Application of laser in seam welding of dissimilar steel to aluminium joints for thick structural components. (April 2015)

• Record Type: Journal Article
• Authors: Meco, S.; Pardal, G.; Ganguly, S.; Williams, S.; McPherson, N.
• Is Part Of: Optics and lasers in engineering. Volume 67(2015)
• Page Start: 22
• Page End: 30
• Publication Date: 2015-04
• Subjects: Laser welding-brazing -- Conduction -- Intermetallic compound -- Steel -- Aluminium alloy; Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2014.10.006
• Languages: English
• ISSNs: 0143-8166

Abstract

Abstract: Laser welding-brazing technique, using a continuous wave (CW) fibre laser with 8000 W of maximum power, was applied in conduction mode to join 2 mm thick steel (XF350) to 6 mm thick aluminium (AA5083-H22), in a lap joint configuration with steel on the top. The steel surface was irradiated by the laser and the heat was conducted through the steel plate to the steel-aluminium interface, where the aluminium melts and wets the steel surface. The welded samples were defect free and the weld micrographs revealed presence of a brittle intermetallic compounds (IMC) layer resulting from reaction of Fe and Al atoms. Energy Dispersive Spectroscopy (EDS) analysis indicated the stoichiometry of the IMC as Fe2 Al5 and FeAl3, the former with maximum microhardness measured of 1145 HV 0.025/10. The IMC layer thickness varied between 4 to 21 μm depending upon the laser processing parameters. The IMC layer showed an exponential growth pattern with the applied specific point energy ( E sp ) at a constant power density ( PD ). Higher PD values accelerate the IMC layer growth. The mechanical shear strength showed a narrow band of variation in all the samples (with the maximum value registered at 31.3 kN), with a marginal increase in the applied E sp . This could be explained by the fact that increasing the E sp results into an increase in the wetting and thereby the bonded area in the steel-aluminium interface. Highlights: Laser welding-brazing was applied to join 6 mm thick AA5083 and 2 mm XF350 steel. Intermetallic compound growth was correlated to fundamental processing parameters. IMC layer found to grow exponentially with the specific point energy. Laser power density plays a dominant role as compared to the interaction time. Strong lap joints with maximum tensile load of 30 kN were observed.