Effect of dual laser beam on dissimilar welding-brazing of aluminum to galvanized steel

• Published in: Optics and laser technology 2018-01, Vol.98, p.214-228
• Main Authors: Mohammadpour, Masoud, Yazdian, Nima, Yang, Guang, Wang, Hui-Ping, Carlson, Blair, Kovacevic, Radovan
• Format: Article
• Language: English
• Subjects: Alloying effects; Alloying elements; Aluminum alloy; Aluminum alloys; Aluminum base alloys; Braze welding; Coach peel configuration; Computer simulation; Critical temperature; Cross-beam laser; Dissimilar material joining; Electron microscopy; Finite element; Finite element method; Galvanized steel; Galvanized steels; Galvanizing; In-line beam laser; Laser beam welding; Mathematical models; Microstructure; Surface roughness; Temperature; Tensile strength; Thermal analysis
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2017.07.035

•Two modes of dual laser beams in dissimilar welding-brazing were investigated.•FE thermal simulation was employed to capture temperature history during the process.•The best laser beam mode was introduced based on the mechanical performance, surface and edge quality of joints. In this investigation, the joining of two types of galvanized steel and Al6022 aluminum alloy in a coach peel configuration was carried out using a laser welding-brazing process in dual-beam mode. The feasibility of this method to obtain a sound and uniform brazed bead with high surface quality at a high welding speed was investigated by employing AlSi12 as a consumable material. The effects of alloying elements on the thickness of intermetallic compound (IMC) produced at the interface of steel and aluminum, surface roughness, edge straightness and the tensile strength of the resultant joint were studied. The comprehensive study was conducted on the microstructure of joints by means of a scanning electron microscopy and EDS. Results showed that a dual-beam laser shape and high scanning speed could control the thickness of IMC as thin as 3µm and alter the failure location from the steel-brazed interface toward the Al-brazed interface. The numerical simulation of thermal regime was conducted by the Finite Element Method (FEM), and simulation results were validated through comparative experimental data. FEM thermal modeling evidenced that the peak temperatures at the Al-steel interface were around the critical temperature range of 700–900°C that is required for the highest growth rate of IMC. However, the time duration that the molten pool was placed inside this temperature range was less than 1s, and this duration was too short for diffusion-control based IMC growth.