Mechanical and Microstructure Properties on Al-Cu Joint processed by Friction Stir Welding : The effect of Tilt Angle Tool

The tilt angle tool on Aluminum A5083 and Copper C11000 joint processed by Friction Stir Welding (FSW) was observed in this study. The rotation speed and transverse speed were used as a parameter process for 2500 rpm and 30 mm/min, respectively. The tensile test and microstructure observation were carried out to determine the tensile strength and metal flow on Al-Cu joint, respectively. The result shows that the highest tensile strength was in 2o tilt angle tool for 105 MPa. Its fracture surface was more close to Al and formed brittle formation.The metal flows of Al-Cu with 0o and 2o were not homogeneous and formed an agglomeration of Cu particle to Al surface. Material Science Research India www.materialsciencejournal.org ISSN: 0973-3469, Vol.16, No.(1) 2019, Pg. 56-61 CONTACT Jupri jup.ri11@yahoo.com Department of Mechanical Engineering, Bengkalis State Polytechnic, 28711, Bengkalis-


Introduction
Friction stir welding is one part of solid welding and founded by The Welding Institute in 1991.FSW utilize the heat from friction the tool against the workpiece under the axial pressure of the weld area so as resulting the metal soften, mix and deform, but not the melting of metals. 1,24][5][6] This case was different from fusion welding.[9] Joining material with FSW requires several parameter processes to determine a result of the welding.The tool design can affect the mechanical properties and microstructure of welded joints between Al-Cu. 10,11][14][15][16][17] Mohanty et al. reported that the influence of shoulder and pin probe diameter on the results of welded joints. 180][21][22][23] Threaded pins have the ability to produce and maintain continuous heat [24][25][26] Thus, affecting mechanical properties, [27][28][29] and physical from welded joints. 27,30cording to the best our knowledge, there is a little information about the effect of tool angle on Al-Cu joint processed by FSW.Therefore, the aim of this study was to know the mechanical and microstructural properties of Al-Cu joint fabricated by FSW.The tool material and the welded material were used tool steel H13 and Al A5083-Cu C11000, respectively.

Experimental Procedure (Materials and Methods)
H13 tool steel was produced by means of the annealing process at 845-900 °C and classified into chromium hot work steels due to there are carbide elements such as chromium and vanadium.H13 steel has the toughness and recommended as a tool material due to its resistance to high temperatures.The chemical composition of H13 steel can be seen in Table 1. 31 The aluminum alloy A5083 and Cu C11000 were used as a welded joint material.Aluminum was produced by means of annealing and in the heat treatment process was added 4.5% magnesiumand 0.7% manganese.The addition of elements was to maketolerate ability, rolled ability, improve strength, wear resistance and extrusion. 32

Results and Discussions Tensile Properties
Table 5 shows the mechanical properties of buttjoint welded, wherein the process of Al-Cu joint, theparameters process used were 2500 rpm of spindle rotation speed, 30 mm / min of feeding speed and tool slope angle (0° and 2°).At the Al-Cu joint with a slope angle of 0° the location of the friction stir processed zone is more towards to Al, then on the fracture surface there is a buildup of Cu particles and resulting 90 MPa.
While, Al-Cu joint with a slope angle of 2°, the fractured material location occurs in the friction stir processed zone area towards Al and Cu fractions attached and resulting 105 MPa.The fracture shape of the welded joint with a slope angle of 0° and 2° was brittle due to the shiny surface, there is no necking on the test specimen and extends to form a straight line from the weld joint.The lowest strength of the weld joint on 0° of slope angle due to the non-spread evenly of Al and Cu metal during friction stir welding in the processed zone.

Microstructure
Table 6 displays a microstructural imageof welded joints withslope angles of 0° and 2°.Microstructure C11000 material has 99% Cu content. 33The chemical composition of Cu C11000 can be seen in Table 3.
FSW process was carried out by using a milling machine, the shape of the design tool was trapezoidal and butt-joint welded joints.The FSW joint material was Al A5083 and Cu C11000.The machining parameters and other parameter scan be seen in Table 4.After the welding process then specimen was manufactured which refer to the ASTM E8 / E8M standard for tensile test, 34 and ASM Metal Vol. 9 for microstructure tests. 35bservations were seen through the side, namely top surface(friction stir processed zone.
The microstructure showed differences in the flow of Al-Cu metals.In FSW zone, the Al-Cu flow is not spread evenly due to slight displacement and shaped like a line.While, in the friction stir processed zone, the flow of Al-Cuis not evenly distributed, the transfer of Cu metal to Al is not evenly distributed along the mixing zone and the shape of the surface forms a little zigzag.

Conclusion
Based on the result, we can conclude that: 1.The highest tensile strength was in 2 o slope angle for 105 MPa.This is due to a good Al-Cu flow during friction stir welding in friction stir zone.2.
The microstructural observation showed an inhomogeneous of Al-Cu flow on all side of friction stir processed zone.This research was funded by "LPDP (Indonesia Endowment Fund for Education) from the Ministry of Finance Indonesia with the project name "Master Thesis Research".We also thanks to Ministry of Finance Indonesia for supporting my master study at Andalas University, Indonesia.

Table 1 : Composition limits for hot-work tool steels 31
Table 2 shows the chemical composition of Al A5083.While theCu