Laser keyhole welding on aluminum alloys

Xu, Guoliang; Cheng, Zhaogu; Xia, Ji‐Bao; Li, Xianqin; Jiang, Jinbo

doi:10.1117/12.377081

Cited by 4 publications

(4 citation statements)

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“…98 The welding mode is dependent upon the power density of the heat source, physical properties of the material and welding speed. 58,63,75,82 The hemispherical transverse weld cross-section obtained during conduction mode laser welding is similar to that obtained during arc welding. 58,98 During conduction mode laser welding, the power density of the laser beam 71 is typically less than 10 5 W cm 22 , leading to a shallower and wider weld pool than obtained during keyhole mode laser welding.…”

Section: Laser-materials Interactionssupporting

confidence: 72%

“…58,[65][66][67] As a result, the energy from the laser is able to penetrate to a greater depth into the workpiece without changing the weld width, thus increasing the weld aspect ratio. 50,82 Often in this case, a laser induced plasma forms and some laser energy is absorbed by the plasma phase formed within the keyhole. This condition is most often quantitatively described by the Beer-Lambert law given by 50 I a ~Io exp({m a L P )…”

Section: Absorption Of Arc and Lasermentioning

confidence: 99%

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Problems and issues in laser-arc hybrid welding

Ribic

Palmer

DebRoy

2009

International Materials Reviews

202

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Hybrid welding, using the combination of a laser and an electrical arc, is designed to overcome problems commonly encountered during either laser or arc welding such as cracking, brittle phase formation and porosity. When placed in close contact with each other, the two heat sources interact in such a way as to produce a single high intensity energy source. This synergistic interaction of the two heat sources has been shown to alleviate problems commonly encountered in each individual welding process. Hybrid welding allows increased gap tolerances, as compared to laser welding, while retaining the high weld speed and penetration necessary for the efficient welding of thicker workpieces. A number of simultaneously occurring physical processes have been identified as contributing to these unique properties obtained during hybrid welding. However, the physical understanding of these interactions is still evolving. This review critically analyses the recent advances in the fundamental understanding of hybrid welding processes with emphases on the physical interaction between the arc and laser and the effect of the combined arc/laser heat source on the welding process. Important areas for further research are also identified. List of symbols and acronymsa coefficient in the surface tension pressure term A area of the transverse weld cross-section (mm 2 ) B magnetic flux (kg s 22 A 21 ) c molar concentration of vapour inside keyhole (mol cm 23 ) C concentration of surface active elements (wt-%) C p heat capacity or specific heat (J kg 21 K 21 ) DCEN direct current electrode negative DCEP direct current electrode positive D LA horizontal distance between laser focal point and arc electrode tip dT/dy spatial temperature gradient on the weld pool surface (K mm 21 ) E A attenuated incident radiation (W) f distribution factor F b buoyancy force (N m 23 ) F emf Lorentz or electromagnetic force (N m 23 ) g acceleration due to gravity (m s 22 ) GMA gas metal arc GMAW gas metal arc welding GTA gas tungsten arc GTAW gas tungsten arc welding h depth of keyhole (mm) H heat input per unit length (J mm 21 ) HAZ heat affected zone HCP hexagonal close packed H f latent heat of fusion (J kg 21 ) I arc current (A) I a attenuated laser beam intensity (W) I m imaginary portion of the complex refractive index I o initial laser beam intensity (W) J flux of evaporating particles in keyhole (mol cm 22 s 21 ) J c current density (A m 22 ) k e extinction coefficient k thermal conductivity (W m 21 K 21 ) L characteristic length (half of the weld pool width) (mm) L P length of the plasma (mm) L R characteristic length of the weld pool (mm) m complex refractive index n refractive index N number density of scattering particles (no./mm) Nd:YAG neodymium:yttrium aluminium garnet P incident heat source power (W) P d power density (W mm 22 ) Pe Peclet number P r recoil pressure (Pa) P v vapour pressure (Pa) P n power or nominal power (W) P t total power of the heat source (W) International Materials Reviews 2009 VOL 54 NO 4223 P c pressure due to surfa...

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Section: Laser-materials Interactionssupporting

confidence: 72%

Section: Absorption Of Arc and Lasermentioning

confidence: 99%

Problems and issues in laser-arc hybrid welding

Ribic

Palmer

DebRoy

2009

International Materials Reviews

202

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show abstract

“…For pulsed laser welding, keyhold effect needed to occur on the bath to form high aspect-ratio weld during welding (5)(6)(7). Keyhole effect generated from absorbing laser energy not only made metal melted but also made metal vaporized.…”

Section: Laser Welding Parametersmentioning

confidence: 99%

Laser Sealing Technique for Fuel Cell Application

2014

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Parameter analysis for laser welding, optical measurement tests and tension shear tests are conducted on materials for fuel cell stack bipolar plates, and seven groups of welding parameters are chosen and tested. The optical measurement tests reveal that at the same power and duration time, specimens 1 (20 PPR, 5 mm/s) and 4 (50 PPR, 10 mm/s) obtained greater welding quality with proper welding frequency and velocity. The tension shear tests demonstrate that the bonding strength of both specimen 1 and 4 exceeded 0.4 MPa, the result of which are proper applied to high power fuel cell systems. A new fuel cell stack structure is subsequently designed for this high strength and accuracy modular sealing technique.

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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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Laser keyhole welding on aluminum alloys

Cited by 4 publications

References 0 publications

Problems and issues in laser-arc hybrid welding

Problems and issues in laser-arc hybrid welding

Laser Sealing Technique for Fuel Cell Application

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

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