6728

6279

كارشناسي ارشد

شناسايي و انتخاب و روش ساخت مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1390

سيزده، 93ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

مرتضي شمعانيان، احمد ساعتچي

1/3/91

فخرالدين اشرفي زاده، مسعود عطاپور

1396/10/06

كتابنامه

مواد

مهندسي مواد

ID6279

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Dissimilar Welding of UNS S32750 Super Duplex Stainless Steel AISI 316L Austenitic Stainless Steel and Evaluation of Microstructure and Corrosion Behavior Mahdi Amini m amini@ma iut ac ir Date of Submission 2012 02 20 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors Morteza Shamanian shamanian@cc iut ac irAhmad Saatchi asaatchi@cc iut ac irAbstractIn this study microstructural characteristics and corrosion behavior of UNS S32750 super duplex stainlesssteel AISI 316L austenitic stainless steel dissimilar weldments were evaluated In order to weld the samplesgas tungsten arc welding process with direct current electrode negative polarity GTAW DCEN was appliedwith AWS ER2594 as the filler metal Since heat input plays an important role in the evolution of austenitic ferritic microstructures welding was done at several heat inputs and the effects of heat input onmicrostructural evolution and corrosion resistance of weld zone were investigated The effects of post weldheat treatment at 1125 C were also studied The microstructures were identified using optical microscopy OM and scanning electron microscopy SEM The corrosion resistance was evaluated throughpotentiodynamic polarization and cyclic polarization tests in 3 5 NaCl solution at ambient temperature Theresults showed that an increase in the heat input in a range of 660 825 J mm can lead to increase of the weldmetal austenite content from 60 79 to 74 47 A heat affected zone with about 200 micrometers width wascreated in UNS S32750 super duplex stainless steel base metal due to welding thermal cycles On the otherhand some delta ferrite was formed in the heat affected zone of AISI 316L base metal According to theelectrochemical tests UNS S32750 super duplex stainless steel presented excellent corrosion resistancecomparing AISI 316L austenitic stainless steel which was attributed to its high chromium and molybdenumcontent The UNS S32750 super duplex stainless steel exhibited higher corrosion potential lower corrosioncurrent density and very higher pitting potential than the AISI 316L austenitic stainless steel Evaluation ofweld metals corrosion behaviors showed that increase of austenite content was lead to reduction of generalcorrosion resistance but pitting corrosion resistance was not varied In general the UNS S32750 superduplex stainless steel and weld metals exhibited alike pitting potentials 1 0 Vsce Theoric investigationsbased on several criteria indicated that galvanic corrosion between AISI 316L austenitic stainless steel andweld metal was significant Corrosion resistance of UNS S32750 super duplex stainless steel was notseverely affected by solution annealing heat treatment 1125 C 2hr however post weld heat treatment insame condition improved pitting resistance of weld metals Post weld heat treatment increased pittingpotential of weld metal about 25 mVsce Finally it should be mentioned that using AWS ER2594 filler metaland heat input control can lead to a weld metal with a better corrosion resistance than the base metals Sincethe corrosion resistance of weld metal can not be altered significantly by post weld heat treatment it is notrecommended for this dissimilar joint Keywords Super duplex stainless steel Austenitic stainless steel Dissimilar welding Heat treatment Microstructure Corrosion behavior

مرتضي شمعانيان، احمد ساعتچي

فخرالدين اشرفي زاده، مسعود عطاپور