Effect Of Thermal Deformation On Microstructure And Properties Of Arc Additive 7050 Aluminum Alloy

The emerging arc additive manufacturing technology can form complex components,and has the advantages of high manufacturing flexibility,fast forming speed,and low cost in small batches.However,the components manufactured by this technology have low dimensional accuracy,uneven internal structure,and defects such as pores and microcracks,which result in poor mechanical properties and low service safety of arc additive components,and it is difficult to meet the high standards of aviation industry products.The above-mentioned problems limit the application scope of arc additive technology.At present,it is difficult for a single optimized arc additive manufacturing process to make a substantial leap in performance.Studies have shown that the performance of arc additive components is significantly improved after thermal deformation,which is expected to solve the above problems.This article takes the arc additive 7050 aluminum alloy as the research object,and uses the Gleeble-1500D thermodynamic simulation test machine to test it at a temperature of 360?-450?,a strain rate of 0.001 s^-1-1 s^-1,and a deformation of 20%-60%.Perform a thermal compression test.The influence of temperature and strain rate on the characteristics of true stress-true strain curve in the process of hot compression was studied,and the constitutive equation of arc-added 7050 aluminum alloy hot deformation was established.The microstructure characteristics of the arc additive 7050 aluminum alloy before and after thermal deformation were analyzed by optical microscope and scanning electron microscope equipment.Based on the above research results,through DEFORM-3D software,the finite element analysis of the arc additive 7050 aluminum alloy isothermal forming process is carried out,and the distribution characteristics of the equivalent stress and equivalent strain are analyzed during the isothermal forming process.The arc additive 7050 aluminum alloy was used as the blank to conduct isothermal forming tests.The metal filling behavior of arc additive 7050 aluminum alloy under high temperature conditions,and the effect of isothermal forming and heat treatment on the microstructure and properties of arc additive 7050 aluminum alloy are studied.The research in this paper shows that there are many pore defects in the arc additive7050 aluminum alloy material.After high temperature thermal deformation,the internal pore defects in the material are significantly improved.Under the conditions of deformation temperature of 420?and strain rate of 0.01 s^-1,when the deformation is20%,some pores inside the material are healed,and when the deformation is 40%,the pores inside the material are basically healed.The conditions for critical dynamic recrystallization of arc additive 7050 aluminum alloy during hot compression are deformation temperature T?390?and strain rate (?)?0.1 s^-1.After arc additive 7050aluminum alloy isothermal forming and solution aging treatment,the tensile strength along the vertical direction is 246.9 MPa,which is an increase of 76%,and the elongation is still less than<1%.The horizontal tensile strength is 570.1 MPa,an increase of 168%,reaching the standard for forgings,and the material elongation rate has increased to 3.9%.After arc additive 7050 aluminum alloy isothermal forming and heat treatment,the main reason that the mechanical properties along the vertical direction did not reach the expectation is that there are pore defects in the microstructure that are not fully healed.