Abstract
This paper presents the laser beam welding process of a lap joint between galvanized steel (Z225) and an aluminum alloy (A6000) from an IPG fiber laser. Welding of steel to aluminum has become popular in the automotive industry as a means of reducing the total vehicle body mass. This approach reduces fuel consumption and, ultimately, carbon emissions. Laser welding parameters used to control heat input for the study were laser power ranging between 800 and 1200 W, as well as laser welding speeds between 2 and 4 m/min. Distinct features of the dissimilar joints were microscopically examined. The SEM-EDS technique was employed to study the intermetallic phases along the Fe-Al interface. The outcome revealed the presence of “needle-like phases” and “island-shaped phases” at high heat inputs. Traces of both Fe2Al5 and FeAl3 phases were detected. For low heat input, there was evidence of insufficient fusion. Weld width was influenced by welding parameters and increased with an increase in heat input. Mechanical properties of the joints indicated that the microhardness values of the weld joints were higher than those of both base metals. The maximum tensile shear strength obtained was 1.79 kN for a sample produced at 1200 W and 3 m/min.
Highlights
In the past, car manufacturers produced heavy vehicles in order to meet passenger safety and aesthetic requirements [1]
The New European Driving Cycle (NEDC) reported that there is a proportional relationship between vehicle weight and fuel consumption
The results revealed the presence of intermetallic compounds (IMCs) within the weld zone
Summary
Car manufacturers produced heavy vehicles in order to meet passenger safety and aesthetic requirements [1]. It was concluded that the parameters that produced appropriate microstructure and mechanical properties were laser power ranging between 0.6 and 2.4 kW, welding speed ranging between 0.82 and 3 m/min, focal position between −0.8 and −0.2 mm, and shielding gas of flowrate between 5 and 15 L/min [11]. One of the major challenges encountered during laser fusion welding between galvanized steel and aluminum alloys is the creation of pores within the weld seam, especially when using the keyhole technique [13] This is caused by the fact that the melting and boiling points of Zn are lower than those of Al and Fe. Since high temperatures are applied during fusion welding, the zinc layer covering the steel tends to vaporize and become trapped during solidification creating pores [13,14]. A6000 joints with microstructural and mechanical properties suitable for manufacturing vehicle body parts
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