In the present study, two parts of six millimeters size aluminium 1060 alloy have been welded using FSW. From the extensive literature survey, it has been observed that tool rotation speed, welding speed, tool profile and tool offset are the parameters which affect weld produced. Some work has been done to predict effect of parameters on weld but the effects of interaction need more attention. In present work, four parameters have been studied together and their interaction up to second order has been analyzed. Prior experiments were conducted to find the range of each parameter for which sound welds can be produced 36 . Each parameter has been examined at three levels for conveniently setting the parametric level on the machine. Face-centered central composite design (FCCCD) of response surface methodology (RSM) has been used to reduce the number of experiments. Destructive and non-destructive tests were carried out on the weld samples to get the insight of the weld. Tensile test and flexural test were conducted on the samples to get knowledge about the strength of the weld. Scanning electron microscope (SEM) image of the fracture surface has been studied to predict the type of fracture taken place during the tensile test of weld. Radiography test has been applied to detect any defects present in the weldment and also study material distribution in work piece after FSW. Vickers hardness of weld zone has been calculated to know the hardness of material in different regions. 2 Materials and Methods
Fariasa,n, etal.conducted a study regarding the application of frictionstirwelding (FWS) of titanium alloy Ti6Al4V .Frictionstirwelding is a recent process and is being increasingly applied in many industries from basic materials, such as steel alloys, to high performance alloys, such as titanium. It is a processing great development and has its economic advantages when compared to conventional welding. For high performance alloys such as titanium, a major problem to overcome is the construction of tools that can with stand the extreme process environment. The metallographic analysis of the welds was done and it didn’t show primary defects of voids (tunneling) or similar internal defects due to processing, only defects related to tool wear which can cause loss of weldquality. The severe tool wear caused loss of surface quality and inclusions off ragments inside the joining, which was corrected by means of coating techniques on tool, or the replacement of cemented carbide with tungsten alloys. [24
In this analysisfrictionstirwelding is used. The studied material is AA 5053 sheets, 4 mm thickness for butt joint. A vertical semiautomatic milling machine was used for this process. The tool used for this process was made of H13 steel 18mm diameter with the length of the pin is 4.7mm. Firstly material cut by shear machine as required dimensions of 100 x 100 x 4 mm are prepared and weld was made by joining two pieces. The process of welding is FSW completed by one pass by using H13 steel and weld samples of weld at different conditions by changing the Tool rotational speed, Welding speed, and Angle of the tool. Total number of samples is 27.
The presence of crack like notches (interface between the welded work pieces) and blunt notches (cor- ners and bends in the base metal) were studied with the FE method stress analysis combined with the critical distance method. It was shown that the location of failure and the fatigue limit could be pre- dicted for three of the four types of proﬁles considered. The choice of the welding procedure (clamping condition) was found to inﬂuence signiﬁcantly, the fatigue life and accuracy of prediction. It was also shown that local plastic deformation on the crack tip is induced by clamping, resulting in tensile resid- ual stresses at the crack tip. The position of the failure can be explained by taking the stress intensity factor of the residual stress into account. The fatigue behavior of a FSW extruded aluminum alloy 6005A joint, which is used for train wall sides, was studied by Shahri and Sandström  . The struc- ture used was a lap-butt joint with a sharp notch next to the weld nugget. Fatigue cracks and failure appeared at notches in the proﬁle. In most proﬁles, cracks also started at the sharp notch at the weld, but the propagation was slow and complete fracture never took place there. FE stress analysis com- bined with the theory of critical distance was used to estimate the fatigue limit. The results from the analysis for the fatigue limit were within 3–28% of the observations. The stress analysis correctly predicted that failure would not occur in the welds. The fatigue strength of 2024-T3 aluminum alloy FSW single-lap joints in the presence of two crack-like unwelded zones at the overlap ends was stud- ied  . A FE analysis was performed to predict the crack path and the stress intensity at the crack tip. The lifetime was estimated by examining the crack propagation behavior of the base material using the AFgrow software. The effect of an initial overload was also considered. The crack path was investigated optically and using the ‘‘fatigue failure
For the processes mentioned above, detailed attention is given at the quality of the joints. It should be noted that, both basic and complex configurations are being used for general assembly of the joining applications and also extrusions. The most basic joint design employed by researchers is the lap weld and partial penetration buttweld, which are both intrinsic for high volume production processes.
In this study, latest generation of Al-Li alloy AA 2099 T8 plate with thickness 5 mm were employed to the frictionstirwelding process. Welding surfaces were grounded and cleaned with acetone before welding. The plates were kept on modified backing plate as butt configuration and clamped tightly. Fig 1 and fig 2 represent the schematic diagram of heat assisting backing plate and experimental set up of FSW respectively. Frictionstirwelding was done on BFW Chandra 5 axis CNC vertical milling machine. Three small holes of 1.5 mm diameter and 3 mm depth were drilled from top surface of workpiece at 12 mm, 16 mm and 20 mm from weld line. Thermocouple’s wire was connected with 16 channel data scanner to inspect the
Amongst the emerging new welding technologies, frictionstirwelding (FSW), invented and established by The Welding Institute (TWI) in 1991, is used frequently for the welding of high strength materials such as aluminum alloy, steel alloy, titanium alloy etc. which are difficult to weld by conventional fusion welding techniques. The FSW process parameters such as tool rotational speed, welding speed, axial force, and tool pin profile, etc... Play an important role in deciding the weld joint quality. In this research work, the simulation study has been carried out to observe the effects of rotational speed and traverse speed on output variables like peak temperature and flow stress for aluminum alloy 6061. Both the output variables affect the microstructure and weldquality. Hence, both the output variables need to be analyzed. For this purpose, five levels for each parameter (Rotational speed, Traverse speed) have been selected. Non linear thermal simulations have been carried out using FEA software called Hyperworks.
A rich literature is reported addressing various aspects of joining. Material flow behavior, however is not fully understood and requires further investigation . The recent success of FSW on joining of polymers demands extensive investigations covering all aspects of joining and making this process efficient on polymers as well. Study of material flow is one of the important topics of investigations because the quality of the joint depends on the degree of mixing of the two weld pieces . Material flow in polymers is so far reported by Simoes et al.  with their study on 10 mm thick PMMA sheets by different pin profiles. They concluded that the flow in polymer is different from metals when compared to Arbegast  flow model. It was suggested that the interface of pin affected zone and base material remained straight which showed no material flow from stir zone to base material. Similarly a distinct separation can be seen between shoulder affected zone and pin affected zone.
XRD quantitative analyses of points 1 and 2 in Fig. 4(a) are (98.55% Al, 28.34% Fe) and (98.23% Al, 0.51% Fe, 0.46% Mn in mole fraction), respectively. The atomic ratios of Al to Fe at points 1 and 2 are 2.52 and 6.8, respectively. Therefore, it is probable from the analysis and Al−Fe phase diagram that the phases are the HIF of weld S1 by 20% results in the increase of IMC thickness by a factor of 90% in weld S2. This mater shows that there is a critical heat input factor (HIF) above which the IMC grows rapidly and joint strength decreases drastically The microstructures of welds S1 and S2 are similar to those of the other welds and not presented here. It is necessary to note that a continuous layer of inter-metallic compound was formed at the Al interface identified as Al5Fe2 (the XRD analysis is not shown here). It is worthy to note that by increasing the welding speed from 40.20 mm/min (weld S1) to 41.86 mm/min (weld S2), the large tunnel is eliminated.
compared to weld, where the tool rotates perpendicular to the workpiece, when placed at an angle facing the direction gave high strength joint. As discussed when tool tilted at an angle of more than 1° void formation is observed and this condition is for a plate not more than 4mm thickness. The tool tilt angle is based on the thickness of plates to be used. It is observed that in some cases of FSW steel weld TMAZ zone is not seen and in other cases HAZ and TMAZ zones are clearly distinct. TMAZ zone is influenced by both mechanical and thermal cycles, while HAZ zone is influenced by only thermal cycles. Peak temperatures can be seen only in the HAZ zone, due to this hardness in the region will be more. Differentiating TMAZ zone from HAZ zone is most preferably difficult and hence in most of the weld, the region is differentiated as two zones in HAZ viz. HAZ zone 1 and HAZ zone 2. Fatigue life and fracture toughness of FSW steel weld is not explained and studied till yet. When compared to aluminum and its alloys, the characterization study on FSW steels are very less. Only based on the tensile strength and impact toughness, the quality of FSW steel welds are evaluated. Hence more characterization study is needed for deeper knowledge of FSW welds. Corrosion in steel and iron is a natural phenomenon, which occurs at a faster rate than any other metal. Hence alloying element is added, to improve corrosion resistance. Study of corrosive nature in the weld region of FSW of steel is not carried out in any of the previous studies. Further tool wear is an important criterion to be considered before planning for FSW of steel. One practical remedy for controlling the tool wear is preheating the tool and work piece and the other is as said before that selecting a suitable alloying element. Corrosion and tool wear is not only the properties for study, there is lots of characterization study that is need for FSW of steels to undergo and understand.
Normal FrictionStirWelding (NFSW) is the process of frictionstirwelding which is normally done in air and underwater Frictionstirwelding (UFSW) is the process that is stirred performed under the water. Frictionstirwelding is a solid state joining method based on friction heating and local plastic flow in the joint region by stirring with a rotating tool pin. FSW is to create high-quality, high-strength joints with low distortion and is capable of fabricating either butt or lap joints, in a wide range of materials thickness and lengths. The process is carried out by plunging a rotating tool made of a wear-resistant and high temperature resistant material that is converting into the material to be joined and translating it along the desired weld line. The heat generated by friction at the tool surface and plastic dissipation in the deforming regions of the work pieces soften the material to a plasticized state. It is then extruded around the tool and consolidates to form a weld. In the UFSW the welding zone surroundings are not affected with high temperatures because of using cooling water. Is the Solid state joining process underwater frictionstirwelding reduces those problems like hydrogen embrittlement, oxidation and porosity
There are three different types of pin tool orientations that can be utilized for frictionstirwelding. There are fixed pin, self-reacting pin, and adjustable pin. The welding done in this experiment utilizes a self-reacting pin tool. A self-reacting pin tool is one in where no anvil is present. This is practical as an anvil is not always available on welding certain structures. A self-reacting pin tool consists of the normal shoulder and pin tool, but in addition to this, a bottom shoulder is attached. The bottom shoulder is placed underneath the work piece in where the anvil would normally be placed. This is completed by having the welding machine pull the bottom shoulder up against the work piece while the top shoulder normally presses down against the work piece. Both shoulders having the same pressing force against the workpiece as to not cause any vertical deformation. This method will result in the total net force on the work piece to be zero .
Abstract: Enhancing the heat transfer to the material being welded, instead of the tool, will improve the welding thermal efficiency. Frictionstirwelding of 5 mm thick 6061-T6 aluminium alloy plates was carried out with the newly produced tools. It was found that the thermal efficiency increased by 4.2% using a tool with all the new design features (i.e. hollow, fluted and thermally insulated) compared to the conventional tool for aluminium welding. To assess the benefits of the new tool design on steel FSW, a finite element numerical simulation study was undertaken. In this case, the simulation results yielded a welding thermal efficiency increase of 10-15% using a thermally coated tool, thereby offering potential productivity gains.
It is crucial for every welder to determine the best tool position and starting point of welding process before the welding is performed. The position of tool is one of several issues that need to be further investigated in welding process (Sahu, Pal, Pal, and Jain (2016). Many researches and study were done before to improve the quality of weld with zero defects problems. This scenario happens due to the enlargement of critical industry such as automotive and aerospace. Since these industry used welding as the joining technique, it become inhibitor to the researches to find out more in details about welding process (Dawood, Mohammed, Rahmat, & Uday, 2015).
3.3.2 Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) SEM and EDS-SEM was carried out on the polished and etched (2% Nital) FSW samples using the FEI Nova Nano SEM. The examination includes the surface of the SZ, the HAZ and the PM. The SEM produced high quality and high resolution images of micro constituents by employing the Secondary Electron (SE) imaging mode with an accelerated voltages (10kV- 20 kV) which gives relatively high penetration. The working distance (WD) used was 5 mm but in some cases altered (decreased or increased) to enhance the contrast at high magnification. The main aim of the microstructural examination is to generate clear information about phases which can be found in the welded joint and use that information to understand and predict the welded joints mechanical properties. Another aim is to gather data to identify unsuitable welding parameters which can create defects and may affect the process integrity. EDS-SEM examination is mainly used to analyse the chemical composition of elemental precipitation/segregation. Spot analysis (Point and ID) has been employed to reveal material elements on a small location in the scanned SEM image whereas, mapping technique has been used to analyse the whole scanned SEM image.
During the last few years, as a kind of advanced continuous coiled pipe with high strength and good corrosion resistance, the application of coiled tubing technologies has found its way into several different fields such as work-over, drilling, completion, logging, transporting [1-4]. It will sustain large deformation during winding on and unwinding off the spool, and resists harsh corrosion environment. Excellent properties, such as strength, ductility, corrosion resistance, are needed to avoid predominant failure.
ABSTRACT: An experimental investigation has been carried out, in present paper, on microstructure, Hardness and Tensile strength of weldbutt joints of AA 6082. Two different welding processes have been considered: a conventional tungsten inert gas (TIG) process and an innovative solid state welding process known as frictionstirwelding (FSW).which the relative motion between the tool and the work piece produces heat which makes the material of the two edges being joined plastic atomic diffusion. Tungsten inert gas welding process that uses the heat produced by an electric arc created between non consumable tungsten electrode and the weld pool. In this project an attempt is made to compare and investigate the process parameters of fsw and tig on the mechanical properties of the welds. The hardness, tensile strength is considered for investigation by tool speed, tool feed and maintaining constant depth of penetration of weld. The results indicate than the microstructure of fiction weld is different from the tungsten inert gas welded joint. The weld nugget consists of small grains in frictionstirwelding and those are found in tungsten inert gas weld. The tensile strength of weld joint in frictionstirwelding is more instead of tungsten inert gas Welding. Hardness test of frictionstirwelding is more instead of tungsten inert gas where as in parent material also.
The difficulty of making high-strength, fatigue and fracture resistant welds in aerospace aluminium alloys, such as highly alloyed 2XXX and 7XXX series, has long inhibited the wide use of welding for joining aerospace structures. These aluminium alloys are generally classified as non-weld able because of the poor solidification microstructure and porosity in the fusion zone. Also, the loss in mechanical properties as compared to the base material is very significant. These factors make the joining of these alloys by conventional welding processes unattractive. Some aluminium alloys can be resistance welded, but the surface preparation is expensive, with surface oxide being a major problem. Frictionstirwelding (FSW) was invented at The Welding Institute (TWI) of UK in 1991 as a solid-state joining technique, and it was initially applied to aluminium alloys. The basic concept of FSW is remarkably simple. A non-consumable rotating tool with a specially designed pin and shoulder is inserted into the abutting edges of sheets or plates to be joined and traversed along the line of joint
The following plots obtained from analysis are also used to interpret the terms affecting the response. The normal probability plots of the residual; the plots of the residual vs. fitted value and run order and histogram for UTS are shown in Figure 4. A check on the normal probability plot revealed that the residual generally fall on a straight line implying that the error is distributed normally. Also Figures versus v/s fits and versus v/s order revealed that they have no obvious pattern and unusual structure. This implies that the models proposed are adequate and there is no reason to suspect any violation of the constant variance and independence assumption.
The analysis of the experimental welding of the forged panels of alloys AI 5083 and AI 7075 in the state of the maximum-hardness values showed that the elongation of the welded joint is bigger than that of the parent material, which can be explained with the formation of a structure with small grains in the mixed zone.A coupled thermo-mechanical model was developed to study the temperature fields and the plunge force of alloy AI 5083 under different rotating speeds: (300, 400 and 500) r/min during the FSW process of the plunge stage. The heat transfer through the bottom surface of the welding plate is controlled with the heat transfer coefficient of 1000 W/(m2 K). A constant friction coefficient of 0.3 is assumed between the tool and the welding plate and the penalty contact method is used to model the contact interaction between the two surfaces. The heat convection coefficients on the surface of the welding of 200 °C. the temperature fields in the transverse cross-section near the tool/matrix interface after 22.8 s, when the plunge speed is 12 mm/min and the rotation speed is 400 r/min. The temperature field is symmetric.