Hot Forming-Quenching Integrated Process Of 2195 Aluminum-Lithium Alloy Large-Size Thin-Walled Curved Component

With the development of Chinese aerospace industry,the lightweight manufacturing of the new generation of carrier rockets is becoming increasingly urgent.Aluminum alloy occupies a large proportion in aviation industry materials due to its light weight and corrosion resistance.The aluminum alloy bottom of rocket tank is the key components affecting the reliability of launch vehicle.Replacing conventional aluminum alloys such as 2A14 and 2219 with 2195 Al-Li alloy can greatly reduce the weight of tank structure.However,the traditional forming method has the problems of easy cracking at room temperature,poor dimensional accuracy and low material utilization rate.Therefore,it is urgent to develop a new process to solve the forming problem of rocket tank bottom.In this paper,a new generation of 2195 Al-Li alloy material is taken as the main research object to study the heating rate and plane thermal distortion of aluminum alloy sheet under different heating methods.The forming process of 2195 Al-Li alloy melon petals curved components was simulated,and the macroscopic deformation behavior and springback law under the integrated forming of melon petals curved components were analyzed;6061 aluminum alloy and 2195aluminum-lithium alloy were used to study the hot forming-quenching integrated process of melon petals curved components,and the development of the bottom melon petals of the rocket tank with ?3350mm was completed.Through the heating experiment of aluminum alloy sheets with different heating methods,the heating rate and plane thermal distortion distribution are explored.The contact heating of aluminum alloy sheet with rigid thermal template is much faster than the radiation heating in the furnace.The fastest heating rate can reach 404.3°C/min,which is about 4.7 times of the radiation heating.The deformation of 250×350×0.5mm aluminum alloy sheet is-9.29?5.35 mm after radiation heating,while the blank of the same size sheet is attached to the template after contact heating,and no obvious thermal deformation is observed.Radiation heating experiments were carried out on aluminum alloy sheets with different thicknesses.It was found that there was no obvious deformation of 10 mm aluminum alloy sheets.The finite element simulation method was used to simulate the hot-states mold forming of melon petals curved components,and the macroscopic deformation behavior and springback law of melon petals curved components under different temperature,number of splits,initial thickness and different material conditions were explored.At the temperature of520°C,the springback of the 2195 aluminum-lithium alloy melon petals curved component with 10 mm thickness,which is divided into 8 petals,is within ±0.6mm,and the maximum thinning rate reaches 1%;Under the same forming conditions,the springback deformation of6061 aluminum alloy melon petals curved components is within ±2.5mm,and the maximum thinning rate reaches 1%.The hot forming-quenching integrated forming platform for the melon petals curved components was established.The integrated forming law of it was experimentally explored by using 6061 aluminum alloy and 2195 aluminum-lithium alloy,and the trial production of the melon petals curved components of 2195 aluminum-lithium alloy with ?3350mm was completed.The results show that large end wrinkling occurs within the round corner of the large end of the mold of 6061 aluminum alloy with the thickness of 5mm,and no wrinkling occurs in 6061 aluminum alloy and 2195 aluminum-lithium alloy with the thickness of 10mm;The maximum thickness-thinning rate of the 2195 Al-Li alloy melon petals curved components with the thickness of 10 mm was 2.1%,and the die-fitness was 0.1mm.The tensile strength of this product after aging was 525?558MPa.