10453

9648

كارشناسي ارشد

شناسايي و انتخاب مواد

اصفهان: دانشكده صنعتي اصفهان ، دانشكده مهندسي مواد

1394

شانزده، 100ص.: مصور، جدول، نمودار

رحمت اله عمادي

مرتضي شمعانيان

1394/07/01

علي اشرفي، مسعود عطاپور

1396/10/04

كتابنامه

مواد

مهندسي مواد

ID9648

به فارسي و انگليسي

252 Investigation the effect of friction stir welding on modificationmicrostructure and mechanical properties of 5052 aluminum alloy welded by gas tungsten arc welding Sajjad Ghatei Yousefi S ghateiuosefi@ma iut ac ir 2015 07 12 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Rahmatollah Emadi Associate Professor remadi@cc iut ac irAbstractFusion welding methods like gas tungsten arc welding GTAW have high heat inputwhich can cause problems like porosity in the solidified weld metal and grain growth in theheat affected zone and hence deterioration of the mechanical properties of fusion weldedjoints Friction stir processing FSP is an effective method to modify the microstructureand mechanical properties of fusion welded joints In the present study an Al5052 sheetwith the thickness of 2 mm was first welded by GTAW method with AC current parallel torolling direction Then FSP was employed to modify the as cast microstructure of weldmetal and improve the mechanical properties of welded joints Parameters investigated inthe FSP were tool rotational speed 800 1250 and 1600 rpm and tool traverse speed 12 25 and 40 mm min Among the joints modified with these parameters the samplemodified with the rotational speed of 800 rpm and traverse speed of 25 mm min exhibitedthe best mechanical properties Results of microstructural studies performed by opticalmicroscopy and scanning electron microscopy demonstrated that modification of GTAwelded joints by FSP leads to the refinement of the dendritic microstructure of GTAWprocess and dissolution of precipitates and grain refinement in the stir zone The hardnessof base metal and weld metal after GTAW were respectively 60 and 70 HV whichincreased to 95 HV after modification with the traverse speed of 25 mm min and rotationalspeed of 800 rpm Tensile test results showed that the elongation for the base metal andGTA welded joint were respectively 16 and 17 5 perpendicular to the rolling direction which increased to 24 after FSP with the traverse speed of 25 mm min and rotationalspeed of 800 rpm Moreover the value of elongation for the base metal and GTA weldedjoint were respectively 15 and 21 in the rolling direction which increased to 31 afterFSP with the traverse speed of 25 mm min and rotational speed of 800 rpm Fractographyof the fractured surfaces of all samples showed the presence of dimples which indicatedthat the major fracturing mechanism was ductile The dimples were finer in the modifiedsamples compared with those observed in the fractured surfaces of base metal and GTAwelded specimens Keywords Al 5052 alloy Gas tungsten are welding Friction stir processing Microstructure Mechanical properties Fractography

رحمت اله عمادي

مرتضي شمعانيان

علي اشرفي، مسعود عطاپور