Study On The Hot-press Forming Process Of 7075 Aluminum Alloy Sheet

7075 aluminum alloy is widely used in aerospace and automotive fields because of its high specific strength,low density and corrosion resistance.The results show that the plasticity of aluminum alloy is poor at room temperature,and it is difficult to form complex parts.However,in hot forming,the flow stress is reduced,the deformation resistance is reduced,and the quality and accuracy of formed parts can be improved.Therefore,more and more attention has been paid to the research of hot forming in the field of sheet metal forming,but at present,there is little research on the mechanical properties and process parameters of 7075 aluminum alloy hot forming.Therefore,this paper studies the mechanical properties and forming quality of 7075 aluminum alloy by hot forming process.The main contents are as follows:Study on the mechanical properties and constitutive equation of 7075 aluminum alloy in hot forming.Under the conditions of 440?,460?,480?,500?,strain rate of 0.001s^-1,0.01s^-1,0.1s^-11 and rolling direction of 0°,45°and 90°respectively,the effects of heating temperature,strain rate and rolling direction on the properties of7075 aluminum alloy were studied.The results show that the resistance of 7075aluminum alloy increases with the increase of temperature The tensile strength and yield strength decreased;the higher the strain rate,the greater the tensile strength;when the rolling direction is 0°,the tensile strength is the highest,followed by 45°,and the lowest is 90°.The mechanical properties of 7075 aluminum alloy were determined by fitting the real stress-strain curves obtained from the hot drawing experiment,and the Arrhenius plastic constitutive equation between different deformation temperature,strain rate and flow stress was established.Numerical simulation and experimental verification of 7075 aluminum alloy anti-collision beam.The influence of friction coefficient,heating temperature and forming speed on forming quality was studied by numerical simulation of 7075aluminum alloy impact beam hot stamping.The results show that the hot stamping process has little influence on the springback of the formed parts of the anti-collision beam;with the rise of temperature,the thinning rate of the sheet metal shows an upward trend;the friction coefficient has a greater influence on the thinning rate,the larger the friction coefficient is,the larger the thinning rate is;with the rise of the forming speed,the thinning rate also shows an upward trend.It can be seen that when the heating temperature is 460?,the friction coefficient is 0.1,and the forming speed is 50mm/s,the quality of the forming parts is the best.According to the influence of process parameters on the thinning rate,the regression prediction model of thinning is established.After hot stamping experiment on 7075 aluminum alloy anti-collision beam,the square difference between the measurement results and the prediction results is 0.79,which verifies the rationality of the prediction model.Study on the mechanical properties and microstructure evolution of 7075aluminum alloy crash beam after forming.In this paper,the unidirectional tensile test of 7075 aluminum alloy hot stamping anti-collision beam forming parts is carried out,and the mechanical properties of the formed parts are studied.The results show that:with the rise of temperature,the material properties,yield strength and tensile strength of the formed parts of the anti-collision beam decrease with the rise of temperature,while the elongation after fracture first increases and then decreases;the change of material properties with different holding time is obtained In addition,with the increase of holding time,the yield strength,tensile strength and elongation after fracture of the formed parts of the anti-collision beam increase.The microstructure of7075 aluminum alloy anti-collision beam after hot stamping was observed,and the accuracy of the mechanical properties of the formed parts was verified.The results show that the microstructure is fibrous,which conforms to the tensile effect of the sheet metal.During the temperature of 460?⁵00?,the higher the temperature,the less the precipitation of the second phase,which shows that the mechanical properties are reduced.The longer the holding time is The longer the structure is,the easier dynamic recrystallization will occur and the fine grain strengthening effect will be achieved.