آزمايش عملي و شبيه سازي فرآيند فورج حالت نيمه جامد آلياژ AL6061

چكيده انگليسي :

Experimental Investigation and Simulation of Forging Process for 6061 Al Alloy in Semi Solid State Gholamhossian Aboutalebian g abootalebian@me iut ac ir Date of Submission 2013 01 28 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mehran Moradi moradi@cc iut ac irAbstractIn this thesis forging process of AL6061 in the semi solid state has been experimentally investigated with solidvolume fractions of 0 6 0 7 0 8 and 0 9 and various ram speeds 2 5 and 7 mm min The commercialDEFORM 3D finite element software is used to model the forging process of a cylindrical rod This software istotally used at different deformation methods such as forging rolling In these simulations material model inmacroscopic scenario at high solid volume fraction is considered as viscoplastic when its liquid volumefraction ignored The Sellars and Tegart constitutive model is used to determine material behavior in thissoftware It is assumed that workpiece is able to deform plastically but molds are rigid In addition to frictioncoefficient between specimen and dies is fixed and based on Coulomb s model In the thesis the linearrelationship between temperature and solid volume fraction is considered and that is the case in this study Because of the axisymmetry geometry of experiment only one fourth of the specimen is simulated For theexperimental tests STM 150 compressing and pulling machine is used In order to run simple compression test 6061 Al alloy samples with 10 mm in diameter and 18 mm in height are prepared using turning machine Thesample preparation was based on ASTM STP 608 standard The samples have been put into machine furnaceand heated for 10 min to reach target temperature There are several thermocouples inside the furnace to controlthe temperature gradient inside the chamber and a thermocouple to measure specimen temprature The uppermold compressed the specimen for 10mm To compare simulation and experimental results force stroke curvesare obtained in both processes and the whole solid volume fractions and various ram speeds that are maintained The results show that there are good agreements between simulation and experimental curves at ram speeds of2 5 and 7mm min and solid volume fractions of 0 6 0 7 0 8 and 0 9 They also show that the deformation trendin semi solid state is totally depends upon strain rate It can t be used higher ram speeds in experimental process because the material doesn t have enough time to deform and it collapses Furthermore the semi solid forgingis compared with solid and hot forging simulation By analyzing of results it can be claimed that deformationtrend in semi solid state is totally different with solid and hot forming process In the next section a specimenwith difficult shape is simulated in semi solid state and compared with solid forging This comparison showsthat forging in semi solid state is more useful for complicated forming KeywordsSemi solid state AL6061 alloy force stroke curves viscoplastic forging

ابوطالبيان، غلامحسين

آزمايش عملي و شبيه سازي فرآيند فورج حالت نيمه جامد آلياژ AL6061

نمودار نيرو - جا به جايي , ويسكوپلاستيك