Weld microstructure and shape of laser–arc hybrid welding

Gao, Ming; Zeng, Xiaoyan; Hu, Qianwu; Yan, Jeff

doi:10.1179/174329307x249388

Cited by 39 publications

(47 citation statements)

References 14 publications

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“…For the hybrid welding, ArcZ usually both has almost total arc heat and partial laser heat in upper part. 26 Thus, the cooling rate of this zone is slower and the solidification structure is finer than that of LaserZ as shown in Fig. 6c and d. Besides, as compared to MIG welding, in laser MIG welding, the laser beam provides additional heating at the weld centreline and perhaps reduces the cooling rate at weld centerline.…”

Section: Microstructure Characteristicsmentioning

confidence: 90%

Mechanical properties and microstructures of hybrid laser MIG welded dissimilar Mg–Al–Zn alloys

Gao

Cao

Zeng

et al. 2010

Science and Technology of Welding and Joining

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Bead shape, microstructure changes and mechanical properties of laser metal inert gas (MIG) welded dissimilar Mg-Al-Zn alloys (from AZ31B to AZ61) are studied. The results show that heat ratio of arc to laser (HRAL) and welding speed are dominant parameters for achieving good tensile strength efficiency and elongation property. From AZ31B to AZ61, microstructure changes are observed as cellular dendrites to equiaxed dendrites and fish bone dendrites in the upper part of hybrid weld. Besides, at weld centreline, the solidification structure of lower part is finer than that of upper part. In this study, the maximum tensile strength efficiency and elongation reached 97?6 and 7% respectively. When the HRAL matches welding speed well, the joint achieves higher tensile strength with 45u shearing fracture at heat affected zone because of fewer defects. However, when utilising too low HRAL or fast welding speed, the joints show lower tensile strengths with nearly vertical fracture at fusion zone.

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Section: Microstructure Characteristicsmentioning

confidence: 90%

Mechanical properties and microstructures of hybrid laser MIG welded dissimilar Mg–Al–Zn alloys

Gao

Cao

Zeng

et al. 2010

Science and Technology of Welding and Joining

Self Cite

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“…20,58,62 By adjusting heat source power density, heat input per unit length and filler metal additions the microconstituents, mean grain size, and width and shape of the HAZ and fusion zones can be modified, thus ultimately affecting the mechanical properties of the weldment. 12,20,62,154 Steel hybrid welds Steel microstructures can be manipulated by controlling the cooling rate and weld metal composition. During autogenous laser welding, no filler metal additions are made, which significantly limits the range of alloys that can be laser welded.…”

Section: Role Of Heat Input and Power Densitymentioning

confidence: 99%

“…20 At a heat input of 796 J mm 21 using an arc current and voltage of 120 A and 28 V and laser power of 5 kW, and at a travel speed of 540 mm min 21 , the columnar grains were composed of proeutectoid and acicular ferrite, and the microstructure contained intergranular pearlite. 20 The HAZ of these welds were composed of a large fraction of coarse pearlite with intergranular proeutectoid ferrite. 13 Micrographs of mild steel a base metal, b laser, c arc and d hybrid weld microstructures.…”

Section: Role Of Heat Input and Power Densitymentioning

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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“…Moreover, a series of CO 2 laser-metal inert gas arc hybrid welding experiment investigated the effects of laser/arc energy ratio and groove parameters on the shape and microstructure of weld. In particular, Gao et al showed that increasing arc current and groove cross-section area can reduce the size of laser and arc zone by enhancing the uniform of energy distribution in the molten pool [18]. Detail studies on the interaction between laser radiation and electric arc used in hybrid heat source are available.…”

Section: Introductionmentioning

confidence: 98%