Study On The Microstructure Homogeneity Regulation And It's Microstructure Evolution Of 7050aluminum Die Forgings

China is in urgent need of large and high-performance die forgings in the fields of national defense,aerospace,shipbuilding,and electric power.However,the problems of uneven structure and performance and low material utilization rate of large die forgings are extremely serious,especially the "H" shaped frame and panel die forgings,whose material utilization rate is less than 30%.The uneven microstructure of large die forgings is apparently caused by uneven deformation temperature field.The essential reason lies in the uncontrollable evolution of the microstructure caused by improper adjustment of deformation and energy storage during the entire process of forgings.Therefore,this paper adopts the low temperature and small deformation process to control the overall structure uniformity of aluminum alloy die forgings,and analyzes the microstructure evolution law of the forgings,revealing the physical nature of the low-temperature small deformation process to improve the uniformity of the aluminum alloy die forgings.It provides a theoretical basis for the adjustment of the microstructure uniformity of aluminum alloy die forgings.This paper first simulates and analyzes the hot die forging process and low temperature small deformation process of 7050 aluminum alloy die forgings,and obtains the temperature field and stress and strain field distribution and evolution of aluminum alloy die forgings,thereby clarifying the hot die forging process conditions for the uneven structure of the aluminum alloy die forgings,as well as the appropriate low temperature and small deformation process window to achieve the purpose of improving the structure uniformity of the aluminum alloy die forgings.Then,Through low temperature and small deformation experiments and thermal treatment,the evolution of the grain structure of the surface and center of aluminum alloy die forgings under different process conditions is analyzed.The results show that the structure of the aluminum alloy die forgings after low temperature small deformation and solution treatment is uniform.The optimal low temperature and small deformation process conditions have been clarified: the mold temperature is 300°C,the preform temperature is200°C,the deformation amount is 16%.And the grain sizes of the surface and center of the forging are 79?m and 76?m,respectively.Finally,the XRD linear Fourier analysis method is used to calculate the dislocation density values on the surface and center of the aluminum alloy forgings under different deformation conditions and heat treatment process conditions.It is found that small deformation and low temperature process can improve the aluminum alloy forgings surface and center of dislocation density,and the dislocation density decreased with the increase of the solid solution time.In addition,this article uses scanning electron microscopy to observe the changes in the proportion of deformation and recrystallization areas of aluminum alloy forgings after low temperature small deformation and solution treatment,and uses transmission electron microscopy to observe the evolution of dislocation morphology in the microcosmic structure of aluminum alloy die forgings,revealing The micro-mechanism of the microstructure uniformity of aluminum alloy die forgings controlled by the low temperature and small deformation process.