| The 7050 aluminum alloy based on 7075 is a new kind of high toughness,high strength,and anti-corrosion aluminum alloy due to the development of heat treatment.Its main alloy components of Zn,Cu and Mg are optimized;and Zr is added instead of Cr and Mn;the contents of Fe and Si are substantially reduced impurity.7050 aluminum alloy is low density,high specific strength and toughness,good processing property and formability,lower cost,etc.And it has been widely used in transportation and other high stress structure parts requiring lightweight,high strength and good corrosion resistance.The strength of the alloy is high while the corrosion resistance of the alloy is poor,and this is not helpful to improve the performance of materials.which is not conducive to the comprehensive properties of the materials.In this paper,The microstructure and mechanical properties were studied by using optical microscopy(OM),scanning electron microscopy(SEM)and tensile test,and the experimental research on the corrosion performance of two-stage solution,single aging.I study The effects of two-stage solid solution treatment,single-stage aging and two-stage aging heat treatment on the microstructure evolution,mechanical properties and corrosion behavior of 7050 high strength aluminum alloy.In order to provide some theoretical basis and experimental basis for the comprehensive properties and industrial application of the alloy.The main conclusions are as follows:①The solid solution heat treatment temperature of 7050 aluminum alloy at high temperature of 450℃ was established.The single solid solution and the low temperature pretreatment stage at 450℃ can only make some low melting point of the second phase particles dissolved in the alloy matrix,solid solution effect is not satisfied,the performance of the alloy is not obvious.Compared with the single solution,the eutectic temperature of the single-stage solution temperature cannot exceed the alloy,and two-stage solution heat treatment can exceed the maximum limit temperature of single solid solution,and the alloy has not been burned.②the two-stage solution heat treatment can improve the properties of the alloy.The second phase particles in the alloy thick can more dissolved into the matrix,at the same time,the second level of solution temperature increased from 475℃ to 495℃,The alloy residual coarse second phase volume fraction decreased from 1.346% to 0.206%,the saturation level of alloy increases gradually,strengthening enhancement effect.When the first stage solution is 450 ℃/1h,and the solid solution is at a temperature of 495℃/1h,the decrease of the number of the second phase in the alloy is the most obvious,and the effect is the best.The strength of the material is σb=591MPa,δ=14.16%,and the conductivity is 41.01%IACS when the alloy is treated by two-stage solid solution and two stage aging at 450℃/1h+495℃/1h,120℃/8h+160℃/24 h.③According to the corrosion test,the corrosion resistance of the alloy is reduced in accordance with the order of the two aging time.In dual aging 120 ℃/8h+160℃/24 h heat treatment,In the high temperature phase of double aging treatment,with the aging time expand,the corrosion type alloy by intergranular corrosion gradually turned to intergranular corrosion,the corrosion rate of alloy loss increases;but the corrosion potential of the material increases,improving the corrosion resistance of alloy.the alloy intergranular corrosion corrosion depth is 46μm,grade 3. |
