Improving Mechanical Property and Microstucture Evolution of 7075 Aluminum Panel Formed by Unequal Alternate Double-sided Laser Shock Forming

With thrust weight ratio increasing, integral panel is an important component to reduce the aircraft weight, and it is a great challenges to ensure the forming accuracy and mechanical property in the lager-scale panel. Laser shock forming has a great development prospect in achieving integral panel forming and improving its mechanical properties. This work investigated unequal alternate double-sided laser shock forming, which can make 7075 aluminum panel form and induce harden layer in both panel sides. The improvement in mechanical properties and microstucture evolution of 7074 aluminum panel were analyzed after unequal alternate double-sided laser shock forming. The residual stress and microhardness in surface and subsurface were verified to be enhanced by the laser shock wave. The results of XRD and EBSD provided an evidence of grain refinement. The strengthening mechanism of unequal alternate double-sided laser shock forming was analyzed in this work. The grains are distorted and refined during high strain rate plastic deformation due to dislocation slip and accumulation. The mechanical properties were enhanced by unequal alternate double-sided laser shock forming for harden layers in both panel sides. The harden layers and grain refinement has a great significance in inhibiting the crack generation and growth.

Improvement of Formability and Corrosion Resistance of Az31 Magnesium Alloy by Pulsed Current-assisted Laser Shock Forming

This study adopted a novel pulse current-assisted laser shock AZ31B sheet micro-forming method (EP-LSF). The mechanism of improving the formability of AZ31B Magnesium Alloy by pulse current assisted laser shock forming and the reason of improving the corrosion resistance were studied for the first time. Through laser shock free bulging experiment, tensile test, optical microscope (OM), and X-ray diffraction, the change in formability was studied. After pulse current assisted laser shock forming, the forming height of AZ31B magnesium alloy increases by 28.8%, the thinning rate decreases by 6.7%, and the strain rate sensitivity coefficient increases to 0.1452. The results show that the decrease of grain size and texture density is the reason why EP-LSF can further improve the formability of AZ31B magnesium alloy. The changes in corrosion resistance were studied by scanning electron microscopy and electrochemical tests. The results show that after EP-LSF, the corrosion current density of AZ31 magnesium alloy decreased, and the electrochemical impedance increased, indicating that this method further improved the corrosion resistance.