Study On Microstructure Property And Pre-treatment Process Of AA6016 Aluminum Alloy For Automobile

Automotive AA6016 aluminum alloy sheet is the high quality product among aluminum sheet and strip material,which has a series of excellent performances,low density,high strength and superior processing property,having fine corrosion resistance and recyclability,these indicate that,AA6016 aluminum alloy sheet can be preferred materials on automobile for people,which can makes auto lightweight.However,the key heat-treatment equipment and process is monopolized by foreign at present,which has seriously impede the wide production and application of high quality sheet in the domestic.The object of study is AA6016 aluminum alloy sheet in this work,within hot air circulated furnace,Systematically studying on the heat treatment affect on microstructure and property of alloy,through changing the process parameters of solution,pre-aging,pre-strain and paint treatment,so it can provide theoretical support for practical industrial production.The main contents and conclusions are as follows:(1)Through regulating solution time and temperature parameters of the alloy,it indicate that,the second phase particles dissolve into the matrix,and recrystallization process happened correspondingly within extending of time or increasing of temperature for solution treatment,the recrystallization is faster than dissolve of second phase particles apparently.Recrystallization process is basically completed when the solution time is 2.5min at 560?,extending to 3.5min,above 95%of soluble phase has dissolved into the matrix.When the solution time is 3.5min,the alloy has fine property after pre-aging,the Rp0.2 is 100.81 MPa,the value of n is 0.325,this is beneficial to stamping.(2)Through the combination of different process parameters about pre-aging time and temperature,texting the mechanical properties of alloy.It indicate that,the initial Rp0.2 increased within pre-aging time and temperature increasing.The value of BH decreased correspondingly,when the pre-aging time is 8min at 160?,the value of BH is 121.23Ma,and meeting the paint performance.It shows that,the precipitation active energy after pre-aging is lower than natural aging,pre-aging treatment can decrease difficulty of precipitate phase through the calculation of precipitation kinetics.(3)The best amount of deformation is 2%through pre-strain treatment is applied,and carrying on microstructure characterization,calculation of precipitation kinetics,mechanical properties texted.It indicate that,pre-strain will introduce a large number of dislocation into the matrix.?" phase deposition temperature decreased,but the active energy is constant within deformation increasing.An appropriate amount of deformation can improve the value of BH,continued to increase the amount of deformation,the value of BH improve little.For example,2%deformation is 55.64MPa higher than non-deform,but 5%deformation is just 3.66MPa higher than 2%.(4)For the heat treatment parameters already existed,carrying on paint treatment at different temperature.The value of BH is improved with baking temperature increasing,after baking 30min at 175?,BH value is 121.23MPa,the hardness is 94.48,when the temperature is raised to 200?,the value of BH is 169.02MPa,the hardness is 109.82.The shape of ?" which is major strengthening phase in alloy is needle,the width is about 2nm,length is about 20nm,within monoclinic,and remaining coherent basically with matrix.