Abstract
Conditions were determined for consistent coupling of a CO2 laser beam to weld 5182 aluminum
alloy sheet. Full penetration butt and bead-on-plate welds on 0.8 and 1.8 mm sheets were
performed. Process conditions examined included beam mode, spot size and irradiance,
shielding gas flow, and edge quality and fitup. The observed weld quality variations with the
different process parameters were consistent with physical phenomena and a threshold irradiance
model. Optimal conditions were determined for obtaining consistent welds on 5182 alloy sheets.
Formability and tensile tests were performed on the welded samples. All test failures occurred in
the fusion zone. Reduction in formability and tensile strength of the welded samples are
discussed with respect to weld profiles and process parameters.
Keywords: aluminum, laser beam welding, process parameters, threshold irradiance
Introduction
Use of lightweight materials improves the energy efficiency and fuel economy of automotive
vehicles. An aluminum intensive midsize American sedan could potentially be 20% lighter than
the standard steel based vehicle. This decrease in weight translates into a 12% improvement in
fuel economy [1]. Economically substituting aluminum for steel in body and chassis
components is difficult. It is more cost effective to design a part specifically for aluminum,
taking advantage of its design flexibility and specific stiffness. Aluminum alloys have a higher
thermal conductivity and higher reflectivity, which make welding more difficult than welding
steel. Improvements to conventional welding practices are needed to enhance the welded
properties of aluminum joints.
This paper examines laser beam welding which has been identified as a promising method for
joining aluminum in body applications such as tailored blanks. Initial efforts by other
researchers applied previous experience with steel to aluminum but the process

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