| 6016 aluminum alloy sheet is mainly used for the manufacture of automotive panels,especially automotive exterior and interior covers,rear luggage,door frames and other automotive exterior panels.It is the key material for lightweight vehicles.At present,the domestic aluminum alloy sheet still has the problems of formability,anti-concavity,and poor quality of parts after forming,and cannot meet the requirements for use.Therefore,it is very important to improve the forming quality of the plate by performing the key pre-aging process and the stamping forming process of the 6016 aluminum alloy plate.In this paper,the 6016 aluminum alloy(Al-0.55%Mg-1.0%Si-0.18%Cu)plated in545 ~oC solid solution for 30 min was water quenched,pre-aged at 60 ~oC~160 ~oC×5min~30 min,and kept at room temperature for 25 days,and conducted a 185 ~oC×20min simulated baking.Hardness and tensile tests were combined with differential scanning calorimetry(DSC)and scanning electron microscopy(SEM)to study the influence of pre-aging techniques on the mechanical properties and microstructure of the alloy.The actual stamping process was simulated by numerical simulation to predict the quality defects that may occur after the part is formed,and the key process parameters of the forming are optimized.The results show:(1)Pre-ageing immediately after solution quenching can inhibit the natural aging process.Both the formability and the bake hardening performance of the T4P alloy are improved.The hardness before and after baking increases with the pre-aging temperature,and it tends to increase rapidly after first increasing slowly.The pre-aging temperature is 100 ~oC,and the pre-aging time is 20 min.The yield strength of the alloy before baking is less than 120 MPa,the elongation is about 25%,and the yield strength after baking is higher than 180 MPa(pre-deformation 2%alloy bake hardening value Achieved 104 MPa),the elongation after baking is about 22%,comprehensive comparison is better than other pre-aging techniques.(2)The?”precipitation temperature and activation energy were calculated with the DSC curve.It was found that with the increase of pre-aging temperature,the?”precipitation peak left shifted and the activation energy also decreased.This shows that pre-aging can inhibit the natural aging process of the alloy,improve the T4P formability of the alloy,and promote the precipitation of?”in the baking process,and increase the bake hardening effect.(3)Aiming at the inner panel of aluminum automobile engine hood,a stamping CAE model was established to simulate the sheet metal stamping process.The effect of different forming processes on the maximum thinning rate,maximum thickening rate and maximum rebound volume after forming was studied..(4)For the optimization of multi-factors,the best process parameters are obtained through the grey relational analysis:blank holding force 500 KN,friction coefficient 0.1,concave and convex die clearance 1.1 t(1.32 mm),punch speed 3 m/s After the simulation test,there was a small amount of cracking defects.The intelligent optimization algorithm is further used to optimize the continuous space to obtain the optimal solution:blank holder force 243 KN,friction coefficient 0.11,convex and concave die gap 1.06 t(1.272 mm),and punch speed 8.68 m/s.In-situ stamping test,no cracking defects occurred,and wrinkles on the flange surface could be removed in the subsequent trimming process.The forming quality was good and was in accordance with the simulation results. |
PDF Full Text Request