Study On Twin Roll Casting Process And Microstructure And Properties Of AA6022 Aluminum Alloy Strip

Aluminum alloy is an important automotive lightweight material,and 6000 series aluminum alloy can be used as automobile cover material because of its excellent comprehensive performance.At present,the main production method of aluminum alloy automobile plate is the traditional ingot hot rolling method,but compared with the twin-roll casting technology,there are shortcomings such as long process flow,high energy consumption and high cost,so the production process of the aluminum alloy car plate by the twin-roll casting technology has very good application prospects.The AA6022 aluminum alloy slab with two different thicknesses of 5mm and 20mm was produced by using the twin-roll casting process.The effects of rare earth Ce on the microstructure and properties of the cast-rolled plate were studied.It is hoped that by increasing the thickness of the cast-rolled plate and adding the appropriate amount of rare earth Ce,to solve the casting slab prone segregation problems,resulting in the following conclusions:1)The optimum technological parameters of the twin-roll casted 5mm sheet are as follows:casting speed 1.2m/min,casting temperature 690?;the optimum process parameters of twin-roll casted 20mm slab are:casting speed 0.4m/min,casting temperature 690?.2)The segregation of 20mm cast-rolled slabs has been greatly improved compared to the 5mm cast-rolled sheet.The ductility and formability of 20mm cast-rolled slab after rolling and T4P heat treatment are better than those of 5mm cast-rolled sheet.3)Rare earth Ce has a significant impact on the microstructure and properties of AA6022 aluminum alloy cast-rolled plates.And The optimal addition amount is 0.1%(mass fraction);the dendrites are the main part of the structure,and the dendritic spacing is obviously refined;meanwhile the segregation is greatly improved.After pre-aging,the elongation after break is the highest,and fracture surface is dominated by large and deep dimples;meanwhile,the yield strength is the lowest,and the lacquering sclerosis is the best.And the volume fraction of advantageous texture is the largest;the r value is the largest.4)In AA6022 aluminum alloy twin-roll casted plate,the second phase in the matrix includes Mg2Si,CuAl2,AlMnFeSi and ?(Al)+Si,and so on.After adding a certain amount of rare earth Ce,some secondary phases containing Ce such as AlSiMgCe phase,Al(Ce,Fe)MnSi phase and Al4Cu2Ce phase are formed in the aluminum alloy matrix5)The effect of Al-Ti-B on the microstructure of AA6022 aluminum alloy twin-roll casted plate was different from that of Ce.The microstructure was dominated by equiaxed rose crystals.After adding Al-Ti-B,the macroscopic segregation was greatly improved.There was no macroscopic segregation zone with continuous large area,but microsegregation is more serious.And the impact on performance is relatively poor.