4869

4573

كارشناسي ارشد

شناسايي و انتخاب مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1388

دوازده،90ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

محمدرضا طرقي نژاد،فخرالدين اشرفي زاده

30/9/88

عباس نجفي زاده، حبيب دانش منش

مهندسي مواد

ID4573

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Evaluation of Mechanical properties and Texture of Nanostructured Copper Produced by ECAP Farideh Salimyanfard Salim emsc@ma iut ac ir Department of materials engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors M R Toroghinejad toroghi@cc iut ac ir F Ashrafizadeh ashrafif@cc iut ac ir Abstract Equal Channel Angular Pressing ECAP is a severe plastic process for achieving ultrafine grain materials without changing the sample dimensions In this study ECAP process up to 20 passes equal to strain of 12 6 was carried out with different routes A B30 B45 B60 and BC In the ECAP die the inner and outer angles of channel intersection were 120 and 20 respectively Rod copper billets with the purity of 99 9 and 20 mm diameter 80 mm length were used as the experimental material As the cross section of the specimens was circular new routes with rotating angles of 30 45 and 60 in the same direction between consecutive passes were defined Before each pass of the process samples were lubricated with oil and graphite powder As the original dimensions of the sample is unchanged it is possible to repeat the process to high strains Microstructure characterization of 20 passes ECAP samples with routes B30 and BC were analyzed with Field Emission Scanning Electron Microscopy FESEM Tensile tests and hardness measurements were performed on the samples for evaluating their mechanical properties In order to clarify the failure mode fracture surfaces after tensile tests were observed by Scanning Electron Microscopy SEM Moreover x ray diffraction system equipped by goniometer was utilized to investigate the variation of texture of the samples The results indicated that significant grain refinement was obtained by ECAP and the grain size decreased from 49 micron in original material to below 100 nm after 20 passes ECAP with route BC and a few hundred nm in 20 passes ECAP sample with route B30 After six passes the hardness of the sample was almost two times higher than the original sample ECAP process results in significant increase in tensile strength but elongation of the sample becomes less than half although there is no additional reduction in the ductility with increasing ECAP passes In different routes maximum tensile strength was achieved in different passes These properties maybe explained by evaluation of microstructures Different routes result in different textures in ECAP samples Except route A texture produced by other routes is asymmetric In route A texture is symmetry about TD Predominant texture is the same in different passes of route A Maximum intensity in texture is achieved in sample extruded with route BC Key words Angular Extrusion Copper Hardness Tensile Strength Fractography Texture pdfMachine is a pdf writer that produces quality PDF files with ease Get yours now Thank you very much I can use Acrobat Distiller or the Acrobat PDFWriter but I consider your product a lot easier to use and much preferable to Adobe s A Sarras USA

محمدرضا طرقي نژاد،فخرالدين اشرفي زاده

عباس نجفي زاده، حبيب دانش منش