7075-T T6 .[1] "2 " [2] [3]. [4]. "3 " [5]. [6] [7] Fig. 1 Rotational friction welding machine overview [1]. [8].

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1 mme.modares.ac.ir 7075T6 2 *1 1 2 mzohoor@kntu.ac.ir *. 7075T (t 1) (N) (t 2) (P 2) (P 1) : : : Investigation of cross sectional geometry on temperature and properties of welded area in the rotational friction welding process for AL7075T6 Mehdi Zohoor*, Seyed Masoud Seyed Amirkhani Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran * P.O.B , Tehran, Iran, mzohoor@kntu.ac.ir ARTICLE INFORMATION Original Research Paper Received 01 June 2016 Accepted 26 June 2016 AvailableOnline06August2016 Keywords: Friction Welding Rotational Speed Temperature Element Method ABSTRACT In this paper, the effect of different workpiece geometries on the properties of welded Al7075T6 parts in rotational friction welding process has been investigated by using experimental and finite element approaches. Welding process is continuous drive friction welding. In this research, the samples diameter was selected equal to 25 mm and the samples length was selected equal to 75 mm. The process variables such as friction time (t1), forging time (t2), friction pressure (P1) and forging pressure (P2) were assumed to be constant, whereas rotational speeds were variable and selected equal to 2000 rpm and 2500 rpm. Three cylindrical parts with different cross sectional geometries were adopted as three samples. Finally, to verify the accuracy of numerical analysis, the experimental and thermomechanical simulation results were compared and good agreement was found between them. Since an experimental test is a time consuming and a costly process, it was decided to obtain more results by using an alternative method such as finite element simulation technique. Results of this study showed that changing in front geometric of workpiece is an effective factor for tensile strength, length of workpiece and generated flash in welded area and by changing this factor, properties of welded area can be improved Pleasecitethisarticleusing: : M.Zohoor,S.M.SeyedAmirkhani,InvestigationofcrosssectionalgeometryontemperatureandpropertiesofweldedareaintherotationalfrictionweldingprocessforAL 7075T6,ModaresMechanicalEngineeringVol.16,No.8,pp.1320,2016(inPersian)

2 7075T T (F) (S) (M) (N). "2" (P 2 ) (P 1 ). 1 (t 2 ) (t 1 ) 75 (a) "2" 25(b) 12.. ".. "1 1 (SS) (FF). "3" (FM) Fig. 1 Rotational friction welding machine overview [1]. [1] [1] ().. ) ( :....[2] [3]. [4]. [5].. [6]. [7] [8]

3 7075T6 7075T "4" FF.. "5" FF SS. FM.. FF SS FM FM. Fig. 2 Geometries o welded samples. 2 Table 1 Welding process parameters. t 2 (s) t 1 (s) P 2 (MPa) P 1 (MPa) N (rpm) Table 2 The sample details in welding process. (mm) 10 (mm) 5 (mm) 10 (mm) 5 Fig. 4 The welded samples T6 3 Table 3 Chemical composition of 7075T6 alloy (wt. %) Mn Mg Fe Cu ) Zn Cr 0.21 Ti 0.17 Al 88.5 Si 0.38 Fig. 5 The length of welded samples. 5 Fig. 3 Three types of samples prepared for welding: (1) Simple geometry (SS); (2) Geometry with hole on the workpiece (FF); (3) Geometry with pin and hole on the workpiece (FM) (SS) 3 (FM) (FF)

4 7075T6 (2 (1 :.[10]. "8 " [11] "9" "10" ). 1 (ASTME8 "6" SS FM. FM FF "7 ".. FF 7075T6. [9] Fig. 6 The tensile strength of welded samples. 6 Fig. 8 The failure of welded samples 8 1 Vickers Fig. 7 The cross section of broken welded part in 2500 rpm

5 ..... "11".[13] 7075T : [14] (1) = + [1 + ln][1 ( ) ]. (1).. (1) "10".. FM. w.[12,10] FF Fig. 9 Measured points of hardness distribution along the axis. 9 Fig. 11 The relationship between the variables in continuous rotational friction welding [1] Von Mises Fig. 10 Hardness distribution along the axis

6 7075T6 Fig. 12 Axial Shortening of samples in experiment result and simulation result. 12. FM FM "14" FF. "14" SS. "14 " FF. SS FM..«[1 + ln]».«[1( ) ]» T W/m 2 K D8RT "12" 2000 SS "13" "14". [15] 7075T6 4 Table 4 The JohnsonCook model coefficients for 7075T6 alloy. T m A B n C m C) (MPa) (MPa) Fig. 13 (a) The results of finite element simulation, (b) The experimental results. (b) (a) 13 [16] 7075T6 5 Table 5 Material properties of aluminum alloy 7075T6. T=480 T=300 T=200 T=100 T=20 C C C C C Al 7075T6 (MPa) (Wm 1 c 1 ) (kgm 3 ) (JkgK 1 ) 1 Convection 2 Coulomb

7 7075T6 Fig. 14 Temperature diagram of welded samples (simulation results). ) 14 Fig. 15 Stress distribution across the crosssection of three samples at a rotational speed of 2500 rpm. 15 SS FM FM FM SS 2500 FF. 7075T6 FM SS FF FF. FF F. SS M FF FM. "15" FF SS. FM FF FM... FF T6. FM. FF

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