Modeling And Simulation Of Electrochemical Corrosion Of 2a12 Aluminum Alloy In Marine Atmospheric Environment

2A12 aluminum alloy is widely used as aviation material.However,due to long-term exposure to atmospheric environment,the corrosion problem is inevitable.Therefore,the body corrosion has become one of the important problems threatening the safety of aircraft.Based on the main influencing factors of atmospheric corrosion of 2A12 and analyzes the existing simulation methods of metal materials atmospheric corrosion,the corrosion process of 2A12 under marine atmospheric conditions was studied in this paper.The finite element simulation software COMSOL Multiphysics was used to simulate the electrochemical corrosion of second phase corrosion,passivation film defects and contact with AISI 4030 steel of 2A12 under atmospheric conditions.Quantitatively calculate the effects of relative humidity(RH),salt load density(LD)and oxygen solubility(C_sol)on atmospheric corrosion process of 2A12,explore the relationship between corrosion current and potential on 2A12 surface and complex environment factors.The main results are as follows:1.For the second phase corrosion and the passivation film defect corrosion,the corrosion types start from pitting corrosion,gradually develop to local corrosion,until the full corrosion,and the existence of the second phase will aggravate the corrosion,and the notch size has no obvious effect on the corrosion rate.2.For the atmospheric corrosion of the second phase,the passivation film defect and the direct contact with AISI steel.At the junction of anode and cathode,the local current on the metal surface and the local potential reaches the maximum value.For the galvanic corrosion formed by the direct contact with AISI 4030 steel,the local current density at the junction is about 3-5 orders of magnitude higher than that at the boundary,and the local potential decreases continuously from anode to cathode,and the decreases most rapidly at the junction,the farther away from the junction,the slower the change is.3.For corroded batteries composed of 2A12 in direct contact with AISI 4340steel,the corrosion depth of 2A12 almost doubled with the corrosion time doubled.The surface current distribution is most affected by the C_sol in the electrolyte film,followed by the LD and the RH is the least affected,both of which are positively affected.The surface potential distribution is most affected by the LD in the electrolyte film,while the C_sol and RH have little effect.At the same time,we used COMSOL to calculate the quantitative relationship between the average corrosion current density and RH,LD,and C_sol on the surface of the 2A12(anode),the results show that the average current density(corrosion rate)on the anode surface first increases with the increase of RH,reaches the maximum when the RH is 0.96,and then begins to decrease,and when the RH is greater than 0.96,the greater the LD in the electrolyte membrane,the faster the current drop;The average current density increases with the increase of LD in the liquid film.When RH exceeds 0.96,the current density decreases as a whole,and increases with the increase of LD at first,and reaches the maximum value when the LD is 5g/m².After that,the current density decreases rapidly with the increase of the salt load density.The current density and the oxygen solubility in the liquid film show a purely positive relationship,that is,as the oxygen solubility increases,the current density(corrosion rate)continues to increase.