5481

5141

كارشناسي ارشد

شناسايي و انتخاب مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1389

چهارده،111ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

محمدرضا طرقي نژاد، فخرالدين اشرفي زاده

24/7/89

علي شفيعي، احمد كرمانپور

مهندسي مواد

ID5141

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

112 Effect of ARB process and ageing heat treatment on the microstructure and mechanical properties of 6061 aluminum alloy Mohammad Reza Rezaei mr rezaei@ma iut ac ir April 14 2010 Department of Materials Engineering Isfahan University of Technology 84156 83111 Isfahan IranDegree M Sc Language FarsiDr Mohamad Reza Toroghinejad Assoc Prof Supervisor E mail toroghi@cc iut ac irDr Fakhreddin Ashrafizadeh Prof Supervisor E mail ashrafif@cc iut ac irAbstractAccumulative roll bonding ARB is a severe plastic deformation process to produce high strength metallicsheets with ultra fine grains On the other hand ageing heat treatment is one of the methods for improvingmechanical properties of metals In this study ARB process was carried out on 6061 aluminum alloy sheetsup to 5 cycles at room temperature without lubrication Then ageing heat treatment was carried out in twocycles 160 C for 5 hours and 100 C for 48 hours The quality of roll bonding produced in ARB wasinvestigated using scanning electron microscopy SEM and peeling test Microstructures during ARB andageing treatment were characterized by transmission electron microscopy TEM By using Rietveld method microstructural parameters such as microstrain and dislocation density were quantitively analyzed Tensiletests and Vickers microhardness were measured on produced sheets SEM fractography was also performedin order to clarify the failure mechanism Moreover the texture parameter of the ARBed samples wascalculated using their XRD patterns and the related equation Additionally the texture evolution during ARBprocess was demonstrated by analyzing the measured pole figures orientation distribution functions ODF and skeleton lines The SEM observations and peeling test results revealed that the bonding strength of theARBed sheets was acceptable except those bonds formed in the last cycles After five cycles it was foundthat continuous recrystallization has occurred and the microstructure was covered with the ultrafine equiaxedgrains of an average diameter about 230 nm Three phenomena including grain subdivision formation oflamellar boundaries LBs parallel to the rolling direction and continuous recrystallization in siturecrystallization were identified to be responsible for the grain refinement The tensile strength and hardness

محمدرضا طرقي نژاد، فخرالدين اشرفي زاده

علي شفيعي، احمد كرمانپور