5923

5538

كارشناسي ارشد

خوردگي و حفاظت از مواد

اصفهان: دانشگاه صنعتي اصفهان،دانشكده مواد

1389

نه،138ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

مرتضي شمعانيان، احمد ساعتچي

كيوان رئيسي

25/2/90

علي اشرفي، احمد كرمان پور

مهندسي مواد

ID5538

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Effect of the Pulsed Current in the GTAW process on Corrosion Behaviour of AA5083 Aluminum Alloy Welds Ebad Rastkerdar e rastkerdar@ma iut ac ir Date of Submission 2010 07 12 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 work AA5083 plates were welded using two different methods including ConstantCurrent Gas Tungsten Arc Welding CCGTAW and Pulsed Current Gas Tungsten ArcWelding PCGTAW In both methods sampeles welded with AC and square wavecurrent In order to calculate heat input of welding with AC some relations in bothmethods were obtained Cyclic potentio dynamic polarization susceptibility tointrgranular corrosion NAMLT test and Mott Scotky tests were performed onweldments In order to design potentiodynamic experiments evaluate the effect of eachpulse welding parameters on corrosion resistance of weldments and extract the optimumconditions for welding parameters to achive higher pitting potential Taguchi approach Qualitek software and a L8 array were used Microstructural analysis and micro analysisof base metal heat affected zone HAZ and weld metal were charactersied with scanningelectron microscope SEM and energy dispersive spectroscopy EDS Results showedthat the anodic and cathodic pericipitations in pulsed welded sampeles were less andsmaller than other observed in constant current welded sampeles Although anodic andcathodic precipitations in HAZ grain boundries which were continues in constant currentwelded joints became discreet Results of cyclic polarization showed better corrosionresistance in pulse welded joints The susceptibility to intergranular corrosion testsshowed that three pulse welded sampeles with relative heat input 0 64 0 73 an 0 74 werenot susceptible to intergranular corrosion but the constant current welded joints weresusceptible Mott Scotky analysis showed that passive filmes on AA5083 aluminumalloy in 3 5 NaCl solutions is a n type semiconductor and HAZ of the weldments havemore oxygen vacancies in their passive films HAZ of the pulsed welded joints have lessoxygen vacancies than HAZ of the constant current welded joints Keywords pulse welding alloy AA5083 pitting corrosion Taguchi approach

مرتضي شمعانيان، احمد ساعتچي

كيوان رئيسي

علي اشرفي، احمد كرمان پور