Study On Microstructure Evolution And Corrosion Resistant Properties Of2A02Alloy At High Strain Rates Impact

Nowadays,2A02aluminum alloy has been widely used in aircraft parts, such asthe engine blade, due to its high heat strength, strong intensity and good machin ability.However, similar to most of the hard aluminum alloy, in practical application,corrosion often occurs in the2A02aluminum alloy of aircraft parts which seriouslyaffects the life of the aero-engine. Therefore, the2A02aluminum alloy should havenot only good mechanical properties but also fine corrosion resistance. Laser shockprocessing （LSP） is a technique using shock waves induced by laser to modify theproperties of metal surface. LSP can improve the hardness of metal surface as well asits abrasion resistance and corrosion resistance, so it has more and more applicationsin the study of metal surface modification. In order to open up a new way to improvethe life of aero-engine turbine blade, the effect of impact time on microstructure of2A02aluminum alloy together with its mechanical properties and corrosion resistantwas investigated in the present paper.The effect of different aging treatments and the single pass LSP on microstructureof the2A02aluminum alloy and its mechanical property and corrosion resistance werestudied. The results show that θ（CuAl₂） phase and S（Al₂CuMg） phase wereprecipitated from2A02aluminum alloy, and θ phase was precipitated at the grainboundary, while S phase is observed within grain. The corrosion resistance of alloysafter two-step ageing treatment （120℃/8h+160℃/6h） was best from self-corrosivepotential and intergranular corrosion morphology. After single LSP, the grains of thealloy were refined, and the minimum grain size in the top surface was about300nm-500nm. Also, the microhardness of different aging treatments were obviouslyincreased, and the microhardness of alloys after two-step ageing treatment （120℃/8h+160℃/6h） increased from136HV （before LSP） to179HV （after LSP）. The compressive residual stresses were produced on the sample surface after LSP. Themaximum residual stress of alloys after two-step ageing treatment（120℃/8h+160℃/6h） was-92MPa. Meanwhile, the self-corrosive potential wasincreased, thus, the corrosion resistance of alloys was improved.The2A02aluminum alloy after120℃/8h+160℃/6h aging treatment was treatedby different passes LSP. The effect of impact time on alloy microstructure, mechanicalproperties and its corrosion resistance were studied. The results indicated that with theincreasing number of LSP, the grains of2A02aluminum alloy were further refined.Besides, the microhardness, yielding strength, tensile strength, elongation andcorrosion resistance were also enhanced.