پديد آورنده :
اعتصامي، عليرضا
عنوان :
بررسي تحولات فازي آنيل بين بحراني فولاد مارتنزيتي و فريت - مارتنزيت نورد سردشده
مقطع تحصيلي :
كارشناسي ارشد
گرايش تحصيلي :
انتخاب و شناسايي مواد
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد
صفحه شمار :
يازده، 109ص.: مصور، جدول، نمودار
يادداشت :
ص.ع. به فارسي و انگليسي
استاد راهنما :
محمدحسين عنايتي
استاد مشاور :
ابوذر طاهري زاده
توصيفگر ها :
فولاد دوفازي , آستنيت سوزني , آستنيت چند وجهي , تبلور مجدد فريت
تاريخ نمايه سازي :
3/3/94
استاد داور :
محمدرضا طرقي نژاد، احمد كرمانپور
تاريخ ورود اطلاعات :
1396/10/02
چكيده انگليسي :
332 Investigation of phase transformation during intercritial annealing from as quenched martensite and cold rolled marteniste Seyed Alireza Etesami a etesami@ma iut ac ir Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor M H Enayati ena78@cc iut ac irAdvisor A Taherizadeh a taheri@cc iut ac irAbstractDual phase DP steels have been receiving a great deal of interest in the automotive industries Conventional process for the production of DP steels is the treating ferrite pearlite or cold rolled ferrite pearlite microstructure in the intercritical temperature region for a specific time followed by quenchingto room temperature Previous research showed that the mechanical properties of these microstructuresare not proper candidate as the initial microstructure for the production of DP steel While the mechanicalproperties of DP steels produced from the initial martensitic microstructure are suitable for the DP steelformation To study the phase transformation of martensite in the intercritical annealing the ferrite pearlite microstructure is annealed at 900 C for 1800 s Then the marteniste microstructure is hold at740 C and 770 C for different time The results illustrated that during the intercritical annealing themartensitic structure changes to the tempered martensite with carbides CrC The increasing andintercritical annealing leads to the formation of acicular and globular austenite The globular austenitepreferably nucleates at four and three grain junctions and covers prior austenite grain boundaries Theacicular austenite also nucleates at prior austenite grain boundaries and grows to the ferritic regions Alonger annealing time leads to the coarse globular and thick acicular austenite The globular and acicularaustenite formation is controlled by the diffusion and bainitic mechanism Additionally the cold rolledfeerite martensite structure is cold rolled to 80 and then annealed at 740 C 770 C and 800 C fordifferent time The hardness increases decreases and then increases by increasing annealing time Increasing decreasing and then increasing hardness is due to the formation of carbides recrystallizationand formation of austenite respectively The recrystallization process proceeds much faster withincreasing the annealing temperature Increasing holding temperature leads to the much more austeniteformation Activation energy for the ferrite recrystallization and austenite for the formation is 84344 5and 58059 2 J mol Keywords Dual phase steel acicula austenite globular austenite intercritical annealing ferriterecrystallization
استاد راهنما :
محمدحسين عنايتي
استاد مشاور :
ابوذر طاهري زاده
استاد داور :
محمدرضا طرقي نژاد، احمد كرمانپور
