The Study Of7075Aluminum Alloy To Stress Corrosion Cracking Mechanism

7075Aluminum is widely used in the aerospace field, is a high-strength andlow-density material. In the service process, especially in the coastal environment prone toproduce localized corrosion and cause great flight safety hazard. Domestic and foreignscholars have conducted a lot of research to improve the corrosion resistance, but themechanism for stress corrosion of7075aluminum alloy has not yet to reach a unifiedconclusion. Therefore, studying the stress corrosion mechanism to improve the corrosionresistance of7075aluminum alloy has a certain theoretical and practical significance.This article from7075aluminum alloy hydrogen permeation behavior and stresscorrosion sensitivity relations aspects combined with scanning electrochemical microscopynew experimental techniques to study the stress corrosion behavior of7075aluminumalloy,Experimental results show that the corrosion in different environments,state of thematerial surface passivation film and aggressive ions and correlated emotional stresscorrosion, cathodic hydrogen charging promotes stress corrosion of7075aluminumalloy.When the slow strain rate,the tensile fracture process to the various stages of ACimpedance spectroscopy Show:state of the material surface is regular variation, which ismainly tensile deformation process,lattice slip, causing the surface destruction of themembrane,and then rebuild the passive film,aggressive chloride ion intrusion activeposition,corrosive environment of hydrogen into the material, causing deformationresistance,several factors working together is the result.7075aluminum alloy non-hydrogen charging in3.5%NaCl solution,with the extensionof etching time, the corrosion intensified aluminum surface of the sample surface localizeddissolution;early corrosion, the first selective corrosion uniform corrosion morphology, withtime to grow, some pitting appears with a small amount of micro-cracks.Fewer samplesurface corrosion products,has a relationship with the occurrence of surfaceerosion,corrosion points cylindrical ring,no distribution rules.7075aluminum alloy surfaceactive dissolution of intermetallic compounds are mainly aluminum body with differentpotentials due to corrosion caused by the formation of corrosion micro cells that ηphase(MgZn2) and a small amount of Mg2Si phase surrounding the aluminum matrix as theanode corrosion dissolved.After using constant7075aluminum cathodic current density ofhydrogen charging,the SECM image, the current surface with hydrogen charging timebecomes longer, the current surface becomes volatile,description of the7075aluminum alloy using constant current density of hydrogen will be charged induced sample surfacepitting,peeling or other defects;with the extension of hydrogen charging time, the7075aluminum alloy corrosion resistance is reduced.