International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 11, November 2018, pp. 1600 1607, Article ID: IJMET_09_11_165 Available online at http://www.iaeme.com/ijmet/issues.asp?jtype=ijmet&vtype=9&itype=11 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 IAEME Publication Scopus Indexed IMPACT OF COOLING PROCESS ON FSWED OF 6061 T6 ALUMINUM ALLOYS WITH CHANGING TOOL GEOMETRY Kamarapu Santhosh Assistant Professor, Department of Mechanical Engineering, S R Engineering College, Warangal, Telangana-506371, India. ABSTRACT In the present investigation we had considered that the impact of the geometry of tool profile and the outcome of tool revolution and coolant on the mechanical and microstructural properties of friction stir welded joints made for tests of aluminum combinations. The friction stir weldability, surveyed by weld imperfection investigation and weld quality characterisation, will be identified with the particularly extraordinary plastic behaviour of both base materials. The outcomes acquired from the performed tests demonstrated that tools with created pins created predominant mechanical properties for the FSW joints. It was additionally discovered that general mechanical reaction relied upon the proportion of the tool rotation speed to the tool traverse speed. Keywords: revolution and coolant, FSW joints Cite this Article: Kamarapu Santhosh, Impact of Cooling Process on Fswed of 6061 T6 Aluminum Alloys with Changing Tool Geometry, International Journal of Mechanical Engineering and Technology, 9(11), 2018, pp. 1600 1607. http://www.iaeme.com/ijmet/issues.asp?jtype=ijmet&vtype=9&itype=11 1. INTRODUCTION Friction-stir welding (FSW) is a solid-state joining method that is energy and eco-friendly and adaptable [1]. FSW intersections have high fatigue strength; require fewer preparation [2]. These welds have fewer flaws than fusion welds and the process enable the welding of metals [3]. The FSW process factors and tool factors having major role deciding the strength of the joint [4]. Peer learners are already made an attempt to establish process factors relations between tool geometry and welding speed, axial force, Pin diameter, hardness of the tool [5]. They also discussed the detection and analysis of acoustic emission signals as a possible technique for the in process monitoring of the FSW process [6]. Studied microstructures of FSW joints between an aluminium-base metal matrix composite and a monolithic aluminium alloy [7]. The liquid phase has the traditional form of grain boundary films in the thermo mechanical process zone [8]. Authors studied a continuous dynamic recrystallization during FSW of high strength aluminum alloys with different cooling techniques [9]. The joints made by straight cylindrical pin profile tool resulted in very much smaller equiaxed grains compared to base material. It is observed that microhardness increases than as received Aluminum alloy. It is seen that all the tensile properties http://www.iaeme.com/ijmet/index.asp 1600 editor@iaeme.com
Kamarapu Santhosh of FSWed Al is increased as compared with the as-received Al alloy [10]. It is revealed that using with specified geometrical tool shapes then increasing the rotational speed decreases UTS, YS and % EL [11]. It is observed that increase in volume percentage of TiB2, microhardness increases up to 132 Hv and which is higher than as-received Aluminum alloy (104 Hv). This is due to fact that at 1120 rpm, tool shoulder supplied enough heat input and shear force to make the reinforcement particles more easily wrapped by the softening metal and rotated with FSP tool which results in well separation and distribution in the nugget zone [12]. 2. EXPERIMENTATION FSW is a mixing of two traditional manufacturing process such as extruding and forging and it is become an artificial welding for the new age joining problems of metals. The FSW procedure contains the construal of a turning rotating cylindrical tool along the edge between two plates. The weld is framed by the misshaping of the material at temperatures beneath the liquefying temperature. In this study in the first step, Aluminum plates of 200x300x5mm dimensions, were joined by reconfigured milling machine. Tool was rotated at 900 rpm and the tool was fixed to head without keeping any angle and used three tool geometrical shapes triangle, square, circle and shoulder plunge depth of 3mm below the plate surface. By fixing tool given rotation on the clockwise direction, the base plate which were tightly fixed at the backing plate, were travelled. The test piece was fixed onto a steel plate horizontally. Welding direction was perpendicular to the rolled direction of the Aluminum plates. Figure 1: SCHEMATIC ILLUSTRATION OF THE FSW PROCESS 2.1. MICROSTUCTURAL ANALYSIS Micro structural changes from the weld zone to the unaffected base metal were examined with the optical microscope. Specimen preparation has become a long established art in the optical microscopy of materials, particularly in the fields of metallurgy and mineralogy. For optical microscopy, cross sections were polished and etched using a Keller s reagent. After preparation steps, all specimens investigated with optical microscope and photographed on the base and near the weld zone. Polished and etched Al parts photographed to investigate for this study. Optical photographs are taken in 5X, 10X and 45X scales from optical microscope with capture. At higher magnifications, the optical micrographs show extremely fine and equated grains in the recrystallized zones. 2.2. EVALUATION OF THE HARDNESS TEST Hardness tests were conducted on Rockwell hardness machine on the welded joints to examine on the HAZ. Hardness test followed by ASTM E 10-93. The hardness tests were conducted on the static tests specimens, at intervals of 5 mm along the mid-plane of the plates. http://www.iaeme.com/ijmet/index.asp 1601 editor@iaeme.com
Impact Of Cooling Process on Fswed of 6061 T6 Aluminum Alloys with Changing Tool Geometry 2.3. EVALUATION OF TENSILE TEST The tensile behaviour of the different tools welded specimens, were examined by conducting tensile tests on specimens of each types. The test was performed on the Universal Testing Machine. Table below shows the average tensile test results with each joint condition. 3. RESULTS AND DISCUSIONS (a) (b) (c) Optical micro structural analysis of FS WELDED base metal (a) (b) (c) Optical micro structural analysis of friction stir welded joint obtained by circular shaped probed tool (without heat treatment) (a) (b) (c) Optical micro structural analysis of FS Welded joint obtained by the square shaped tool. (Without heat treatment) (a) http://www.iaeme.com/ijmet/index.asp (b) (c) 1602 editor@iaeme.com
Kamarapu Santhosh Optical micro structural analysis of FS Welded joint obtained by the triangular shaped probe tool (without heat treatment) Optical micro structural analysis of friction stir welded joint obtained by circular Shaped probed tool (with heat treatment) Optical micro structural analysis of FS Welded joint obtained by the square shaped tool. (With heat treatment and air cooling) Optical micro structural analysis of friction stir welded joint obtained by triangular Shaped probed tool (with heat treatment and air cooling) Optical micro structural analysis of friction stir welded joint obtained by circular Shaped probed tool (with heat treatment and water cooling) http://www.iaeme.com/ijmet/index.asp 1603 editor@iaeme.com
Impact Of Cooling Process on Fswed of 6061 T6 Aluminum Alloys with Changing Tool Geometry Optical micro structural analysis of FS Welded joint obtained by the square shaped tool. (With heat treatment and water cooling) Optical micro structural analysis of friction stir welded joint obtained by triangular Shaped probed tool (with heat treatment and water cooling) Figure 2: Representing the Micrographs of three different types of tools (a) with heat treatment of air cooling (b) without heat treatment (c) with heat treatment of water cooling 4. HARDNESS TEST Rockwell hardness test was conducted on the FSWed aluminium joints. The variations in the measured hardness values are respectively plotted in Figures. AIR COOLING ON SQUARE air cooling on circular air cooling on triangle hardness 35 30 25 20 15 10 5 0 0 10 20 30 40 Series1 hardness 35 30 25 20 15 10 5 0 0 10 20 30 40 Series1 hardness 35 30 25 20 15 10 5 0 0 10 20 30 40 Series1 distance in mm distance in mm distance in mm Figure 3: Representing the Rockwell hardness test conducted on the FSW plates with different tool profiles. (Air cooling) http://www.iaeme.com/ijmet/index.asp 1604 editor@iaeme.com
Kamarapu Santhosh Figure 4: Representing the Rockwell hardness test conducted on the FSW plates with different tool profiles. (Water cooling) 5. TENSILE TEST From the results obtained it has been noticed that the strength of the specimens is much lower than that of the base metal. The weld obtained by the circular probe tool showed better results in comparison with the square and triangular shaped probes. The fracture was produced in the weld zone. Figure 5: showing the tensile test specimen of Heat treatment & air cooling, without heat treatment and heat treatment with water of circular tool profile Figure 6: showing the tensile test specimen of Heat treatment & air cooling, without heat treatment and heat treatment with water of square tool profile http://www.iaeme.com/ijmet/index.asp 1605 editor@iaeme.com
Impact Of Cooling Process on Fswed of 6061 T6 Aluminum Alloys with Changing Tool Geometry Figure 7: showing the tensile test specimen of Heat treatment & air cooling, without heat treatment and heat treatment with water of triangle tool profile 6. CONCLUSION The present examination showed that FSW welding of commercial grade aluminium alloys can be successfully performed so as to achieve desired properties with the FSW process using 10 mm/min welding speeds and 900 rpm. Based on the analysed results we had drawn some conclusions that are explained: Circular tool pin profile gives higher tensile strength and shows fine grains at weld centre. Square tool pin profile gives higher hardness. Triangular tool pin profile gives higher % of elongation. The Rockwell hardness tests have been conducted on the welded joints and base materials, in which Rockwell hardness number 30 is reached in the centre weld by circular tool, 28 in case of square probe and 29 in case of the triangular probe in air cooling and also which ranges from 25 to 28 in water cooling and was found that the hardness is more for the water cooled specimens.s The tensile behaviour of the base materials and the FSW joints has been examined by conducting tensile tests on specimens that are FSWed with different tool pin profiles. REFERENCES [1] Su, J. Q., Nelson, T. W., Mishra, R., and Mahoney, M. Microstructural investigation of friction stir welded 7050-T651 aluminium. Acta Mater. 2003, 51(3), 713 729. [2] Mishra, R. S. and Ma, Z. Y. Friction stir welding and processing. Mater. Sci. Engng Rep., 2005, 50(1-2), 1 78. [3] Rajakumar, S., Muralidharan, C., and Balasubramanian, V. Optimization of the friction stir welding process and tool parameters to attain a maximum tensile strength of AA7075-T6 aluminium alloy. Proc. IMechE, Part B: J. Engng Mf. 2010, 224(8), 1175 1191. [4] Dawes, C. J. and Thomas, W. M. Development of improved tool designs for friction stir welding of aluminium. In Proceedings of the 1st International Friction Stir Welding Symposium, Thousand Oaks, California, 14 16 June 1999. [5] Sato, Y. S., Urata, M., and Kokawa, H. Parameters controlling microstructure and hardness during friction-stir welding of precipitation-hardenable aluminum alloy 6063. Metall. Mater. Trans. A, Phys. Metall. Mater. Sci., 2002, 33, 625 635. [6] Lee, W. B., Yeon, Y. M., and Jung, S. B. Evaluation of the microstructure and mechanical properties of friction stir welded 6005 aluminum alloy. Mater. Sci. Technol., 2003, 19(11), 1513 1518. http://www.iaeme.com/ijmet/index.asp 1606 editor@iaeme.com
Kamarapu Santhosh [7] Lim, S., Kim, S., Lee, C. G., and Kim, S. J. Tensile behavior of friction-stir-welded Al 6061- T651. Metall. Mater. Trans. A, Phys. Metall. Mater. Sci., 2004, 35, 2829 2835. [8] Liu, F. C. and Ma, Z. Y. Influence of tool dimension and welding parameters on microstructure and mechanical properties of friction-stir-welded 6061- T651 aluminum alloy. Metall. Mater. Trans. A, Phys. Metall. Mater. Sci., 2008, 39, 2378 2388. [9] B.aditya, A.devaraju, B.manichandra. Impact of dry ice cooling on microstructure and mechanical properties of FSW 2014 AA., ISSN 2321-581X.volume -9 2018. [10] Harish Akarapu., Devaraju.A.,Sathish Kumar.B. Effect of Friction Stir Welding process parameters on microstructure and Tensile properties of 6061 Aluminium alloy. Volume 2, Issue 12, Page No(s) 552-557, DEC. 2015, [ISSN(Print):2348 7968] [11] Kamarapu Santhosh., Aruri Devaraju. Practices in fsw welding and Investigate effect of tool turning Speed on tensile properties and Microhardness of dissimilar Aluminium alloys 2024 & 6061. Volume 8, Issue 11, Page No(s) 165-172, Nov. 2017, [ISSN(Print):0976 6340] [12] V. Kishan, Aruri Devaraju., K. Prasanna Lakshmi. Tribological Properties of Nano TiB2 particle Reinforced 6061-T6 Aluminum Alloy Surface Composites via Friction stir processing." in Materials Today: Proceedings Elsevier, Volume 5, Issue 1, Page No(s) 1615-1619, FEB. 2018, [ISSN(Print):2214-7853] http://www.iaeme.com/ijmet/index.asp 1607 editor@iaeme.com