Research on the forming ability and mechanism of laser impact micro isothermal forging

Abstract

High-performance monolithic forming of thin-walled complex structures from difficult-to-deform lightweight materials is an urgent need for the development of microdevices, the microforging forming of which has been an unsolved challenge. We propose a laser shock micro isothermal forging method that combines pulsed laser shock microforming and isothermal forging. The forming performance and mechanism of 2024 aluminum alloy miniature spacer frames are investigated through simulations and experiments. We examine the effects of different laser energies and forging temperatures on the forming ability of workpieces. The results show that at constant laser energy, thermal activation and dynamic recovery mechanisms cause the forming height to increase with temperature. At constant temperature, the forming height increases with increasing laser energy, but at room temperature, increasing the laser energy alone is insufficient for the desired forming. At the same laser energy, 350 °C offers better forming than 20 °C, with higher forming limits and potential for further improvement by a larger laser energy. Analysis of elastic–plastic wave transfer and stress–strain indicates that before the positive plastic wave acts on the forming, reflected elastic waves induce strain in initial contact area with the die. Material flow analysis reveals forming and reverse plastic deformation mechanisms unique to dynamic loading. Key factors include cross-region material replenishment, work hardening, and plastic wave reflection, leading to material inflow into fluted cavities and reverse plastic deformation in web regions. The degree of reverse plastic deformation increases with increasing laser energy but enhances overall formation until a threshold is reached.