in-line process monitoring has proven to be difficult. By using a green laser with a wavelength of λ=515 nm, the welding process of copper benefits from an increased absorption, resulting in a shallow and stable deep penetration welding process. This opens up new possibilities for the process monitoring. In this contribution, the monitoring of the capillary depth in micro copper welding, with welding depth of up to 1 mm, was performed coaxially using an optical coherence tomography (OCT) system. By comparing the measured capillary depth and the actual welding depth, a good correlation between two measured values could be shown independently of the investigated process parameters and stability. Measuring the capillary depth allows a direct determination of the present aspect ratio in the welding process. For deep penetration welding, aspect ratios as low as 0.35 could be shown. By using an additional scanning system to superimpose the welding motion with a spacial oscillating of the OCT beam perpendicular to the welding motion, multiple information about the process could be determined. Using this method, several process information can be measured simultaneously and is shown for the weld seam width exemplarily. Full article
(This article belongs to the Special Issue Modelling of Laser Welding)
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Article
A Numerical Investigation of Laser Beam Welding of Stainless Steel Sheets with a Gap
Appl. Sci. 2021, 11(6), 2549; https://doi.org/10.3390/app11062549 - 12 Mar 2021
Cited by 1 | Viewed by 719
Abstract
Keyhole laser beam welding (LBW) of 304L stainless steel sheets with a gap in between was numerically simulated with a three-dimensional, transient, multi-physical model for laser material processing based on the finite volume method (FVM). First, the model’s ability to reproduce experimental results [...] Read more.
Keyhole laser beam welding (LBW) of 304L stainless steel sheets with a gap in between was numerically simulated with a three-dimensional, transient, multi-physical model for laser material processing based on the finite volume method (FVM). First, the model’s ability to reproduce experimental results on a relatively coarse computational mesh within reasonable computing time, so as to serve as process optimization tool, is presented. An example of process optimization is shown, wherein a given set of weld seam quality criteria is fulfilled by iteratively optimizing a secondary laser beam. The relatively coarse mesh, in combination with a good model calibration for the experimental conditions, allows for sufficiently fast simulations to use this approach for optimization tasks. Finally, using a finer spatial and temporal discretization, the dynamic processes in the vicinity of the keyhole leading to the formation of pores are investigated. The physical phenomena predicted by the simulation are coherent with experimental observations found in literature. Full article
(This article belongs to the Special Issue Modelling of Laser Welding)
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