The objective of the report is to investigate the feasibility and reliability of additivefrictionstirmanufacturing of 7055aluminumalloy. This is a technique in which multiple lap welds are performed to create a three-dimensional part out of relatively thin plate aluminum. To accomplish this, a four inch stack of 7055aluminumalloy lap welds must be created. The solid weld nugget is then machined out of the center of the welded stack to create ASTM approved subsize tensile coupons. Rockwell hardness, yield strength, ultimate tensile strength, and percent elongation information is gathered from the tensile coupons to investigate the effectiveness of the additivefrictionstirmanufacturing process. The data shows that the additive manufactured material experiences a significant reduction in strength and percent elongation while not showing any significant response to heat treatment. Suggestions are made regarding possible changes to the weld schedule that could improve the material properties of the additive manufactured aluminum.
exponent and poor uniform elongation. In contrast, the fully annealed O samples possessed excellent ductility and a larger work hardening exponent but suﬀered from lower tensile ﬂow stress. Note that though the manufacturing careers of the aluminum sheets prior to FSP were diﬀerent (H14 and O), little diﬀerence could be recognized between H-FSP 1:1 par
FrictionStir Welding (FSW) is a new welding method that could applied for wide range of metals and alloys compared to conventional welding methods. FSW could apply for same or different types of materials like brass, mix copper and titanium as well as aluminum. In addition, wide different type of machine in different type of application and material areas could be used in FSW like longitudinal, horizontal and vertical in manufacturing area like the floor panel of modern train or ships. Furthermore, FSW has wide applications in modern automotive industries.
The aluminium alloy AA2219 (AleCueMg alloy) is widely used in the fabrication of lightweight structures with high strength-to-weight ratio and good corrosion resistance. Welding is main fabrication method of AA2219 alloy for manufacturing various engineering compo- nents. Frictionstir welding (FSW) is a recently developed solid state welding process to overcome the problems encountered in fusion welding. This process uses a non-consumable tool to generate frictional heat on the abutting surfaces. The welding parameters, such as tool pin profile, rotational speed, welding speed and axial force, play major role in determining the microstructure and corrosion resistance of welded joint. The main objective of this work is to develop a mathematical model to predict the corrosion resistance of frictionstir welded AA2219 aluminium alloy by incorporating FSW process parameters. In this work a central composite design with four factors and five levels has been used to minimize the experimental conditions. Dynamic polarization testing was carried out to determine critical pitting potential in millivolt, which is a criteria for measuring corrosion resistance and the data was used in model. Further the response surface method (RSM) was used to develop the model. The developed mathematical model was optimized using the simulated annealing algorithm optimizing technique to maximize the corrosion resistance of the frictionstir welded AA2219 aluminium alloy joints.
tool and the base metal to flow, and under the action of extrusion of the tool, the welding seam is formed. Recently, FSW is the major aircraft manufacturing enterprises due to the reduction of the molten defects in the welded joints and the improvement of the welding quality [1-3]. Aircraft operation environment is bad, especially the international long distance transport aircraft. The aircraft always fly in the changing environment, sometimes in the harsh environment. The corrosion has a great impact on the plane because of long exposure in the atmosphere. As the aircraft structures, the corrosion resistance of aluminumalloy becomes one of the hottest researches [4-7]. Yong et al.  studied the stress corrosion behavior of frictionstir welding joint using slow strain tensile and electrochemical corrosion of 7A52 aluminumalloy, and find out that impressed cathodic polarization increases the stress corrosion index of 7A52 aluminumalloy. Zhang et al.  studied the corrosion properties of the welded joints of 2219 aluminumalloy in 3.5% NaCl solution, and pointed out that the corrosion resistance of the frictionstir welding joint is superior to those of other fusion welding joints. Lu et al.  prepared a layer of micro-arc oxidation film on the surface of frictionstir welding joints in 5083 aluminumalloy, showed that the micro-arc oxide film layer could improve the corrosion resistance of joint. Ji et al.  investigated the corrosion resistance of frictionstir welding joints of 5383 aluminium alloy, showed that the corrosion resistance welded joint S line is the worst. Hu et al.  studied the corrosion resistance of frictionstir welding joint of LY12 aluminumalloy in 3.5% NaCl solution, and find out that the corrosion resistance of the heat affected zone is the worst, the corrosion resistance of heat-affected zone is the best. Dong et al.  studied the corrosion resistance of frictionstir welded joint of 2A12 aluminumalloy coated with aluminum layer in the solution of 0.2 mol/L NaHSO 3 + 0.6 mol/L NaCl at room temperature, and pointed out that the package aluminum
The steady state welding stage is modeled in the Eulerian formulation, where materials flow into the computational domain with the prescribed welding speed while the tool stays at the same location with only the rotational motion. Solid state metals are treated as non-Newtonian fluids with high viscosities. Accordingly the flow field belongs to laminar regime and the viscosity is a function of temperature and strain rate. Aluminum and steel are treated as different phases. Based on the topology of phase distribution, multiple phase flow can be categorized into two general groups: separated flow and dispersed flow. In the former one, different phases are continuous and separated by a clearly-defined interface. The latter group corresponds to flow of discrete phases, such as bubbles, droplets and particles, in a continuous primary phase. According to experimental observations of weld cross section macrostructure in Chapter 3, both aluminum and steel are basically continuous. Only a small amount of steel or intermetallic compound particles are dispersed in the aluminum matrix. However, the quantity and sizes of these particles are small, which are neglected in the current model for simplification. The dissimilar FSW process is therefore modeled as a separated multiple phase flow problem.
Frictionstir welding (FSW) process is a solid state joining process in which a non-consumable tool is used to generate frictional heat in the abutting surfaces. The welding parameter such as welding speed, tool rotational speed, and tool profile plays a major role in deciding the weld joint strength. In this investigation, effect of welding parameters and tool pin profile on Mechanical properties in AA6061 aluminium alloy was studied. Frictionstir welding of aluminium alloy plates with a thickness of 6 mm are used to perform FrictionStir Weld joints. Tapered cylindrical, and square pin profiles have been used to fabricate the joints at three different rotational speeds i.e. 1500, 2000 and 2500 rpm with two traverse speeds of 20 and 40 mm/min. The mechanical properties (tensile strength, hardness) of the joints have been evaluated and analysed. It has been observed that the design of tool pin profile has considerable effect on tensile properties. Square pin profile tool produces the best tensile properties compared to tapered cylindrical tool pin profiles.
Abstract -FrictionStir Welding is a solid state joining technique which is widely being used for aerospace, marine, automotive and other applications for joining similar and dissimilar metals. Compared to other welding techniques FSW produces better mechanical properties in the weld zone. The main objective of this article is to investigate the similar joints of AA8011 alloy mechanical behavior with different process parameters. Three major factors at three levels namely tool angle, rotational speed and weld speed are considered for the present study. The uncontrollable factors include ultimate tensile strength, percentage of elongation which can be converted to signal-to noise ratios, by using Taguchi method used to optimize the factors. The ultimate tensile strength and percentage of elongation values for different combinations are noted from the response table and we get the optimum rank for the process parameters. Hence the prediction of the optimum process parameters using Taguchi technique is investigated.
The microstructures of pitted surfaces shown in Fig 6a-c and it reveals clearly that pit density of weld region is much less than that of base metal and TMAZ. Hence it can be concluded that pitting resistance of weld region is better than that of base metal and TMAZ. However there exists a problem of galvanic kind of corrosion because of difference in pitting potentials across the friction welded joint, especially in aggressive environments containing halide ions. Therefore corrosion protection of these welds with conversion layer coatings is highly desirable.
On the BM zone the elongated grains were observed the heat associated with welding changes the microstructure of the material HV min and HV max represent the hardness in the solution- treated and crystallization. The effect of welding is to cause a drop in hardness from HV max towards HV min as the peak temperature experienced increases. This is because grains will coarsen and reduce in number density in regions remote from heat source, and will re-enter solution when the peak temperature is sufficiently high . Some changes may occur during the cooling part of thermo cycle, resulting in hardness value beyond HV min, ultimate result is a minimum in hardness somewhere in HAZ and TMAZ due to the competing effects of dissolution and recrystallization has taken place during the frictionstir welding . The transformation of initial elongated grain structure into fine equi axed grains in the weld nugget is reported to be dynamic recrystallization so the hardness is higher than the other zones we observed. [16-19]
submicrocrystalline structure was successfully obtained through only a single pass of FSP. This feature is clearly one of the unique advantages of the FSP technique, because ECAP and ARB generally require several passes. Further- more, the mechanical properties, such as hardness and tensile strength, were also improved more than those of the cold- rolled 1050 Al alloy (starting material), which resulted from the grain reﬁnement eﬀect. It was clariﬁed from these results that the FSP technique is highly eﬀective in producing UFG materials with excellent mechanical properties. It was also revealed that there was the diﬀerence in the hardness distribution between retreating side (RS) and advancing side (AS) for relatively low tool rotation speeds. However, the overall hardness distribution within the FZ was not examined in detail. In addition, although the qualitative evidences were shown, the tensile strength could not be investigated quantitatively, which resulted from the geometry of tensile test specimen.
was applied to flatten the weld surface after the creation of the spot welding. Applying this technique eliminated the keyhole defect, which improved the physical properties of the joints. The examination of particle formation revealed no IMC layer. Figner et al.  welded aluminumalloy 5754 to galvanized steel HX 340LAD. They found that increasing the spindle speed at the constant dwell time will lead to higher strength. It is mainly due to the fine dispersed particle observed in the cross section area. The authors also mentioned that a higher amount of IMC was observed when the dwell time increased at constant spindle speed. Liu et al.  applied FSW of aluminumalloy 6061 to TRIP 780/800 steel with a butt joint configuration. They showed that the maximum tensile strength achieved by FSW was about 85% of the base Al alloy. This was obtained under the following conditions: rotation speed of 1800 rpm, welding speed of 90 mm/min and tool offset of 1.63 mm. Hong et al.  welded 1.5 mm TRIP 780 sheet with 1.4 mm HSBS sheet with FSSW technique. The failure mode and fatigue behavior were examined in their paper. They found that the weld gap and the bend distance were significant in affecting the weld fatigue life.
Aluminum and aluminum alloys are widely used in various industries including structural, transportation, shipbuilding, and aerospace. The main reasons for using this material are the result of its favorable mechanical properties, acceptable corrosion resistance, light weight, appropriate weldability, and increased toughness. Recently, aluminum alloys have become very attractive materials for scientists and engineers, and they have been studied extensively due to their beneficial properties . AlMgSi alloys, often referred to as the 6XXX series, are wrought; The strength- to-weight ratio offered by AA6XXX alloys and their enhanced mechanical properties have become crucial criteria for their use in the transport, aerospace, and automotive industry, as well as for architectural and marine applications. The main application is as extruded products and approximately half of all extruded profiles produced worldwide are AlMgSi alloys . AA 6061 (Al-Mg-Si alloy), examined in this study, is a precipitation hardening aluminium alloy, containing magnesium and silicon as its major alloying elements. It has good mechanical properties and exhibits good weldability. It is one of the most common alloys of aluminium for general purpose use. Applications include construction of aircraft structures, such as wings and fuselages, ship structures, marine frames, pipeline, storage tank, automotive parts, such as wheel spacers. Many aluminium docks and gangways are constructed with 6061-T6 extrusions, and welded into place. Although this kind of aluminium alloy is tried to join by conventional fusion welding processes, but it is difficult to make a joining due to creation of solidification cracking, liquation cracking and micro porosity formation in the fusion zone. Accordingly, FrictionStir Welding (FSW) has increasingly been applied particularly in situations where these defects need to be avoided.
Dinaharan et al.  investigated the effect of material locations and tool ro- tational speed on the microstructure and tensile strength of the dissimilar fric- tion stir welded, cast and wrought aluminumalloy AA6061. They concluded that the material placed in the advancing side (AS) occupied the major portion of the weld zone when tool rotational speed was increased, where the AS of the weld is hotter than the retreating side as proved by Cole et al. . In addition, Sunda- ram and Murugan  studied the effect of the pin profile used in FSW on the mechanical properties of 2024-T6/5083-H321 dissimilar aluminum alloys where the alloy of higher strength (2024) was located at the retreating side (RS). They proved that when the combinations of parameters create either very low or very high frictional heat, a plastic flow of material, lower tensile strength and elonga- tion is observed. Furthermore, Khodir and Shibayanagi  experimentally ex- amined the FSW of dissimilar materials, namely AA2024 and AA7075 and rec- ommended that the low-strength material should be placed on the AS to pro- duce better welds. On the other hand, Jata et al.  and Xue et al.  con- firmed that locating hard materials at the AS will improve the joint strength. Accordingly, the material flow and the joint performance, irrespective of materi- al placement, are dependent on the welding conditions and on their effects on generated heat and stir zone (SZ) temperatures  . Additionally, heat dis- sipation depends on material thickness, the welding speed and the ambient temperature  . The use of high heat input such as low welding speed and high rotation rate can result in improper tool/material contact conditions (slip- ping conditions) which can produce joints with defects . Otherwise, El-Sayed et al.  were proved, experimentally and theoretically, that tool pin profile has a minor effect on the maximum temperature of the welded joints at the same welding speed.
metallurgical properties, and reduced need for human skill are amongst the most important advantages of FSW in comparison with conventional fusion welding methods . FSW uses a rotating cylindrical tool with a pin to heat the material by friction. The tool pin stirs the plasticized material and therefore joins two pieces together when it is moved along the welding line. Advantages of this
This paper contains the study done on the fracture toughness of butt-jointed FS Welded AluminumAlloy 5083 and 6061. FSW was done using a belt-driven milling machine to investigate the flexibility of the welding process. Custom jigs and tool bit were added while parameters such as tool rotational speed, travel speed, plunge depth and tilt were varied to fit the milling machine for FSW purposes. Tensile testing and Single Edge Notch
FSW is a solidstate joining process that was orig- inally introduced by The Welding Institute . The operation is conducted by rotation and transverse mo- tion of a predesigned tool generating an exceptional quality joint with significantly lower residual stresses, . Low cost, energy consumption, and environmental pollution in addition to desirable strength to weight ratio, turns FSW to one of the most appropriate alter- native welding methods, especially in aerospace appli- cations involving aluminum alloys . Attractive fea- tures of this newly developed welding method led to a large number of studies, including micro and macro structural properties, mechanical properties, tool pa- rameter effect, which have become the baseline of this study. Briefly, results of these published researches are summarized here. Understanding the effect of process parameters on the material flow behavior, microstruc- ture formation, mechanical properties of frictionstir welded joints, and finding the most effective param- eters on properties of frictionstir welds have been a major concern for researchers, , , and . Consid- ering the study of Rajakumar et al. , the predomi- nant factors that have the most considerable influence on the fabricated joints are rotational speed, welding transverse speed, axial force, shoulder diameter, pin diameter, and tool material hardness;  it was also demon-strated that the well-defined parameter could provide high strength and void-free joint.
In Frictionstir welding a constantly rotated, non consumable welding tool consists of two features, a shoulder and a pin or probe. For a given joint design in FSW the weld quality, cost and tool wear are important consideration in the selection of the tool material and tool geometry. Tool design is the most powerful aspect of FSW process for development joint without any defects such as voids incomplete root penetration etc. In the welding tool, the tool shoulders are designed to produce heat through friction and material deformation to the surface of work-piece. The diameter of shoulders is generally depends on the pin size adopted. Generally the concave, convex scroll, flat shoulders should be used for joining for dissimilar materials. The designs of tool pin are much more complex compared to the shoulders. Tool pin is designed to disrupt the faying surface of the work-piece. Generally the threads, steps, flats pin have been widely used for control the material flow for better mechanical mixing. The welding tool has mainly 3 functions; heating the work-piece, movement of material to produce the joint and containment of the hot metal beneath the tool shoulders. Weld quality and tool wear are two important factors in the selection of tool material. Due to the severe heating of the tool during FSW significantly wear may result if the tool material has low yield strength at high temperature. Stresses experienced by the tool are dependent on the yield strength of the work-piece at high temperature. Temperature in the work-piece depends on the material properties of tool such as the thermal conductivity and co-efficient of thermal expansion which also effect the thermal stresses in the tool.
Frictionstir welding is the renowned technology widely used for joining materials. It avoids many of the common problems that persist in fusion welding. It is most suitable for joining soft materials like Aluminum and Magnesium alloys. Though this technology has been proven commercially feasible for soft materials, the same for harder alloys is yet to be established. The development of cost effective and durable tools, which lead to structurally sound welds, is still awaited. Material selection and design intensely affect the performance the tools.. Investigation effort has been made for newer compositions of heavy alloy tool manufactured through powder metallurgy route. Establishing welding parameters such as tool rotations speed, traverse speed and various mechanical properties of Heavy alloy tool by numerical analysis and computational fluid dynamics model predicted values from it. Heavy alloy tool is suitable for cost effective and durable tool in hard alloys such as stainless steel.
requirements and inconsistent quality of the spot welds. Frictionstir spot welding 4 6) (FSSW), a derivative of frictionstir welding (FSW), is an efﬁcient method for reﬁning microstructure that produces a speciﬁc welding region, called the stirring zone (SZ), with ﬁne and equiaxed grains due to dynamic recrystallization. 7 12) FSSW is the preferred method for joining aluminum structural components, and is currently used for applications such as land transportation vehicles, airplanes, and ships. Three factors affect the quality of FSSW joints, 3,1315) namely penetration depth of the tool pin, the rotation speed of the tool, and welding duration. According to previous reports, 1315) FSSW joint defects affect the fatigue life of FSSW joints. Based on previous studies, 1621) the tensile failure strength of FSSW joints has a relatively wide distribution and the joints have lower reliability. Weibull model 22,23) can be used to evaluate the failure probability