The Effect Of High Speed Milling Process On Surface Integrity And The Corrosion Resistance Of 7055-T6I4 Aluminum Alloy

7055 aluminum alloy has high strength,low density,high fracture toughness and excellent resistance to fatigue crack expansion and many other advantages,has great potential application in the field of aeronautics and astronautics.Aeronautical parts are mostly adopts high-speed machining.Milling process on the machined surface physical and chemical characteristics such as micro cracks causes different effects.The physical and chemical characteristics will affect the corrosion resistance in the working environment and reduce the service life of aviation parts.Therefore,it is of great theoretical and practical significance to study the effect of high speed milling process on surface integrity and its corrosion resistance.In this paper,the influence of the surface quality of 7055-T6I4 aluminum alloy on the corrosion resistance of high-speed milling was studied,using scanning electron microscopy,transmission electron microscopy,high-speed milling test,super-depth microscope and electrochemical corrosion test.The following conclusions were obtained:?1?Compared with 7055-T6 aluminum alloy,7055-T6I4 aluminum alloy precipitation phase particles are more compact and dense,in the cutting process due to the cutting temperature gradient is greater,the precipitation phase is more likely to dissolves back,the pinning effect of the precipitates on the dislocation and grain boundary has decreased,lead to reduce cutting force.The workability of the 7055-T6I4 aluminum alloy is better than that of the 7055-T6 aluminum alloy.?2?The same situation in other processing conditions,increasing the cutting speed,surface roughness increases first and then gradually reduce,the adhesion between the surface and the chip has the growth trend with the cutting speed increases;increasing the axial cutting depth,the surface roughness gradually increases,the number of cracks gradually increases,the cracks are perpendicular to the processing surface,and deep into the internal matrix.?3?The corrosion resistance of the 7055 aluminum alloy was improved during the milling process due to the squeezing and strengthening effect of the flank face on the machined surface.With the increase of cutting speed,the corrosion potential presented to move to the anode first the move to cathode.With the increase of the axial cutting depth,the self-corrosion currents gradually moved to the negative and the current density showed an increasing trend.The corrosion current has the lowest self-corrosion current density and the corrosion resistance of the surface has the strongest corrosion resistance at cutting speed of 1256m/min,the axial cutting depth of 0.25 mm,feeding of 0.1mm/r.?4?The corrosion resistance of the material is closely related to the surface quality of the machined surface.The presence of micro-cracks will accelerate the damage of the oxide film on the surface of the material,and it will fail to protect the surface of the alloy.The surface corrosion occurs in the defective surface preferentially,and it shows corrosive pitting in the early stage of corrosion.As the corrosion continues,the corrosion pits become larger and finally corrodes,and the corrosion products are mainly Al?OH?₃.