Two-dimensional Ultrasonic Assisted Preparation And Characterization Of Nano-gradient Structure Of Aluminum Alloy

The engineering technology of Chinese manufacturing industry in the marine development industry focuses on marine equipment,the utilization and development of the ocean also depends on marine equipment.The foundation of marine equipment is focused on materials,while the manifestation of material properties is focused on the material matrix and surface properties.Further,the surface properties determine the service life of components.Aluminum alloys are widely used in marine equipment due to its advantages of high specific strength and processability.However,aluminum alloys are prone to wear and lead to increased corrosion and failure facing to Severe marine working environment.Therefore,it is imperative to strengthen the aluminum alloy parts surface.Rolling processing,as a traditional surface modification technology,has mature applications in the processing field.With the introduction of ultrasonic vibration can improve the optimization effect and efficiency,and induce the plastic deformation of surface materials to form a gradient nanocrystalline / ultrafine structure layer with higher strength and deeper impact zone.In this paper,7075-T6 aluminum alloy was selected as the research carrier,and a two-dimensional ultrasonic-assisted rolling process was used to prepare a gradient structure strengthening layer on the aluminum alloy surface.In order to explore the influence of two-dimensional ultrasonic vibration on rolling processing and the modification of aluminum alloy surface by two-dimensional ultrasonic-assisted rolling processing,this article mainly researches and discusses the following aspects:(1)A two-dimensional ultrasonic-assisted rolling processing platform that meets the requirements of the experiment is designed and constructed,and a matching flat multi-balls rolling tool is developed to build a consummate processing system to achieve the preparation of a gradient reinforced layer on the surface of aluminum alloy.(2)The uniform design experiment method was used to optimize the parameters of the two-dimensional ultrasonic-assisted rolling process,a rolling process regression model was established,and the mapping relationship between the processing parameters and the surface properties of the processed samples was clarified to form a mature processing technology.(3)By monitoring the three-dimensional rolling pressure during the twodimensional ultrasonic-assisted rolling process,the differences between traditional rolling,vertical ultrasonic-assisted rolling,transverse ultrasonic-assisted rolling,and two-dimensional ultrasonic-assisted rolling are explored and analyzed.By combining 3D-Deform to analyze the effect of ultrasonic in different directions on rolling processing,the mechanism of ultrasonic intervention on the gradient structure strengthening layer and the evolution model of grain refinement during processing are studied.(4)The surface and near-surface morphology of the aluminum alloy surface gradient structure reinforced layer prepared by two-dimensional ultrasonic-assisted rolling processing was characterized.The mechanical and mechanical properties of the cross-section were measured by nanoindentation experiments,and the friction was completed under dry friction conditions.The wear test analyzes the morphology and mechanical properties of the reinforced layer of the gradient structure from multiple angles.