Study On Optimization Of Forming Process And Multi Stage Aging For 7050 Alloy T Shape Section With High Reinforcement And Thin Wall Forgings

With the rapid development of the aerospace industry,the development of lightweight and nearly net forming forged parts have become a general trend,the original steel forgings are gradually replaced by aluminum alloy forgings.In order to reach the further weight loss,aluminum forgings are designed to have a rib structure,widely used in aerospace manufacturing.However,the kinds of forging deformation prone to reinforcement of filling,large deformation load and low heat treatment of comprehensive performance(mechanical properties and corrosion resistance).This topic which the porthole forging cooperatively exploited by Chongqing university and Southwest aluminum group co.,LTD.as the research object.Besides,the finite element simulation software deform was used to study the defects of the shape of the porthole forgings(filling discontent,streamline disorder etc.)and forming load were analyzed,optimized blank shape and formed process parameters,as well as designed isothermal molding die and heating system.At the same time,the influence of different aging heat treatment system on the mechanical properties,resistance to intergranular corrosion and electrochemical corrosion of 7050 aluminum alloy was studied by means of experimental method,and the comprehensive performance of forgings was improved.This article mainly performed on the study from the following aspects:(1)Initially,the paper describes the domestic and foreign research on aluminum alloy high-gluten thin-walled forging process and aging heat treatment research status quo.Then,the three-dimensional model of the porthole part is established,and the structure and craftsmanship of the aluminum alloy porthole forgings are analyzed.The forming process scheme is established and the three-dimensional model of the forging is built according to the part drawing.The hot forging die is pre-designed with the porthole hot forging model.(2)Analysis of portholes forging a metal forming the overall situation,the filling of the tendons and forming load.Optimize the shape and size of the blank,for the forging process in the forming process of the ribs filling and forming a large load problem,put forward a solution.The influence of blank width,mold temperature,loading speed and friction coefficient on the filling performance and forming load of forging bars was analyzed by Deform-2D simulation method.The suitable of each parameter range was determined.(3)Using the finite element simulation software Deform-2D and the response surface method optimization method to establish the second-order substitution on the blank width,the mold temperature,the forming speed and the friction coefficient as the variables,the filling height and the forming load as the objective function;The blank width x2=170mm,the mold temperature x2 = 420 ?,the friction coefficient x3 = 0.26,the forming speed x4 = 1mm·s-1,and the simulation parameters of the optimized parameters are simulated by using the design-expert.By simulating and analyzing the die stress,the isothermal dies were designed and the heating system was constructed preliminary.According to the die stress distribution,the molds manufacture plan was proposed.(4)The influence of different aging heat treatment system on the comprehensive performance of 7050 aluminum alloy was studied and revealed.It was found that the strength and elongation of the samples after the peak aging treatment(T6)were higher than those of the two stage aging(T74)samples.The strength of the RRA treated samples was even higher than that of the T6 aging samples,but the elongation of the RRA treated samples was higher,and the strength and elongation of the sample treated with regression were reduced with the further extension of the regression time.T74 and RRA aging treated samples have better resistance to intergranular corrosion and resistance to electrochemical corrosion than those after T6 aging,and samples after pre-stretching aging(T651 and RRA51-60),but the pre-strentching aging treatment can improve the yield strength of the sample and its tensile strength of the sample is better than that of the sample.