Research On Laser Peen Forming Of Fe-based Metallic Glass

Laser peen forming (LPF) is a high strain rate plastic forming technology, which applies high-amplitude shock wave pressure induced by pulsed laser irradiation to form thin sheets to plastic deformation or to adjust finished shapes. It has been extensively used for the forming of aluminum, copper and other ductile sheet metals. For metallic glasses, laser shock forming is more difficult to be implemented because amorphous alloys exhibit little macroscopic plasticity at room temperature especially under uniaxial compressive, high strain rate, or tensile conditions.In this paper, Fe78Si9B13 metallic glass films and Fe73.5Nb3Cu1Si13.5B9 nanocrystalline alloy films with the thickness of 0.03 mm are used for laser shock forming experiments. The influences of laser parameters on bending angles are studied.Among all the experiments, Nd:YAG laser was selected, with the clamp method of cantilever clamped with a board. And all experiments were completely carried out in air without any absorbent coatings or confining overlays on the films. Structural changes of the glass film before and after laser shock forming are studied by X-ray diffraction (XRD), the X-ray diffraction curves show that no crystallization is observed when the films were subjected to laser shock forming. And large plastic bending deformation of Fe78Si9B13 metallic glass films has been achieved by laser shock. Besides, in the repeated shock experiments, the bending angle increases with the increase of the number of laser shocks and with the increase of the overlapping rate of laser spots, but the rate of increase decreases gradually.Based on the incremental sheet forming idea, the single rate surface forming experimental system was set up. The corner (bending area) of the laser shock formed part is very smooth without any signs of fracture. And the bending angle increases linearly with the increase of scanning passes.According to the research of the relationship between the laser energy and the bending angle, both the bending angle and growth rate increases with the increasing of laser energy. However.the bending angle of Fe73.5Nb3Cu1Si13.5B9 nanocrystalline alloy strips is larger than the Fe78SigB13 amorphous alloy strips".By comparing the bending angle of five different material strips, it can be inferred that the final bending angle has a great relationship with the characteristics of the material and the differences of the laser absorption rate.