Influence of Laser Wavelength on Melt Bath Dynamics and Resulting Seam Quality at Welding of Thick Plates

Haug, Patrick; Rominger, Volker; Speker, Nicolai; Weber, Rudolf; Graf, Th.; Weigl, M.; Schmidt, Michael

doi:10.1016/j.phpro.2013.03.051

Cited by 25 publications

(12 citation statements)

References 3 publications

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“…Although a high-quality seam can be obtained with austenitic stainless steel (10 mm), the output range of 200 watts is too small for industrial application. With ferritic stainless steel (10 mm), on the other hand, it was not possible to obtain any acceptable weld seams, as there is an immediate transition from dropping to molten spatter flying downward [6]. using a CO 2 laser, however, the weld seam quality is significantly less dependent on the material used ( fig.…”

Section: The Influence Of Materials On Weld Seam Qualitymentioning

confidence: 99%

High‐power Full Penetration Welding Behavior

Romminger

Haug²,

Speker³

et al. 2013

Laser Technik Journal

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AuTHORSDue to their different physical beam characteristics, there are fundamental differences in the process behavior of Co 2 lasers and solid-state lasers during deep penetration welding. High-quality full penetration welds can be achieved in thick sheet metal with both beam sources. However, the beam sources differ in regards to productivity, process stability, and seam quality depending on the material being welded.CO 2 lasers and solid-state lasers (SSLs) are the most commonly used beam sources for laser welding. featuring high laser power combined with high beam quality, CO 2 lasers have been on the market since the 1980s. Thanks to their high electrical efficiency and the simplicity of guiding the beam through appropriate cables, SSLs with wavelengths around the 1 µm mark are increasingly used in industrial manufacturing. The development of diode-pumped disk and fiber lasers enabled these laser systems to catch up on CO 2 lasers regarding power and beam parameter product, resulting in an increase in the maximum attainable weld depth.Virtually all industrial thick sheet metal applications larger than 8 mm require a full penetration weld for reasons of strength, for example in the fields of shipbuilding, train and railroad construction, and pipeline engineering as well as for welding axle drives [1]. While deep penetration welding using CO 2 lasers is characterized by outstanding seam quality allied to high process reliability over a broad range of parameters, the seam quality achieved using solid-state lasers is more dependent on the material and process parameters. This article will compare the suitability of the two beam sources for full penetration welding.

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Section: The Influence Of Materials On Weld Seam Qualitymentioning

confidence: 99%

High‐power Full Penetration Welding Behavior

Romminger

Haug²,

Speker³

et al. 2013

Laser Technik Journal

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“…Underfilling and undercuts are very common in LBW where filler wire is not used. Underfilling is mostly related to melt dropouts caused by gravity effect [9,10]. The same parameters were applied with the arc added (LAHW, Weld No.…”

Section: Testing and Characterizationmentioning

confidence: 99%

“…However, in case of similar fusion zone width in the root area, humping has high probability to occur. Based on the work by Haug et al [9], it was shown that melt flow dynamics can play a significant role, especially in application of 1030-nm wavelength laser beam source. The macrographs examined did not show any surface cracking or pores in any of the welds.…”

Section: Testing and Characterizationmentioning

confidence: 99%

“…Moreover, backing systems for laser beam welding are not well developed and not readily available in the market. Haug et al [9] studied the effect of laser power and welding speed on root formation in welding of 12-mm thick steel with two types of laser sources, 1030-nm wavelength (disk laser) and 10,600-nm wavelength (CO 2 laser). It was found that 1030-μm wavelength lasers have very narrow process window due to higher absorption coefficient and subsequent melt overheat in welding of carbon steels.…”

Section: Introductionmentioning

confidence: 99%

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Laser-arc hybrid welding of 12- and 15-mm thick structural steel

Bunaziv

Dørum

Nielsen

et al. 2020

Int J Adv Manuf Technol

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High-power lasers are very effective in welding of plates thicker than 10 mm due to the keyhole mode. High-power intensity generates a vapor-filled cavity which provides substantial penetration depth. Due to the narrow and deep weld geometry, there is susceptibility to high hardness and weld defects. Imperfections occur due to keyhole instability. A 16-kW disk laser was used for single-pass welding of 12-to 15-mm thick plates in a butt joint configuration. Root humping was the main imperfection and persisted within a wide range of process parameters. Added arc source to the laser beam process may cause increased root humping and sagging due to accelerated melt flow. Humping was mitigated by balancing certain arc and other process parameters. It was also found that lower welding speeds (< 1.2 m/min) combined with lower laser beam power (< 13 kW) can be more positive for suppression of humping. Machined edges provided more consistent root quality and integrity compared with plasma cut welded specimens. Higher heat input (> 0.80 kJ/mm) welds provided hardness level below 325 HV. The welded joints had good Charpy toughness at − 50°C (> 50 J) and high tensile strength.

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“…Moreover, it was proven that some factors, such as the difference of absorptivity and a laser with a wavelength of 1 µm (i.e., fiber, disc, and yttrium aluminum garnet (YAG)) would accelerate the melt flow to the keyhole exits more than conventional CO 2 lasers with a wavelength of 10 µm [18]. Haug et al [19] also confirmed that the welding by CO 2 lasers was more robust and less susceptible for the formation of root humps.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms for Improvement of Weld Appearance in Autogenous Fiber Laser Welding of Thick Stainless Steels

Zhang

Chen

Zhang

et al. 2018

Metals

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High-power fiber laser welding is an efficient and effective way to produce heavy section structures. However, there is a significant challenge in producing the welds with free of imperfections such as nail-head-shaped welds, spatters, and root sagging. This is partially due to a lack of understanding of the welding mechanism of high-power fiber laser. In this paper, we were especially interested in the mechanism to improve the appearance of welds, and we focused on the autogenous laser welding on thick stainless steel plates by a 10 kW fiber laser. To look into the relations of process parameters and the quality of welds, a high-speed imaging system was applied to observe the molten pool flow and vapor plume during the welding process. The appearances of welds subjected to different welding conditions were analyzed. The results showed that (1) nail-head-shaped welds were suppressed by using a gas jet during laser welding process. (2) In the forward welding, a gentle upwelling molten metal flow on the rear keyhole wall, a deeper weld pool and a weaker vapor plume resulted in no spatter. (3) The gravity affected the formation of underfills and root sagging significantly during autogenous laser welding of thick plates. (4) When the workpiece was placed vertically in the transverse position, the welding process was stable without an aggregation of molten melt at the back surface. Moreover, the mechanisms of forming root sagging and humps were different at the top surface.

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Influence of Laser Wavelength on Melt Bath Dynamics and Resulting Seam Quality at Welding of Thick Plates

Cited by 25 publications

References 3 publications

High‐power Full Penetration Welding Behavior

High‐power Full Penetration Welding Behavior

Laser-arc hybrid welding of 12- and 15-mm thick structural steel

Mechanisms for Improvement of Weld Appearance in Autogenous Fiber Laser Welding of Thick Stainless Steels

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