Numerical Simulation And Experimental Study On Laser Shock Processing Of Aging Aluminum Alloy

In this paper,a novel technology of aging-laser shock processing of 6061 aluminum alloy has been explored by numerical simulation,experimental study and theoretical analysis,which can change the surface residual stress state and construct a new surface microstructure,thereby developing the control methods and theory of surface residual stress and microstructure of aluminum Alloy,breaking the bottleneck of the existing preparation technology and providing the technical and theoretical guidance for the preparation of high-performance aluminum alloy materials.Based on the platform of ABAQUS analysis software,the finite element model of Mg2Si/Al material has been established by connecting the matrix material and the precipitated second phase particles using bundling constraints.The laws of laser shock wave propagation in Mg2Si/Al material and internal energy change have been analyzed.The results show that the presence of nanoparticles hinders the propagation of pressure shock wave,which increases the ratio of internal energy to total laser shock energy,thereby resulting in more energy being stored in the material as plastic strain and residual compressive stress.In addition,the influence law of nanoparticle orientation and shape on the surface residual stress of laser shock processed Mg2Si/Al has been simulated.When the reinforced particles are oriented horizontally,the peak residual compressive stress is increased by 53.00% compared with the case without nanoparticle(171.68MPa).When the reinforced particles are oriented vertically,the peak residual compressive stress is 66.85% higher than that without nanoparticle.When the reinforced particles are with mixed orientation(half of the particles in the horizontal orientation,the other half in the vertical orientation),the peak residual compressive stress is improved by about 100.57%.Under the condition that all parameters are invariable,the residual compressive stress after two laser shocks is increased by about 20.05% compared with that after one shock,and the distance of the maximum residual compressive stress appearance from the shocked surface is increased with increasing the shock numbers.The effects of laser shock processing on the surface morphology,residual stress,microstructure and macroscopic mechanical properties(microhardness,tensile strength and elongation)of the aged aluminum alloy have been studied through its laser shock processing experiments.The plastic deformation of aged aluminum alloy induced by laser shock processing occurs,forming the surface residual compressive stress,the variation law of which is consistent with the numerical simulation results.This also verifies the effectiveness of Mg2Si/Al laser shock processing model established by finite element method.The macroscopic mechanical properties of aged aluminum alloy are effectively improved by laser shock processing.As the aging time is prolonged,the microhardness and tensile strength of the laser shock processed specimen are both improved,but the elongation decreases gradually and the dimples of fracture gradually become less and more shallow.