Optimization Of Process Parameters And Microstructure Analysis Of 5052 Aluminum Alloy After Tube Flaring Process Based On Orthogonal Test

5 series aluminum alloy is a non-heat treatment strengthened aluminum alloy.It has been widely used in shipbuilding,ocean engineering,aerospace and other fields due to its good machinability,welding performance and corrosion resistance.In the field of aviation,5 series aluminum alloy is often used as the connection tube for the aim of conducting oil,but the uneven deformation of the thin-walled tube in the process of tube flaring is prone to produce quality problems such as bulging,crack and peeling on the surface,which will influence the connection performance of the flaring tube.It has become a hidden danger that the connection of product fails,and the consequences will be unexpected.At present,the research of tube flaring focuses on the aspects of the process design,simulation and equipment optimization.However,there is a lack of systematic and depth research on the wear mechanism.Therefore,for the aim of ensuring the safe operation of components and improving the service life of components.Researching the surface quality of flaring and optimizing the relevant process parameters are very important.The results of this research will help to understand the evolution mechanism of roughness under uneven deformation,and provide theoretical basis as well as data support for the production of aluminum alloy under tube flaring.In this paper,5052 aluminum alloy thin-walled tube were used as the research object,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,back scattering diffraction（EBSD）,finite element simulation and other testing technology were applied to study the effect of the initial state（composition,surface morphology,etc.）and the flaring process（spindle speed,feed rate,holding time）on the surface topography of the tube.The friction and wear mechanism are elucidated.（1）The results show that Fe-rich intermetallic compounds（such as Al₅Si Fe phase）appear in the microstructure with the increase of Fe content in the alloy,and the appearance of these hard and brittle phases is the main cause of abrasive wear during the flaring process.The initial appearance of the tube wall is directly related to the final surface quality.In the experiment,the corroded pitted appearance is more likely to cause uneven plastic deformation during the tube flaring,resulting in serious folding phenomenon of the surface after adhesive wear,and even fall off.（2）Under the influence of process parameters,the main wear mechanism of the tube wall is adhesive wear,and dynamic recrystallization（DRX）is observed near the surface at higher spindle speeds.In contrast,the increase of feed rate and holding time only resulted in more substructure without a significant increase in recrystallized grains.The effect of grain orientation on wear behavior is considered and a potential model is proposed.Soft orientation and hard orientation lead to non-uniform strain distribution and different deformation sequences,resulting in discontinuity of deformation and surface fluctuation.（3）According to the analysis of ANOVA and SVM,it is found that the spindle speed is the most important parameter affecting microhardness and surface roughness,feed rate is the second important parameter,and hold time has little effect.According to the comparison of simulation and experimental results,it is found that the surface roughness will be initially increase,and then decrease with the increase of strain.This non-monotonic trend is related to the evolution of strain（strain rate,strain path,etc.）,microstructure（DRX,texture,etc.）,and hardening.