9364

8646

كارشناسي ارشد

مواد - شناسايي و انتخاب مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1393

چهارده،72ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

حميدرضا سليمي جزي، محمدعلي گلعذار

18/9/93

محمود منير واقفي، علي اشرفي

مهندسي مواد

ID8646

Influence of heat treatment parameters on the microstructure and mechanical properties of H11 tool steel Alireza Aghababaei Samani a samani@ma iut ac ir Department of Materials Engineering Isfahan University of Technology 84156 83111 Isfahan IranDegree M Sc Language FarsiDr Hamid Reza Salimi Jazi Assist Prof Supervisor E mail hrjazi@cc iut ac irDr Mohamad Ali Golozar Prof Supervisor E mail golozar@cc iut ac irAbstractThe aim of this research is improving the performance of H11 hot work tool steel by optimizing the heattreatment parameters response surface method RSM experimental design technique was performed tooptimize the heat treatment parameters After the initial investigations three parameters includingaustenizing time and tempreture and tempering temperature were selected from most effective parameters ontoughness hardness and thermal fatigue in order to design the heat treatment experiments A two steptempering with optimum time duration of 2 hours was applied The lowest and highest levels for austenizingtemperatures were 995 C and 1025 C for austenizing time were 60 and 100 and for tempering temperature were 600 C and 670 C Responses including impact energy as a measure of toughness hardness and crackdensity were selected The purpose was to achieve the highest impact energy the optimum hardness 320Vickers and the lowest crack density Hardness measurement impact test and thermal fatigue test wereused Heat treatment cycles were evaluated by scanning electron microscopy EDS analysis X ray diffractionanalysis micro hardness and crack density measurement by image processing software The frequent thermaland mechanical stresses induced on the surface of the substrates caused as a consequent of the stressconcentration in high energy areas such as grain boundaries fatigue crack growth originated from these areasand propagated along the grain boundaries of initial austenite After statistical investigations the austenizingtemperature of 995 C the austinizing time of 100 minutes and tempering temperature of 646 C wereidentified as optimal conditions The average hardness of 320 Vickers average impact energy of 54 J andaverage crack density of 6 8 were obtained after applying the optimum heat treatment cycle Microstructuralinvestigations showed that the finer austenite grain size resulted in greater toughness and more heat checkingresistance Keywords H11 tool steel heat treatment design of experiment heat checking

حميدرضا سليمي جزي، محمدعلي گلعذار

محمود منير واقفي، علي اشرفي