Welding properties of thin steel sheets by laser-arc hybrid welding: laser focused arc welding

Ono, M.; Shinbo, Yukio; Yoshitake, Akihide; Ohmura, Masanori

doi:10.1117/12.497756

Cited by 14 publications

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“…146 Blowhole macroporosity occurs during the laser lap welding of zinc coated steels. 52,54,147 The boiling point of zinc is approximately 900uC, which is significantly lower than the melting point of iron (1538uC). When zinc coated sheets are lap welded, zinc vapour filled bubbles form and blowholes are generated in the final weldment.…”

Section: Defect Formationmentioning

confidence: 99%

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: Defect Formationmentioning

confidence: 99%

Problems and issues in laser-arc hybrid welding

Ribic

Palmer

DebRoy

2009

International Materials Reviews

202

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“…Nowadays, 2-10 KW lasers, sometimes even 20 KW, 1,2) are used in laser welding and about 2 KW lasers 3,4) are used in laser-arc hybrid welding, in which there is a serious problem of energy loss. On the one hand, the photoelectric transformation efficiency of laser is so low that much energy was wasted.…”

Section: Forewordmentioning

confidence: 99%

A New Laser-Arc Hybrid Welding Technique Based on Energy Conservation

2006

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Aiming at the problem of energy loss in the process of welding at present, a new hybrid welding technique that low powered laser (about 400 W) combined with arc was put forward. Taking magnesium alloys as objects, it was found that the new technique had many advantages such as high welding speed, deep penetration and high quality welded joint comparing with that welded by laser or arc alone. Besides, the mechanical properties of the welded joint were improved remarkably. Comparing with high powered laser (about 2000 W)-arc hybrid welding, the laser used in the new technique was about 400 W, which was about 1/5 of that of the former, so the welding costs could be reduced markedly, while a great deal of energy was saved. In the research of arc behaviors, a new hybrid mechanism was proposed, in which the ability of arc to discharge was improved mainly because the laser pulse acted on the negative arc (electrode was positive and the specimen was negative) during the hybrid welding. Keywords: low powered laser-arc hybrid welding, energy conservation, magnesium alloys ForewordEnergy problem has been one of the three important problems for all over the world in the 21th century. With the development of materials manufacture, there are lots of higher requirements for welding technology, especially on energy conservation.As a new energy source, laser is used more and more widely in the field of welding. Nowadays, 2-10 KW lasers, sometimes even 20 KW, 1,2) are used in laser welding and about 2 KW lasers 3,4) are used in laser-arc hybrid welding, in which there is a serious problem of energy loss. On the one hand, the photoelectric transformation efficiency of laser is so low that much energy was wasted. For example, the photoelectric transformation efficiency of a CO 2 laser is merely 10-15%, 5) so the higher laser power is, the larger energy waste is. On the other hand, there are much plasma in laser welding alone, especially in high powered laser welding and it can absorb and scatter laser energy, which would reduce the utilization percent of laser energy. 6) Besides, it has been studied that arc has an effect to absorb and defocus the laser beam when laser penetrates through the arc during the process of hybrid welding. It is found that the stronger the laser power is, the larger the energy loss is. 7) For the problems mentioned above, using high-powered laser, most of the energy is wasted in the process of welding and the costs increases obviously which is not benefit for this technique to be applied in manufacture fields.In the research of hybrid welding, arc behaviors of TIG welding with alternating current mode and low powered laser-arc hybrid welding were observed by high speed camera, which was shown in Fig. 1. It was found that there were great differences between them. During TIG welding alone, in the positive wave of arc, tungsten electrode was negative (ACEN) and the arc was used to heat the base metal; in the negative wave of arc, the electrode is positive (ACEP) and the arc mainly contributed to clear the o...

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“…Good welding results were achieved with a combination of a Nd:YAG laser beam and a MAG welding process arranged behind the laser. 63,64 The improvement of the weld was explained by an elongated melt pool that offers the zinc vapor sufficient time to escape the weld seam region. Additionally, the integrated supply of filler material by the consumable electrode enables refill of possible blowholes.…”

Section: Overlap Welding Of Zinc-coated Steelmentioning

confidence: 99%

Hybrid laser beam welding—Classification, characteristics, and applications

Mahrle

Beyer

2006

Journal of Laser Applications

111

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Hybrid laser welding technologies can be defined as the combination of a high quality laser heat source with an additional secondary heat source. Based on such a definition, known hybrid techniques are classified by the type of the heat sources used as well as their arrangement relative to each other. The classification is followed by a discussion of different theoretical aspects occuring during a hybrid laser beam welding process concerning the plasma characteristics and the resultant temperature distribution of the superposed heat sources. Finally, some practical examples demonstrate how the potential of hybrid technologies can be used to extend the application spectrum of the laser beam welding process.

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Welding properties of thin steel sheets by laser-arc hybrid welding: laser focused arc welding

Cited by 14 publications

References 0 publications

Problems and issues in laser-arc hybrid welding

Problems and issues in laser-arc hybrid welding

A New Laser-Arc Hybrid Welding Technique Based on Energy Conservation

Hybrid laser beam welding—Classification, characteristics, and applications

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