The Organization And Performance Of The Electrolysis Of Titanium Car Of Al-mg-si Sheet

In this paper, aiming to obtain the Al-Mg-Si auto sheet, five kinds of auto sheets were produced with electrolytic low-titanium aluminium alloys. The effect of Mg, Si content and heat treatment process on the microstructure and mechanical properties of the Al-Mg-Si sheets are investigated using microscope, Transmission Electron Microseope(TEM), Scanning Electron Microscope (SEM), X-ray Energy-Dispersive Spectrocopy (EDS), Diferential Scanning Calorimeter(DSC), microhardness measurement, tensile testing, and X-Ray Difraction methods. The results may have an important theoretical and practical significance to the application of electrolytic low-titanium aluminium alloys in auto sheets.The results show that with the increasing of excess Si content in the alloys, the size of the secondary phasse precipitates is decreased and the distribution is densified. Both strength and elongation are increased before baking. After baking, however, the increasing trend of strength decreases and the change of elongation is trifling. Therefore, it is beneficial to the formability and performance of sheets when alloys contain certain content of excess Si. The reason is that excess Si decreases the Mg/Si mass ratio of the precipitates and increases the size of the precipitates,which results in the increase of age hardening.With the increase of Mg₂Si content in the alloys, the size of the precipitates is increased and the distribution is densified obviously.The reason is that the amount of effective precipitates is increased. Though the strength of sheets is increased with raising Mg₂Si content before or after baking, the trend of the increase of strenth is more obvious after baking. The elongation is somewhat decreased other than that of the sheets treated by T4P procees is increased. Therefore, raising the Mg₂Si content in the alloys can increase the performance while keeping the formability of sheets. Based on the results of tensile testing, a linear regression analysis of the yield strength data for all the alloys gives the following relations:T4 process: YS(MPa) = 211.31─77.66 × Mg/Si+43.97 × (Mg%);T6 process: YS(MPa) = 207.50─19.05 ×Mg/Si+136.31 × (Mg%);T4P process: YS(MPa) = 188.90-37.55 × Mg/Si +15.43 × (Mg%); T4P+ baking process: YS(MPa) = 144.56-23.50 × Mg/Si+152.23 × (Mg%).