Energy efficiency and cut-quality improvement during fiber laser cutting of aluminum alloy in the different hardened conditions

The high thermal conductivity of aluminum alloys reduces the processing efficiency during fiber laser cutting due to a large wastage of the incident laser energy in the base metal. This degrades the quality and properties of the processed material (mechanical strength) by producing cuts with a large heat-affected zone (HAZ). Previous studies mainly focused on the improvement of the surface quality of the cut edge driven by the potential application in the automotive industry; however, the simultaneous improvement of both the surface quality and mechanical properties is essential for the aeronautic industry due to the common requirement of processing the material in its hardened state. This work introduces a novel approach to improve simultaneously the surface quality, mechanical properties and the energy efficiency of the process. It was based on the selection of the linear energy density (LE) as the experimental response of the process, and then optimizing the processing parameters (laser power, cutting speed, and assist gas pressure) by means of grey relational analyses (GRA). In a 1.5 mm and 2 mm thick sheets, the combination of LE with other responses improved the fatigue strength by 39.76% and 7.26%, and the energy efficiency of the process by 200% and 100%, respectively. The influence on the corrosion resistance, HAZ extension, average roughness (R_a) and energy efficiency during the fiber laser cutting of an aluminum alloy (AA2B06) in the O- and T4-states was analyzed to determine the best temper condition after processing. The energy efficiency during laser cutting in the O-state is a 50% higher, and the average roughness (R_a) two times lower than in the T-4 state.