Prediction Of Failure Behavior Of Aluminum Alloy In Corrosive Environment

Corrosion is very common in various engineering applications,resulting in huge economic losses and waste of resources,so the research of metal corrosion is of great significance.Aluminum alloy is widely used as a green environmental protection material.There are still many problems in the prediction of structural damage caused by local corrosion.It is very important to predict the failure behavior of aluminum alloy in corrosive environment by using finite element analysis method,which has important academic significance and good application prospect for evaluating the strength and service life of metal materials.In this paper,the 6061-aluminum alloy rolling plate was taken as the object.The corrosion behavior of 6061 aluminum alloy in salt spray environment was studied by using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),microhardness tester and other equipment.Combined with quasi-static tensile test at room temperature,the effect of salt spray corrosion behavior on mechanical properties of 6061 aluminum alloy at different time was studied.The results show that:(1)local corrosion of 6061 aluminum alloy occured in salt spray environment,mainly pitting corrosion,accompanied by a certain degree of intergranular corrosion and exfoliation corrosion;(2)with the increase of corrosion time,the self-corrosion potential of 6061 aluminum alloy shifted negatively,the polarization resistance decreased,and the corrosion rate increased significantly;(3)The tensile test showed that the tensile strength decreased about 5%and the elongation decreased about 50%with the corrosion time of 60 days.The mechanical properties of 6061 aluminum alloy were mainly affected by corrosion pits.Through the secondary development of LS-DYNA,the material constitutive model and failure criterion were defined in UMAT file.Then,considering the influence of corrosion pit depth on mechanical properties,the corrosion damage parameter C was introduced,and the relationship between corrosion damage parameter and fracture criterion parameter We was established.According to the comparison and analysis of different corrosion time test and simulation results,it was proved that the method is correct to calculate the cumulative strain energy Wc’ corresponding to different corrosion time.The model was used to predict the compression deformation and failure behavior of the thin-walled structure after salt spray corrosion.