4872

4576

كارشناسي ارشد

ريخته گري

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1388

ده،95ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

محمود مرآتيان، احمد كرمانپور

محمد حسين فتحي

30/9/88

بهزاد نيرومند،رحمت ا... عمادي

مهندسي مواد

ID4576

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Evaluation of the Investment Casting Parameters on Microstructure and Wear Behavior of Biocompatible F 75 Cobalt Base Alloy Hossein Ghazvinizadeh Hogha168 @yahoo com April 2009 Department of Material Science and Technology Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSuppervisors M Meratian Mmeratian@cc iut ac ir A Kermanpur Ahmad k@cc iut ac ir AbstractThe ASTM F 75 cobalt base alloy is widely used as a surgical implant material due to its highcorrosion and wear resistance and biocompatibility The alloy is usually produced by investmentcasting method In this work effects of mold preheating temperatures type of mold materialsand pouring temperature on the as cast microstructure and wear behavior of the alloy werestudied The investment cast specimens were solutionized for 1 and 4 h at 1220 C followed byisothermally aging for 7 and 10 h at 850 C Samples were characterized by optical microscopy scanning electron microscopy X ray diffraction differential thermal analysis macro hardnessand wear test Effects of the casting parameters on as cast microstructure and wear behavior ofthe alloy was also simulated by using ProCAST software The size of secondary dendrite armspacing in as cast microstructure was measured and compared to the simulated results TheSDAS grain size volume fraction of carbides ratio of the volume fraction of blocky carbides tothat of eutectic carbides in the microstructure were slightly decreased when the type of mold wasslightly changed although the wear behavior and hardness of the alloy were not changed in thiscondition The predicted results were in good agreement with the measured ones In fact thecooling capability of molds A and B was in the same order According to the result of this model several mold preheating temperature such as 550 700 850 and 1000 C was selected The resultsshowed that increasing the mold preheating temperature led to considerable change of thevolume fraction of carbides in grain boundaries increasing of average grain size from 50 to 150 m and SDAS and improving of wear behavior of the alloy The results showed that change ofpouring temperature from 1430 to 1490 C led to the coarsening of dendrites and increasing ofSDAS The solution heat treatment resulted in removing of eutectic carbides appropriatedistribution of blocky carbides and grain growth The main structural change observed as a resultof aging was the face centered cubic Fcc to hexagonal close packed Hcp martensitictransformation that led to improvement of wear behavior The volume fraction of thetransformed hcp martensite was a function of time and temperature According to theexperimental and modeling results investment casting of the F 75 alloy using mold A at moldpreheating temperature of 1000 C and pouring temperature of 1470 C were determined as theappropriate casting conditions Keywords Investment cast Co alloy Microstructure Wear behavior pdfMachine Is a pdf writer that produces quality PDF files with ease Produce quality PDF files in seconds and preserve the integrity of your original documents Compatible across nearly all Windows platforms if you can print from a windows application you can use pdfMachine Get yours now

محمود مرآتيان، احمد كرمانپور

محمد حسين فتحي

بهزاد نيرومند،رحمت ا... عمادي