پديد آورنده :
بهجتي پورناكي، پيمان
عنوان :
ارزيابي ريز ساختار و خواص مكانيكي فولادهاي آستنيتي شبه پايدار Fe-Cr-Mn-N نانو/فوق ريز دانه شده توسط عمليات ترموديناميكي مارتنزيت
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد
صفحه شمار :
شش،124ص.: مصور،جدول،نمودار
يادداشت :
ص.ع.به فارسي و انگليسي
استاد راهنما :
عباس نجفي زاده، احمد كرمانپور
توصيفگر ها :
فولادهاي آستنيتي , تغيير شكل , دوقلويي , ريز دانه كردن
تاريخ نمايه سازي :
29/2/93
استاد داور :
محمدعلي گلعذار، محمدرضا طرقي نژاد، رامين ابراهيمي
كد ايرانداك :
ID622 دكتري
چكيده انگليسي :
121 Evaluation of microstructure and mechanical properties ofnano ultrafinegrained Fe Cr Mn N metastable austenitic steels prepared by martensite thermo mechanical treatment Peiman Behjati Pournaki p behjatipournaki@ma iut ac ir February 15 2014 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree PhD Language FarsiSupervisors Abbas Najafizadeh181 a najafi@cc iut ac ir Ahmad Kermanpur181 ahmad k@cc iut ac irDepartment Graduate Coordinator Keyvan RaeissiAbstractIn this work microstructure and mechanical properties of metastableaustenitic Fe Cr Mn N steels containing different amount of N less than 0 5wt was studied In addition possibility of application of martensitethermomechanical treatment for grain refinement of these steels down tonano ultrafine range was explored It was observed that stacking faults and martensite needles decreases with N conversely short range ordering anddeformation twinning increases Further it was found that yield strength andhardness of the alloys linearly increases with N In contrast elongation andtensile strength of the alloys changed nonlinearly with increasing N Influenceof N on mechanical properties was mainly related to its effect on solidsolution strength and deformation induced martensitic transformation Martensite thermomechanical treatment was employed to refine themicrostructure of the steels down to nano ultrafine size It was observed thatthe finest austenitic microstructure is achieved in the 0 36 wt N steelreversion annealed at 1173 K 900 C for 100 s with an average grain size ofabout 217 nm However the superior mechanical properties was achieved inthe 0 44 wt N steel exhibiting an ultrahigh strength yield strength of 1324MPa and tensile strength of 1467 MPa with a good elongation of 17 Keywords Austenitic steels Microstructure deformation Martensite Twinning Grain refinement 1 IntroductionAustenitic stainless steels are widely used in many important industries due to excellentformability weldability and work hardening high corrosion resistance and energyabsorption capabilities Fe Cr Ni and Fe Cr Mn N are the main alloying systems ofaustenitic stainless steels Previous investigations are mainly focused on the earlier one However replacement of Ni and improvement of mechanical and corrosion propertieshave caused attention of many researchers towards the later system with a rising trend Most of these studies are devoted to steels with stable austenite and metastable grades havenot received enough attention so far whereas it is known that metastable austenitic steels
استاد راهنما :
عباس نجفي زاده، احمد كرمانپور
استاد داور :
محمدعلي گلعذار، محمدرضا طرقي نژاد، رامين ابراهيمي
