10010

9241

كارشناسي ارشد

شناسايي و انتخاب مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1393

نه، 78ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

فتح ا... كريم زاده، محمدحسين عنايتي

94/2/21

محمدعلي گلعذار، حسين ادريس

1396/09/27

كتابنامه

مواد

مهندسي مواد

ID9241

Development of bimodal structure nano micro on the surface of AISI316 stainless steel alloys by ultrasonic surface nanocrystalization treatment and evaluation its properties Masoud Hosseini Ballam Masoud hosseini@ma iut ac ir Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors Fatollah Karimzadeh karimzadeh f@cc iut ac ir Mohammad Hossein Enayati ena78@cc iut ac ir Abstract One of the newest and most economical methods of grain refining on the surface is the ultrasonic nano crystallization process In this study the properties and microstructure of austenitic stainless steel AISI316 were investigated before and after this new treatment After preparation of specimens the treated zone was recognized by using optical and scanning electron microscopes To confirm the refinement of grains grain sizes in less than 100 nano meter scale were then observed in treated zone by using transmission electron microscope XRD measurements were next performed for untreated and treated specimens and besides the observation of martensite phase in the treated structure the crystallite sizes and their dislocation density were also measured Micro hardness test showed an increase of about 40 percent on the surfaces of specimens after the application of this process Roughness test indicated that the surface flatness of the treated specimens has improved by 15 percent with respect to the untreated one Compressive residual stress at the surface was measured and compared before and after treatment The results showed that about 530 Mpa residual stress of compressive type has been formed at the surface of specimens after treatment which decreases gradually from surface to the depth of 200 micron meters Wear test results illustrated that mass loss percentage wear rate and friction coefficient have decreased by about 46 50 and 50 percent respectively after treatment At the end these results were attributed to sever plastic deformation of the surface and formation of nano crystalline structure at a certain depth of surface and a mechanism responsible for the improvement of mechanical properties of AISI316 steel was proposed Keywords Ultrasonic Surface Nanocrystalization Nanostructure Severe plastic deformation Surface treatment

فتح ا... كريم زاده، محمدحسين عنايتي

محمدعلي گلعذار، حسين ادريس