Influence of CO 2 -Ar Mixtures as Shielding Gas on Laser Welding of Al-Mg Alloys
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TRADITIONAL welding processes present a series of disadvantages when applied to aluminum alloys, which have sometimes discouraged the use of such welded materials. The poor welding reliability of aluminum alloys lies in their physical properties, especially their high thermal conductivity, high reflectivity, and low viscosity.[1] During the last two decades, significant and improved solutions for welding aluminum alloys have been developed.[2–5] Laser welding is now a competitive alternative to the conventional technologies (GMAW and GTAW), presenting important advantages such as the low heat input, high localization ability, high welding speed, high flexibility, high weld quality, and high production rate.[6–11] Numerous studies dealing with laser welding of aluminum alloys are available.[6–13] Although the majority of them are performed ZOUHAIR BOUKHA, Researcher, and JAVIER BOTANA, Professor, are with the LABCYP, Departamento de Ciencia de los Materiales e Ingenierı´ a Metalu´rgica y Quı´ mica Inorga´nica, CASEM, Universidad de Ca´diz, Campus Rı´ o San Pedro, 11510 Puerto Real, Ca´diz, Spain. JOSE´ MARI´A SA´NCHEZ-AMAYA, and LEANDRO GONZA´LEZ-ROVIRA, Researchers, are with the LABCYP, Departamento de Ciencia de los Materiales e Ingenierı´ a Metalu´rgica y Quı´ mica Inorga´nica, CASEM, Universidad de Ca´diz, and also with the Titania, Ensayos y Proyectos Industriales S.L. Parque Tecnolo´gico TecnoBahı´ a Edif. RETSE, Nave 4. Ctra. Sanlu´car Km 7, 11510 El Puerto de Santa Marı´ a, Ca´diz, Spain. Contact e-mail: josemaria. [email protected] ELOY DEL RIO, Researcher, and GINESA BLANCO, Professor, are with the IMEYMAT, Departamento de Ciencia de los Materiales e Ingenierı´ a Metalu´rgica y Quı´ mica Inorga´nica, Facultad de Ciencias, Universidad de Ca´diz. Manuscript submitted February 14, 2013. Article published online September 17, 2013 METALLURGICAL AND MATERIALS TRANSACTIONS A
under keyhole regime, recent research projects are alternatively using conduction regime because it has the advantage of reducing the formation of porosity, cracks, and undercutting in the welds. In addition to these wellknown regimes, AssunC¸ao et al.[14] have just proved the existence of a third welding mode so-called transition regime, leading to welds with characteristics of both keyhole (undercut, not flat top profile, and small depression at the surface) and conduction (low aspect ratio). High-power CO2[8–11] and neodymium-doped yttrium aluminium garnet (Nd:YAG)[6,7,15] lasers are the most common equipments employed to weld aluminum alloys. High-power diode laser (HPDL) has been used in fewer works,[16–21] although it offers a clear advantage: The absorption of the HPDL wavelength by aluminum alloys is higher than the CO2 and Nd:YAG wavelengths.[19] Thus, the emission wavelength of the HPDL (808 nm) provokes a higher absorptivity in aluminum than the longer wavelengths of Nd:YAG (1064 nm) and CO2 (10640 nm) lasers. As a consequence, HPDL is being widely used in surface engineering technology.[22,23] To preserve the properties of materi
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