عنوان :
ارزيابي امكان توليد فولاد فوق ريز / نانو دانه با شروع از ساختار بينيتي از طريق فرايند ترمو مكانيكي
مقطع تحصيلي :
كارشناسي ارشد
گرايش تحصيلي :
شناسايي و انتخاب مواد فلزي
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد
صفحه شمار :
دوازده، 88ص.: مصور، جدول، نمودار
يادداشت :
ص.ع. به فارسي و انگليسي
استاد راهنما :
عباس نجفي زاده، احمد كرمانپور
توصيفگر ها :
فولاد كم كربن , نانو ساختار , فرايند مكانيكي-حرارتي , بينيت , نورد سرد , آنيل
تاريخ نمايه سازي :
1/3/91
استاد داور :
محمدعلي گلعذار، علي شفيعي
تاريخ ورود اطلاعات :
1396/10/06
چكيده فارسي :
به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي
چكيده انگليسي :
89 Evaluating the Production of the Nano Ultrafine Grained Steel with The Bainitic Starting Microstructure by Thermomechanical Treatment Mahdi Hamzeh M hamzeh@ma iut ac ir Date of Submission February 28 2011 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors A Najafizadeh Prof and A Kermanpur Assoc Prof AbstractIn recent years there is a growing interest in developing the third generation of advanced highstrength steels including stainless steels for light weight constructions Properties of materialsespecially their mechanical properties are strongly affected by grain size Hall Petch equationrepresents this effect That s why nowadays grain refinement is one of the important subjects inenhancing mechanical properties This method is the only way that improves strength and toughnesssimultaneously Steels are attractive alloys in this area because of their wide use in industry Different researchers invented many process for grain refining of steel Between those severe plasticdeformation and thermomechanical treatments gained more attention In theromechanical treatmentcontrol of rolling and microstructure are done in specific procedures to create ultrafine grain size One of these processes is cold rolling and annealing of product phase Cold working increases thestored energy and with subsequent annealing static recrystallization will take place that will lead to asignificant grain refinement the annealing process involving nucleation and growth of new strain free and equi axed grains in the microstructure of a plastically deformed metal The grain size of arecrystallized metallic material depends on the rates of nucleation and subsequent growth of therecrystallized grains Martensite is a phase used in this process martensite process But it is a brittlephase that induces cracks near the edge of the specimen during rolling Bianite is similar tomartensite in formation mechanism but is tougher than martensite Bainite consists of small packetsof lath like ferrite grains with low misorientation between the grains and high angle boundariesbetween the packets consequently bainite as a Prerefine structure have high grain boundary density Therefore in this study we have tried to represent a simple process for grain refining For thispurpose thermomechanical treatment was done on low alloy low carbon steel Thermal treatmentswere austenizing at 925oC for 45 60 minute and isothermal transformation in 3 differenttemperatures in molten salt bath for 30 minute The best temperature for isothermal transformationwas 410oc that produced 90 bainite Mechanical treatment was included 90 cold rolling of thebainite Rolling induced a lamellar structure with thickness of 410 nm Then Annealing was done in500 700oC with temperature interval of 50oC Results showed that recovery was the main softeningprocess during annealing at 500 and 550oC With annealing of lamellar structure at 650oC for 120minute and 700oC for 10 minute static recrystallization take placed and grains with mean grain sizeof 550 and 560 nm were obtained respectively KeywordsLow alloy low carbon steel Ultrafine thermo mechanical treatment Bainite Coldrolling Annealing
استاد راهنما :
عباس نجفي زاده، احمد كرمانپور
استاد داور :
محمدعلي گلعذار، علي شفيعي
