Optimization Of Hot Stamping Process And Fatigue Performance Of 7075 Aluminum Alloy

Due to its light weight,high strength and heat treatment,more and more aluminum alloys are used in automobile body parts.In order to solve the problems of fracture,springback and thermal deformation in the forming process of aluminum alloy sheet,the hot stamping forming technology of heat treatable aluminum alloy sheet is put forward.However,the application of hot stamping is restricted by the long solution and aging time and low production efficiency.In view of the above problems,this paper takes 7075 aluminum alloy as the research object,and studies such aspects as the high-efficiency solid solution process and multi-stage aging process in hot stamping production,the impact of mold temperature on the final comprehensive performance in hot stamping forming and quenching,and the fatigue performance and fatigue fracture mechanism of the alloy under different aging times.Attempt in 7075 aluminum alloy sheet metal surface coating graphite or boron nitride and molybdenum disulfide this three kinds of different coating,and the final mechanical properties compared with bare plate,the results show that the effect is best,graphite coating can make solid solution by conventional heating time of 10 min to 2.5 min,and coating graphite coating in the process of forming quenching can act as a lubricant used,improved in the process of 7075 aluminum alloy hot stamping formability.The effects of different die temperatures on the mechanical properties of hot stamping parts of aluminum alloy were studied,and it was found that the alloy treated with solid solution could be rapidly quenched to avoid dissolving and precipitation,and the solid solution with high supersaturation could be obtained,which laid a foundation for improving the strength of the alloy with aging.When quenching,the cooling rate is too slow,which will reduce the precipitated strengthening phase of the alloy during aging,and the final mechanical properties cannot meet the requirements.By changing the cooling rate of flat die quenching and measuring the final mechanical properties,the upper temperature limit of die quenching is determined.Based on the 7075 aluminum alloy aging time and improve the hot stamping production process continuity requirements,combined with the actual production in the industrial processing of the lacquer that bake,put forward a bipolar aging process,studied the artificialaging and natural aging effect on the final mechanical properties,and put forward the path of7075 aluminum alloy after aging process optimization,make the mechanical properties of7075 aluminum alloy obtained industrial production at the same time,the aging time shorten from 24 h to 2 h.Fatigue is an important factor affecting the life of aluminum alloy parts.In the process of using aluminum alloy products,sometimes there will be no signs of fracture,which is difficult to detect and prevent most of the time.This paper studies the 7075 aluminum alloy after different ageing time and simulation of the lacquer that bake of fatigue strength and fatigue crack propagation properties,and through the scanning electron microscope(SEM)split to observe the microscopic morphology of fatigue fracture,illuminates the fatigue fracture mechanism of 7075 aluminum alloy under different ageing time,provide a reference for the actual production of the aluminum alloy hot stamping process.