10397

9592

كارشناسي ارشد

جوشكاري

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1394

چهارده، 99ص.: مصور، جدول

مرتضي شمعانيان، حسين ادريس

مسعود عطاپور

1394/06/07

فتح الله كريم زاده، عبدالمجيد اسلامي

1396/10/04

كتابنامه

مواد

مهندسي مواد

ID9592

به فارسي و انگليسي

96 Joining of UNS S327850 stainless steel by friction stir welding and gas tungsten arc welding and evaluation microstructure and mechanical properties Seyed Mohammad Ahl Sarmadi m ahl@ma iut ac ir Date of submission 2015 6 14 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors M Shamanian Shamanian@cc iut ac irH Edris h edris@cc iut ac irAbstractSuper duplex stainless steel is a kind of duplex stainless steel that has over 40 pittingresistant equivalent number UNS S32750 is a common super duplex stainless steel Thathas a lot of applications in oil industries Therefore joining of these steel by welding isimportant and a most common problem in welding of these materials is decrease incorrosion resistance and mechanical properties after welding In this research UNSS32750 has been joined by friction stir welding FSW and gas tungsten arc welding GTAW method The tool that used in this research is made of WC with 16mm shoulderdiameter and 5mm pin diameter For GTAW method the AWS ER2594 has been used asthe filler metal Having a lower heat input for both methods X ray diffraction showed thatno harmful phases such as Sigma and Chi had been formed in the weld zone Themicrostructure indicated grain refinement with reduced size in the stir zone Moderatemicrohardness of base metal was 285 Vickers but in the stir zone microhardness increasedto 360 Vickers The cyclic polarization test determined that potential and current density ofjoint metal by friction stir welding method was similar to base metal For GTAW weldedspecimens the microstructure showed that final austenite phase was grown in ferritematrix with dendritic structure Hardness in weld zone of GTAW welded specimendecreased to 250 Vickers because of increase in austenite volume percentage However because of decrease in austenite volume percentage and precipitation of chromiumcarbides the hardness increased in heat affected zone HAZ The microstructure figurerevealed that ferrite percentage in stir zone didn t decrease very much in comparison toGTAW because in FSW process the heat input is much lower The cyclic polarization teston GTAW welded specimens showed that increasing in heat input increases the pittingcurrent density Additionally increasing heat input in GTAW process results in moredecrease in hardness and tensile strength because of increase in grain size of weld zone Keywords Super duplex stainless steel Friction Stir Welding Gas Tungsten Arc Welding Microstructure Mechanical properties

مرتضي شمعانيان، حسين ادريس

مسعود عطاپور

فتح الله كريم زاده، عبدالمجيد اسلامي