| Aluminum alloy has the advantages of low density,high plasticity,good corrosion resistance and etc.It is widely used in aerospace,nautical ships,automobiles,high-speed trains and other manufacturing fields.Aluminum alloy materials tend to easily form electrochemical corrosion in the corrosive environment.However,by strengthening the surface of the component,the electrochemical corrosion resistance can be effectively enhanced.Laser shock peening is a new type of surface strengthening technology,which can effectively improve the surface mechanical properties and the corrosion resistance of materials.This subject selected6061-T6 aluminum alloy as the research object material,the effects of laser shock peening with different parameters on the corrosion sensitivity of 6061-T6 aluminum alloy in Cl~-solution were studied.The main contents are as follows:(1)The numerical analysis of 6061-T6 aluminum alloy with the different energy and different spot diameters were performed through numerical simulation,which provided relevant research basis for the performance test of laser shock peening.Simulation results showed that:3 J-3 mm?5 J-3 mm?7 J-3 mm and 5 J-2mm laser shock peening specimens had the residual compressive stress values of-100MPa,-120 Mpa,-160 MPa and-140 MPa,and the depth of the residual compressive stress influence were 0.55 mm,0.60 mm,0.85 mm and 0.73 mm,respectively.At a spot diameter of 3 mm,with the increase of the single pulse energy,the greater the residual compressive stress,the greater the depth of the residual compressive stress influence;Under 5 J energy,the smaller the spot diameter,the greater the residual compressive stress,The greater the depth of the residual compressive stress influence.The distribution of high-amplitude residual compressive stress generated by laser shock peening was uniform and stable,and it decayed faster along the shock direction.The distribution in the shock direction exhibited a state of"compress stress-tensile stress-0".(2)Effect of laser shock peening on surface microstructure and mechanical properties of 6061-T6 aluminum alloy under different energy?different spot diameter and different layers with the same energy was studied,which provided the basis for analysis of the electrochemical corrosion sensitivity research.The results showed that:When the single pulse energy was from 3J to 7J,the surface roughness increased from 2.030?m to 3.213?m,the residual compressive stress increased from-70 MPa to-165 MPa,and the depth of the grain refinement layer increased from 80?m to 115?m;Under 5 J energy,at 2 mm and 3 mm spot diameters,the surface roughness were 2.612?m and 2.769?m,the residual compressive stress values were-115 MPa and-145 MPa,the depth of the grain refinement layer were100?m and 115?m;The shock layer from one to three layers,the surface roughness increased from 2.612?m to 8.968?m,the residual compressive stress increased from-115 MPa to-190 MPa,and the depth of the grain refinement layer increased from100?m to 140?m.At a spot diameter of 3 mm,with the increase of the single pulse energy,the greater the surface roughness,the greater the depth of the grain refinement layer;Under the energy of 5 J,the smaller the spot diameter,the greater the surface roughness and the greater the depth of the grain refinement layer;at 5 J-3 mm,as the number of shock layers increased from one to three,the greater the surface roughness,the greater the depth of the grain refinement layer.(3)The electrochemical corrosion resistance of 6061-T6 aluminum alloy specimens treated with single pulse energy under 3J,5J and 7J laser shock peening in a corrosion solution was studied,and the influence on corrosion behavior was analyzed.Experimental results showed that:The open circuit voltages of the untreated specimens,LSP-3 J,LSP-5 J and LSP-7 J laser shock peening specimens were:-0.71V vs.SCE,-0.65V vs.SCE,-0.62V vs.SCE and-0.618V vs.SCE;Self-corrosion potentials were:-1.276V,-1.210V,-1.192V,and-1.041V,and the corresponding self-corrosion current densities were:154.5?A/cm~2,14.3?A/cm~2,11.17?A/cm~2,and9.53?A/cm~2,respectively.At a spot diameter of 3 mm,with the increase of the single pulse energy,the closer the open-circuit voltage was to a positive value,the self-corrosion potential continued to increase,the self-corrosion current density decreased continuously,the impedance spectrum radius continued to increase,and the electrochemical corrosion resistance of material became stronger.(4)The electrochemical corrosion resistance of 6061-T6 aluminum alloy specimens treated by laser shock peeening with different spot diameters of 2 mm and 3 mm under single pulse energy of 5 J in corrosive solution was studied,and the influence on corrosion behavior was analyzed.Experimental results showed that:The open circuit voltages of the untreated specimens,LSP-5 J-2 mm and LSP-5 J-3 mm specimens were:-0.71 V vs.SCE,-0.66V vs.SCE and-0.62 V vs.SCE,the self-corrosion potentials were:-1.276V,-1.216 V and-1.192 V,and the corresponding self-corrosion current densities were:154.5?A/cm~2,14.7?A/cm~2And 11.17?A/cm~2.Compared with 2 mm laser shock peening specimens,the open-circuit voltage and potentiodynamic polarization curves of the 3 mm laser shock peening specimens were more positively shifted,the impedance spectral radius was increased,and the electrochemical corrosion resistance was enhanced.Under the energy of 5 J,when the shock spot diameter was increased,the electrochemical corrosion resistance of the material was enhanced and the corrosion sensitivity was weakened.(5)The electrochemical corrosion resistance of the 6061-T6 aluminum alloy specimen treated by laser shock peening of one layer,two layers and three layers at 5 J-3 mm in corrosive solution was studied,and the influence on corrosion behavior was analyzed.Experimental results showed that:The open circuit voltage of the untreated specimens,LSP-5 J-1 layer,LSP-5 J-2 layers and LSP-5 J-3 layers laser shock specimens were-0.71 V vs.SCE,-0.62 V vs.SCE,-0.58 V vs.SCE and-0.64 V vs.SCE;the self-corrosion potentials were:-1.276 V,-1.192 V,-1.171 V and-1.288 V,and the corresponding self-corrosion current densities were:154.5?A/cm~2,11.7?A/cm~2,13.4?A/cm~2and 31.6?A/cm~2,respectively.When the two layers of laser shock peening were strengthened,the open-circuit voltage and potentiodynamic polarization curves of the materials moved the most forward,the impedance spectrum radius was the largest,and the electrochemical corrosion resistance was the best.When the number of impact layers was not more than two layers,with the increase of the number of shock layers,the electrochemical corrosion resistance of the material increased.While the three layers of laser shock peening,the electrochemical corrosion resistance of the material decreased sharply. |
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