Effect Of Rolling Process On Microstructure And Fatigue Crack Growth Rate Of 2060 Al-Li Alloy

Al-Li alloy has the advantages of low density,high elastic modulus,high specific strength and stiffness,good corrosion resistance and welding performance.It is a promising structural material in the field of aerospace.As a very dangerous failure form,fatigue failure often leads to catastrophic casualties and economic losses.Therefore,improving the fatigue performance of Al-Li alloy plays an important role in ensuring the structural safety of aircraft in the service cycle.In this paper,the effects of rolling temperature and rolling deformation on the mechanical properties and fatigue crack growth rate of 2060 Al Li alloy were studied by hardness,room temperature tensile test and compact tensile C(T)specimens.The microstructure and fracture surface of 2060 Al Li alloy were analyzed by optical microscope(OM),scanning electron microscope(SEM),electron backscatter diffraction(EBSD)and transmission electron microscope(TEM),so as to reveal the relevant mechanism.The main conclusions are as follows:(1)The effect of rolling temperature and deformation on the grain structure of rolled plate after solution treatment was studied.When the rolling temperature rises from room temperature to 480 ℃,the grains of the rolled plate with 50% deformation after solution treatment change from fine short rod like grains to mixed fibrous and equiaxed grains,and the recrystallization degree decreases from 67.1% to 34.8%.When the rolling temperature is 480 ℃,the deformation increases from 50% to 83%.After solution treatment,the grain of the plate gradually changes into fine short rod grain,and the recrystallization degree increases from 34.8% to 59.4%.(2)The effect of rolling temperature on the fatigue crack growth rate after solution aging was investigated.The hot rolled plate mainly propagates through the grain,and the fatigue crack propagation rate is the slowest,followed by the hot rolled plate,and the cold rolled plate has the fastest fatigue crack propagation rate.(3)The effect of rolling deformation at 480 ℃ on the fatigue crack growth rate after solution aging was revealed.The fatigue crack growth rate of 70% hot rolled plate is the slowest,50% hot rolled plate is the second,and 83% hot rolled plate is the fastest.