Sustainability of Welding Process through Bobbin Friction Stir Welding

Science.gov (United States)

Sued, M. K.; Samsuri, S. S. M.; Kassim, M. K. A. M.; Nasir, S. N. N. M.

2018-03-01

Welding process is in high demand, which required a competitive technology to be adopted. This is important for sustaining the needs of the joining industries without ignoring the impact of the process to the environment. Friction stir welding (FSW) is stated to be benefitting the environment through low energy consumption, which cannot be achieved through traditional arc welding. However, this is not well documented, especially for bobbin friction stir welding (BFSW). Therefore, an investigation is conducted by measuring current consumption of the machine during the BFSW process. From the measurement, different phases of BFSW welding process and its electrical demand are presented. It is found that in general total energy in BFSW is about 130kW inclusive of all identified process phases. The phase that utilise for joint formation is in weld phase that used the highest total energy of 120kWs. The recorded total energy is still far below the traditional welding technology and the conventional friction stir welding (CFSW) energy demand. This indicates that BFSW technology with its vast benefit able to sustain the joining technology in near future.

Mechanism for Self-Reacted Friction Stir Welding

Science.gov (United States)

Venable, Richard; Bucher, Joseph

2004-01-01

A mechanism has been designed to apply the loads (the stirring and the resection forces and torques) in self-reacted friction stir welding. This mechanism differs somewhat from mechanisms used in conventional friction stir welding, as described below. The tooling needed to apply the large reaction loads in conventional friction stir welding can be complex. Self-reacted friction stir welding has become popular in the solid-state welding community as a means of reducing the complexity of tooling and to reduce costs. The main problems inherent in self-reacted friction stir welding originate in the high stresses encountered by the pin-and-shoulder assembly that produces the weld. The design of the present mechanism solves the problems. The mechanism includes a redesigned pin-and-shoulder assembly. The welding torque is transmitted into the welding pin by a square pin that fits into a square bushing with set-screws. The opposite or back shoulder is held in place by a Woodruff key and high-strength nut on a threaded shaft. The Woodruff key reacts the torque, while the nut reacts the tensile load on the shaft.

Weld defect identification in friction stir welding using power spectral density

Science.gov (United States)

Das, Bipul; Pal, Sukhomay; Bag, Swarup

2018-04-01

Power spectral density estimates are powerful in extraction of useful information retained in signal. In the current research work classical periodogram and Welch periodogram algorithms are used for the estimation of power spectral density for vertical force signal and transverse force signal acquired during friction stir welding process. The estimated spectral densities reveal notable insight in identification of defects in friction stir welded samples. It was observed that higher spectral density against each process signals is a key indication in identifying the presence of possible internal defects in the welded samples. The developed methodology can offer preliminary information regarding presence of internal defects in friction stir welded samples can be best accepted as first level of safeguard in monitoring the friction stir welding process.

Friction Stir Welding Process: A Green Technology

OpenAIRE

Esther T. Akinlabi; Stephen A. Akinlabi

2012-01-01

Friction Stir Welding (FSW) is a solid state welding process invented and patented by The Welding Institute (TWI) in the United Kingdom in 1991 for butt and lap welding of metals and plastics. This paper highlights the benefits of friction stir welding process as an energy efficient and a green technology process in the field of welding. Compared to the other conventional welding processes, its benefits, typical applications and its use in joining similar and dissimilar materia...

Weldability of AISI 304 to copper by friction welding

Energy Technology Data Exchange (ETDEWEB)

Kirik, Ihsan [Batman Univ. (Turkey); Balalan, Zulkuf [Firat Univ., Elazig (Turkey)

2013-06-01

Friction welding is a solid-state welding method, which can join different materials smoothly and is excessively used in manufacturing industry. Friction welding method is commonly used in welding applications of especially cylindrical components, pipes and materials with different properties, for which other welding methods remain incapable. AISI 304 stainless steel and a copper alloy of 99.6 % purity were used in this study. This couple was welded in the friction welding machine. After the welding process, samples were analyzed macroscopically and microscopically, and their microhardness was measured. Tensile test was used to determine the bond strength of materials that were joined using the friction welding method. At the end of the study, it was observed that AISI 304 stainless steel and copper could be welded smoothly using the friction welding method and the bond strength is close to the tensile strength of copper. (orig.)

Properties of Friction Welding of Dissimilar Metals WCu-Cu Weld for Electrical Contact Device

Energy Technology Data Exchange (ETDEWEB)

An, Y. H.; Yoon, G. G. [Korea Electrotechnology Research Institute (Korea); Min, T. K. [Chungnam National University (Korea); Han, B. S. [Chonbuk National University (Korea)

2000-04-01

A copper-tungsten sintered alloy(WCu) has been friction-welded to a tough pitch copper (Cu) in order to investigate friction weldability. The maximum tensile strength of the WCu-Cu friction welded joints had up to 96% of those of the Cu base metal under the condition of friction time 0.6sec, friction pressure 45MPa, upset pressure 125MPa and upset time 5.0sec. And it is confirmed that the tensile strength of friction welded joints are influenced highly by upset pressure rather than friction time. And it is considered that mixed layer was formed in the Cu adjacent side to the weld interface, W particles included in mixed layer induced fracture in the Cu adjacent side to the weld interface and also, thickness of mixed layer was reduced as upset pressure increase. (author). refs., figs., tabs.

Gimballed Shoulders for Friction Stir Welding

Science.gov (United States)

Carter, Robert; Lawless, Kirby

2008-01-01

In a proposed improvement of tooling for friction stir welding, gimballed shoulders would supplant shoulders that, heretofore, have been fixedly aligned with pins. The proposal is especially relevant to self-reacting friction stir welding. Some definitions of terms, recapitulated from related prior NASA Tech Briefs articles, are prerequisite to a meaningful description of the proposed improvement. In friction stir welding, one uses a tool that includes (1) a rotating shoulder on top (or front) of the workpiece and (2) a pin that rotates with the shoulder and protrudes from the shoulder into the depth of the workpiece. In conventional friction stir welding, the main axial force exerted by the tool on the workpiece is reacted through a ridged backing anvil under (behind) the workpiece. When conventional friction stir welding is augmented with an auto-adjustable pin-tool (APT) capability, the depth of penetration of the pin into the workpiece is varied in real time by a position- or forcecontrol system that extends or retracts the pin as needed to obtain the desired effect. In self-reacting (also known as self-reacted) friction stir welding as practiced heretofore, there are two shoulders: one on top (or front) and one on the bottom (or back) of the workpiece. In this case, a threaded shaft protrudes from the tip of the pin to beyond the back surface of the workpiece. The back shoulder is held axially in place against tension by a nut on the threaded shaft. Both shoulders rotate with the pin and remain aligned coaxially with the pin. The main axial force exerted on the workpiece by the tool and front shoulder is reacted through the back shoulder and the threaded shaft into the friction-stir-welding machine head, so that a backing anvil is no longer needed. A key transmits torque between the bottom shoulder and the threaded shaft, so that the bottom shoulder rotates with the shaft. This concludes the prerequisite definitions of terms.

Friction welding of steel to ceramic

OpenAIRE

Rombaut, Pieter; De Waele, Wim; Faes, Koenraad

2011-01-01

The goal of this paper is to give a clear summary of the literature review performed during the master thesis on friction welding on dissimilar materials. Of main interest for this work is the welding of steel to a ceramic material such as alumina (Al2O3). Because of the difficulties involved in producing a sound weld for this material combination, not a lot of literature is available on this topic. This paper starts with a discussion on the basics of friction welding and typical problems enc...

Gimbaled-shoulder friction stir welding tool

Science.gov (United States)

Carter, Robert W. (Inventor); Lawless, Kirby G. (Inventor)

2010-01-01

A gimbaled-shoulder friction stir welding tool includes a pin and first and second annular shoulders coupled to the pin. At least one of the annular shoulders is coupled to the pin for gimbaled motion with respect thereto as the tool is rotated by a friction stir welding apparatus.

Friction Welding of Titanium and Carbon Steel

OpenAIRE

Atsushi, HASUI; Yoichi, KIRA; Faculty of Science and Technology, Keio University; Ishikawajima-Harima Heavy Industries, Co., Ltd.

1985-01-01

Titanium-steel is a combination of dissimilar materials, which are difficult to weld in general, owing to inevitable formation of brittle intermetallic compounds. A prominent feature of friction welding process is ability to weld dissimilar materials in many kinds of combinations. This report deals with friction weldabilily of pure titanium and S25C steel, which are 12 mm in diameter. Main results are summarized as follows; (1) Suitable welding conditions to obtain a sound weld, which has a j...

Friction Pull Plug Welding in Aluminum Alloys

Science.gov (United States)

Brooke, Shane A.; Bradford, Vann

2012-01-01

NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

Damage Tolerance Assessment of Friction Pull Plug Welds in an Aluminum Alloy

Science.gov (United States)

McGill, Preston; Burkholder, Jonathan

2012-01-01

Friction stir welding is a solid state welding process used in the fabrication of cryogenic propellant tanks. Self-reacting friction stir welding is one variation of the friction stir weld process being developed for manufacturing tanks. Friction pull plug welding is used to seal the exit hole that remains in a circumferential self-reacting friction stir weld. A friction plug weld placed in a self-reacting friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data relating residual strength capability to flaw size in an aluminum alloy friction plug weld will be presented.

Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy.

Science.gov (United States)

Campanelli, Sabina Luisa; Casalino, Giuseppe; Casavola, Caterina; Moramarco, Vincenzo

2013-12-18

Friction Stir Welding (FSW) is a solid-state joining process; i.e. , no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.

Damage Tolerance Behavior of Friction Stir Welds in Aluminum Alloys

Science.gov (United States)

McGill, Preston; Burkholder, Jonathan

2012-01-01

Friction stir welding is a solid state welding process used in the fabrication of various aerospace structures. Self-reacting and conventional friction stir welding are variations of the friction stir weld process employed in the fabrication of cryogenic propellant tanks which are classified as pressurized structure in many spaceflight vehicle architectures. In order to address damage tolerance behavior associated with friction stir welds in these safety critical structures, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data describing fracture behavior, residual strength capability, and cyclic mission life capability of friction stir welds at ambient and cryogenic temperatures have been generated and will be presented in this paper. Fracture behavior will include fracture toughness and tearing (R-curve) response of the friction stir welds. Residual strength behavior will include an evaluation of the effects of lack of penetration on conventional friction stir welds, the effects of internal defects (wormholes) on self-reacting friction stir welds, and an evaluation of the effects of fatigue cycled surface cracks on both conventional and selfreacting welds. Cyclic mission life capability will demonstrate the effects of surface crack defects on service load cycle capability. The fracture data will be used to evaluate nondestructive inspection and proof test requirements for the welds.

Friction stir spot welding of dissimilar aluminium alloys

International Nuclear Information System (INIS)

Bozkurt, Yahya

2016-01-01

Friction stir spot welding (FSSW) has been proposed as an effective technology to spot weld the so-called “difficult to be welded” metal alloys such as thin sheets aluminum alloys and dissimilar materials. FSSW is derived from friction stir welding technology, its principle benefit being low cost joining, lower welding temperature and shorter welding time than conventional welding methods. In this study, dissimilar AlMg 3 and AlCu 4 Mg 1 aluminium alloy plates were FSSWed by offsetting the low strength sheet on upper side of the weld. The effects of tool rotation speed on the microstructure, lap shear fracture load (LSFL), microhardness and fracture features of the weld are investigated by constant welding parameters. The maximum LSFL was obtained by increasing the tool rotational speed. However, the joints exhibited pull-out nugget fracture mode under lap shear tensile testing conditions. The largest completely bonded zone was observed as 5.86 mm which was narrower at the opposite position of the joint. Key words: friction stir spot welding, aluminium alloys, mechanical properties, dissimilar joint, welding parameters

FRICTION - WELDING MACHINE AUTOMATIC CONTROL CIRCUIT DESIGN AND APPLICATION

OpenAIRE

Hakan ATEŞ; Ramazan BAYINDIR

2003-01-01

In this work, automatic controllability of a laboratory-sized friction-welding machine has been investigated. The laboratory-sized friction-welding machine was composed of motor, brake, rotary and constant samples late pliers, and hydraulic unit. In automatic method, welding parameters such as friction time, friction pressure, forge time and forge pressure can be applied sensitively using time relays and contactors. At the end of the experimental study it's observed that automatic control sys...

Microstructure Evolution during Friction Stir Spot Welding of TRIP Steel

DEFF Research Database (Denmark)

Lomholt, Trine Colding; Pantleon, Karen; Somers, Marcel A. J.

2010-01-01

In this study, the feasibility of friction stir spot welding of TRIP steel is investigated. In addition to manufacturing successful welds, the present study aims at a fundamental understanding of the mechanisms occurring at the (sub)micron scale during friction stir spot welding. As one of the ma...... electron microscopy, and electron backscatter diffraction. Microhardness measurements and lap-shear tensile tests completed the investigations of the welded samples and allow evaluation of the quality of the welds.......In this study, the feasibility of friction stir spot welding of TRIP steel is investigated. In addition to manufacturing successful welds, the present study aims at a fundamental understanding of the mechanisms occurring at the (sub)micron scale during friction stir spot welding. As one of the main...... parameters to control friction stir welding, the influence of the rotational speed of the tool was investigated. Three different rotational speeds (500 rpm, 1000 rpm and 1500 rpm, respectively) were applied. The microstructure of the welded samples was investigated with reflected light microscopy, scanning...

Application of acoustic emission technique and friction welding for excavator hose nipple

International Nuclear Information System (INIS)

Kong, Yu Sik; Lee, Jin Kyung

2013-01-01

Friction welding is a very useful joining process to weld metals which have axially symmetric cross section. In this paper, the feasibility of industry application was determined by analyzing the mechanical properties of weld region for a specimen of tube-to-tube shape for excavator hose nipple with friction welding, and optimized welding variables were suggested. In order to accomplish this object, friction heating pressure and friction heating time were selected as the major process variables and the experiment was performed in three levels of each parameter. An acoustic emission(AE) technique was applied to evaluate the optimal friction welding conditions nondestructively. AE parameters of accumulative count and event were analyzed in terms of generating trend of AE signals across the full range of friction weld. The typical waveform and frequency spectrum of AE signals which is generated by friction weld were discussed. From this study the optimal welding variables could be suggested as rotating speed of 1300 rpm, friction heating pressure of 15 MPa, and friction heating time of 10 sec. AE event was a useful parameter to estimate the tensile strength of tube-to tube specimen with friction weld.

Probing weld quality monitoring in friction stir welding through characterization of signals by fractal theory

Energy Technology Data Exchange (ETDEWEB)

Das, Bipul; Bag, Swarup; Pal, Sukhomay [Indian Institute of Technology Guwahati, Assam (India)

2017-05-15

Providing solutions towards the improvisation of welding technologies is the recent trend in the Friction stir welding (FSW) process. We present a monitoring approach for ultimate tensile strength of the friction stir welded joints based on information extracted from process signals through implementing fractal theory. Higuchi and Katz algorithms were executed on current and tool rotational speed signals acquired during friction stir welding to estimate fractal dimensions. Estimated fractal dimensions when correlated with the ultimate tensile strength of the joints deliver an increasing trend with the increase in joint strength. It is observed that dynamicity of the system strengthens the weld joint, i.e., the greater the fractal dimension, the better will be the quality of the weld. Characterization of signals by fractal theory indicates that the single-valued indicator can be an alternative for effective monitoring of the friction stir welding process.

Probing weld quality monitoring in friction stir welding through characterization of signals by fractal theory

International Nuclear Information System (INIS)

Das, Bipul; Bag, Swarup; Pal, Sukhomay

2017-01-01

Providing solutions towards the improvisation of welding technologies is the recent trend in the Friction stir welding (FSW) process. We present a monitoring approach for ultimate tensile strength of the friction stir welded joints based on information extracted from process signals through implementing fractal theory. Higuchi and Katz algorithms were executed on current and tool rotational speed signals acquired during friction stir welding to estimate fractal dimensions. Estimated fractal dimensions when correlated with the ultimate tensile strength of the joints deliver an increasing trend with the increase in joint strength. It is observed that dynamicity of the system strengthens the weld joint, i.e., the greater the fractal dimension, the better will be the quality of the weld. Characterization of signals by fractal theory indicates that the single-valued indicator can be an alternative for effective monitoring of the friction stir welding process.

Effects of welding parameters on friction stir spot welding of high density polyethylene sheets

International Nuclear Information System (INIS)

Bilici, Mustafa Kemal; Yukler, Ahmet Irfan

2012-01-01

Graphical abstract: (a) Schematic illustration of the cross section of a friction stir spot weld and (b) Geometry of the weld bonded area, x: nugget thickness and y: the thickness of the upper sheet. Highlights: → Welding parameters affect the FSSW nugget formation and the strength of the joint. → Melting of polyethylene occurred in the vicinity of the tool pin. → The joint that fractures with a pull nugget failure mode has a higher strength. -- Abstract: Friction stir spot welding parameters affect the weld strength of thermoplastics, such as high density polyethylene (HDPE) sheets. The effects of the welding parameters on static strength of friction stir spot welds of high density polyethylene sheets were investigated. For maximizing the weld strength, the selection of welding parameters is very important. In lap-shear tests two fracture modes were observed; cross nugget failure and pull nugget failure. The tool rotational speed, tool plunge depth and dwell time were determined to be important in the joint formation and its strength. The joint which had a better strength fails with a pull nugget failure morphology. Weld cross section image analysis of the joints were done with a video spectral comparator. The plunge rate of the tool was determined to have a negligible effect on friction stir spot welding.

The investigation of typical welding defects for 5456 aluminum alloy friction stir welds

International Nuclear Information System (INIS)

Chen Huabin; Yan Keng; Lin Tao; Chen Shanben; Jiang Chengyu; Zhao Yong

2006-01-01

The external factors on the friction stir welding defects are so abundant that the experiments of friction stir welding were conducted for 5456 aluminum alloy. With the changes of the tool tilt angle and material condition, defects can be generated. These defects can be conventional ones (lack of penetration or voids), or lazy S, which are unique to friction stir welding. However, the origin of the defects remains an area of uncertainty. In this study, an attempt has been made to investigate the formation of these defects. The typical welding defects of friction stir welding joint for 5456 aluminum alloy were analyzed and discussed, respectively, by using optical microscopy (OM), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscope (SEM). The microscopic examination of the nugget zone and fracture location of the weld confirms that the tilt angle can change the plastic material flow patterns in the stir zone and accordingly control the weld properties. In addition, the oxide layer from the initial butt surface during FSW is dispersed at the grain boundary. These A1 2 O 3 particles are actually the major cause of failure of the joint

FRICTION - WELDING MACHINE AUTOMATIC CONTROL CIRCUIT DESIGN AND APPLICATION

Directory of Open Access Journals (Sweden)

Hakan ATEŞ

2003-02-01

Full Text Available In this work, automatic controllability of a laboratory-sized friction-welding machine has been investigated. The laboratory-sized friction-welding machine was composed of motor, brake, rotary and constant samples late pliers, and hydraulic unit. In automatic method, welding parameters such as friction time, friction pressure, forge time and forge pressure can be applied sensitively using time relays and contactors. At the end of the experimental study it's observed that automatic control system has been worked successfully.

Metallurgical joining of engine parts. Inertia welding of nickel superalloy HP compressor disks

International Nuclear Information System (INIS)

Ferte, J.P.

1993-01-01

The main part of this paper describes upside metallurgical and mechanical work done at SNECMA, on inertia welding of powder metallurgy nickel base superalloys ASTROLOY and N18, allowing appliance of this process to engine parts : Inertia welding of superalloys leads to deap microstructural changes in the H.A.Z. which have been, as well as upset, correlated to process parameters, weld geometry and base material microstructure; a full mechanical testing of welds shown properties equivalent to base material ones up to 650 C except for fatigue crack growth behavior under specific conditions (T>600 C-hold time at maximum load) which is drastically reduced for in weld plane propagation. A significant improvement of this later property has been done through post-welding heat treatment and optimization of welding parameters. Last part of this paper summarize the main teachings gained, on the complete welding procedure, from welding of scale one parts. (orig.)

Enabling high speed friction stir welding of aluminum tailor welded blanks

Science.gov (United States)

Hovanski, Yuri

Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding (FSW) has traditionally been applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translate to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum FSW components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability using a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.

Corrosion Behavior of Arc Weld and Friction Stir Weld in Al 6061-T6 Alloys

International Nuclear Information System (INIS)

Yoon, Byoung Hyun; Kim, Heung Ju; Chang, Woong Seong; Kweon, Young Gak

2006-01-01

For the evaluation of corrosion resistance of Al 6061-T6 Alloy, Tafel method and immersion test was performed with Friction Stir Weld(FSW) and Gas Metal Arc Weld(GMAW). The Tafel and immersion test results indicated that GMA weld was severely attacked compared with those of friction stir weld. It may be mainly due to the galvanic corrosion mechanism act on the GMA weld

The study on the properties of AISI 4140 and AISI 1040 steel rods welded by friction welding

Directory of Open Access Journals (Sweden)

Thanee Toomprasen

2014-06-01

Full Text Available This paper is aimed to investigate the properties of joint between AISI 4140 and AISI 1040 welded by friction welding. The specimens were prepared in round shape of 13 mm diameter and 100 mm long. They were welded by friction welding method under the following conditions; friction pressure of 183 MPa, friction time of 12 sec, upset pressure of 428 MPa, upset time of 7 sec. and rotational speed of 1400 rpm. The strength and hardness were tested on the welded area. The result showed finer grains. in the welded area. This is the result of friction pressure and upset pressure in the welding process. In addition, the observation result indicated some changes of Ferrite and Pearlite in welded zone. This phase change resulted in the increment of hardness in AISI 4140 at the contact area and adjacent. In part of AISI 1040, the portion of Pearlite and Ferrite are not significantly changed, therefore the value of hardness is almost constant.

Effect of friction time on the microstructure and mechanic properties of friction welded AISI 1040/Duplex stainless steel

Directory of Open Access Journals (Sweden)

İhsan Kırık

2000-06-01

Full Text Available In this study, the effect on the characteristic microstructure and mechanic properties of friction time on the couple steels AISI 1040/AISI 2205 stainless steel joining with friction welding method was experimentally investigated. Friction welding experiment were carried out in privately prepared PLC controlled continuous friction welding machine by us. Joints were carried out under 1700 rpm rotation speed, with 30MPa process friction pressure, 60MPa forging pressure, 4 second forging pressure and under 3, 5, 7, 9 and 11 second friction time, respectively. After friction welding, the bonding interface microstructures of the specimens were examined by SEM microscopy and EDS analysis. After weld microhardness and tensile strength of specimens were carried out. The result of applied tests and observations pointed out that the properties of microstructure were changed with friction time increased. The excellent tensile strength of joint observed on 1700 rpm rotation speed and 3 second friction time sample.

Corrosion resistance of «tube – tubesheet» weld joint obtained by friction welding

Directory of Open Access Journals (Sweden)

RIZVANOV Rif Garifovich

2017-08-01

Full Text Available Shell-and-tube heat exchangers are widely applied for implementation of various processes at ventures of fuel and energy complex. Cost of production and reliability of heat exchangers of this type is to a wide extent determined by corresponding characteristics of tube bundle, «tube – tubesheet» is its typical joint in particular when welding operations are used in order to attach tubes to tubesheet in addition to expansion. When manufacturing such equipment of heat-resistant chrome-bearing or chromium-molybdenum steels including steel 15H5M, the process of fixed joint manufacturing gets significantly more complicated and costly due to the necessity to use thermal treatment before, during and after welding (this problem is particularly applicable for manufacturing of large-size equipment. One of the options to exclude thermal treatment from manufacturing process is to use «non-arc» welding methods – laser welding, explosion welding as well as friction welding. Use of each of the welding methods mentioned above during production of heat-exchange equipment has its process challenges and peculiarities. This article gives a comparative analysis of weld structure and distribution of electrode potentials of welded joints and parent metal of the joints simulating welding of tube to tubesheet of steel 15H5M using the following welding methods: shielded manual arc welding, tungsten-arc inert-gas welding and friction welding. Comparative analysis of macro- and microstructures of specific zones of the studied welded joints showed that the joints produced by arc welding methods do not exhibit evident inhomogeneity of the structure after application of thermal treatment which is explained by the correctness of thermal treatment. Joints obtained via friction welding are characterized by structural inhomogeneity of the welded joint zone metal microstructure. The ultra-fine-grained structure obtained as a result of friction welding makes it possible to

Friction welding of A 6061 aluminum alloy and S45C carbon steel

Energy Technology Data Exchange (ETDEWEB)

Shinoda, T. [Nagoya Univ., Furo-cho, Chikusa-ku, Nagoya (Japan); Kawata, S. [Post Graduate Student, Nagoya Univ., Nagoya (Japan)

2004-07-01

Many researches for friction welding of aluminum with either carbon steel or stainless steel have been carried out. From those results, it is concluded that the greatest problem is the formation of brittle intermetallic compounds at weld interface. However, it is not clearly demonstrated the effect of friction welding parameters on the formation of intermetallic compounds. This research purposes are to evaluate the formation of intermetallic compounds and to investigate the effect of friction welding parameters on the strength of welded joint. For these purposes, A6061 aluminum alloy and S45C carbon steel were used with a continuous drive vertical friction welding machine. Tensile test results revealed that the maximum tensile strength was achieved at extremely short friction time and high upset. The joint strength reached 92% of the tensile strength of A6061 base metal. Tensile strength of friction welding was increasing with increasing upset pressure when friction time 1sec. However, tensile properties were deteriorated with increasing friction time. It was observed that the amount of formed intermetallic compound was increasing with increasing friction time at weld interface. Partly formed intermetallic compound on weld interface were identified when friction time 1 sec. However, intermetallic compound layer were severely developed with longer friction time at weld interface. It was concluded that intermetallic compound layer deteriorated the tensile properties of weld joints. (orig.)

Characterization of friction welding for IN713LC and AISI 4140 steel

International Nuclear Information System (INIS)

Yeom, J.T.; Park, N.K.; Park, J.H.; Lee, J.W.

2004-01-01

Friction welding of dissimilar materials, Ni-base superalloy IN713LC and oil-quench plus tempered AISI 4140 steel, was investigated. Friction welding was carried out with various process variables such as friction pressure and time. The quality of welded joints was tested by applying bending stresses in an appropriate jig. Microstructures of the heat-affected zone (HAZ) were investigated along with micro-hardness tests over the friction weld joints. DEFORM-2D FE code was used to simulate the effect of welding variables in friction welding process on the distributions of the state variables such as strain, strain rate and temperature. The formation of the metal burr during the friction welding process was successfully simulated, and the temperature distribution in the heat-affected zone indicated a good agreement with the variation of the microstructures in the HAZ. (orig.)

Characterization of friction welding for IN713LC and AISI 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Yeom, J.T.; Park, N.K. [Dept. of Materials Processing, Korea Inst. of Machinery and Materials, Kyungnam (Korea); Park, J.H.; Lee, J.W. [ENPACO Co., Changwon (Korea)

2004-07-01

Friction welding of dissimilar materials, Ni-base superalloy IN713LC and oil-quench plus tempered AISI 4140 steel, was investigated. Friction welding was carried out with various process variables such as friction pressure and time. The quality of welded joints was tested by applying bending stresses in an appropriate jig. Microstructures of the heat-affected zone (HAZ) were investigated along with micro-hardness tests over the friction weld joints. DEFORM-2D FE code was used to simulate the effect of welding variables in friction welding process on the distributions of the state variables such as strain, strain rate and temperature. The formation of the metal burr during the friction welding process was successfully simulated, and the temperature distribution in the heat-affected zone indicated a good agreement with the variation of the microstructures in the HAZ. (orig.)

Microstructures and electrochemical behaviors of the friction stir welding dissimilar weld.

Science.gov (United States)

Shen, Changbin; Zhang, Jiayan; Ge, Jiping

2011-06-01

By using optical microscope, the microstructures of 5083/6082 friction stir welding (FSW) weld and parent materials were analyzed. Meanwhile, at ambient temperature and in 0.2 mol/L NaHS03 and 0.6 mol/L NaCl solutionby gravimetric test, potentiodynamic polarization curve test, electrochemical impedance spectra (EIS) and scanning electron microscope (SEM) observation, the electrochemical behavior of 5083/6082 friction stir welding weld and parent materials were comparatively investigated by gravimetric test, potentiodynamic polarization curve test, electrochemical impedance spectra (EIS) and scanning electron microscope (SEM) observation. The results indicated that at given processing parameters, the anti-corrosion property of the dissimilar weld was superior to those of the 5083 and 6082 parent materials. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Recent developments in Micro Friction Stir Welding: A review

International Nuclear Information System (INIS)

Sithole, Keydon; Rao, Veeredhi Vasudeva

2016-01-01

The advent of friction stir welding (FSW) in 1991 has been evolutionary in the joining of metals and related materials. Friction stir welding has enabled the joining of metals that could not be joined by other welding processes. Research has shown that dissimilar materials with very different properties, plastics, composites and even wood can be joined by FSW. Recent activities in the application of FSW has seen the development of micro friction stir welding (μFSW), which is the FSW of very thin sections of thickness 1000 μm (1 mm) or less. Micro friction stir welding further extends the applications of FSW to areas such as copper electrical contacts, tailor-welded blanks, wood. Though μFSW is relatively new development significant work has been done to date with interesting research findings being reported. This paper aims to review developments in μFSW to date. The focus of the paper will be on problems peculiar to μFSW due to downscaling to the micro scale and other practical considerations. (paper)

Mechanical properties of dissimilar friction welded steel bars in relation to post weld heat treatment

Energy Technology Data Exchange (ETDEWEB)

Kong, Yu Sik; Kim, Seon Jin [Pukyong National University, Busan (Korea, Republic of)

2006-04-15

Dissimilar friction welding were produced using 15(mm) diameter solid bar in chrome molybedenum steel(KS SCM440) to carbon steel(KS S45C) to investigate their mechanical properties. The main friction welding parameters were selected to endure good quality welds on the basis of visual examination, tensile tests, Vickers hardness surveys of the bond of area and H.A.Z and microstructure investigations. The specimens were tested as-welded and Post-Weld Heat Treated(PWHT). The tensile strength of the friction welded steel bars was increased up to 100% of the S45C base metal under the condition of all heating time. Optimal welding conditions were n=2,000(rpm), P{sub 1}=60(MPa), P{sub 2}=100(MPa), t{sub 1}=4(s), t{sub 2}=5(s) when the total upset length is 5.4 and 5.7(mm), respectively. The peak of hardness distribution of the friction welded joints can be eliminated by PWHT. Two different kinds of materials are strongly mixed to show a well-combined structure of macro-particles without any molten material and particle growth or any defects.

Deconvoluting the Friction Stir Weld Process for Optimizing Welds

Science.gov (United States)

Schneider, Judy; Nunes, Arthur C.

2008-01-01

In the friction stir welding process, the rotating surfaces of the pin and shoulder contact the weld metal and force a rotational flow within the weld metal. Heat, generated by the metal deformation as well as frictional slippage with the contact surface, softens the metal and makes it easier to deform. As in any thermo-mechanical processing of metal, the flow conditions are critical to the quality of the weld. For example, extrusion of metal from under the shoulder of an excessively hot weld may relax local pressure and result in wormhole defects. The trace of the weld joint in the wake of the weld may vary geometrically depending upon the flow streamlines around the tool with some geometry more vulnerable to loss of strength from joint contamination than others. The material flow path around the tool cannot be seen in real time during the weld. By using analytical "tools" based upon the principles of mathematics and physics, a weld model can be created to compute features that can be observed. By comparing the computed observations with actual data, the weld model can be validated or adjusted to get better agreement. Inputs to the model to predict weld structures and properties include: hot working properties ofthe metal, pin tool geometry, travel rate, rotation and plunge force. Since metals record their prior hot working history, the hot working conditions imparted during FSW can be quantified by interpreting the final microstructure. Variations in texture and grain size result from variations in the strain accommodated at a given strain rate and temperature. Microstructural data from a variety of FSWs has been correlated with prior marker studies to contribute to our understanding of the FSW process. Once this stage is reached, the weld modeling process can save significant development costs by reducing costly trial-and-error approaches to obtaining quality welds.

Performance Improvement of Friction Stir Welds by Better Surface Finish

Science.gov (United States)

Russell, Sam; Nettles, Mindy

2015-01-01

The as-welded friction stir weld has a cross section that may act as a stress concentrator. The geometry associated with the stress concentration may reduce the weld strength and it makes the weld challenging to inspect with ultrasound. In some cases, the geometry leads to false positive nondestructive evaluation (NDE) indications and, in many cases, it requires manual blending to facilitate the inspection. This study will measure the stress concentration effect and develop an improved phased array ultrasound testing (PAUT) technique for friction stir welding. Post-welding, the friction stir weld (FSW) tool would be fitted with an end mill that would machine the weld smooth, trimmed shaved. This would eliminate the need for manual weld preparation for ultrasonic inspections. Manual surface preparation is a hand operation that varies widely depending on the person preparing the welds. Shaving is a process that can be automated and tightly controlled.

Tensile Strength and Hardness Correlations with Microscopy in Friction welded Aluminium to Copper

Science.gov (United States)

Satish, Rengarajan; Seshagiri Rao, Vaddi; Ananthapadmanaban, Dattaguru; Ravi, Balappa

2016-01-01

Aluminium and copper are good conductors of heat and electricity, copper being the better conductor, is a costly metal indeed. On the other hand, aluminium is cheap, easily available and also has a lower density than copper. Hence, worldwide efforts are being made to partially replace copper wire. Solid state welding should be used to join aluminium to copper. This is because the use of fusion welding results in brittle phases formed in the weld interface. One of the solid state welding techniques used for joining aluminium to copper is friction welding. In this paper, an attempt has been made to join aluminium to copper by friction welding by varying the friction welding parameters, namely friction pressure, upset pressure, burn-off length and speed of rotation of the workpiece. Nine different friction welding parameter combinations were used during welding in accordance with ASTM standards and results have been reported. Tensile strength and hardness tests were carried out for each parameter combination. Optimum friction welding parameter combination was identified with respect to tensile strength. Scanning Electron Microscopy and Electron dispersive spectroanalysis were obtained to identify modes of fracture and presence of intermetallic phases for each friction welding combination with the aim to narrow down friction welding parameters that give good properties on the whole.

Friction stir welding tool

Science.gov (United States)

Tolle,; Charles R. , Clark; Denis E. , Barnes; Timothy, A [Ammon, ID

2008-04-15

A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

Friction stir welding tool and process for welding dissimilar materials

Science.gov (United States)

Hovanski, Yuri; Grant, Glenn J; Jana, Saumyadeep; Mattlin, Karl F

2013-05-07

A friction stir welding tool and process for lap welding dissimilar materials are detailed. The invention includes a cutter scribe that penetrates and extrudes a first material of a lap weld stack to a preselected depth and further cuts a second material to provide a beneficial geometry defined by a plurality of mechanically interlocking features. The tool backfills the interlocking features generating a lap weld across the length of the interface between the dissimilar materials that enhances the shear strength of the lap weld.

Friction welding of AZ31 magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Tsujino, R.; Ochi, H. [Osaka Inst. of Tech., Osaka (Japan); Kawai, G. [Osaka Sangyo Univ., Osaka (Japan); Yamaguchi, H.; Ogawa, K. [Osaka Prefecture Univ., Osaka (Japan); Suga, Y. [Keio Univ., Kanagawa (Japan)

2003-07-01

In this paper, for an acceleration of utilization of magnesium alloy which is being interested in recent years, friction welding of AZ31 magnesium alloy was carried out, and the joint performance was discussed in relation to the deformation heat input in the upset stage and upset loss as a evaluation factor. Where, the deformation heat input in the upset stage is mechanical work represented by the product of upset speed and axial pressure. As a result, it was made clear that the friction welding of AZ31 magnesium alloy was easy in the atmosphere, and good welded joints without a non- adhesion area at the weld interface could de obtained. Moreover, the evaluation factors discussed were possible to evaluate to joint performance. (orig.)

Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

Science.gov (United States)

2013-08-01

Sterling, R.J. Steel, C.-O. Pettersson. “Microstructure and mechanical properties of friction stir welded SAF 2507 super duplex stainless steel.” Mater...MICROSTRUCTURAL CHARACTERIZATION OF FRICTION STIR WELDED ALUMINUM-STEEL JOINTS By ERIN ELIZABETH PATTERSON A thesis submitted in...for his work producing the dissimilar weld samples used in this study. Without his work, this project would not have been possible. I would also

Effect of welding speed on microstructural and mechanical properties of friction stir welded Inconel 600

International Nuclear Information System (INIS)

Song, K.H.; Fujii, H.; Nakata, K.

2009-01-01

In order to evaluate the properties of a friction stir welded Ni base alloy, Inconel 600 (single phase type) was selected. Sound friction stir welds without weld defect were obtained at 150 and 200 mm/min in welding speed, however, a groove like defect occurred at 250 mm/min. The electron back scattered diffraction (EBSD) method was used to analyze the grain boundary character distribution. As a result, dynamic recrystallization was observed at all conditions, and the grain refinement was achieved in the stir zone, and it was gradually accelerated from 19 μm in average grain size of the base material to 3.4 μm in the stir zone with increasing the welding speed. It also has an effect on the mechanical properties so that friction stir welded zone showed 20% higher microhardness and 10% higher tensile strength than those of base material.

Development of friction welding process of Zr-based bulk metallic glasses

International Nuclear Information System (INIS)

Shin, Hyung Seop; Jeong, Young Jin; Kim, Ki Hyun

2004-01-01

Bulk Metallic Glasses(BMG) with good mechanical properties have problems that engineering application fields have been limited because of limitation of the alloy size. In order to solving this problem, the friction welding of BMG has been tried using the superplastic-like deformation behavior under the supercooled liquid region. The apparatus for friction welding test was designed and constructed using pneumatic cylinder and gripper based on a conventional lathe. Friction welding have been tried to combination of same BMG alloy and crystalline alloys. The results of welding test were evaluated by X-ray diffraction, measurement of hardness and mechanical properties test. In order to obtain the optimized welding test conditions the temperature of friction interface was measured using Infrared thermal imager

Heat Control via Torque Control in Friction Stir Welding

Science.gov (United States)

Venable, Richard; Colligan, Kevin; Knapp, Alan

2004-01-01

In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

A preliminary study on the application of Friction Welding in structural repairs

Energy Technology Data Exchange (ETDEWEB)

Pauly, D.; Santos, J.F. dos [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung; Blakemore, G.R. [Pressure Products Group, Aberdeen (United Kingdom); Gibson, D. [National Hyperbaric Centre, Aberdeen (United Kingdom)

1998-11-01

Friction Welding is characterised by the absence of a fusion zone associated with comparatively low temperatures in the weld. These features allow the application of this welding process in joining and repair of most engineering structures, especially in hazardous environments. This work presents a preliminary study on different friction welding processes, including the recently developed Friction Hydro-Pillar Processing (FHPP) and Friction Stitch Welding, as joining technologies for thick-walled structures. The use of these welding processes in different industrial applications, compared with the commonly used arc welding counterparts, as well as the influence of welding parameters on the weldment integrity are discussed. A brief description of a portable friction welding equipment and its possible implementation for FHPP are presented. Stud welds produced in the commissioning phase of this equipment have been analysed and tested to assess their quality. (orig.) [Deutsch] Da die Schweisszonentemperatur waehrend des Reibschweissvorganges vergleichsweise niedrig ist, bildet sich kein Schmelzbad aus. Anwendbar ist dieses Schweissverfahren zur Verbindung oder Reparatur der meisten Metallkonstruktionen, speziell in risikobehafteter Umgebung. Diese Arbeit enthaelt eine Vorstudie zu verschiedenen Reibschweissprozessen, einschliesslich der neu entwickelten Friction Hydro-Pillar Processing (FHPP)- und Friction Stitch Welding-Verfahren, als Fuegetechniken fuer dickwandige Strukturen. Die Anwendbarkeit dieser Schweissprozesse in verschiedenen Industrien, verglichen mit herkoemmlich verwendeten Lichtbogenschweissverfahren, sowie der Einfluss von Schweissparametern auf die Guete der Verbindung werden diskutiert. Praesentiert wird ausserdem eine tragbare Reibschweissmaschine und ihre moegliche Verwendung zum FHPP-Schweissen. Bolzenschweissungen, die waehrend der Inbetriebnahmephase dieser Maschine hergestellt wurden, sind zur Charakterisierung ihrer Qualitaet analysiert und

Tensile Properties of Friction Stir Welded Joints of AA 2024-T6 Alloy at Different Welding Speeds

Science.gov (United States)

Avula, Dhananjayulu; Devuri, Venkateswarlu; Cheepu, Muralimohan; Dwivedi, Dheerendra Kumar

2018-03-01

The influence of welding speed on the friction stir welded joint properties of hardness, tensile properties, defects and microstructure characterization are studied in the present study. The friction stir welding was conducted on AA2014-T6 heat treated alloy with 5 mm thickness plate in butt joint configuration. The welding speed was varied from 8 mm/min to 120 mm/min at the fixed travel speed and load conditions. It is observed that the welding speeds at higher rate with wide range can be possible to weld this alloy at higher rates of tool revolution suggesting that the inherent capability of friction stir welding technique for aluminum 2014 alloys. The strength of the joints gradually increases with enhancing of welding speed. The micro structural observations exhibited the formation of equiaxed grains in the stir zone and slightly in the thermo-mechanically affected zone. In addition, the size of the grains decreases with increase in welding speed owing to the presence of low heat input. Hence the hardness of the joints slightly increased in the stir zones over the other zones of the weld nugget. The joint strength initially increases with the welding speed and starts to decreases after reaching to the maximum value. The relationship between the welding conditions and friction stir welded joint properties has been discussed.

Friction Stir Weld Restart+Reweld Repair Allowables

Science.gov (United States)

Clifton, Andrew

2008-01-01

A friction stir weld (FSW) repair method has been developed and successfully implemented on Al 2195 plate material for the Space Shuttle External Fuel Tank (ET). The method includes restarting the friction stir weld in the termination hole of the original weld followed by two reweld passes. Room temperature and cryogenic temperature mechanical properties exceeded minimum FSW design strength and compared well with the development data. Simulated service test results also compared closely to historical data for initial FSW, confirming no change to the critical flaw size or inspection requirements for the repaired weld. Testing of VPPA fusion/FSW intersection weld specimens exhibited acceptable strength and exceeded the minimum design value. Porosity, when present at the intersection was on the root side toe of the fusion weld, the "worst case" being 0.7 inch long. While such porosity may be removed by sanding, this "worst case" porosity condition was tested "as is" and demonstrated that porosity did not negatively affect the strength of the intersection weld. Large, 15-inch "wide panels" FSW repair welds were tested to demonstrate strength and evaluate residual stresses using photo stress analysis. All results exceeded design minimums, and photo stress analysis showed no significant stress gradients due to the presence of the restart and multi-pass FSW repair weld.

Bobbin-Tool Friction-Stir Welding of Thick-Walled Aluminum Alloy Pressure Vessels

Energy Technology Data Exchange (ETDEWEB)

Dalder, E C; Pastrnak, J W; Engel, J; Forrest, R S; Kokko, E; Ternan, K M; Waldron, D

2007-06-06

It was desired to assemble thick-walled Al alloy 2219 pressure vessels by bobbin-tool friction-stir welding. To develop the welding-process, mechanical-property, and fitness-for-service information to support this effort, extensive friction-stir welding-parameter studies were conducted on 2.5 cm. and 3.8 cm. thick 2219 Al alloy plate. Starting conditions of the plate were the fully-heat-treated (-T62) and in the annealed (-O) conditions. The former condition was chosen with the intent of using the welds in either the 'as welded' condition or after a simple low-temperature aging treatment. Since preliminary stress-analyses showed that stresses in and near the welds would probably exceed the yield-strength of both 'as welded' and welded and aged weld-joints, a post-weld solution-treatment, quenching, and aging treatment was also examined. Once a suitable set of welding and post-weld heat-treatment parameters was established, the project divided into two parts. The first part concentrated on developing the necessary process information to be able to make defect-free friction-stir welds in 3.8 cm. thick Al alloy 2219 in the form of circumferential welds that would join two hemispherical forgings with a 102 cm. inside diameter. This necessitated going to a bobbin-tool welding-technique to simplify the tooling needed to react the large forces generated in friction-stir welding. The bobbin-tool technique was demonstrated on both flat-plates and plates that were bent to the curvature of the actual vessel. An additional issue was termination of the weld, i.e. closing out the hole left at the end of the weld by withdrawal of the friction-stir welding tool. This was accomplished by friction-plug welding a slightly-oversized Al alloy 2219 plug into the termination-hole, followed by machining the plug flush with both the inside and outside surfaces of the vessel. The second part of the project involved demonstrating that the welds were fit for the intended

Mechanical properties of friction stir welded aluminum alloys 5083 and 5383

Directory of Open Access Journals (Sweden)

Jeom Kee Paik

2009-09-01

Full Text Available The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships. While various welding methods are used today to fabricate aluminum ship structures, namely gas metallic arc welding (GMAW, laser welding and friction stir welding (FSW, FSW technology has been recognized to have many advantages for the construction of aluminum structures, as it is a low-cost welding process. In the present study, mechanical properties of friction stir welded aluminum alloys are examined experimentally. Tensile testing is undertaken on dog-bone type test specimen for aluminum alloys 5083 and 5383. The test specimen includes friction stir welded material between identical alloys and also dissimilar alloys, as well as unwelded (base alloys. Mechanical properties of fusion welded aluminum alloys are also tested and compared with those of friction stir welded alloys. The insights developed from the present study are documented together with details of the test database. Part of the present study was obtained from the Ship Structure Committee project SR-1454 (Paik, 2009, jointly funded by its member agencies.

Optimization of Friction Stir Welding Tool Advance Speed via Monte-Carlo Simulation of the Friction Stir Welding Process.

Science.gov (United States)

Fraser, Kirk A; St-Georges, Lyne; Kiss, Laszlo I

2014-04-30

Recognition of the friction stir welding process is growing in the aeronautical and aero-space industries. To make the process more available to the structural fabrication industry (buildings and bridges), being able to model the process to determine the highest speed of advance possible that will not cause unwanted welding defects is desirable. A numerical solution to the transient two-dimensional heat diffusion equation for the friction stir welding process is presented. A non-linear heat generation term based on an arbitrary piecewise linear model of friction as a function of temperature is used. The solution is used to solve for the temperature distribution in the Al 6061-T6 work pieces. The finite difference solution of the non-linear problem is used to perform a Monte-Carlo simulation (MCS). A polynomial response surface (maximum welding temperature as a function of advancing and rotational speed) is constructed from the MCS results. The response surface is used to determine the optimum tool speed of advance and rotational speed. The exterior penalty method is used to find the highest speed of advance and the associated rotational speed of the tool for the FSW process considered. We show that good agreement with experimental optimization work is possible with this simplified model. Using our approach an optimal weld pitch of 0.52 mm/rev is obtained for 3.18 mm thick AA6061-T6 plate. Our method provides an estimate of the optimal welding parameters in less than 30 min of calculation time.

Low temperature friction stir welding of P91 steel

Directory of Open Access Journals (Sweden)

Prasad Rao Kalvala

2016-08-01

Full Text Available Bead-on-plate friction stir welds were made on P91 alloy with low and high rotational speeds (100 and 1000 RPM to study their effects on weld microstructural changes and impression creep behavior. Temperatures experienced by the stir zone were recorded at the weld tool tip. Different zones of welds were characterized for their microstructural changes, hardness and creep behavior (by impression creep tests. The results were compared with submerged arc fusion weld. Studies revealed that the stir zone temperature with 100 RPM was well below Ac1 temperature of P91 steel while it was above Ac3 with 1000 RPM. The results suggest that the microstructural degradation in P91 welds can be controlled by low temperature friction stir welding technique.

A Brief Introduction to the Theory of Friction Stir Welding

Science.gov (United States)

Nunes, Arthur C., Jr.

2008-01-01

Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and is already an important welding process for the aerospace industry, where welds of optimal quality are demanded. The structure of welds determines weld properties. The structure of friction stir welds is determined by the flow field in the weld metal in the vicinity of the weld tool. A simple kinematic model of the FSW flow field developed at Marshall Space Flight Center, which enables the basic features of FSW microstructure to be understood and related to weld process parameters and tool design, is explained.

Understanding Friction Stir Welding

Science.gov (United States)

Nunes, A. C., Jr.

2018-01-01

This Technical Memorandum explains the friction stir welding process in terms of two basic concepts: the concentration of deformation in a shear surface enveloping the tool and the composition of the overall plastic flow field around the tool from simple flow field components. It is demonstrated how weld structure may be understood and torque, drag, and lateral tool forces may be estimated using these concepts. Some discrepancies between computations and accompanying empirical data are discussed in the text. This work is intended to be helpful to engineers in diagnosing problems and advancing technology.

Fatigue and Damage Tolerance of Friction Stir Welded Joints for Aerospace Applications

NARCIS (Netherlands)

Lemmen, H.J.K.

2010-01-01

Friction stir welding is a young welding process with high potential to replace riveted joints in aerospace structures like the fuselage. Friction stir welding is a robust process and capable of welding high strength aluminum alloys. Therefore it can lead to both costs and weight savings. To

Structure formation of 5083 alloy during friction stir welding

Science.gov (United States)

Zaikina, A. A.; Kolubaev, A. V.; Sizova, O. V.; Ivanov, K. V.; Filippov, A. V.; Kolubaev, E. A.

2017-12-01

This paper provides a comparative study of structures obtained by friction stir welding and sliding friction of 5083 Al alloy. Optical and electron microscopy reveals identical fine-grained structures with a grain size of ˜5 µm both in the weld nugget zone and subsurface layer in friction independently of the initial grain size of the alloy. It has been suggested that the grain boundary sliding is responsible for the specific material flow pattern in both techniques considered.

Friction stir welding process to repair voids in aluminum alloys

Science.gov (United States)

Rosen, Charles D. (Inventor); Litwinski, Edward (Inventor); Valdez, Juan M. (Inventor)

1999-01-01

The present invention provides an in-process method to repair voids in an aluminum alloy, particularly a friction stir weld in an aluminum alloy. For repairing a circular void or an in-process exit hole in a weld, the method includes the steps of fabricating filler material of the same composition or compatible with the parent material into a plug form to be fitted into the void, positioning the plug in the void, and friction stir welding over and through the plug. For repairing a longitudinal void (30), the method includes machining the void area to provide a trough (34) that subsumes the void, fabricating filler metal into a strip form (36) to be fitted into the trough, positioning the strip in the trough, and rewelding the void area by traversing a friction stir welding tool longitudinally through the strip. The method is also applicable for repairing welds made by a fusing welding process or voids in aluminum alloy workpieces themselves.

Laser beam welding and friction stir welding of 6013-T6 aluminium alloy sheet

International Nuclear Information System (INIS)

Braun, R.; Dalle Donne, C.; Staniek, G.

2000-01-01

Butt welds of 1.6 mm thick 6013-T6 sheet were produced using laser beam welding and friction stir welding processes. Employing the former joining technique, filler powders of the alloys Al-5%Mg and Al-12%Si were used. Microstructure, hardness profiles, tensile properties and the corrosion behaviour of the welds in the as-welded condition were investigated. The hardness in the weld zone was lower compared to that of the base material in the peak-aged temper. Hardness minima were measured in the fusion zone and in the thermomechanically affected zone for laser beam welded and friction stir welded joints, respectively. Metallographic and fractographic examinations revealed pores in the fusion zone of the laser beam welds. Porosity was higher in welds made using the filler alloy Al-5%Mg than using the filler metal Al-12%Si. Transmission electron microscopy indicated that the β '' (Mg 2 Si) hardening precipitates were dissolved in the weld zone due to the heat input of the joining processes. Joint efficiencies achieved for laser beam welds depended upon the filler powders, being about 60 and 80% using the alloys Al-5%Mg and Al-12%Si, respectively. Strength of the friction stir weld approached over 80% of the ultimate tensile strength of the 6013-T6 base material. Fracture occurred in the region of hardness minima unless defects in the weld zone led to premature failure. The heat input during welding did not cause a degradation of the corrosion behaviour of the welds, as found in continuous immersion tests in an aqueous chloride-peroxide solution. In contrast to the 6013-T6 parent material, the weld zone was not sensitive to intergranular corrosion. Alternate immersion tests in 3.5% NaCl solution indicated high stress corrosion cracking resistance of the joints. For laser beam welded sheet, the weld zone of alternately immersed specimens suffered severe degradation by pitting and intergranular corrosion, which may be associated with galvanic coupling of filler metal and

Retractable Pin Tools for the Friction Stir Welding Process

Science.gov (United States)

1998-01-01

Two companies have successfully commercialized a specialized welding tool developed at the Marshall Space Flight Center (MSFC). Friction stir welding uses the high rotational speed of a tool and the resulting frictional heat created from contact to crush, 'stir' together, and forge a bond between two metal alloys. It has had a major drawback, reliance on a single-piece pin tool. The pin is slowly plunged into the joint between two materials to be welded and rotated as high speed. At the end of the weld, the single-piece pin tool is retracted and leaves a 'keyhole,' something which is unacceptable when welding cylindrical objects such as drums, pipes and storage tanks. Another drawback is the requirement for different-length pin tools when welding materials of varying thickness. An engineer at the MSFC helped design an automatic retractable pin tool that uses a computer-controlled motor to automatically retract the pin into the shoulder of the tool at the end of the weld, preventing keyholes. This design allows the pin angle and length to be adjusted for changes in material thickness and results in a smooth hole closure at the end of the weld. Benefits of friction stir welding, using the MSFC retractable pin tool technology, include the following: The ability to weld a wide range of alloys, including previously unweldable and composite materials; provision of twice the fatigue resistance of fusion welds and no keyholes; minimization of material distortion; no creation of hazards such as welding fumes, radiation, high voltage, liquid metals, or arcing; automatic retraction of the pin at the end of the weld; and maintaining full penetration of the pin.

Effect of tool geometry on friction stir spot welding of polypropylene sheets

Directory of Open Access Journals (Sweden)

M. K. Bilici

2012-10-01

Full Text Available The effects of tool geometry and properties on friction stir spot welding properties of polypropylene sheets were studied. Four different tool pin geometries, with varying pin angles, pin lengths, shoulder diameters and shoulder angles were used for friction stir spot welding. All the welding operations were done at the room temperature. Lap-shear tensile tests were carried out to find the weld static strength. Weld cross section appearance observations were also done. From the experiments the effect of tool geometry on friction stir spot weld formation and weld strength were determined. The optimum tool geometry for 4 mm thick polypropylene sheets were determined. The tapered cylindrical pin gave the biggest and the straight cylindrical pin gave the lowest lap-shear fracture load.

Friction stir welding and processing of oxide dispersion strengthened (ODS) alloys

Science.gov (United States)

Ren, Weiju

2014-11-11

A method of welding including forming a filler material of a first oxide dispersoid metal, the first oxide dispersoid material having first strengthening particles that compensate for decreases in weld strength of friction stir welded oxide dispersoid metals; positioning the filler material between a first metal structure and a second metal structure each being comprised of at least a second oxide dispersoid metal; and friction welding the filler material, the first metal structure and the second metal structure to provide a weld.

The Influence of Friction Stir Weld Tool Form and Welding Parameters on Weld Structure and Properties: Nugget Bulge in Self-Reacting Friction Stir Welds

Science.gov (United States)

Schneider, Judy; Nunes, Arthur C., Jr.; Brendel, Michael S.

2010-01-01

Although friction stir welding (FSW) was patented in 1991, process development has been based upon trial and error and the literature still exhibits little understanding of the mechanisms determining weld structure and properties. New concepts emerging from a better understanding of these mechanisms enhance the ability of FSW engineers to think about the FSW process in new ways, inevitably leading to advances in the technology. A kinematic approach in which the FSW flow process is decomposed into several simple flow components has been found to explain the basic structural features of FSW welds and to relate them to tool geometry and process parameters. Using this modelling approach, this study reports on a correlation between the features of the weld nugget, process parameters, weld tool geometry, and weld strength. This correlation presents a way to select process parameters for a given tool geometry so as to optimize weld strength. It also provides clues that may ultimately explain why the weld strength varies within the sample population.

Hybrid friction stir welding for dissimilar materials through electro-plastic effect

Science.gov (United States)

Liu, Xun; Lan, Shuhuai; Ni, Jun

2018-05-29

A hybrid Friction Stir Welding approach and device for dissimilar materials joining employing Electro-Plastic Effect. The approach and device include an introduction of high density, short period current pulses into traditional friction stir welding process, which therefore can generate a localized softened zone in the workpiece during plastic stirring without significant additional temperature increase. This material softened zone is created by high density current pulses based on Electro-Plastic Effect and will move along with the friction stir welding tool. Smaller downward force, larger processing window and better joint quality for dissimilar materials are expected to be achieved through this hybrid welding technique.

Mechanical properties of friction stir welded 11Cr-ferritic/martensitic steel

International Nuclear Information System (INIS)

Yano, Y.; Sato, Y.S.; Sekio, Y.; Ohtsuka, S.; Kaito, T.; Ogawa, R.; Kokawa, H.

2013-01-01

Friction stir welding was applied to the wrapper tube materials, 11Cr-ferritic/martensitic steel, designed for fast reactors and defect-free welds were successfully produced. The mechanical and microstructural properties of the friction stir welded steel were subsequently investigated. The hardness values of the stir zone were approximately 550 Hv (5.4 GPa) with minimal dependence on the rotational speed, even though they were much higher than those of the base material. However, tensile strengths and elongations of the stir zones were high at 298 K, compared to those of the base material. The excellent tensile properties are attributable to the fine grain formation during friction stir welding

Recent Developments and Research Progress on Friction Stir Welding of Titanium Alloys: An Overview

Science.gov (United States)

Karna, Sivaji; Cheepu, Muralimohan; Venkateswarulu, D.; Srikanth, V.

2018-03-01

Titanium and its alloys are joined by various welding processes. However, Fusion welding of titanium alloys resulted solidification problems like porosity, segregation and columnar grains. The problems occurred in conventional welding processes can be resolved using a solid state welding i.e. friction stir welding. Aluminium and Magnesium alloys were welded by friction stir welding. However alloys used for high temperature applications such as titanium alloys and steels are arduous to weld using friction stir welding process because of tool limitations. Present paper summarises the studies on joining of Titanium alloys using friction stir welding with different tool materials. Selection of tool material and effect of welding conditions on mechanical and microstructure properties of weldments were also reported. Major advantage with friction stir welding is, we can control the welding temperature above or below β-transus temperature by optimizing the process parameters. Stir zone in below beta transus condition consists of bi-modal microstructure and microstructure in above β-transus condition has large prior β- grains and α/β laths present in the grain. Welding experiments conducted below β- transus condition has better mechanical properties than welding at above β-transus condition. Hardness and tensile properties of weldments are correlated with the stir zone microstructure.

Physics-based process model approach for detecting discontinuity during friction stir welding

Energy Technology Data Exchange (ETDEWEB)

Shrivastava, Amber; Pfefferkorn, Frank E.; Duffie, Neil A.; Ferrier, Nicola J.; Smith, Christopher B.; Malukhin, Kostya; Zinn, Michael

2015-02-12

The goal of this work is to develop a method for detecting the creation of discontinuities during friction stir welding. This in situ weld monitoring method could significantly reduce the need for post-process inspection. A process force model and a discontinuity force model were created based on the state-of-the-art understanding of flow around an friction stir welding (FSW) tool. These models are used to predict the FSW forces and size of discontinuities formed in the weld. Friction stir welds with discontinuities and welds without discontinuities were created, and the differences in force dynamics were observed. In this paper, discontinuities were generated by reducing the tool rotation frequency and increasing the tool traverse speed in order to create "cold" welds. Experimental force data for welds with discontinuities and welds without discontinuities compared favorably with the predicted forces. The model currently overpredicts the discontinuity size.

Friction welding of ductile cast iron using interlayers

International Nuclear Information System (INIS)

Winiczenko, Radoslaw; Kaczorowski, Mieczyslaw

2012-01-01

Highlights: → The results of the study of the friction welding of ductile cast iron using interlayers are presented. → The results of the analysis shows that the joint has the tensile strength compared to that of basic material. → In case of ductile cast iron, it is possible to reach the tensile strength equals even 700 MPa. → The process of friction welding was accompanied with diffusion of Cr, Ni and C atoms across the interface. -- Abstract: In this paper, ductile cast iron-austenitic stainless steel, ductile cast iron-pure Armco iron and ductile cast iron-low carbon steel interlayers were welded, using the friction welding method. The tensile strength of the joints was determined, using a conventional tensile test machine. Moreover, the hardness across the interface of materials was measured on metallographic specimens. The fracture surface and microstructure of the joints was examined using either light stereoscope microscopy as well as electron microscopy. In this case, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied. The results of the analysis shows that the joint has the tensile strength compared to that of basic material. In case of ductile cast iron, it is possible to reach the tensile strength equals even 700 MPa. It was concluded that the process of friction welding was accompanied with diffusion of Cr, Ni and C atoms across the ductile cast iron-stainless steel interface. This leads to increase in carbon concentration in stainless steel where chromium carbides were formed, the size and distribution of which was dependent on the distance from the interface.

Friction Stir Welding of Tapered Thickness Welds Using an Adjustable Pin Tool

Science.gov (United States)

Adams, Glynn; Venable, Richard; Lawless, Kirby

2003-01-01

Friction stir welding (FSW) can be used for joining weld lands that vary in thickness along the length of the weld. An adjustable pin tool mechanism can be used to accomplish this in a single-pass, full-penetration weld by providing for precise changes in the pin length relative to the shoulder face during the weld process. The difficulty with this approach is in accurately adjusting the pin length to provide a consistent penetration ligament throughout the weld. The weld technique, control system, and instrumentation must account for mechanical and thermal compliances of the tooling system to conduct tapered welds successfully. In this study, a combination of static and in-situ measurements, as well as active control, is used to locate the pin accurately and maintain the desired penetration ligament. Frictional forces at the pin/shoulder interface were a source of error that affected accurate pin position. A traditional FSW pin tool design that requires a lead angle was used to join butt weld configurations that included both constant thickness and tapered sections. The pitch axis of the tooling was fixed throughout the weld; therefore, the effective lead angle in the tapered sections was restricted to within the tolerances allowed by the pin tool design. The sensitivity of the FSW process to factors such as thickness offset, joint gap, centerline offset, and taper transition offset were also studied. The joint gap and the thickness offset demonstrated the most adverse affects on the weld quality. Two separate tooling configurations were used to conduct tapered thickness welds successfully. The weld configurations included sections in which the thickness decreased along the weld, as well as sections in which the thickness increased along the weld. The data presented here include weld metallography, strength data, and process load data.

Thermal modelling of friction stir welding

DEFF Research Database (Denmark)

Schmidt, Henrik Nikolaj Blicher; Hattel, Jesper Henri

2008-01-01

The objective of the present work is to present the basic elements of the thermal modelling of friction stir welding as well as to clarify some of the uncertainties in the literature regarding the different contributions to the heat generation. Some results from a new thermal pseudomechanical model...... in which the temperature-dependent yield stress of the weld material controls the heat generation are also presented....

Friction stir welding of single crystal aluminium

DEFF Research Database (Denmark)

Fonda, Richard Warren; Wert, John A.; Reynolds, A.P.

2007-01-01

Friction stir welds were prepared in different orientations in an aluminium single crystal. The welds were quenched to preserve the microstructure surrounding the tool and then electron backscattered diffraction was used to reveal the generation of grain boundaries and the evolution...... of crystallographic texture around the tool in each weld. The extent of both dynamic recrystallisation and conventional recrystallisation varied considerably as a function of weld orientation. As the base plate begins to interact with the deformation field surrounding the tool, regions of the single crystal rotate...

Multiple pass and multiple layer friction stir welding and material enhancement processes

Science.gov (United States)

Feng, Zhili [Knoxville, TN; David, Stan A [Knoxville, TN; Frederick, David Alan [Harriman, TN

2010-07-27

Processes for friction stir welding, typically for comparatively thick plate materials using multiple passes and multiple layers of a friction stir welding tool. In some embodiments a first portion of a fabrication preform and a second portion of the fabrication preform are placed adjacent to each other to form a joint, and there may be a groove adjacent the joint. The joint is welded and then, where a groove exists, a filler may be disposed in the groove, and the seams between the filler and the first and second portions of the fabrication preform may be friction stir welded. In some embodiments two portions of a fabrication preform are abutted to form a joint, where the joint may, for example, be a lap joint, a bevel joint or a butt joint. In some embodiments a plurality of passes of a friction stir welding tool may be used, with some passes welding from one side of a fabrication preform and other passes welding from the other side of the fabrication preform.

Friction stir welding of Aluminium matrix composites – A Review

Directory of Open Access Journals (Sweden)

Subramanya Prabhu

2018-01-01

Full Text Available Friction stir welding (FSW is established as one of the prominent welding techniques to join aluminium matrix composites (AMCs. It is a solid state welding process, takes place well below the melting temperature of the material, eliminates the detrimental effects of conventional fusion welding process. Although the process is capable to join AMCs, challenges are still open that need to be fulfill to widen its applications. This paper gives the outline of the friction stir welding technique used to join AMCs. Effect of process variables on the microstructure and mechanical properties of the joints, behavior of reinforcing materials during welding, effect of tool profiles on the joint strength are discussed in detail. Few improvements and direction for future research are also proposed.

Experimental studies of parameters affecting the heat generation in friction stir welding process

Directory of Open Access Journals (Sweden)

Mijajlović Miroslav M.

2012-01-01

Full Text Available Heat generation is a complex process of transformation of a specific type of energy into heat. During friction stir welding, one part of mechanical energy delivered to the welding tool is consumed in the welding process, another is used for deformational processes etc., and the rest of the energy is transformed into heat. The analytical procedure for the estimation of heat generated during friction stir welding is very complex because it includes a significant number of variables and parameters, and many of them cannot be fully mathematically explained. Because of that, the analytical model for the estimation of heat generated during friction stir welding defines variables and parameters that dominantly affect heat generation. These parameters are numerous and some of them, e. g. loads, friction coefficient, torque, temperature, are estimated experimentally. Due to the complex geometry of the friction stir welding process and requirements of the measuring equipment, adequate measuring configurations and specific constructional solutions that provide adequate measuring positions are necessary. This paper gives an overview of the process of heat generation during friction stir welding, the most influencing parameters on heat generation, constructional solutions for the measuring equipment needed for these experimental researches and examples of measured values.

Orbital friction stir welding of aluminium pipes

International Nuclear Information System (INIS)

Engelhard, G.; Hillers, T.

2002-01-01

Friction stir welding (FSW) was originally developed for flat plates. This contribution shows how it can be applied to the welding of aluminium pipes. Pipes made of AlMG 3 (EN5754), AlMg 4.5Mn (EN5083) and AlMgSi 0.5 (EN6106) with dimensions of Da 600 and 520 x 10-8 mm were welded. The FSW orbital system comprises an annular cage with integrated FSW head, a hydraulic system, and a control unit. The welds were tested successfully according to EN 288. The mechanical and technical properties of the welds were somewhat better than with the TIG orbital process, and welding times were about 40 percent shorter [de

Effect of tool shape and welding parameters on mechanical properties and microstructure of dissimilar friction stir welded aluminium alloys

OpenAIRE

Chetan Aneja; Amit Handa

2016-01-01

In the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW) process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases w...

Assessment of microstructure and tensile behavior of continuous drive friction welded titanium tubes

International Nuclear Information System (INIS)

Palanivel, R.; Dinaharan, I.; Laubscher, R.F.

2017-01-01

Friction welding process has been applied to join Grade 2 titanium alloy tubes of outer diameter 60 mm and wall thickness 3.9 mm. In this research work, five different friction times (24, 28, 32, 36 and 40 s) were used to evaluate the ultimate tensile strength (UTS) and microstructure of welded tubes. Recording of the process parameters during welding was done. Optical microscopy, electron back scattered diffraction and transmission electron microscopy were used to study the microstructure. The results showed that the friction time had a significant influence on the microstructure and UTS. The rate of deformation increased with friction time and refined the grains in the weld zone. Coarse grain structure was observed from the center of the weld zone towards the flash. Identical grain structure was observed in the heat affected zone (HAZ) and the parent metal. It was found that a maximum joint efficiency of 98.3% was achieved at a friction time of 32 s.The details of microhardness, failure location and fracture surface of the welded tubes were reported.

Assessment of microstructure and tensile behavior of continuous drive friction welded titanium tubes

Energy Technology Data Exchange (ETDEWEB)

Palanivel, R., E-mail: rpalanivelme@gmail.com; Dinaharan, I., E-mail: dinaweld2009@gmail.com; Laubscher, R.F., E-mail: rflaubscher@uj.ac.za

2017-02-27

Friction welding process has been applied to join Grade 2 titanium alloy tubes of outer diameter 60 mm and wall thickness 3.9 mm. In this research work, five different friction times (24, 28, 32, 36 and 40 s) were used to evaluate the ultimate tensile strength (UTS) and microstructure of welded tubes. Recording of the process parameters during welding was done. Optical microscopy, electron back scattered diffraction and transmission electron microscopy were used to study the microstructure. The results showed that the friction time had a significant influence on the microstructure and UTS. The rate of deformation increased with friction time and refined the grains in the weld zone. Coarse grain structure was observed from the center of the weld zone towards the flash. Identical grain structure was observed in the heat affected zone (HAZ) and the parent metal. It was found that a maximum joint efficiency of 98.3% was achieved at a friction time of 32 s.The details of microhardness, failure location and fracture surface of the welded tubes were reported.

Microstructures of friction welded joints of AZ31 to AM60 magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Fukumoto, S.; Ono, T.; Tanaka, S.; Tsubakino, H. [Graduate School of Engineering, Himeji Inst. of Tech., Hyogo (Japan); Tomita, T.; Aritoshi, M. [Hyogo Prefectural Inst. of Industrial Research, Kobe, Hyogo (Japan); Okita, K. [Inst. of Industrial Research, Osaka Sangyo Univ., Osaka (Japan)

2003-07-01

AZ31 magnesium alloy was friction-welded to AM60 and the microstructures and the friction welding process were studied. The microstructures changed near the weld interface. The AZ31 was refined to a grain size of several {mu}m near the weld interface. The nucleation occurred in the shear bands that were introduced during the welding process. On the other hand, the eutectic structure was deformed and the lamellar structure which was composed of {alpha}-Mg and Mg{sub 17}Al{sub 12} was formed near the weld interface in AM60 alloy. In the friction process, the adhesion and peel off occurred alternately between AZ31 and AM60. Eventually, bonding was completed during upset process. (orig.)

Similar and dissimilar friction welding of Zr-Cu-Al bulk glassy alloys

International Nuclear Information System (INIS)

Shin, Hyung-Seop; Park, Jung-Soo; Jung, Yoon-Chul; Ahn, Jung-Ho; Yokoyama, Yoshihiko; Inoue, Akihisa

2009-01-01

The friction welding of three kinds of Zr-Cu-Al bulk glassy alloys (BGAs) which show eutectic or hypoeutectic compositions to similar and dissimilar BGAs and crystalline metals has been tried. The shape and volume of the protrusion formed at the weld interface were investigated. In order to characterize the friction welded interface, micrographic observation and X-ray diffraction analysis on the weld cross-section were carried out. A successful joining of Zr-Cu-Al bulk glassy alloys to similar and dissimilar BGAs was achieved without occurrence of crystallizations at the weld interface through the precise control of friction conditions. In addition, the joining of Zr 50 Cu 40 Al 10 BGA to crystalline alloys was tried, but it was only successful for specific material combinations. The residual strength after welding of dissimilar BGAs was evaluated by the four-point bending test.

Microstructure and properties of friction stir butt-welded AZ31 magnesium alloy

International Nuclear Information System (INIS)

Wang Xunhong; Wang Kuaishe

2006-01-01

Friction stir welding (FSW) is a relatively new joining technique particularly for magnesium and aluminum alloys that are difficult to fusion weld. In this paper, an excellent friction stir weld of AZ31 magnesium alloy was obtained at proper parameter. In the friction stir zone (FSZ), the microstructure of the base material (BM) is replaced by fine grains and small particles of intermetallic compounds. The average microhardness of the friction stir zone is higher than that of the base material. The maximum tensile strength of joint can reach 93% that of the base material. And the failure locations are almost at the heating affected zone

Automatic Gap Detection in Friction Stir Welding Processes (Preprint)

National Research Council Canada - National Science Library

Yang, Yu; Kalya, Prabhanjana; Landers, Robert G; Krishnamurthy, K

2006-01-01

.... This paper develops a monitoring algorithm to detect gaps in Friction Stir Welding (FSW) processes. Experimental studies are conducted to determine how the process parameters and the gap width affect the welding process...

Defect Detectability Improvement for Conventional Friction Stir Welds

Science.gov (United States)

Hill, Chris

2013-01-01

This research was conducted to evaluate the effects of defect detectability via phased array ultrasound technology in conventional friction stir welds by comparing conventionally prepped post weld surfaces to a machined surface finish. A machined surface is hypothesized to improve defect detectability and increase material strength.

Thermomechanical Modelling of Friction Stir Welding

DEFF Research Database (Denmark)

Hattel, Jesper Henri; Schmidt, Henrik Nikolaj Blicher; Tutum, Cem Celal

2009-01-01

Friction Stir Welding (FSW) is a fully coupled thermomechanical process and should in general be modelled as such. Basically, there are two major application areas of thermomechanical models in the investigation of the FSW process: i) Analysis of the thermomechanical conditions such as e.g. heat...... generation and local material deformation (often referred to as flow) during the welding process itself. ii) Prediction of the residual stresses that will be present in the joint structure post to welding. While the former in general will call for a fully-coupled thermomechanical procedure, however...... for the FSW process at hand, the heat generation must either be prescribed analytically or based on a fully coupled analysis of the welding process itself. Along this line, a recently proposed thermal-pseudo-mechanical model is presented in which the temperature dependent yield stress of the weld material...

Effects of Laser Peening, and Shot Peening, on Friction Stir Welding

Science.gov (United States)

Hatamleh, Omar; Hackel, Lloyd; Rankin, Jon; Truong, Chanh; Walter, Matt

2006-01-01

A viewgraph presentation describing the effects of laser peening and shot peening on friction stir welding is shown. The topics include: 1) Background; 2) Friction Stir Welding (FSW); 3) Microstructure; 4) Laser & Shot Peening; 5) Residual Stresses; 6) Tensile Behavior; 7) Fatigue Life & Surface Roughness; 8) Crack Growth; and 9) Benefits.

Modelling of the temperature field that accompanies friction stir welding

Directory of Open Access Journals (Sweden)

Nosal Przemysław

2017-01-01

Full Text Available The thermal modelling of the Friction Stir Welding process allows for better recognition and understanding of phenomena occurring during the joining process of different materials. It is of particular importance considering the possibilities of process technology parameters, optimization and the mechanical properties of the joint. This work demonstrates the numerical modelling of temperature distribution accompanying the process of friction stir welding. The axisymmetric problem described by Fourier’s type equation with internal heat source is considered. In order to solve the diffusive initial value problem a fully implicit scheme of the finite difference method is applied. The example under consideration deals with the friction stir welding of a plate (0.7 cm thick made of Al 6082-T6 by use of a tool made of tungsten alloy, whereas the material subjected to welding was TiC powder. Obtained results confirm both quantitatively and qualitatively experimental observations that the superior temperature corresponds to the zone where the pin joints the shoulder.

Friction stir welding of F82H steel for fusion applications

Energy Technology Data Exchange (ETDEWEB)

Noh, Sanghoon, E-mail: shnoh@kaeri.re.kr [Fusion Structural Materials Division, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Nuclear Materials Division, Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon (Korea, Republic of); Ando, Masami; Tanigawa, Hiroyasu [Fusion Structural Materials Division, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka (Japan); Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto (Japan)

2016-09-15

In the present study, friction stir welding was employed to join F82H steels and develop a potential joining technique for a reduced activation ferritic/martensitic steel. The microstructures and mechanical properties on the joint region were investigated to evaluate the applicability of friction stir welding. F82H steel sheets were successfully butt-joined with various welding parameters. In welding conditions, 100 rpm and 100 mm/min, the stirred zone represented a comparable hardness distribution with a base metal. Stirred zone induced by 100 rpm reserved uniformly distributed precipitates and very fine ferritic grains, whereas the base metal showed a typical tempered martensite with precipitates on the prior austenite grain boundary and lath boundary. Although the tensile strength was decreased at 550 °C, the stirred zone treated at 100 rpm showed comparable tensile behavior with base metal up to 500 °C. Therefore, friction stir welding is considered a potential welding method to preserve the precipitates of F82H steel.

Friction stir welding of F82H steel for fusion applications

International Nuclear Information System (INIS)

Noh, Sanghoon; Ando, Masami; Tanigawa, Hiroyasu; Fujii, Hidetoshi; Kimura, Akihiko

2016-01-01

In the present study, friction stir welding was employed to join F82H steels and develop a potential joining technique for a reduced activation ferritic/martensitic steel. The microstructures and mechanical properties on the joint region were investigated to evaluate the applicability of friction stir welding. F82H steel sheets were successfully butt-joined with various welding parameters. In welding conditions, 100 rpm and 100 mm/min, the stirred zone represented a comparable hardness distribution with a base metal. Stirred zone induced by 100 rpm reserved uniformly distributed precipitates and very fine ferritic grains, whereas the base metal showed a typical tempered martensite with precipitates on the prior austenite grain boundary and lath boundary. Although the tensile strength was decreased at 550 °C, the stirred zone treated at 100 rpm showed comparable tensile behavior with base metal up to 500 °C. Therefore, friction stir welding is considered a potential welding method to preserve the precipitates of F82H steel.

In temperature forming of friction stir lap welds in aluminium alloys

Science.gov (United States)

Bruni, Carlo; Cabibbo, Marcello; Greco, Luciano; Pieralisi, Massimiliano

2018-05-01

The objective of such investigation is the study in depth of the forming phase of welds realized on three sheet metal blanks in aluminium alloys by friction stir lap welding. Such forming phase was performed by upsetting at different constant forming temperatures varying from 200°C to 350°C with constant ram velocities of 0.01 and 0.1 mm/s. The temperature values were obtained by the use of heating strips applied on the upper tool and on the lower tool. It was observed an increase in the friction factor, acting at the upsetting tool-workpiece interface, with increasing temperature that is very useful in producing the required localized deformation with which to improve the weld. It was also confirmed that the forming phase allows to realize a required thickness in the weld area allowing to neglect the surficial perturbation produced by the friction stir welding tool shoulder. The obtained thickness could be subjected to springback when too low temperatures are considered.

Tensile behavior of dissimilar friction stir welded joints of aluminium alloys

International Nuclear Information System (INIS)

Shanmuga Sundaram, N.; Murugan, N.

2010-01-01

The heat treatable aluminium alloy AA2024 is used extensively in the aircraft industry because of its high strength to weight ratio and good ductility. The non-heat treatable aluminium alloy AA5083 possesses medium strength and high ductility and used typically in structural applications, marine, and automotive industries. When compared to fusion welding processes, friction stir welding (FSW) process is an emerging solid state joining process which is best suitable for joining these alloys. The friction stir welding parameters such as tool pin profile, tool rotational speed, welding speed, and tool axial force influence the mechanical properties of the FS welded joints significantly. Dissimilar FS welded joints are fabricated using five different tool pin profiles. Central composite design with four parameters, five levels, and 31 runs is used to conduct the experiments and response surface method (RSM) is employed to develop the model. Mathematical regression models are developed to predict the ultimate tensile strength (UTS) and tensile elongation (TE) of the dissimilar friction stir welded joints of aluminium alloys 2024-T6 and 5083-H321, and they are validated. The effects of the above process parameters and tool pin profile on tensile strength and tensile elongation of dissimilar friction stir welded joints are analysed in detail. Joints fabricated using Tapered Hexagon tool pin profile have the highest tensile strength and tensile elongation, whereas the Straight Cylinder tool pin profile have the lowest tensile strength and tensile elongation. The results are useful to have a better understanding of the effects of process parameters, to fabricate the joints with desired tensile properties, and to automate the FS welding process.

Microstructure and microtexture studies of a friction stir welded Al 6061 alloy

International Nuclear Information System (INIS)

Kumbhar, N.T.; Tewari, R.; Dey, G.K.; Bhanumurthy, K.; Sahoo, S.K.; Samajdar, I.

2009-01-01

Friction stir welding is a solid state joining technique used extensively for the joining of various metals and alloys and also has been applied to the joining of steels. The friction stir welding of Al and its alloys has been extensively delt with over a period exceeding the last decade and a half due to its numerous advantages over other conventional fusion welding techniques in terms of weld quality, efficiency, cost effectiveness etc. to name a few. This technique is being increasingly seeked by industries in mass production/engineering such as the railways, marine and aerospace industries. The friction stir welding of a precipitation hardened Al 6061 alloy plates of 6 mm. thickness was performed at various tool rotation speeds and tool traverse speeds with a constant tilt of 3 deg using a high strength steel (HSS) tool of appropriate dimensions. The cross section of the weld perpendicular to the welding direction was analyzed for a detailed microstructural investigation using electron probe microanalysis, orientation imaging microscopy and transmission electron microscopy. Various microstructural changes are observed in the various regions of the friction stir welded AA 6061. The nugget region which is highly deformed is characterized by the dissolution and reprecipitation of the coarse precipitates, grain size refinement and recrystallization. The adjoining regions near the nugget viz the thermomechanically affected zone (TMAZ) and the heat affected zone (HAZ) also show heterogeneous microstructure in terms of grain size and precipitation which is mainly attributed to the heating cycle experienced during welding. This heterogeneity is also evident from the plot of microhardness distribution across the cross section of the weld region. However, the electron probe microanalysis studies do not show any significant pickup of oxygen in the weld interior as compared to a little oxygen pickup upto 30 μm from the top surface. Further, using orientation imaging

Boundary element analysis of stress singularity in dissimilar metals by friction welding

International Nuclear Information System (INIS)

Chung, N. Y.; Park, C. H.

2012-01-01

Friction welded dissimilar metals are widely applied in automobiles, rolling stocks, machine tools, and various engineering fields. Dissimilar metals have several advantages over homogeneous metals, including high strength, material property, fatigue endurance, impact absorption, high reliability, and vibration reduction. Due to the increased use of these metals, understanding their behavior under stress conditions is necessary, especially the analysis of stress singularity on the interface of friction-welded dissimilar metals. To establish a strength evaluation method and a fracture criterion, it is necessary to analyze stress singularity on the interface of dissimilar metals with welded flashes by friction welding under various loads and temperature conditions. In this paper, a method analyzing stress singularity for the specimens with and without flashes set in friction welded dissimilar metals is introduced using the boundary element method. The stress singularity index (λ) and the stress singularity factor (Γ) at the interface edge are computed from the stress analysis results. The shape and flash thickness, interface length, residual stress, and load are considered in the computation. Based on these results, the variations of interface length (c) and the ratio of flash thickness (t2 t1) greatly influence the stress singularity factors at the interface edge of friction welded dissimilar metals. The stress singularity factors will be a useful fracture parameter that considers stress singularity on the interface of dissimilar metals

Prediction of mechanical properties in friction stir welds of pure copper

International Nuclear Information System (INIS)

Heidarzadeh, A.; Saeid, T.

2013-01-01

Highlights: • Range of parameters for defect-free friction stir welded pure copper was reached. • Models were developed for predicting UTS, TE and hardness of pure copper joints. • Analysis of variance was used to validate the developed models. • Effect of welding parameters on mechanical behavior of welded joints was explored. • The microstructure and fracture surface of welded joints were investigated. - Abstract: This research was carried out to predict the mechanical properties of friction stir welded pure copper joints. Response surface methodology based on a central composite rotatable design with three parameters, five levels, and 20 runs, was used to conduct the experiments and to develop the mathematical regression model by using of Design-Expert software. The three welding parameters considered were rotational speed, welding speed, and axial force. Analysis of variance was applied to validate the predicted models. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters on mechanical properties of friction stir welded joints were analyzed in detail. The results showed that the developed models were reasonably accurate. The increase in welding parameters resulted in increasing of tensile strength of the joints up to a maximum value. Elongation percent of the joints increased with increase of rotational speed and axial force, but decreased by increasing of welding speed, continuously. In addition, hardness of the joints decreased with increase of rotational speed and axial force, but increased by increasing of welding speed. The joints welded at higher heat input conditions revealed more ductility fracture mode

Unraveling the Processing Parameters in Friction Stir Welding

Science.gov (United States)

Schneider, Judy; Nunes, Arthur C., Jr.

2005-01-01

In friction stir welding (FSW), a rotating threaded pin tool is translated along a weld seam, literally stirring the edges of the seam together. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path or paths is required. In this study, various markers are used to trace the flow paths of the metal. X-ray radiographs record the segmentation and position of the wire. Several variations in the trajectories can be differentiated within the weld zone.

Friction Welding of Aluminium and Aluminium Alloys with Steel

Directory of Open Access Journals (Sweden)

Andrzej Ambroziak

2014-01-01

Full Text Available The paper presents our actual knowledge and experience in joining dissimilar materials with the use of friction welding method. The joints of aluminium and aluminium alloys with the different types of steel were studied. The structural effects occurring during the welding process were described. The mechanical properties using, for example, (i microhardness measurements, (ii tensile tests, (iii bending tests, and (iv shearing tests were determined. In order to obtain high-quality joints the influence of different configurations of the process such as (i changing the geometry of bonding surface, (ii using the interlayer, or (iii heat treatment was analyzed. Finally, the issues related to the selection of optimal parameters of friction welding process were also investigated.

Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions

Science.gov (United States)

2013-01-01

REPORT Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions 14. ABSTRACT 16. SECURITY...properties and of the attendant ballistic-impact failure mechanisms in prototypical friction stir welding (FSW) joints found in armor structures made of high...mechanisms, friction stir welding M. Grujicic, B. Pandurangan, A. Arakere, C-F. Yen, B. A. Cheeseman Clemson University Office of Sponsored Programs 300

Welding of AA1050 aluminum with AISI 304 stainless steel by rotary friction welding process

OpenAIRE

Alves, Eder Paduan; Piorino Neto, Francisco; An, Chen Ying

2010-01-01

Abstract: The purpose of this work was to assess the development of solid state joints of dissimilar material AA1050 aluminum and AISI 304 stainless steel, which can be used in pipes of tanks of liquid propellants and other components of the Satellite Launch Vehicle. The joints were obtained by rotary friction welding process (RFW), which combines the heat generated from friction between two surfaces and plastic deformation. Tests were conducted with different welding process parameters. The ...

Friction Stir Welding of Dissimilar Al/Al and Al/Non-Al Alloys: A Review

Science.gov (United States)

Wang, Xiangbin; Pan, Yi; Lados, Diana A.

2018-05-01

Friction stir welding is a solid-state welding technique that has many advantages over traditional fusion welding, and has been widely adopted in the aerospace and automotive industries. This article reviews research developments in friction stir welding of dissimilar alloys systems, including combinations of aluminum alloys with Mg alloys, Cu, and steel. Microstructural evolution, hardness, tensile and fatigue properties, residual stresses, and corrosion behavior of dissimilar welds will be reported. The effects of processing parameters such as tool rotation and traverse speeds, tool position, material position, and tool geometry on the weld quality are also presented. Discussions on future research directions in friction stir welding will also be provided in the context of existing literature and future high-integrity applications.

Experimental study of mechanical properties of friction welded AISI ...

Indian Academy of Sciences (India)

to their wide application in the manufacturing industry. For the first set of ... the friction welded joint; destructive testing and non-destructive testing. ..... hardness was found at the weld interfaces for almost every case, this might be attributed to.

Metal Flow in Friction Stir Welding

Science.gov (United States)

Nunes, Arthur C., Jr.

2006-01-01

The plastic deformation field in Friction Stir Welding (FSW) is compared to that in metal cutting. A shear surface around the FSW tool analogous to the metal cutting shear plane is identified and comprises the basis of the "rotating plug" flow field model and the "wiping" model of tool interaction with weld metal. Within the context of these models: The FSW shear rate is estimated to be comparable to metal cutting shear rates. The effect of tool geometry on the FSW shear surface is discussed and related to published torque measurements. Various FS W structural features are explained, including a difference in structure of bimetallic welds when alloys on the advancing and retreating sides of the weld seam are exchanged. The joining mechanism and critical parameters of the FSW process are made clear.

Friction stir scribe welding technique for dissimilar joining of aluminium and galvanised steel

Energy Technology Data Exchange (ETDEWEB)

Wang, Tianhao [Center for Friction Stir Processing, Department of Materials Science and Engineering, University of North Texas, Denton, TX, USA; Sidhar, Harpreet [Center for Friction Stir Processing, Department of Materials Science and Engineering, University of North Texas, Denton, TX, USA; Mishra, Rajiv S. [Center for Friction Stir Processing, Department of Materials Science and Engineering, University of North Texas, Denton, TX, USA; Hovanski, Yuri [Pacific Northwest National Laboratory, Energy Materials and Manufacturing, Richland, WA, USA; Upadhyay, Piyush [Pacific Northwest National Laboratory, Energy Materials and Manufacturing, Richland, WA, USA; Carlson, Blair [General Motors Technical Center, Warren, MI, USA

2017-10-04

Friction stir scribe technology, a derivative of friction stir welding, was applied for the dissimilar lap welding of an aluminum alloy and galvanized mild steel sheets. During the process, the rotating tool with a cobalt steel scribe first penetrated the top material — aluminum — and then the scribe cut the bottom material — steel. The steel was displaced into the upper material to produce a characteristic hook feature. Lap welds were shear tested, and their fracture paths were studied. Welding parameters affected the welding features including hook height, which turned out to be highly related to fracture position. Therefore, in this paper, the relationships among welding parameters, hook height, joint strength and fracture position are presented. In addition, influence of zinc coating on joint strength was also studied. Keywords: friction stir scribe technology; dissimilar material welding; zinc coating; hook height; joint strength; fracture position

Effect of Process Parameters on Friction Model in Computer Simulation of Linear Friction Welding

Directory of Open Access Journals (Sweden)

A. Yamileva

2014-07-01

Full Text Available The friction model is important part of a numerical model of linear friction welding. Its selection determines the accuracy of the results. Existing models employ the classical law of Amonton-Coulomb where the friction coefficient is either constant or linearly dependent on a single parameter. Determination of the coefficient of friction is a time consuming process that requires a lot of experiments. So the feasibility of determinating the complex dependence should be assessing by analysis of effect of approximating law for friction model on simulation results.

Friction stir weld tools having fine grain structure

Science.gov (United States)

Grant, Glenn J.; Frye, John G.; Kim, Jin Yong; Lavender, Curt A.; Weil, Kenneth Scott

2016-03-15

Tools for friction stir welding can be made with fewer process steps, lower cost techniques, and/or lower cost ingredients than other state-of-the-art processes by utilizing improved compositions and processes of fabrication. Furthermore, the tools resulting from the improved compositions and processes of fabrication can exhibit better distribution and homogeneity of chemical constituents, greater strength, and/or increased durability. In one example, a friction stir weld tool includes tungsten and rhenium and is characterized by carbide and oxide dispersoids, by carbide particulates, and by grains that comprise a solid solution of the tungsten and rhenium. The grains do not exceed 10 micrometers in diameter.

Mitigating Abnormal Grain Growth for Friction Stir Welded Al-Li 2195 Spun Formed Domes

Science.gov (United States)

Chen, Po-Shou; Russell, Carolyn

2012-01-01

Formability and abnormal grain growth (AGG) are the two major issues that have been encountered for Al alloy spun formed dome development using friction stir welded blanks. Material properties that have significant influence on the formability include forming range and strain hardening exponent. In this study, tensile tests were performed for two 2195 friction stir weld parameter sets at 400 F to study the effects of post weld anneal on the forming range and strain hardening exponent. It was found that the formability can be enhanced by applying a newly developed post weld anneal to heat treat the friction stir welded panels. This new post weld anneal leads to a higher forming range and much improved strain hardening exponent. AGG in the weld nugget is known to cause a significant reduction of ductility and fracture toughness. This study also investigated how AGG may be influenced by the heating rate to the solution heat treatment temperature. After post-weld annealing, friction stir welds were strained to 15% and 39% by compression at 400 F before they were subjected to SHT at 950 F for 1 hour. Salt bath SHT is very effective in reducing the grain size as it helps arrest the onset of AGG and promote normal recrystallization and grain growth. However, heat treating a 18 ft dome using a salt bath is not practical. Efforts are continuing at Marshall Space Flight Center to identify the welding parameters and heat treating parameters that can help mitigate the AGG in the friction stir welds.

Frictional properties of jointed welded tuff

International Nuclear Information System (INIS)

Teufel, L.W.

1981-07-01

The results of the experiments on simulated joints in welded tuff from the Grouse Canyon Member of the Belted Range Tuff warrant the following conclusions: (1) The coefficient of friction of the joints is independent of normal stress at a given sliding velocity. (2) The coefficient of friction increases with both increasing time of stationary contact and decreasing sliding velocity. (3) Time and velocity dependence of friction is due to an increase in the real area of contact on the sliding surface, caused by asperity creep. (4) Joints in water-saturated tuff show a greater time and velocity dependence of friction than those in dehydrated tuff. (5) The enhanced time and velocity dependence of friction with water saturation is a result of increased creep at asperity contacts, which is in turn due to a reduction in the surface indentation hardness by hydrolytic weakening and/or stress corrosion cracking

Unstable Temperature Distribution in Friction Stir Welding

Directory of Open Access Journals (Sweden)

Sadiq Aziz Hussein

2014-01-01

Full Text Available In the friction stir welding process, a nonuniform and high generated temperature is undesirable. Unstable temperature and distribution affect thermal and residual stresses along the welding line, thus necessitating mitigation. This paper presents a simple method to prevent significant temperature difference along the welding line and also to help nullifying some defect types associated with this welding, such as end-hole, initial unwelded line, and deformed areas. In the experimental investigation, a heat and force thermocouple and dynamometer were utilized while couple-field thermomechanical models were used to evaluate temperature and its distribution, plastic strain, and material displacement. The suggested method generated uniform temperature distributions. Measurement results are discussed, showing a good correlation with predictions.

The effect of post-welding conditions in friction stir welds: From weld simulation to Ductile Failure

DEFF Research Database (Denmark)

Hattel, Jesper Henri; Nielsen, Kim Lau; Tutum, Cem Celal

2012-01-01

software ANSYS, a thermo-mechanical model is employed to predict the thermally induced stresses and strains during welding, while an in-house finite element code is used to study the plastic flow localization and failure in a subsequent structural analysis. The coupling between the two models is made......The post-welding stress state, strain history and material conditions of friction stir welded joints are often strongly idealized when used in subsequent modeling analyses, typically by neglecting one or more of the features above. But, it is obvious that the conditions after welding do influence......, showed the largest influence of the post-welding conditions, even though significant relaxation of the residual stress state was predicted....

Effect of Trailing Intensive Cooling on Residual Stress and Welding Distortion of Friction Stir Welded 2060 Al-Li Alloy

Science.gov (United States)

Ji, Shude; Yang, Zhanpeng; Wen, Quan; Yue, Yumei; Zhang, Liguo

2018-04-01

Trailing intensive cooling with liquid nitrogen has successfully applied to friction stir welding of 2 mm thick 2060 Al-Li alloy. Welding temperature, plastic strain, residual stress and distortion of 2060 Al-Li alloy butt-joint are compared and discussed between conventional cooling and trailing intensive cooling using experimental and numerical simulation methods. The results reveal that trailing intensive cooling is beneficial to shrink high temperature area, reduce peak temperature and decrease plastic strain during friction stir welding process. In addition, the reduction degree of plastic strain outside weld is smaller than that inside weld. Welding distortion presents an anti-saddle shape. Compared with conventional cooling, the reductions of welding distortion and longitudinal residual stresses of welding joint under intense cooling reach 47.7 % and 23.8 %, respectively.

Effect of friction time on the properties of friction welded YSZ‐alumina composite and 6061 aluminium alloy

Directory of Open Access Journals (Sweden)

Uday M. Basheer

2012-03-01

Full Text Available The aim of this work was to study the effect of friction time on the microstructure and mechanical properties of alumina 0, 25, 50 wt% yttria stabilized zirconia (YSZ composite and 6061 aluminium alloy joints formed by friction welding. The alumina-YSZ composites were prepared through slip casting in plaster of Paris molds (POP and subsequently sintered at 1600°C, while the aluminium rods were machined down using a lathe machine to the dimension required. The welding process was carried out under different rotational speeds and friction times, while friction force (0.5 ton-force was kept constant. Scanning electron microscopy was used to characterize the interface of the joints structure. The experimental results showed that the friction time has a significant effect on joint structure and mechanical properties.

Fatigue behaviour of friction welded medium carbon steel and austenitic stainless steel dissimilar joints

International Nuclear Information System (INIS)

Paventhan, R.; Lakshminarayanan, P.R.; Balasubramanian, V.

2011-01-01

Research highlights: → Fusion welding of dissimilar metals is a problem due to difference in properties. → Solid state welding process such as friction welding is a solution for the above problem. → Fatigue life of friction welded carbon steel and stainless steel joints are evaluated. → Effect of notch on the fatigue life of friction welded dissimilar joints is reported. → Formation of intermetallic is responsible for reduction in fatigue life of dissimilar joints. -- Abstract: This paper reports the fatigue behaviour of friction welded medium carbon steel-austenitic stainless steel (MCS-ASS) dissimilar joints. Commercial grade medium carbon steel rods of 12 mm diameter and AISI 304 grade austenitic stainless steel rods of 12 mm diameter were used to fabricate the joints. A constant speed, continuous drive friction welding machine was used to fabricate the joints. Fatigue life of the joints was evaluated conducting the experiments using rotary bending fatigue testing machine (R = -1). Applied stress vs. number of cycles to failure (S-N) curve was plotted for unnotched and notched specimens. Basquin constants, fatigue strength, fatigue notch factor and notch sensitivity factor were evaluated for the dissimilar joints. Fatigue strength of the joints is correlated with microstructure, microhardness and tensile properties of the joints.

A fundamental study on the structural integrity of magnesium alloys joined by friction stir welding

Science.gov (United States)

Rao, Harish Mangebettu

The goal of this research is to study the factors that influence the physical and mechanical properties of lap-shear joints produced using friction stir welding. This study focuses on understanding the effect of tool geometry and weld process parameters including the tool rotation rate, tool plunge depth and dwell time on the mechanical performance of similar magnesium alloy and dissimilar magnesium to aluminum alloy weld joints. A variety of experimental activities were conducted including tensile and fatigue testing, fracture surface and failure analysis, microstructure characterization, hardness measurements and chemical composition analysis. An investigation on the effect of weld process conditions in friction stir spot welding of magnesium to magnesium produced in a manner that had a large effective sheet thickness and smaller interfacial hook height exhibited superior weld strength. Furthermore, in fatigue testing of friction stir spot welded of magnesium to magnesium alloy, lap-shear welds produced using a triangular tool pin profile exhibited better fatigue life properties compared to lap-shear welds produced using a cylindrical tool pin profile. In friction stir spot welding of dissimilar magnesium to aluminum, formation of intermetallic compounds in the stir zone of the weld had a dominant effect on the weld strength. Lap-shear dissimilar welds with good material mixture and discontinues intermetallic compounds in the stir zone exhibited superior weld strength compared to lap-shear dissimilar welds with continuous formation of intermetallic compounds in the stir zone. The weld structural geometry like the interfacial hook, hook orientation and bond width also played a major role in influencing the weld strength of the dissimilar lap-shear friction stir spot welds. A wide scatter in fatigue test results was observed in friction stir linear welds of aluminum to magnesium alloys. Different modes of failure were observed under fatigue loading including crack

Improving friction stir welding of blanks of different thicknesses

Energy Technology Data Exchange (ETDEWEB)

Fratini, L. [Dipartimento di Tecnologia Meccanica, Produzione e Ingegneria Gestionale, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy)], E-mail: abaqus@dtpm.unipa.it; Buffa, G. [Dipartimento di Tecnologia Meccanica, Produzione e Ingegneria Gestionale, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Shivpuri, R. [Ohio State University, Department of Industrial, Welding and Systems Engineering, 1971 Neil Avenue, 210 Baker Systems, Columbus, Ohio 43210 (United States)

2007-06-25

Friction stir welding (FSW) appears to be a promising process even in the welding of blanks of different thicknesses. Actually, such particular tailor welded blanks (TWBs) are usually characterized by a reduction in ductility due to the utilized fusion welding process. In this paper the authors, starting from a preliminary feasibility study, investigate the possibility to improve the mechanical performances of friction stir welded blanks of aluminum alloy with different thicknesses. Both experiments and a FE analyses are developed for a few case studies with different thickness ratios between the blanks. The numerical investigations are performed with the aim to highlight the material temperature distribution during the process in order to determine process conditions for which an almost symmetric thermal flow is obtained in the two blanks of the joint. In this way, a few simple process design rules are derived and verified through experiments. In particular a thickness ratio up to 2 was considered and a joint resistance of about the 80% of the parent material ultimate tensile strength was observed.

Improving friction stir welding of blanks of different thicknesses

International Nuclear Information System (INIS)

Fratini, L.; Buffa, G.; Shivpuri, R.

2007-01-01

Friction stir welding (FSW) appears to be a promising process even in the welding of blanks of different thicknesses. Actually, such particular tailor welded blanks (TWBs) are usually characterized by a reduction in ductility due to the utilized fusion welding process. In this paper the authors, starting from a preliminary feasibility study, investigate the possibility to improve the mechanical performances of friction stir welded blanks of aluminum alloy with different thicknesses. Both experiments and a FE analyses are developed for a few case studies with different thickness ratios between the blanks. The numerical investigations are performed with the aim to highlight the material temperature distribution during the process in order to determine process conditions for which an almost symmetric thermal flow is obtained in the two blanks of the joint. In this way, a few simple process design rules are derived and verified through experiments. In particular a thickness ratio up to 2 was considered and a joint resistance of about the 80% of the parent material ultimate tensile strength was observed

On the Similarity of Deformation Mechanisms During Friction Stir Welding and Sliding Friction of the AA5056 Alloy

Science.gov (United States)

Kolubaev, A. V.; Zaikina, A. A.; Sizova, O. V.; Ivanov, K. V.; Filippov, A. V.; Kolubaev, E. A.

2018-04-01

A comparative investigation of the structure of an aluminum-manganese alloy is performed after its friction stir welding and sliding friction. Using the methods of optical and electron microscopy, it is shown that during friction identical ultrafine-grained structures are formed in the weld nugget and in the surface layer, in which the grains measure 5 μm irrespective of the initial grain size of the alloy. An assumption is made that the microstructure during both processes under study is formed by the mechanism of rotational plasticity.

The effect of postprocessing on tensile property and microstructure evolution of friction stir welding aluminum alloy joint

International Nuclear Information System (INIS)

Hu, Z.L.; Wang, X.S.; Pang, Q.; Huang, F.; Qin, X.P.; Hua, L.

2015-01-01

Friction stir welding is an efficient manufacturing method for joining aluminum alloy and can dramatically reduce grain size conferring excellent plastic deformation properties. Consequently, friction stir welding is used to manufacture tailor welded blanks to optimize weight or performance in the final component. In the study, the microstructural evolution and mechanical properties of friction stir welding joint during plastic forming and subsequent heat treatment were investigated. The microstructural characteristics of the friction stir welding joints were studied by Electron Backscattered Diffraction and Transmission Electron Microscopy. The mechanical properties were evaluated by tensile and microhardness tests. It is found that the tensile and yield strengths of friction stir welding joints are significantly improved after severe plastic deformation due to the grain refinement. Following heat treatment, the strength of the friction stir welding joints significantly decrease due to the obvious abnormal grain growth. Careful attention must be given to the processing route of any friction stir welding joint intended for plastic forming, especially the annealing between forming passes. Severe plastic deforming of the friction stir welding joint leads to a high level of stored energy/dislocation density, which causes the abnormal grain growth during subsequent heat treatment, and consequently reduce the mechanical properties of the friction stir welding joint. - Highlights: • Great changes are observed in the microstructure of FSW joint after postprocessing. • Postprocessing shows great effect on the microstructure stability of FSW joint. • The weld shows more significant decrease in strength than the BM due to the AGG. • Attention must be given to the processing route of FSW joint for plastic forming

High-Speed Friction-Stir Welding to Enable Aluminum Tailor-Welded Blanks

Science.gov (United States)

Hovanski, Yuri; Upadhyay, Piyush; Carsley, John; Luzanski, Tom; Carlson, Blair; Eisenmenger, Mark; Soulami, Ayoub; Marshall, Dustin; Landino, Brandon; Hartfield-Wunsch, Susan

2015-05-01

Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and they have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high volumes. While friction-stir welding (FSW) has been traditionally applied at linear velocities less than 1 m/min, high-volume production applications demand the process be extended to higher velocities more amenable to cost-sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low-to-moderate welding velocities do not directly translate to high-speed linear FSW. Therefore, to facilitate production of high-volume aluminum FSW components, parameters were developed with a minimum welding velocity of 3 m/min. With an emphasis on weld quality, welded blanks were evaluated for postweld formability using a combination of numerical and experimental methods. An evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum TWBs, which provided validation of the numerical and experimental analysis of laboratory-scale tests.

Stir zone microstructure of commercial purity titanium friction stir welded using pcBN tool

International Nuclear Information System (INIS)

Zhang Yu; Sato, Yutaka S.; Kokawa, Hiroyuki; Park, Seung Hwan C.; Hirano, Satoshi

2008-01-01

In the present study, friction stir welding was applied to commercial purity titanium using a polycrystalline cubic boron nitride tool, and microstructure and hardness in the weld were examined. Additionally, the microstructural evolution during friction stir welding was also discussed. The stir zone consisted of fine equiaxed α grains surrounded by serrate grain boundaries, which were produced through the β → α allotropic transformation during the cooling cycle of friction stir welding. The fine α grains caused higher hardness than that in the base material. A lath-shaped α grain structure containing Ti borides and tool debris was observed in the surface region of the stir zone, whose hardness was the highest in the weld

Application of Taguchi approach to optimize friction stir welding parameters of polyethylene

Directory of Open Access Journals (Sweden)

Bejaoui S.

2010-06-01

Full Text Available This paper presents experimental and numerical results of butt friction stir welding of high density polyethylene. The FSW designed tool insulates the welded samples and preserves the heat gained from friction thus avoiding the appearance of blisters and splits after welding. The experimental tests, conducted according to combinations of process factors such as rotation speed, welding speed, pin diameter and hold time at beginning welding, were carried out according the Taguchi orthogonal table L27 in randomized way. Temperatures in the joint during the welding operation and flow stresses from the tensile tests of welded samples were measured and variances were analyzed. Identified models were used to simulate, by finite elements, the tensile tests performed on specimens having a weld cordon in their active area. The results show coherence between the numerical predictions and experimental observations in different cases of weld cordon mechanical behaviour.

Some microstructural characterisations in a friction stir welded oxide dispersion strengthened ferritic steel alloy

International Nuclear Information System (INIS)

Legendre, F.; Poissonnet, S.; Bonnaillie, P.; Boulanger, L.; Forest, L.

2009-01-01

The goal of this study is to characterize microstructure of a friction stir welded oxide dispersion strengthened alloy. The welded material is constituted by two sheets of an yttria-dispersion-strengthened PM 2000 ferritic steel. Different areas of the friction stir welded product were analyzed using field emission gun secondary electron microscopy (FEG-SEM) and electron microprobe whereas nanoindentation was used to evaluate mechanical properties. The observed microstructural evolution, including distribution of the yttria dispersoids, after friction stir welding process is discussed and a correlation between the microstructure and the results of nanoindentation tests is established.

Tensile behavior of friction stir welded AA 6061-T4 aluminum alloy joints

International Nuclear Information System (INIS)

Heidarzadeh, A.; Khodaverdizadeh, H.; Mahmoudi, A.; Nazari, E.

2012-01-01

Highlights: ► Range of parameters for defect-free friction stir welded AA 6061-T4 was reached. ► A model was developed for predicting UTS and EL of friction stir welded AA 6061-T4. ► The maximum values of UTS and EL of joints were estimated by developed model. ► The optimum values of FSW process parameters were determined. -- Abstract: In this investigation response surface methodology based on a central composite rotatable design with three parameters, five levels and 20 runs, was used to develop a mathematical model predicting the tensile properties of friction stir welded AA 6061-T4 aluminum alloy joints at 95% confidence level. The three welding parameters considered were tool rotational speed, welding speed and axial force. Analysis of variance was applied to validate the predicted model. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters on tensile properties of friction stir welded joints were analyzed in detail. The results showed that the optimum parameters to get a maximum of tensile strength were 920 rev/min, 78 mm/min and 7.2 kN, where the maximum of tensile elongation was obtained at 1300 rev/min, 60 mm/min and 8 kN.

Microstructure characterization of Friction Stir Spot Welded TRIP steel

DEFF Research Database (Denmark)

Lomholt, Trine Colding; Adachi, Yoshitaka; Peterson, Jeremy

2012-01-01

Transformation Induced Plasticity (TRIP) steels have not yet been successfully joined by any welding technique. It is desirable to search for a suitable welding technique that opens up for full usability of TRIP steels. In this study, the potential of joining TRIP steel with Friction Stir Spot...

A continuum based fem model for friction stir welding-model development

Energy Technology Data Exchange (ETDEWEB)

Buffa, G. [Ohio State University, Department of Industrial, Welding and Systems Engineering, 1971 Neil Avenue, 210 Baker Systems, Columbus, OH 43210 (United States) and Dipartimento di Tecnologia Meccanica, Produzione e Ingegneria Gestionale, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy)]. E-mail: g.buffa@dtpm.unipa.it; Hua, J. [Ohio State University, Department of Industrial, Welding and Systems Engineering, 1971 Neil Avenue, 210 Baker Systems, Columbus, OH 43210 (United States)]. E-mail: hua.14@osu.edu; Shivpuri, R. [Ohio State University, Department of Industrial, Welding and Systems Engineering, 1971 Neil Avenue, 210 Baker Systems, Columbus, OH 43210 (United States)]. E-mail: shivpuri.1@osu.edu; Fratini, L. [Dipartimento di Tecnologia Meccanica, Produzione e Ingegneria Gestionale, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy)]. E-mail: abaqus@dtpm.unipa.it

2006-03-15

Although friction stir welding (FSW) has been successfully used to join materials that are difficult-to-weld or unweldeable by fusion welding methods, it is still in its early development stage and, therefore, a scientific knowledge based predictive model is of significant help for thorough understanding of FSW process. In this paper, a continuum based FEM model for friction stir welding process is proposed, that is 3D Lagrangian implicit, coupled, rigid-viscoplastic. This model is calibrated by comparing with experimental results of force and temperature distribution, then is used to investigate the distribution of temperature and strain in heat affect zone and the weld nugget. The model correctly predicts the non-symmetric nature of FSW process, and the relationships between the tool forces and the variation in the process parameters. It is found that the effective strain distribution is non-symmetric about the weld line while the temperature profile is almost symmetric in the weld zone.

Emission of nanoparticles during friction stir welding (FSW) of aluminium alloys.

Science.gov (United States)

Gomes, J F; Miranda, R M; Santos, T J; Carvalho, P A

2014-01-01

Friction stir welding (FSW) is now well established as a welding process capable of joining some different types of metallic materials, as it was (1) found to be a reliable and economical way of producing high quality welds, and (2) considered a "clean" welding process that does not involve fusion of metal, as is the case with other traditional welding processes. The aim of this study was to determine whether the emission of particles during FSW in the nanorange of the most commonly used aluminum (Al) alloys, AA 5083 and AA 6082, originated from the Al alloy itself due to friction of the welding tool against the item that was being welded. Another goal was to measure Al alloys in the alveolar deposited surface area during FSW. Nanoparticles dimensions were predominantly in the 40- and 70-nm range. This study demonstrated that microparticles were also emitted during FSW but due to tool wear. However, the biological relevance and toxic manifestations of these microparticles remain to be determined.

A continuum based fem model for friction stir welding-model development

International Nuclear Information System (INIS)

Buffa, G.; Hua, J.; Shivpuri, R.; Fratini, L.

2006-01-01

Although friction stir welding (FSW) has been successfully used to join materials that are difficult-to-weld or unweldeable by fusion welding methods, it is still in its early development stage and, therefore, a scientific knowledge based predictive model is of significant help for thorough understanding of FSW process. In this paper, a continuum based FEM model for friction stir welding process is proposed, that is 3D Lagrangian implicit, coupled, rigid-viscoplastic. This model is calibrated by comparing with experimental results of force and temperature distribution, then is used to investigate the distribution of temperature and strain in heat affect zone and the weld nugget. The model correctly predicts the non-symmetric nature of FSW process, and the relationships between the tool forces and the variation in the process parameters. It is found that the effective strain distribution is non-symmetric about the weld line while the temperature profile is almost symmetric in the weld zone

Residual stresses analysis of friction stir welding using one-way FSI simulation

International Nuclear Information System (INIS)

Kang, Sung Wook; Jang, Beom Seon; Song, Ha Cheol

2015-01-01

When certain mechanisms, such as plastic deformations and temperature gradients, occur and are released in a structure, stresses remain because of the shape of the structure and external constraints. These stresses are referred to as residual stresses. The base material locally expands during heating in the welding process. When the welding is completed and cooled to room temperature, the residual stresses are left at nearly the yield strength level. In the case of friction stir welding, the maximum temperature is 80% to 90% of the melting point of the materials. Thus, the residual stresses in the welding process are smaller than those in other fusion welding processes; these stresses have not been considered previously. However, friction stir welding residual stresses are sometimes measured at approximately 70% or above. These residual stresses significantly affect fatigue behavior and lifetime. The present study investigates the residual stress distributions in various welding conditions and shapes of friction stir welding. In addition, the asymmetric feature is considered in temperature and residual stress distribution. Heat transfer analysis is conducted using the commercial computational fluid dynamics program Fluent, and results are used in the finite element structural analysis with the ANSYS Multiphysics software. The calculated residual stresses are compared with experimental values using the X-ray diffraction method.

Characterization of Friction Stir Welded Tubes by Means of Tube Bulge Test

International Nuclear Information System (INIS)

D'Urso, G.; Longo, M.; Giardini, C.

2011-01-01

Mechanical properties of friction stir welded joints are generally evaluated by means of conventional tensile test. This testing method might provide insufficient information because maximum strain obtained in tensile test before necking is small; moreover, the application of tensile test is limited when the joint path is not linear or even when the welds are executed on curved surfaces. Therefore, in some cases, it would be preferable to obtain the joints properties from other testing methods. Tube bulge test can be a valid solution for testing circumferential or longitudinal welds executed on tubular workpieces. The present work investigates the mechanical properties and the formability of friction stir welded tubes by means of tube bulge tests. The experimental campaign was performed on tubular specimens having a thickness of 3 mm and an external diameter of 40 mm, obtained starting from two semi-tubes longitudinally friction stir welded. The first step, regarding the fabrication of tubes, was performed combining a conventional forming process and friction stir welding. Sheets in Al-Mg-Si-Cu alloy AA6060 T6 were adopted for this purpose. Plates having a dimension of 225x60 mm were bent (with a bending axis parallel to the main dimension) in order to obtain semi-tubes. A particular care was devoted to the fabrication of forming devices (punch and die) in order to minimize the springback effects. Semi-tubes were then friction stir welded by means of a CNC machine tool. Some preliminary tests were carried out by varying the welding parameters, namely feed rate and rotational speed. A very simple tool having flat shoulder and cylindrical pin was used. The second step of the research was based on testing the welded tubes by means of tube bulge test. A specific equipment having axial actuators with a conical shape was adopted for this study. Some analyses were carried out on the tubes bulged up to a certain pressure level. In particular, the burst pressure and the

Cladding of Advanced Al Alloys Employing Friction Stir Welding

NARCIS (Netherlands)

van der Stelt, A.A.; Bor, Teunis Cornelis; Geijselaers, Hubertus J.M.; Akkerman, Remko; van den Boogaard, Antonius H.

2013-01-01

In this paper an advanced solid state cladding process, based on Friction Stir Welding, is presented. The Friction Surface Cladding (FSC) technology enables the deposition of a solid-state coating using filler material on a substrate with good metallurgical bonding. A relatively soft AA1050 filler

Joining of Cu-Mg-Mn Aluminum Alloy with Linear Friction Welding

OpenAIRE

A. Medvedev; V. Bychkov; A. Selivanov; Yu. J. Ershova; B. Bolshakov; I.V. Alexаndrov; F. F. Musin

2014-01-01

Al-Cu-Mg-Mn alloy samples were joined together with linear friction welding in two conditions, as is, without pretreatment, and after etching the welding interface. The effect of the welding interface condition was evaluated based on microstructure analysis, microhardness and tensile testing at room temperature. Also, the temperature distribution during welding was estimated with an analytical one-dimensional heat conduction model of the welding process and welding process data

Material Characterization of Dissimilar Friction Stir Spot Welded Aluminium and Copper Alloy

Science.gov (United States)

Sanusi, K. O.; Akinlabi, E. T.

2017-08-01

In this research study, material characterization of dissimilar friction stir spot welded Aluminium and Copper was evaluated. Rotational speeds of 800 rpm and transverse speeds of 50 mm/min, 150 mm/min and 250 mm/min were used. The total numbers of samples evaluated were nine altogether. The spot welds were characterised by microstructure characterization using optical microscope (OEM) and scanning electron microscopy technique (SEM) by observing the evolution of the microstructure across the weld’s cross-section. lap-shear test of the of the spot weld specimens were also done. From the results, it shows that welding of metals and alloys using Friction stir spot welding is appropriate and can be use in industrial applications.

Friction stir welding of 6061 aluminium alloy

International Nuclear Information System (INIS)

Abdel Rahman, M.A.M.S.

2009-01-01

6061 AA (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio and good corrosion resistance such as marine frames, pipelines, storage tanks, and aircraft components [1]. It is also used for the manufacturing of fuel elements in the nuclear research reactors. Compared to many of the fusion welding processes that are routinely used for joining structural alloys, friction stir welding (FSW) is a solid state joining process in which the material that is being welded is not melted and recast [2]. The welding parameters such as tool rotational speed, welding traverse speed, and tool profile play a major role in deciding the weld quality. Several FSW tools (differ from each other in pin angle, shoulder diameter, and shoulder concavity) have been used to fabricate a number of joints in order to obtain a tool with which a sound weld can be produced. It was found that the FSW tool with tapered cone pin, concave shoulder, and shoulder diameter equal to four times the welded plate thickness is suitable to produce a sound weld. The effect of the traverse speed on the global and local tensile properties of friction stir welded joints has been investigated in the 6061-T6 AA. The global tensile properties of the FSW joints were improved with increasing the traverse speed at constant rotation rate. It is found that the global tensile strength of the FSW joint is limited by the local tensile strength of the nearest region to the weld center at which the cross section is composed mainly of the HAZ. The effect of the initial butt surface on the formation of the zigzag line on the tensile properties of the welds was examined by using three types of welding samples differ in the preparation of the initial butt surface. The first type of samples welded without removing the oxide layer from the initial butt surface (uncleaned butt surfaces joint). In the second type of samples the oxide layer was removed from

Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

International Nuclear Information System (INIS)

Mazumder, B.; Yu, X.; Edmondson, P.D.; Parish, C.M.; Miller, M.K.; Meyer, H.M.; Feng, Z.

2016-01-01

Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygen-enriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the size of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.

Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

Energy Technology Data Exchange (ETDEWEB)

Mazumder, B., E-mail: mazumderb@ornl.gov [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Yu, X.; Edmondson, P.D.; Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Miller, M.K. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Meyer, H.M.; Feng, Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2016-02-15

Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygen-enriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the size of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.

Effect of process control mode on weld quality of friction stir welded plates

Energy Technology Data Exchange (ETDEWEB)

Shazly, Mostafa; Sorour, Sherif; Alian, Ahmed R. [Faculty of Engineering, The British University in Egypt, Cairo (Egypt)

2016-01-15

Friction stir welding (FSW) is a solid state welding process which requires no filler material where the heat input is generated by frictional energy between the tool and workpiece. The objective of the present work is to conduct a fully coupled thermomechanical finite element analysis based on Arbitrary Lagrangian Eulerian (ALE) formulation for both 'Force-Controlled' and 'Displacement-Controlled' FSW process to provide more detailed insight of their effect on the resulting joint quality. The developed finite element models use Johnson- Cook material model and temperature dependent physical properties for the welded plates. Efforts on proper modeling of the underlying process physics are done focusing on the heat generation of the tool/workpiece interface to overcome the shortcomings of previous investigations. Finite elements results show that 'Force-Controlled' FSW process provides better joint quality especially at higher traveling speed of the tool which comes to an agreement with published experimental results.

In-Space Friction Stir Welding Machine, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Longhurst Engineering, PLC, and Vanderbilt University propose an in-space friction stir welding (FSW) machine for joining complex structural aluminum components. The...

Friction stir welding (FSW of aluminium foam sandwich panels

Directory of Open Access Journals (Sweden)

M. Bušić

2016-07-01

Full Text Available The article focuses on the influence of welding speed and tool tilt angle upon the mechanical properties at the friction stir welding of aluminium foam sandwich panels. Double side welding was used for producing butt welds of aluminium sandwich panels applying insertion of extruded aluminium profile. Such insertion provided lower pressure of the tool upon the aluminium panels, providing also sufficient volume of the material required for the weldment formation. Ultimate tensile strength and flexural strength for three-point bending test have been determined for samples taken from the welded joints. Results have confirmed anticipated effects of independent variables.

The inhomogeneous microstructure and deformation of similar and dissimilar Al-Zn containing Mg friction stir welds

Science.gov (United States)

Hiscocks, Jessica

The magnesium-based aluminum-zinc alloys have excellent stiffness to weight ratios, and may be combined by friction stir welding to expand the possible applications. The high aluminum alloy AZ80 in particular has the advantage of being relatively stiff but still extrudable. However limited friction stir welding research is available for this alloy and extrapolation from the extensive work in aluminum alloys is impractical due differences in precipitation behaviour, and magnesium's high plastic anisotropy and tendency to form strong textures during friction stir welding. This work investigates the correlations between local friction stir welded microstructures, textures, residual strains, and the local deformation behaviour based on strain mapping during tensile tests. Covering bead-on-plate and butt configurations, joining of similar and dissimilar materials, and a range of processing conditions, many findings of interest for deformation modelling and industrial applications are presented. Synchrotron x-ray diffraction study of an entire friction stir weld was used to determine texture, residual strain and dislocation density data from a single experiment. A number of unique findings were made, mainly related to the asymmetric distribution of properties both between sides of the weld and through the depth. Particularly in the case of strain measurements, features not detectable at coarser measurement spacing or by line scan are presented and compared for multiple processing conditions. Investigation of the longitudinal material flow during welding showed that even when periodicity in grain size, precipitate distribution, or texture was not observed, periodic changes in texture intensity resulting from compaction of material behind the tool were present, providing evidence that movement of nugget material remained periodic. Strain localisation and fracture behaviour were found to be completely different between good quality similar and dissimilar friction stir welds

Welding of AA1050 aluminum with AISI 304 stainless steel by rotary friction welding process

Directory of Open Access Journals (Sweden)

Chen Ying An

2010-09-01

Full Text Available The purpose of this work was to assess the development of solid state joints of dissimilar material AA1050 aluminum and AISI 304 stainless steel, which can be used in pipes of tanks of liquid propellants and other components of the Satellite Launch Vehicle. The joints were obtained by rotary friction welding process (RFW, which combines the heat generated from friction between two surfaces and plastic deformation. Tests were conducted with different welding process parameters. The results were analyzed by means of tensile tests, Vickers microhardness, metallographic tests and SEM-EDX. The strength of the joints varied with increasing friction time and the use of different pressure values. Joints were obtained with superior mechanical properties of the AA1050 aluminum, with fracture occurring in the aluminum away from the bonding interface. The analysis by EDX at the interface of the junction showed that interdiffusion occurs between the main chemical components of the materials involved. The RFW proves to be a great method for obtaining joints between dissimilar materials, which is not possible by fusion welding processes.

Metal Cutting Theory and Friction Stir Welding Tool Design

Science.gov (United States)

Payton, Lewis N.

2003-01-01

Friction Stir Welding (FSW) is a relatively new industrial process that was invented at The Weld Institute (TWI, United Kingdom) and patented in 1992 under research funded by in part by the National Aeronautics and Space Administration (NASA). Often quoted advantages of the process include good strength and ductility along with minimization of residual stress and distortion. Less well advertised are the beneficial effects of this solid state welding process in the field of occupational and environmental safety. It produces superior weld products in difficult to weld materials without producing any toxic fumes or solid waste that must be controlled as hazardous waste. In fact, it reduces noise pollution in the workspace as well. In the early days of FSW, most welding was performed on modified machine tools, in particular on milling machines with modified milling cutters. In spite of the obvious milling heritage of the process, the techniques and lessons learned from almost 250 years of successful metalworking with milling machines have not been applied in the field of modern Friction Stir Welding. The goal of the current research was to study currently successful FSW tools and parameterize the process in such a way that the design of new tools for new materials could be accelerated. Along the way, several successful new tooling designs were developed for current issues at the Marshall Space Flight Center with accompanying patent disclosures

Effect of weld morphology on mechanical response and failure of friction stir welds in a naturally aged aluminium alloy

International Nuclear Information System (INIS)

Imam, Murshid; Biswas, Kajal; Racherla, Vikranth

2013-01-01

Highlights: ► Friction stir welds of AA 6063-T4 are obtained using three tool pin profiles. ► Signature of weld defects in mechanical response of welds is investigated. ► Correlation between peak temperatures in HAZs and their hardness is studied. ► Reasons for strengthening of WNZ and softening of HAZs are found using TEM and XRD. ► A FEM model for the weld zone is developed and validated. -- Abstract: Friction stir butt welds in 6063-T4 aluminium alloy were obtained using square and two tapered tool pin profiles. Tensile tests at 0°, 45°, and 90° to the weld line, hardness contours in the weld cross-section, temperatures in the heat affected zones, cross-sectional macrographs, transmission electron micrographs, and X-ray diffraction studies were used to characterize the welds. In transverse weld specimen, tunnel defects appearing at higher weld speeds for tapered pin profiles, were found to result in mechanical instabilities, i.e. sharp drops in load–displacement curves, much before macroscopic necking occured. Further, in comparison to the base metal, a marked reduction in ductility was observed even in transverse specimen with defect free welds. Hardness contours in the weld cross-section suggest that loss in ductility is due to significant softening in heat affected zone on the retreating side. Transmission electron microscopy images demonstrate that while recovery and overaging are responsible for softening in the heat affected zone, grain size refinement from dynamic recrystallization is responsible for strengthening of the weld nugget zone. X-ray diffraction studies in the three weld zones: weld nugget zone, heat affected zone, and the base metal corroborate these findings. A weld zone model, for use in forming simulations on friction stir welded plates of naturally aged aluminium alloys, was proposed based on mechanical characterization tests. The model was validated using finite element analysis.

Systematic investigation of the fatigue performance of a friction stir welded low alloy steel

International Nuclear Information System (INIS)

Toumpis, Athanasios; Galloway, Alexander; Molter, Lars; Polezhayeva, Helena

2015-01-01

Highlights: • The fatigue behaviour of a friction stir welded low alloy steel has been assessed. • The welds’ fatigue lives outperform the International Institute of Welding’s recommendations for fusion welds. • The slow weld exhibits the best fatigue performance of the investigated welds. • Fracture surface analysis shows that minor embedded flaws do not offer crack initiation sites. • Process-related surface breaking flaws have a significant effect on the fatigue life. - Abstract: A comprehensive fatigue performance assessment of friction stir welded DH36 steel has been undertaken to address the relevant knowledge gap for this process on low alloy steel. A detailed set of experimental procedures specific to friction stir welding has been put forward, and the consequent study extensively examined the weld microstructure and hardness in support of the tensile and fatigue testing. The effect of varying welding parameters was also investigated. Microstructural observations have been correlated to the weldments’ fatigue behaviour. The typical fatigue performance of friction stir welded steel plates has been established, exhibiting fatigue lives well above the weld detail class of the International Institute of Welding even for tests at 90% of yield strength, irrespective of minor instances of surface breaking flaws which have been identified. An understanding of the manner in which these flaws impact on the fatigue performance has been established, concluding that surface breaking irregularities such as these produced by the tool shoulder’s features on the weld top surface can be the dominant factor for crack initiation under fatigue loading

Numerical Simulation of Mechanical Property of Post Friction Stir Weld Artificial Ageing of Aluminum Alloy

Directory of Open Access Journals (Sweden)

WAN Zhenyu

2017-08-01

Full Text Available KWN model was used to establish the precipitation evolution model of friction stir welding of Al-Mg-Si alloy. The yield strength was divided into three parts:the contribution from grain size, the contribution from solid solution and the contribution from the precipitations. Based on this model, the yield strength and hardness of friction stir weld was predicted. The effect of post weld artificial ageing on mechanical properties of friction stir weld was further investigated. The results indicate that longer holding time can be beneficial to the recovery of mechanical properties in the stirring zone. Higher temperature can lead to quick recovery of mechanical properties in the stirring zone, but when the holding temperature is higher than 200℃, longer holding time can lead the base metal softened, which is harmful to the service of friction stir welds. The mechanical property in the heat affected zone cannot be improved by post weld artificial ageing.

Friction welding of bulk metallic glasses to different ones

International Nuclear Information System (INIS)

Shoji, Takuo; Kawamura, Yoshihito; Ohno, Yasuhide

2004-01-01

For application of bulk metallic glasses (BMGs) as industrial materials, it is necessary to establish the metallurgical bonding technology. The BMGs exhibit high-strain-rate superplasticity in the supercooled liquid state. It has been reported that bulk metallic glasses were successfully welded together by friction, pulse-current, explosion and electron-beam methods. In this study, friction welding of the BMGs to different ones were tried for Pd 40 Ni 40 P 20 , Pd 40 Cu 30 P 20 Ni 10 , Zr 55 Cu 30 Al 10 Ni 5 and Zr 41 Be 23 Ti 14 Cu 12 Ni 10 BMGs. Successful welding was obtained in the combinations of the Pd 40 Ni 40 P 20 and Pd 40 Cu 30 P 20 Ni 10 BMGs, and the Zr 55 Cu 30 Al 10 Ni 5 and Zr 41 Be 23 Ti 14 Cu 12 Ni 10 ones. No crystallization was observed and no visible defect was recognized in the interface. The joining strength of the welded BMGs was the same as that of the parent BMG or more. BMGs seem to be successfully welded to the different ones with a difference below about 50 K in glass transition temperature

Quantification of Microtexture at Weld Nugget of Friction Stir-Welded Carbon Steel

Science.gov (United States)

Husain, Md M.; Sarkar, R.; Pal, T. K.; Ghosh, M.; Prabhu, N.

2017-05-01

Friction stir welding of C-Mn steel was carried out under 800-1400 rpm tool rotation. Tool traversing speed of 50 mm/min remained same for all joints. Effect of thermal state and deformation on texture and microstructure at weld nugget was investigated. Weld nugget consisted of ferrite + bainite/Widmanstatten ferrite with different matrix grain sizes depending on peak temperature. A texture around ( ϕ 2 = 0°, φ = 30°, ϕ 2 = 45°) was developed at weld nugget. Grain boundary misorientation at weld nugget indicated that continuous dynamic recrystallization influenced the development of fine equiaxed grain structure. Pole figures and orientation distribution function were used to determine crystallographic texture at weld nugget and base metal. Shear texture components D1, D2 and F were present at weld nugget. D1 shear texture was more prominent among all. Large number of high-angle grain boundaries ( 60-70%) was observed at weld nugget and was the resultant of accumulation of high amount of dislocation, followed by subgrain formation.

Multi-objective Optimization of Friction Welding Process Parameters using Grey Relational Analysis for Joining Aluminium Metal Matrix Composite

Directory of Open Access Journals (Sweden)

Sreenivasan KONGANAPURAM SUNDARARAJAN

2018-05-01

Full Text Available Aluminium metal matrix composites has gained importance in recent time because of its improved mechanical and metallurgical properties. The welding of aluminium metal matrix composites using conventional welding process has got many demerits so in order to overcome them a solid state welding process is to be employed. To achieve a good strength weld in the aluminium metal matrix composite bars an efficient and most preferred technique is friction welding. In this work the aluminium metal matrix composite AA7075 + 10 % vol SiC-T6 is selected and friction welded. The combination of friction welding process parameters such as spindle speed, friction pressure, upset pressure and burn-off- length for joining the AA7075 + 10 % vol SiCP-T6 metal matrix composite bars are selected by Taguchi’s design of experiment. The optimum friction welding parameters were determined for achieving improved ultimate tensile strength and the hardness using grey relational analysis. A combined grey relational grade is found from the determined grey relational coefficient of the output responses and the optimum friction welding process parameters were obtained as spindle speed – 1200 rpm, friction pressure – 100 MPa, upset pressure – 250 MPa, Burn-off-Length – 2 mm. Analysis of variance (ANOVA performed shows that the friction pressure is the most significant friction welding parameter that influences the both the ultimate tensile strength and hardness of friction welded AA7075 + 10 % volSiCP-T6 joints. The fractured surface under microstructure study also revealed good compliance with the grey relational grade result. DOI: http://dx.doi.org/10.5755/j01.ms.24.2.17725

Controlling Force and Depth in Friction Stir Welding

Science.gov (United States)

Adams, Glynn; Loftus, Zachary; McCormac, Nathan; Venable, Richard

2005-01-01

Feedback control of the penetration force applied to a pin tool in friction stir welding has been found to be a robust and reliable means for controlling the depth of penetration of the tool. This discovery has made it possible to simplify depth control and to weld with greater repeatability, even on workpieces with long weld joints. Prior to this discovery, depths of penetration in friction stir welding were controlled by hard-tooled roller assemblies or by depth actuators controlled by feedback from such external sensors as linear variable-differential transformers or laser-based devices. These means of control are limited: A hard-tooled roller assembly confines a pin tool to a preset depth that cannot be changed easily during the welding process. A measurement by an external sensor is only an indirect indicative of the depth of penetration, and computations to correlate such a measurement with a depth of penetration are vulnerable to error. The present force-feedback approach exploits the proportionality between the depth and the force of penetration Unlike a depth measurement taken by an external sensor, a force measurement can be direct because it can be taken by a sensor coupled directly to the pin tool. The reading can be processed through a modern electronic servo control system to control an actuator to keep the applied penetration force at the desired level. In comparison with the older depth-control methods described above, this method offers greater sensitivity to plasticizing of the workpiece metal and is less sensitive to process noise, resulting in a more consistent process. In an experiment, a tapered panel was friction stir welded while controlling the force of penetration according to this method. The figure is a plot of measurements taken during the experiment, showing that force was controlled with a variation of 200 lb (890 N), resulting in control of the depth of penetration with a variation of 0.004 in. (0.1 mm).

Torque Control of Friction Stir Welding, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Longhurst Engineering, PLC and Vanderbilt University propose the innovation of torque control of friction stir welding (FSW) as a replacement to force control of...

Microstructural evolution in friction stir welding of nanostructured ODS alloys

International Nuclear Information System (INIS)

Chen, C.-L.; Tatlock, G.J.; Jones, A.R.

2010-01-01

Nanostructured oxide dispersion strengthened (ODS) Fe-based alloys manufactured by mechanical alloying (MA) are generally considered to be promising candidate materials for high-temperature applications up to at least 1100 o C because of their excellent creep strength and good oxidation resistance. However, a key issue with these alloys is the difficulty in using fusion welding techniques to join components due to oxide particle agglomeration and loss in the weld zone and the disruption and discontinuity in the grain structure introduced at the bond. In this study, the evolution of microstructure has been comprehensively studied in friction stir welds in a ferritic ODS alloy. Initially, electron backscattering diffraction (EBSD) was used to analyze the grain orientation, the grain boundary geometries and recrystallization behaviour. It suggested that deformation heterogeneities were introduced during the friction stirring process which facilitated the onset of recrystallization. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used to observe the effects of the friction stir welding (FSW) process on the grain structure and the distribution of Y 2 O 3 and other particles in the metal substrates in the FSW and adjacent regions, after the alloys had been recrystallized at temperatures up to 1380 o C for 1 h in air. The results show that fine-equiaxed grains and a uniform distribution of oxide particles were present in the friction stirred region but that the grain boundaries in the parent metal were pinned by particles. Friction stirring appeared to release these boundaries and allowed secondary recrystallization to occur after further heat treatment. The FSW process appears to be a promising technique for joining ferritic ODS alloys in the form of sheet and tube.

Development of a process envelope for friction stir welding of DH36 steel – A step change

International Nuclear Information System (INIS)

Toumpis, Athanasios; Galloway, Alexander; Cater, Stephen; McPherson, Norman

2014-01-01

Highlights: • The friction stir welding speed on DH36 steel has been substantially increased. • Excellent quality welds offering potential economic advantages are obtained. • Friction stir welding of steel generates a very complex metallurgical system. • Slow and intermediate welding speed tensile samples fractured in the parent material. • Increasing traverse speed is seen to improve the impact toughness of the weld. - Abstract: Friction stir welding of steel presents an array of advantages across many industrial sectors compared to conventional fusion welding techniques. However, the fundamental knowledge of the friction stir welding process in relation to steel remains relatively limited. A microstructure and property evaluation of friction stir welded low alloy steel grade DH36 plate, commonly used in ship and marine applications has been undertaken. In this comprehensive study, plates of 2000 × 200 × 6 mm were butt welded together at varying rotational and traverse speeds. Samples were examined microscopically and by transverse tensile tests. In addition, the work was complemented by Charpy impact testing and micro-hardness testing in various regions of the weld. The study examined a wide range of process parameters; from this, a preliminary process parameter envelope has been developed and initial process parameter sets established that produce commercially attractive excellent quality welds through a substantial increase in the conventionally recognised weld traverse speed

Modelling the Thermomechanical Conditions in Friction Stir Welding

DEFF Research Database (Denmark)

Schmidt, Henrik Nikolaj Blich

Friction Stir Welding is a solid-state welding process invented by TWI in 1991. The FSW process is unique in the sense that joining of un-weldable alloys readily can be made. The thermomechanical conditions present in the workpiece during the welding process are of great interest since...... these control the properties of the weld. In the present work, a set of experimental, analytical and numerical analyses are carried out in order to evaluate the thermomechanical conditions descriptive for welding of aluminium, in this case AA2024-T3, under a specific set of welding parameters. Despite...... these specific data, the developed models can be applied for other alloys and welding parameters as well. A detailed experiment is carried out which constitutes the basis for the development and validation of the numerical and analytical models presented in this work. The contact condition at the tool...

Numerical optimisation of friction stir welding: review of future challenges

DEFF Research Database (Denmark)

Tutum, Cem Celal; Hattel, Jesper Henri

2011-01-01

During the last decade, the combination of increasingly more advanced numerical simulation software with high computational power has resulted in models for friction stir welding (FSW), which have improved the understanding of the determining physical phenomena behind the process substantially....... This has made optimisation of certain process parameters possible and has in turn led to better performing friction stir welded products, thus contributing to a general increase in the popularity of the process and its applications. However, most of these optimisation studies do not go well beyond manual...

Effect of tool shape and welding parameters on mechanical properties and microstructure of dissimilar friction stir welded aluminium alloys

Directory of Open Access Journals (Sweden)

Chetan Aneja

2016-07-01

Full Text Available In the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases with decreasing welding speed. Furthermore mechanical properties were also found to improve as the rotary speed increases and the same phenomenon was found to happen while using straight cylindrical threaded pin profile tool. The microstructure of the dissimilar joints revealed that at low welding speeds, the improved material mixing was observed. The similar phenomenon was found to happen at higher rotational speeds using straight cylindrical threaded tool.

The Concept of Electrically Assisted Friction Stir Welding (EAFSW) and Application to the Processing of Various Metals

National Research Council Canada - National Science Library

Ferrando, William A

2008-01-01

This report introduces a novel variant of conventional friction stir welding (FSW). Since 1991, friction stir welding provides an alternative to arc welding as a metal joining method in numerous applications...

Microstructure evolution in dissimilar AA6060/copper friction stir welded joints

Science.gov (United States)

Kalashnikova, T. A.; Shvedov, M. A.; Vasilyev, P. A.

2017-12-01

Friction stir welding process has been applied for making a dissimilar copper/aluminum alloy joint. The grain microstructure and mechanical properties of the obtained joint were studied. The structure of the cross-section of the FSW compound was analyzed. The microstructural evolution of the joint was examined using optical microscopy. The mechanical properties of the intermetallic particles were evaluated by measuring the microhardness according to the Vickers method. The microhardness of the intermetallic particles was by a factor of 4 lower than that of the particles obtained by fusion welding. The results of the investigations enable using friction stir welding for making dissimilar joints.

Prediction and optimization of friction welding parameters for super duplex stainless steel (UNS S32760) joints

International Nuclear Information System (INIS)

Udayakumar, T.; Raja, K.; Afsal Husain, T.M.; Sathiya, P.

2014-01-01

Highlights: • Corrosion resistance and impact strength – predicted by response surface methodology. • Burn off length has highest significance on corrosion resistance. • Friction force is a strong determinant in changing impact strength. • Pareto front points generated by genetic algorithm aid to fix input control variable. • Pareto front will be a trade-off between corrosion resistance and impact strength. - Abstract: Friction welding finds widespread industrial use as a mass production process for joining materials. Friction welding process allows welding of several materials that are extremely difficult to fusion weld. Friction welding process parameters play a significant role in making good quality joints. To produce a good quality joint it is important to set up proper welding process parameters. This can be done by employing optimization techniques. This paper presents a multi objective optimization method for optimizing the process parameters during friction welding process. The proposed method combines the response surface methodology (RSM) with an intelligent optimization algorithm, i.e. genetic algorithm (GA). Corrosion resistance and impact strength of friction welded super duplex stainless steel (SDSS) (UNS S32760) joints were investigated considering three process parameters: friction force (F), upset force (U) and burn off length (B). Mathematical models were developed and the responses were adequately predicted. Direct and interaction effects of process parameters on responses were studied by plotting graphs. Burn off length has high significance on corrosion current followed by upset force and friction force. In the case of impact strength, friction force has high significance followed by upset force and burn off length. Multi objective optimization for maximizing the impact strength and minimizing the corrosion current (maximizing corrosion resistance) was carried out using GA with the RSM model. The optimization procedure resulted in

INVESTIGATION OF SINGLE-PASS/DOUBLE-PASS TECHNIQUES ON FRICTION STIR WELDING OF ALUMINIUM

Directory of Open Access Journals (Sweden)

N.A.A. Sathari

2014-12-01

Full Text Available The aim of this research is to study the effects of single-pass/ double-pass techniques on friction stir welding of aluminium. Two pieces of AA1100 with a thickness of 6.0 mm were friction stir welded using a CNC milling machine at rotational speeds of 1400 rpm, 1600 rpm and 1800 rpm respectively for single-pass and double-pass. Microstructure observations of the welded area were studied using an optical microscope. The specimens were tested by using a tensile test and Vickers hardness test to evaluate their mechanical properties. The results indicated that, at low rotational speed, defects such as ‘surface lack of fill’ and tunnels in the welded area contributed to a decrease in mechanical properties. Welded specimens using double-pass techniques show increasing values of tensile strength and hardness. From this investigation it is found that the best parameters of FSW welded aluminium AA1100 plate were those using double-pass techniques that produce mechanically sound joints with a hardness of 56.38 HV and 108 MPa strength at 1800 rpm compared to the single-pass technique. Friction stir welding, single-pass/ double-pass techniques, AA1100, microstructure, mechanical properties.

Design of Friction Stir Spot Welding Tools by Using a Novel Thermal-Mechanical Approach.

Science.gov (United States)

Su, Zheng-Ming; Qiu, Qi-Hong; Lin, Pai-Chen

2016-08-09

A simple thermal-mechanical model for friction stir spot welding (FSSW) was developed to obtain similar weld performance for different weld tools. Use of the thermal-mechanical model and a combined approach enabled the design of weld tools for various sizes but similar qualities. Three weld tools for weld radii of 4, 5, and 6 mm were made to join 6061-T6 aluminum sheets. Performance evaluations of the three weld tools compared fracture behavior, microstructure, micro-hardness distribution, and welding temperature of welds in lap-shear specimens. For welds made by the three weld tools under identical processing conditions, failure loads were approximately proportional to tool size. Failure modes, microstructures, and micro-hardness distributions were similar. Welding temperatures correlated with frictional heat generation rate densities. Because the three weld tools sufficiently met all design objectives, the proposed approach is considered a simple and feasible guideline for preliminary tool design.

Ultrasonic evaluation of friction stud welded AA 6063/AISI 1030 steel joints

International Nuclear Information System (INIS)

Hynes, N. Rajesh Jesudoss; Nagaraj, P.; Sujana, J. Angela Jennifa

2014-01-01

Highlights: • Friction stud welding of AA 6063 and AISI 1030 was done successfully. • Ultrasonic evaluation of interfacial properties. • EDX analysis confirms intermetallic compound (FeAl) in the interfacial region. - Abstract: Friction stud welding is a promising technique in many applications related to oil and gas industries. It is used to attach grating to offshore oil platforms in areas where arc welding is not permitted because of the risk of causing a fire or explosion. Attachment of anodes inside seawater discharge pipelines in a gas processing plant is performed by this process. This solid state joining process permits metal combinations such as welding of aluminum studs to steel which would be problematic with arc welding because of the formation of thick and brittle inter-metallic compounds. In the present work, AA 6063 is joined to AISI 1030 steel using friction stud welding machine. Properties that are of interest to manufacturing applications such as Young’s modulus, longitudinal velocity, bulk modulus and shear modulus are evaluated by means of an ultrasonic flaw detector. At the interface of the joint, there is an increase of 4.4%, 1.8%, 1.15% and 4.42% is observed for the properties Young’s modulus, longitudinal velocity, bulk modulus and shear modulus respectively. This is due to the formation of intermetallic compound and increase in hardness at the interfacial region. Energy Dispersive X-ray analysis confirms the presence of FeAl as the intermetallic compound. Scanning Electron Microscope evaluation shows the presence of an unbound zone at the center of the inner region which is due to the minimum rotational speed and low axial load experienced at that point. In the unbound zone, there is an incomplete bond between dissimilar metals and it is detrimental to joint strength. Optimum value of friction time and usage of pure aluminum interlayer during the friction stud welding process hinders the formation of unbound zone and enhances the

Microstructure and microhardness of Ti6246 linear friction weld

International Nuclear Information System (INIS)

Guo, Yina; Jung, Taenam; Chiu, Yu Lung; Li, Hangyue; Bray, Simon; Bowen, Paul

2013-01-01

The microhardness and microstructure of linear friction welded Ti–6Al–2Sn–4Zr–6Mo (Ti6246) alloys were studied, in both as-welded and post-weld heat-treated conditions. It has been found that the as-welded Ti6246 has a lower microhardness value of about 360 HV in the central weld zone than that of the base material of about 420 HV. Post-weld heat-treatment of the Ti6246 weld at 600 °C for 1 h has led to the hardness increase of about 180 HV at the central weld zone. Transmission electron microscopy studies show that the microstructure at the central weld zone of the as-welded Ti6246 consists of fine grains with dense acicular orthorhombic α″ martensite. The soft α″ martensite is believed to account for the low hardness measured in the as-welded conditions. Phase transformation from orthorhombic α″ to hexagonal α occurred during the PWHT, resulting in the observed hardness increase.

Near Net Manufacturing Using Thin Gage Friction Stir Welding

Science.gov (United States)

Takeshita, Jennifer; Potter, David; Holquin, Michael

2006-01-01

Friction Stir Welding (FSW) and near net spin forming of FSW aluminumn blanks were investigated for large-scale pressure vessel applications. With a specific focus on very thin gage 2xxx and 7xxx aluminum alloys, the program concentrated on the following: the criteria used for material selection, a potential manufacturing flow, and the effectiveness and associated risks of near net spin forming. Discussion will include the mechanical properties of the friction stir welds and the parent material from before and after the spin forming process. This effort was performed under a NASA Space Exploration initiative focused on increasing the affordability, reliability and performance of pressure vessels larger than 10 ft. diameter.

A Survey on Friction Stir Welding Of Dissimilar Magnesium Alloys

Science.gov (United States)

Unnikrishnan, M. A.; Raja, Dhas. J. Edwin

2017-10-01

There is a consistent demand for superior materials in every industry. The areas on demand are automobile and aerospace sectors in major.. The most commonly used material in these fields is Aluminium.Though it possess all the properties up to some extent constant demand is pushing for alternate materials. Dissimilar alloys have been a relatively new approach towards these fields.. Friction stir welding dissimilar alloys is a big leap in Automobile sector. In this paper a detailed review of Friction stir welding of Dissimilar Magnesium alloys has been done. This work will serve as a reference to subsequent researchers.

Weldability of an iron meteorite by Friction Stir Spot Welding: A contribution to in-space manufacturing

Science.gov (United States)

Evans, William Todd; Neely, Kelsay E.; Strauss, Alvin M.; Cook, George E.

2017-11-01

Friction Stir Welding has been proposed as an efficient and appropriate method for in space welding. It has the potential to serve as a viable option for assembling large scale space structures. These large structures will require the use of natural in space materials such as those available from iron meteorites. Impurities present in most iron meteorites limit its ability to be welded by other space welding techniques such as electron beam laser welding. This study investigates the ability to weld pieces of in situ Campo del Cielo meteorites by Friction Stir Spot Welding. Due to the rarity of the material, low carbon steel was used as a model material to determine welding parameters. Welded samples of low carbon steel, invar, and Campo del Cielo meteorite were compared and found to behave in similar ways. This study shows that meteorites can be Friction Stir Spot Welded and that they exhibit properties analogous to that of FSSW low carbon steel welds. Thus, iron meteorites can be regarded as another viable option for in-space or Martian construction.

Pengaruh waktu kontak terhadap kualitas sambungan hasil las gesek (Friction Welding Magnesium AZ-31

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Solihin Solihin

2018-01-01

Full Text Available Abstrak: Pengelasan merupakan salah suatu proses penyambungan dua atau lebih bahan teknik, dengan atau tanpa peroses pencairan logam dasarnya. Teknologi Las Gesek (Friction Welding, FW merupakan salah satu teknik pengelasan padat atau pengelasan tanpa proses pencairan (solid-state welding. Pembangkitan panas dalam proses FW dihasilkan dengan cara menggesekkan permukaan material las (base metal hingga mencapai temperatur penyambungannya (semi-solid temperature atau sekitar 80% dari temperature cair bahan, dan dalam hal Magnesium AZ31 adalah sekitar temperatur 5500C. Setelah bahan mencapai temperatur semi-solid tersebut, kemudian diberi tekanan agar terjadi proses penyambungan. Penelitian ini bertujuan untuk mengetahui pengaruh variasi proses terhadap kualitas hasil pengelasan gesek, yang meliputi: kekuatan tarik, struktur makro, dan nilai kekerasan bahan hasil las. Parameter pengujiannya adalah variasi waktu kontak las, yaitu selama 3, 5, dan 10 menit. Kecepatan putar spindle selama proses pengelasan ditetapkan 1400 rpm. Hasil pengelasan menunjukkan bahwa waktu kontak gesek 3 menit menghasilkan kekuatan tarik tertinggi (16,78 MPa, bila dibandingkan dengan dua parameter lain. Hasil uji keras pada daerah las (stir zone menunjukkan angka kekerasan rata-rata yang relative konsisten, atau sebesar 60 HRE untuk semua parameter, sedangkan angka kekerasan rata-rata di daerah terpengaruh panas (heat affected zone, HAZ untuk waktu kontak gesek 3, 5 dan 10 menit secara berturut-turut adalah sebesar 69,6; 64,6; dan 60,6 HRE. Hasil penelitian awal ini memberikan potensi studi lanjutan pada berbagai parameter pengelasan lain agar didapatkan kualitas sambungan las gesek yang optimum untuk proses pengelasan gesek Magnesium AZ-31. Kata Kunci: Las gesek, Magnesium AZ-31, struktur makro, cacat void. Abstract: Welding is a process technology aiming to join two or more materials. Friction Welding (FW is including in a solid-state technology cluster, where the heat is

Friction Pull Plug and Material Configuration for Anti-Chatter Friction Pull Plug Weld

Science.gov (United States)

Littell, Justin Anderson (Inventor)

2016-01-01

A friction pull plug is provided for use in forming a plug weld in a hole in a material. The friction pull plug includes a shank and a series of three frustoconical sections. The relative sizes of the sections assure that a central one of the sections defines the initial contact point between the hole's sides. The angle defined by the central one of the sections reduces or eliminates chatter as the plug is pulled into the hole.

Microstructure of friction stir welded joints of 2017A aluminium alloy sheets.

Science.gov (United States)

Mroczka, K; Dutkiewicz, J; Pietras, A

2010-03-01

The present study examines a friction stir welded 2017A aluminium alloy. Transmission electron microscope investigations of the weld nugget revealed the average grain size of 5 microm, moderate density of dislocations as well as the presence of nanometric precipitates located mostly in grains interiors. Scanning electron microscope observations of fractures showed the presence of ductile fracture in the region of the weld nugget with brittle precipitates in the lower part. The microhardness analysis performed on the cross-section of the joints showed fairly small changes; however, after the artificial ageing process an increase in hardness was observed. The change of the joint hardness subject to the ageing process indicates partial supersaturation in the material during friction stir welding and higher precipitation hardening of the joint.

Pin Tool Geometry Effects in Friction Stir Welding

Science.gov (United States)

Querin, J. A.; Rubisoff, H. A.; Schneider, J. A.

2009-01-01

In friction stir welding (FSW) there is significant evidence that material can take one of two different flow paths when being displaced from its original position in front of the pin tool to its final position in the wake of the weld. The geometry of the pin tool, along with the process parameters, plays an important role in dictating the path that the material takes. Each flow path will impart a different thermomechanical history on the material, consequently altering the material microstructure and subsequent weld properties. The intention of this research is to isolate the effect that different pin tool attributes have on the flow paths imparted on the FSWed material. Based on published weld tool geometries, a variety of weld tools were fabricated and used to join AA2219. Results from the tensile properties and microstructural characterization will be presented.

The Role of Friction Stir Welding in Nuclear Fuel Plate Fabrication

International Nuclear Information System (INIS)

Burkes, D.; Medvedev, P.; Chapple, M.; Amritkar, A.; Wells, P.; Charit, I

2009-01-01

The friction bonding process combines desirable attributes of both friction stir welding and friction stir processing. The development of the process is spurred on by the need to fabricate thin, high density, reduced enrichment fuel plates for nuclear research reactors. The work seeks to convert research and test reactors currently operating on highly enriched uranium fuel to operate on low enriched uranium fuel without significant loss in reactor performance, safety characteristics, or significant increase in cost. In doing so, the threat of global nuclear material proliferation will be reduced. Feasibility studies performed on the process show that this is a viable option for mass production of plate-type nuclear fuel. Adapting the friction stir weld process for nuclear fuel fabrication has resulted in the development of several unique ideas and observations. Preliminary results of this adaptation and process model development are discussed

Structure and Mechanical Properties of Friction Stir Weld Joints of Magnesium Alloy AZ31

Science.gov (United States)

Nagasawa, T.; Otsuka, M.; Yokota, T.; Ueki, T.

The applicability of friction stir welding to hot rolled sheet of commercial magnesium alloy AZ31 plates has been investigated. Friction stir weld joint showed mechanical strength comparable to that of base material, though the ductility remained at one half of that of the latter. The results are consistent with the microstructure which is characterized by a fine grained bond layer bounded by-intermediate grained base metals. It is found that both anodizing treatment and insertion of aluminum foil between batting faces do not degrade the joint properties at all. The results suggest that friction stir welding can be potentially applied to magnesium alloy.

Friction stir welding (FSW process of copper alloys

Directory of Open Access Journals (Sweden)

M. Miličić

2016-01-01

Full Text Available The present paper analyzes the structure of the weld joint of technically pure copper, which is realized using friction stir welding (FSW. The mechanism of thermo-mechanical processes of the FSW method has been identified and a correlation between the weld zone and its microstructure established. Parameters of the FSW welding technology influencing the zone of the seam material and the mechanical properties of the resulting joint were analyzed. The physical joining consists of intense mixing the base material along the joint line in the “doughy” phase. Substantial plastic deformations immediately beneath the frontal surface of tool provide fine-grained structure and a good quality joint. The optimum shape of the tool and the optimum welding regime (pressure force, rotation speed and the traverse speed of the tool in the heat affected zone enable the achievement of the same mechanical properties as those of the basic material, which justifies its use in welding reliable structures.

Wear Resistance Analysis of A359/SiC/20p Advanced Composite Joints Welded by Friction Stir Welding

Directory of Open Access Journals (Sweden)

O. Cuevas Mata

Full Text Available Abstract Advancement in automotive part development demands new cost-effective materials with higher mechanical properties and improved wear resistance as compared to existing materials. For instance, Aluminum Matrix Composites (AMC shows improved mechanical properties as wear and abrasion resistance, high strength, chemical and dimensional stability. Automotive industry has focused in AMC for a variety of applications in automotive parts in order to improve the fuel economy, minimize vehicle emissions, improve design options, and increase the performance. Wear resistance is one of the most important factors in useful life of the automotive components, overall in those components submitted to mechanical systems like automotive brakes and suspensions. Friction Stir Welding (FSW rises as the most capable process to joining AMC, principally for the capacity to weld without compromising their ceramic reinforcement. The aim of this study is focused on the analysis of wear characteristics of the friction-stir welded joint of aluminum matrix reinforced with 20 percent in weight silicon carbide composite (A359/SiC/20p. The experimental procedure consisted in cut samples into small plates and perform three welds on these with a FSW machine using a tool with 20 mm shoulder diameter and 8 mm pin diameter. The wear features of the three welded joints and parent metal were analyzed at constant load applying 5 N and a rotational speed of 100 rpm employing a Pin-on - Disk wear testing apparatus, using a sapphire steel ball with 6 mm diameter. The experimental results indicate that the three welded joints had low friction coefficient compared with the parent metal. The results determine that the FSW process parameters affect the wear resistance of the welded joints owing to different microstructural modifications during welding that causes a low wear resistance on the welded zone.

A Study on Tooling and Its Effect on Heat Generation and Mechanical Properties of Welded Joints in Friction Stir Welding

Science.gov (United States)

Tikader, Sujoy; Biswas, Pankaj; Puri, Asit Baran

2018-04-01

Friction stir welding (FSW) has been the most attracting solid state welding process as it serves numerous advantages like good mechanical, metallurgical properties etc. Non weldable aluminium alloys like 5XXX, 7XXX series can be simply joined by this process. In this present study a mathematical model has been developed and experiments were successfully performed to evaluate mechanical properties of FSW on similar aluminium alloys i.e. AA1100 for different process parameters and mainly two kind of tool geometry (straight cylindrical and conical or cylindrical tapered shaped pin with flat shoulder). Tensile strength and micro hardness for different process parameters are reported of the welded plate sample. It was noticed that in FSW of similar alloy with tool made of SS-310 tool steel, friction is the major contributor for the heat generation. It was seen that tool geometry, tool rotational speed, plunging force by the tool and traverse speed have significant effect on tensile strength and hardness of friction stir welded joints.

Effect of process parameters on microstructure and mechanical properties of friction stir welded joints: A review

Science.gov (United States)

Wanare, S. P.; Kalyankar, V. D.

2018-04-01

Friction stir welding is emerging as a promising technique for joining of lighter metal alloys due to its several advantages over conventional fusion welding processes such as low thermal distortion, good mechanical properties, fine weld joint microstructure, etc. This review article mainly focuses on analysis of microstructure and mechanical properties of friction stir welded joints. Various microstructure characterization techniques used by previous researchers such as optical microscopes, x-ray diffraction, electron probe microscope, transmission electron microscope, scanning electron microscopes with electron back scattered diffraction, electron dispersive microscopy, etc. are thoroughly overviewed and their results are discussed. The effects of friction stir welding process parameters such as tool rotational speed, welding speed, tool plunge depth, axial force, tool shoulder diameter to tool pin diameter ratio, tool geometry etc. on microstructure and mechanical properties of welded joints are studied and critical observations are noted down. The microstructure examination carried out by previous researchers on various zones of welded joints such as weld zone, heat affected zone and base metal are studied and critical remarks have been presented. Mechanical performances of friction stir welded joints based on tensile test, micro-hardness test, etc. are discussed. This article includes exhaustive literature review of standard research articles which may become ready information for subsequent researchers to establish their line of action.

Microstructure and microhardness of Ti6246 linear friction weld

Energy Technology Data Exchange (ETDEWEB)

Guo, Yina; Jung, Taenam [School of Metallurgy and Materials, University of Birmingham, Birmingham, B15 2TT (United Kingdom); Chiu, Yu Lung, E-mail: y.chiu@bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, Birmingham, B15 2TT (United Kingdom); Li, Hangyue [School of Metallurgy and Materials, University of Birmingham, Birmingham, B15 2TT (United Kingdom); Bray, Simon [Rolls-Royce plc, PO Box 31, Derby DE24 8BJ (United Kingdom); Bowen, Paul [School of Metallurgy and Materials, University of Birmingham, Birmingham, B15 2TT (United Kingdom)

2013-02-01

The microhardness and microstructure of linear friction welded Ti-6Al-2Sn-4Zr-6Mo (Ti6246) alloys were studied, in both as-welded and post-weld heat-treated conditions. It has been found that the as-welded Ti6246 has a lower microhardness value of about 360 HV in the central weld zone than that of the base material of about 420 HV. Post-weld heat-treatment of the Ti6246 weld at 600 Degree-Sign C for 1 h has led to the hardness increase of about 180 HV at the central weld zone. Transmission electron microscopy studies show that the microstructure at the central weld zone of the as-welded Ti6246 consists of fine grains with dense acicular orthorhombic {alpha} Double-Prime martensite. The soft {alpha} Double-Prime martensite is believed to account for the low hardness measured in the as-welded conditions. Phase transformation from orthorhombic {alpha} Double-Prime to hexagonal {alpha} occurred during the PWHT, resulting in the observed hardness increase.

Welding parameter optimization of alloy material by friction stir welding using Taguchi approach and design of experiments

Science.gov (United States)

Karwande, Amit H.; Rao, Seeram Srinivasa

2018-04-01

Friction stir welding (FSW) a welding process in which metals are joint by melting them at their solid state. In different engineering areas such as civil, mechanical, naval and aeronautical engineering beams are widely used of the magnesium alloys for different applications and that are joined by conventional inert gas welding process. Magnesium metal has less density and low melting point for that reason large heat generation in the common welding process so its necessity to adapt new welding process. FSW process increases the weld quality which observed under various mechanical testing by using different tool size.

Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

Science.gov (United States)

2011-01-01

structures in Finland; (b) manufacture of Al-Mg-Si-based alloy 181 FSW-joined bullet- train cabins in Japan; (c) fabrication of 182 Al-Cu-based alloy...Simonsen, Visualisation of Material 857Flow in an Autogenous Friction Stir Weld, Proc. 1st International 858Symp. FSW, Thousand Oaks, CA, 1999 85928...A.P. Reynolds, Visualization of Material Flow in an Autogenous 860Friction Stir Weld, Sci. Technol. Weld. Join., 2000, 5, p 120–124 86129. T.U. Seidel

Immersed friction stir welding of ultrafine grained accumulative roll-bonded Al alloy

International Nuclear Information System (INIS)

Hosseini, M.; Danesh Manesh, H.

2010-01-01

In this research, ultrafine grained strips of commercial pure strain hardenable aluminum (AA1050) were produced by accumulative roll-bonding (ARB) technique. These strips were joined by friction stir welding (FSW) in immersed (underwater) and conventional (in-air) conditions to investigate the effect of the immersion method on the microstructure and mechanical properties of the joint, aiming to reduce the deterioration of the mechanical properties of the joint. Transmission electron microscopy and X-ray diffraction analyses were used to evaluate the microstructure, showing smaller grains and subgrains in the stir zone of the immersed FSW condition with respect to the conventional FSW method. The hardness and tensile properties of the immersed friction stir welded sample and ARBed base metal show more similarity compared to the conventional friction stir welded sample. Moreover, the aforementioned method can result in the enhancement of the superplasticity tendency of the material.

Micro friction stir welding of copper electrical contacts

Directory of Open Access Journals (Sweden)

D. Klobčar

2014-10-01

Full Text Available The paper presents an analysis of micro friction stir welding (μFSW of electrolytic tough pitch copper (CuETP in a lap and butt joint. Experimental plan was done in order to investigate the influence of tool design and welding parameters on the formation of defect free joints. The experiments were done using universal milling machine where the tool rotation speed varied between 600 and 1 900 rpm, welding speed between 14 and 93 mm/min and tilt angle between 3° and 5°. From the welds samples for analysis of microstructure and samples for tensile tests were prepared. The grain size in the nugget zone was greatly reduced compared to the base metal and the joint tensile strength exceeded the strength of the base metal.

A review of literature from the First International Conference on Friction Stir Welding

International Nuclear Information System (INIS)

Bowyer, W.H.

2000-06-01

The papers from the first international conference on Friction Stir Welding (FSW) have been reviewed. Taken together the papers provide a very optimistic picture for the development and application of friction stir welding in general and to the case of the copper canister in particular. Whilst a considerable development effort is in progress the process has been industrialised for joining of aluminium sheet and it is accepted by Lloyds register for this purpose. Development of procedures and equipment to weld thicker materials and a wider range of materials is progressing ahead of the research activity to aid the understanding of the process at this stage. Nevertheless, well-established weld assessment procedures are being applied to experimental welds with very encouraging results. Summaries of the key papers are presented in an appendix

Joint properties of dissimilar Al6061-T6 aluminum alloy/Ti–6%Al–4%V titanium alloy by gas tungsten arc welding assisted hybrid friction stir welding

International Nuclear Information System (INIS)

Bang, HanSur; Bang, HeeSeon; Song, HyunJong; Joo, SungMin

2013-01-01

Highlights: • Hybrid friction stir welding for Al alloy and Ti alloy joint has been carried out. • Mechanical strength of dissimilar joint by HFSW and FSW has been compared. • Microstructure of dissimilar joint by HFSW and FSW has been compared. - Abstract: Hybrid friction stir butt welding of Al6061-T6 aluminum alloy plate to Ti–6%Al–4%V titanium alloy plate with satisfactory acceptable joint strength was successfully achieved using preceding gas tungsten arc welding (GTAW) preheating heat source of the Ti alloy plate surface. Hybrid friction stir welding (HFSW) joints were welded completely without any unwelded zone resulting from smooth material flow by equally distributed temperature both in Al alloy side and Ti alloy side using GTAW assistance for preheating the Ti alloy plate unlike friction stir welding (FSW) joints. The ultimate tensile strength was approximately 91% in HFSW welds by that of the Al alloy base metal, which was 24% higher than that of FSW welds without GTAW under same welding condition. Notably, it was found that elongation in HFSW welds increased significantly compared with that of FSW welds, which resulted in improved joint strength. The ductile fracture was the main fracture mode in tensile test of HFSW welds

Microstructure, mechanical properties and microtexture of friction stir welded S690QL high yield steel

Energy Technology Data Exchange (ETDEWEB)

Paillard, Pascal [Institut des Matériaux Jean Rouxel, UMR 6205, Polytech Nantes, Site de la Chantrerie, BP 50609, 44306 Nantes cedex 3 (France); Bertrand, Emmanuel, E-mail: emmanuel.bertrand@univ-nantes.fr [Institut des Matériaux Jean Rouxel, UMR 6205, Polytech Nantes, Site de la Chantrerie, BP 50609, 44306 Nantes cedex 3 (France); Allart, Marion; Benoit, Alexandre [Institut de Recherche Technologique Jules Verne, Chemin du Chaffault, 44340 Bouguenais (France); Ruckert, Guillaume [DCNS Research, Technocampus Ocean, 5 rue de l' Halbrane, 44340 Bouguenais (France)

2016-12-15

Two try-out campaigns of friction stir welding (FSW) were performed with different friction parameters to join S690QL high yield strength steel. The welds were investigated at macroscopic and microscopic scales using optical and electronic microscopy and microhardness mapping. Welds of the second campaign exhibit microstructures and mechanical properties in accordance with requirements for service use. Microtexture measurements were carried out in different zones of welds by electron backscattered diffraction (EBSD). It is shown that that texture of the bottom of the weld is similar to that of the base metal, suggesting a diffusion bonding mechanism. Finally, the mechanical properties (tensile strength, resilience, bending) were established on the most promising welds. It is shown that it is possible to weld this high yield strength steel using FSW process with satisfactory geometric, microstructural and mechanical properties. - Highlights: •1000 mm ∗ 400 mm ∗ 8 mm S690QL steel plates are joined by friction stir welding (FSW). •Maximum hardness is reduced by optimization of process parameters. •Various microstructures are formed but no martensite after process optimization. •Texture is modified in mechanically affected zones of the weld. •Texture in the bottom of the weld is preserved, suggesting diffusion bonding.

Study of Dissimilar Welding AA6061 Aluminium Alloy and AZ31B Magnesium Alloy with ER5356 Filler Using Friction Stir Welding

Science.gov (United States)

Mahamud, M. I. I.; Ishak, M.; Halil, A. M.

2017-09-01

This paper is to study of dissimilar welding AA6061 aluminium alloy and AZ31B magnesium alloy with ER5356 filler using friction stir welding. 2 mm thick plates of aluminium and magnesium were used. Friction stir welding operations were performed at different rotation and travel speeds and used the fixed tilt angle which is 3°. The rotation speeds varied from 800 to 1100 rpm, and the travel speed varied from 80 to 100 mm/min. In the range rotation speed of 800 to 1000 rpm and welding speed of 80 to 100 mm/min there are no defect at the weld. Tensile test show the higher tensile strength is 198 MPa and the welding efficiency is about 76%.

Initial Development in Joining of ODS Alloys Using Friction Stir Welding

Energy Technology Data Exchange (ETDEWEB)

Ren, Weiju [ORNL; Feng, Zhili [ORNL

2007-08-01

Solid-state welding of oxide-dispersion-strengthened (ODS) alloy MA956 sheets using friction stir welding (FSW) was investigated. Butt weld was successfully produced. The weld and base metals were characterized using optical microscopy, scanning electronic microscopy, transmission electronic microscopy, and energy dispersion x-ray spectrum. Microhardness mapping was also conducted over the weld region. Analyses indicate that the distribution of the strengthening oxides was preserved in the weld. Decrease in microhardness of the weld was observed but was insignificant. The preliminary results seem to confirm the envisioned feasibility of FSW application to ODS alloy joining. For application to Gen IV nuclear reactor heat exchanger, further investigation is suggested.

The Simulation of Precipitation Evolutions and Mechanical Properties in Friction Stir Welding with Post-Weld Heat Treatments

Science.gov (United States)

Zhang, Z.; Wan, Z. Y.; Lindgren, L.-E.; Tan, Z. J.; Zhou, X.

2017-12-01

A finite element model of friction stir welding capable of re-meshing is used to simulate the temperature variations. Re-meshing of the finite element model is used to maintain a fine mesh resolving the gradients of the solution. The Kampmann-Wagner numerical model for precipitation is then used to study the relation between friction stir welds with post-weld heat treatment (PWHT) and the changes in mechanical properties. Results indicate that the PWHT holding time and PWHT holding temperature need to be optimally designed to obtain FSW with better mechanical properties. Higher precipitate number with lower precipitate sizes gives higher strength in the stirring zone after PWHT. The coarsening of precipitates in HAZ are the main reason to hinder the improvement of mechanical property when PWHT is used.

An analytical model for the heat generation in friction stir welding

DEFF Research Database (Denmark)

Schmidt, Henrik Nikolaj Blich; Hattel, Jesper; Wert, John

2004-01-01

The objective of this work is to establish an analytical model for heat generation by friction stir welding (FSW), based on different assumptions of the contact condition between the rotating tool surface and the weld piece. The material flow and heat generation are characterized by the contact...

Structural Phase Evolution in Ultrasonic-Assisted Friction Stir Welded 2195 Aluminum Alloy Joints

Science.gov (United States)

Eliseev, A. A.; Fortuna, S. V.; Kalashnikova, T. A.; Chumaevskii, A. V.; Kolubaev, E. A.

2017-10-01

The authors examined the structural and phase state of fixed joints produced by method of friction stir welding (FSW) and ultrasonic-assisted friction stir welding (UAFSW) from extruded profile of aluminum alloy AA2195. In order to identify the role of ultrasonic application in the course of welding, such characteristics, as volume fraction and average size of secondary particles are compared in the base material and stir zones of FSW and UAFSW joints. By applying the methods of SEM and TEM analysis, researchers established the complex character of phase transitions as a result of ultrasonic application.

Dissimilar Joining of ODS and F/M Steel Tube by Friction Stir Welding

Energy Technology Data Exchange (ETDEWEB)

Kang, Suk Hoon; Noh, Sanghoon; Kim, Jun Hwan; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Oxide Dispersion strengthened (ODS) steels, it is well known that uniform nano-oxide dispersoids act as pinning points to obstruct dislocation and grain boundary motion, however, those advantages will be disappeared while the material is subjected to the high temperature of conventional fusion welding. Rotary friction welding, also referred to as friction stir welding (FSW), has shown great promise as a method for welding traditionally difficult to weld materials such as aluminum alloys. This relatively new technology has more recently been applied to higher melting temperature alloys such as steels, nickel-based and titanium alloys. Friction stir processing (FSP) is a method of changing the properties of a metal through intense, localized plastic deformation. FSW is the precursor of the FSP technique. When ideally implemented, this process mixes the material without changing the phase and creates a microstructure with fine, equiaxed grains. This homogeneous grain structure, separated by high-angle boundaries, allows some alloys to take on superplastic properties. In this study, FSW is used as a substitutive welding process between FMS tube and ODS parts. The dimension of tube is 7.0 OD, 0.5 T. During the FSW, dynamic-recrystallized grains are developed; the uniform oxides Dispersion is preserved in the metal matrix. The microstructure and microtexture of the material near the stir zone is found to be influenced by the rotational behavior of the tool. The additive effect from FSP on sample surface is considered. Since the mechanical alloying (MA) and FSP commonly apply extreme shear deformation on materials, the Dispersion of oxide particle in ODS steels is very active during both processes. Friction stir welding appears to be a very promising technique for the welding of FMS and ODS steels in the form of sheet and tube. FSW could successfully produce defect-free welds on FMS tubes and ODS ring assembly. FSW produces a fine grain structure consisting of ferrite and

Dissimilar Joining of ODS and F/M Steel Tube by Friction Stir Welding

International Nuclear Information System (INIS)

Kang, Suk Hoon; Noh, Sanghoon; Kim, Jun Hwan; Kim, Tae Kyu

2014-01-01

Oxide Dispersion strengthened (ODS) steels, it is well known that uniform nano-oxide dispersoids act as pinning points to obstruct dislocation and grain boundary motion, however, those advantages will be disappeared while the material is subjected to the high temperature of conventional fusion welding. Rotary friction welding, also referred to as friction stir welding (FSW), has shown great promise as a method for welding traditionally difficult to weld materials such as aluminum alloys. This relatively new technology has more recently been applied to higher melting temperature alloys such as steels, nickel-based and titanium alloys. Friction stir processing (FSP) is a method of changing the properties of a metal through intense, localized plastic deformation. FSW is the precursor of the FSP technique. When ideally implemented, this process mixes the material without changing the phase and creates a microstructure with fine, equiaxed grains. This homogeneous grain structure, separated by high-angle boundaries, allows some alloys to take on superplastic properties. In this study, FSW is used as a substitutive welding process between FMS tube and ODS parts. The dimension of tube is 7.0 OD, 0.5 T. During the FSW, dynamic-recrystallized grains are developed; the uniform oxides Dispersion is preserved in the metal matrix. The microstructure and microtexture of the material near the stir zone is found to be influenced by the rotational behavior of the tool. The additive effect from FSP on sample surface is considered. Since the mechanical alloying (MA) and FSP commonly apply extreme shear deformation on materials, the Dispersion of oxide particle in ODS steels is very active during both processes. Friction stir welding appears to be a very promising technique for the welding of FMS and ODS steels in the form of sheet and tube. FSW could successfully produce defect-free welds on FMS tubes and ODS ring assembly. FSW produces a fine grain structure consisting of ferrite and

Rotary Bending Fatigue Characteristics According to Optimal Friction Welding of SF45 to SM45C Steel Bars

Energy Technology Data Exchange (ETDEWEB)

Kong, Yu Sik; Park, Young Whan [Pukyong Nat’l Univ., Busan (Korea, Republic of)

2017-03-15

A study on dissimilar friction-welded joints was performed for cam shaft applications using solid bar samples, 20mm in diameter, of forging steel(SF45) and carbon steel(SM45C). The main parameters of friction welding such as tensile tests, Vickers hardness surveys of the bond of area, the heat affected zone (HAZ), and the observation of microstructure were investigated to ensure a good quality of friction welding through visual observations. The specimens were tested as-welded and post weld heat treatment(PWHT). This paper deals with optimizing the welding conditions and analyzing various rotary bending fatigue test(RBFT) properties about heat-treated base metal(BM), as-welded and PWHT. Consequently, two materials for friction welding are strongly mixed with a well-combined structure of micro-particles without any molten material, particle growth, or any defect. Moreover, the fatigue limit of BM(SF45) and PWHT for the RBFT were observed as 180MPa and 250MPa, respectively. It was confirmed that the PWHT causes approximately 40% improvement in the fatigue limit when compared to the BM(SF45).

Rotary Bending Fatigue Characteristics According to Optimal Friction Welding of SF45 to SM45C Steel Bars

International Nuclear Information System (INIS)

Kong, Yu Sik; Park, Young Whan

2017-01-01

A study on dissimilar friction-welded joints was performed for cam shaft applications using solid bar samples, 20mm in diameter, of forging steel(SF45) and carbon steel(SM45C). The main parameters of friction welding such as tensile tests, Vickers hardness surveys of the bond of area, the heat affected zone (HAZ), and the observation of microstructure were investigated to ensure a good quality of friction welding through visual observations. The specimens were tested as-welded and post weld heat treatment(PWHT). This paper deals with optimizing the welding conditions and analyzing various rotary bending fatigue test(RBFT) properties about heat-treated base metal(BM), as-welded and PWHT. Consequently, two materials for friction welding are strongly mixed with a well-combined structure of micro-particles without any molten material, particle growth, or any defect. Moreover, the fatigue limit of BM(SF45) and PWHT for the RBFT were observed as 180MPa and 250MPa, respectively. It was confirmed that the PWHT causes approximately 40% improvement in the fatigue limit when compared to the BM(SF45).

Effect of weld line shape on material flow during friction stir welding of aluminum and steel

International Nuclear Information System (INIS)

Yasui, Toshiaki; Ando, Naoyuki; Morinaka, Shinpei; Mizushima, Hiroki; Fukumoto, Masahiro

2014-01-01

The effect of weld line shape on material flow during the friction stir welding of aluminum and steel was investigated. The material flow velocity was evaluated with simulated experiments using plasticine as the simulant material. The validity of the simulated experiments was verified by the marker material experiments on aluminum. The circumferential velocity of material around the probe increased with the depth from the weld surface. The effect is significant in cases where the advancing side is located on the outside of curve and those with higher curvature. Thus, there is an influence of weld line shape on material flow

Development of liquid-nitrogen-cooling friction stir spot welding for AZ31 magnesium alloy joints

Science.gov (United States)

Wu, Dong; Shen, Jun; Zhou, Meng-bing; Cheng, Liang; Sang, Jia-xing

2017-10-01

A liquid-nitrogen-cooling friction stir spot welding (C-FSSW) technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone (SZ) and the heat-affected zone (HAZ) of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone (TMAZ) increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding (FSSW)-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time.

Material Flow and Oxide Particle Distributions in Friction-Stir Welded F/M-ODS Sheets

Energy Technology Data Exchange (ETDEWEB)

Kang, Suk Hoon; Noh, Sanghoon; Jin, Hyun Ju; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

It is well known that uniform nano-oxide dispersoids act as pinning points to obstruct dislocation and grain boundary motion in ODS(Oxide dispersion strengthened) steel. However, these advantages will disappear while the material is subjected to the high temperature of conventional fusion welding. There is only limited literature available on the joining of ODS steels. Friction stir welding (FSW) is considered to be the best welding technique for welding ODS steels as the technique helps in retaining the homogeneous nano-oxide particles distributions in matrix. FSW is a solid.state, hot.shear joining process in which a rotating tool with a shoulder and terminating in a threaded pin, moves along the butting surfaces of two rigidly clamped plates placed on a backing plate. Heat generated by friction at the shoulder and to a lesser extent at the pin surface, softens the material being welded. Severe plastic deformation and flow of this plasticised metal occurs as the tool is translated along the welding direction. Material is transported from the front of the tool to the trailing edge where it is forged into a joint. Friction stir welding appears to be a very promising technique for the welding of FMS and ODS steels. This study found that, during FSW, the forward movement of the tool pin results in loose contact between the tool pin and the receding material on the advancing side.

Prolegomena to the Study of Friction Stir Welding

Science.gov (United States)

Nunes, Arthur C., Jr.

2010-01-01

The literature contains many approaches toward modeling of the friction stir welding (FSW) process with varying treatments of the weld metal properties. It is worthwhile to consider certain fundamental features of the process before attempting to interpret FSW phenomena: Because of the unique character of metal deformation (as opposed to, say, viscous deformation) a velocity "discontinuity" or shear surface occurs in FSW and determines much of the character of the welding mechanism. A shear surface may not always produce a sound bond. Balancing mechanical power input against conduction and convection heat losses yields a relation, a "temperature index", between spindle speed and travel speed to maintain constant weld temperature. But many process features are only weakly dependent upon temperature. Thus, unlike modeling of metal forming processes, it may be that modeling the FSW process independently of the material conditions has some merit.

The investigation of abnormal particle-coarsening phenomena in friction stir repair weld of 2219-T6 aluminum alloy

International Nuclear Information System (INIS)

Li, Bo; Shen, Yifu

2011-01-01

Highlights: → Defective friction stir welds were repaired by overlapping FSW technique. → Abnormal Al 2 Cu-coarsening phenomena were found in 2219-T6 friction stir repair weld. → Three formation mechanisms were proposed for reasonable explanations. -- Abstract: The single-pass friction stir weld of aluminum 2219-T6 with weld-defects was repaired by overlapping friction stir welding technique. However, without any post weld heat treatment process, it was found that the phenomena of abnormal particle-coarsening of Al 2 Cu had occurred in the overlapping friction stir repair welds. The detecting results of non-destructive X-ray inspection proved that not only one group of repair FSW process parameters could lead to occurrence of the abnormal phenomena. And the abnormally coarsened particles always appeared on the advancing side of repair welds rather than the retreating side where the fracture behaviors occurred after mechanical tensile testing. The size of the biggest particle lying in the dark bands of 'Onion-rings' was more than 150 μm. After the related investigation by scanning electron microscope and X-ray energy spectrometer, three types of formation mechanisms were proposed for reasonably explaining the abnormal phenomenon: Aggregation Mechanism, Diffusion Mechanisms I and II. Aggregation Mechanism was according to the motion-laws of stir-pin. Diffusion Mechanisms were based on the classical theories of precipitate growth in metallic systems. The combined action of the three detailed mechanisms contributed to the abnormal coarsening behavior of Al 2 Cu particles in the friction stir repair weld.

Microstructures and mechanical properties of magnesium alloy and stainless steel weld-joint made by friction stir lap welding

International Nuclear Information System (INIS)

Wei, Yanni; Li, Jinglong; Xiong, Jiangtao; Huang, Fu; Zhang, Fusheng

2012-01-01

Highlights: → Friction stir lap welding technology with cutting pin was successfully employed to form lap joint of magnesium and steel. → The cutting pin made the lower steel participate in deformation and the interface was no longer flat. → A saw-toothed structure formed due to a mechanical mixing of the magnesium and steel was found at the interface. → A high-strength joint was produced which fractured in the magnesium side. -- Abstract: Friction stir lap welding was conducted on soft/hard metals. A welding tool was designed with a cutting pin of rotary burr made of tungsten carbide, which makes the stirring pin possible to penetrate and cut the surface layer of the hard metal. Magnesium alloy AZ31 and stainless steel SUS302 were chosen as soft/hard base metals. The structures of the joining interface were analyzed by scanning electron microscopy (SEM). The joining strength was evaluated by tensile shear test. The results showed that flower-like interfacial morphologies were presented with steel flashes and scraps, which formed bonding mechanisms of nail effect by long steel flashes, zipper effect by saw-tooth structure and metallurgical bonding. The shear strength of the lap joint falls around the shear strength of butt joint of friction stir welded magnesium alloy.

Microstructural transformations and mechanical properties of cast NiAl bronze: Effects of fusion welding and friction stir processing

International Nuclear Information System (INIS)

Fuller, M.D.; Swaminathan, S.; Zhilyaev, A.P.; McNelley, T.R.

2007-01-01

A plate of as-cast NiAl bronze (NAB) material was sectioned from a large casting. A six-pass fusion weld overlay was placed in a machined groove; a portion of the weld reinforcement was removed by milling and a single friction stir processing (FSP) pass was conducted in a direction transverse to the axis of and over the weld overlay. A procedure was developed for machining of miniature tensile samples and the distributions of strength and ductility were evaluated for the fusion weld metal; for the stir zone (SZ) produced by the friction stir processing; and for a region wherein friction stir processing had taken place over the fusion weld. A region of low ductility in the heat affected zone (HAZ) of the fusion weld and in the thermomechanically affected zone (TMAZ) of friction stir processed material was attributed to partial reversion of an equilibrium lamellar eutectoid constituent upon local heating above ∼800 deg. C and formation of non-equilibrium transformation products upon subsequent cooling. The adverse effect on ductility is worse in the heat affected zone of the fusion weld than in the thermomechanically affected zone of friction stir processing due to the lower heat input of the latter process. The implications of this work to engineering applications of friction stir processing are discussed

Effect of rotation speed and welding speed on Friction Stir Welding of AA1100 Aluminium alloy

Science.gov (United States)

Raja, P.; Bojanampati, S.; Karthikeyan, R.; Ganithi, R.

2018-04-01

Aluminum AA1100 is the most widely used grade of Aluminium due to its excellent corrosion resistance, high ductility and reflective finish, the selected material was welded with Friction Stir Welding (FSW) process on a CNC machine, using a combination of different tool rotation speed (1500 rpm, 2500 rpm, 3500 rpm) and welding speed (10 mm/min, 30 mm/min, 50 mm/min) as welding parameters. The effect of FSW using this welding parameter was studied by measuring the ultimate tensile strength of the welded joints. A high-speed steel tool was prepared for welding the Aluminium AA1100 alloy having an 8mm shoulder diameter and pin dimension of 4mm diameter and 2.8 mm length. The welded joints were tested using the universal testing machine. It was found that Ultimate Tensile Strength of FSW specimen was highest with a value of 98.08 MPa when the weld was performed at rotation speed of 1500 RPM and welding speed of 50 mm/min.

Friction Stir Weld Application and Tooling Design for the Multi-purpose Crew Vehicle Stage Adapter

Science.gov (United States)

Alcorn, John

2013-01-01

The Multi-Purpose Crew Vehicle (MPCV), commonly known as the Orion capsule, is planned to be the United States' next manned spacecraft for missions beyond low earth orbit. Following the cancellation of the Constellation program and creation of SLS (Space Launch System), the need arose for the MPCV to utilize the Delta IV Heavy rocket for a test launch scheduled for 2014 instead of the previously planned Ares I rocket. As a result, an adapter (MSA) must be used in conjunction with the MPCV to account for the variation in diameter of the launch vehicles; 5.5 meters down to 5.0 meters. Prior to ight article fabrication, a path nder (test article) will be fabricated to ne tune the associated manufacturing processes. The adapter will be comprised of an aluminum frustum (partial cone) that employs isogrid technology and circumferential rings on each end. The frustum will be fabricated by friction stir welding (FSW) three individual panels together on a Vertical Weld Tool (VWT) at NASA Marshall Space Flight Center. Subsequently, each circumferential ring will be friction stir welded to the frustum using a Robotic Weld Tool (RWT). The irregular geometry and large mass of the MSA require that extensive tooling preparation be put into support structures for the friction stir weld. The tooling on the VWT will be comprised of a set of conveyors mounted on pre-existing stanchions so that the MSA will have the ability to be rotated after each of the three friction stir welds. The tooling requirements to friction stir weld the rings with the RWT are somewhat more demanding. To support the mass of the MSA and resist the load of the weld tool, a system of mandrels will be mounted to stanchions and assembled in a circle. The goal of the paper will be to explain the design, fabrication, and assembly of the tooling, to explain the use of friction stir welding on the MSA path nder, and also to discuss the lessons learned and modi cations made in preparation for ight article fabrication

Microstructure and mechanical properties of friction stir welded SAF 2507 super duplex stainless steel

International Nuclear Information System (INIS)

Sato, Y.S.; Nelson, T.W.; Sterling, C.J.; Steel, R.J.; Pettersson, C.-O.

2005-01-01

The microstructure and mechanical properties of friction stir (FS) welded SAF 2507 super duplex stainless steel were examined. High-quality, full-penetration welds were successfully produced in the super duplex stainless steel by friction stir welding (FSW) using polycrystalline cubic boron nitride (PCBN) tool. The base material had a microstructure consisting of the ferrite matrix with austenite islands, but FSW refined grains of the ferrite and austenite phases in the stir zone through dynamic recrystallisation. Ferrite content was held between 50 and 60% throughout the weld. The smaller grain sizes of the ferrite and austenite phases caused increase in hardness and strength within the stir zone. Welded transverse tensile specimen failed near the border between the stir zone and TMAZ at the retreating side as the weld had roughly the same strengths as the base material

Fine tuning of dwelling time in friction stir welding for preventing material overheating, weld tensile strength increase and weld nugget size decrease

Directory of Open Access Journals (Sweden)

Mijajlović Miroslav M.

2016-01-01

Full Text Available After successful welding, destructive testing into test samples from Al 2024-T351 friction stir butt welds showed that tensile strength of the weld improve along the joint line, while dimensions of the weld nugget decrease. For those welds, both the base material and the welding tool constantly cool down during the welding phase. Obviously, the base material became overheated during the long dwelling phase what made conditions for creation of joints with the reduced mechanical properties. Preserving all process parameters but varying the dwelling time from 5-27 seconds a new set of welding is done to reach maximal achievable tensile strength. An analytical-numerical-experimental model is used for optimising the duration of the dwelling time while searching for the maximal tensile strength of the welds

Microhardness and Strain Field Characterization of Self-Reacting Friction Stir and Plug Welds of Dissimilar Aluminum Alloys

Science.gov (United States)

Horton, Karla Renee

2011-01-01

Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. Friction plug welding is used to seal the exit hole that remains in a circumferential SR-FSW. This work reports on material properties and strain patterns developed in a SR-FSW with a friction plug weld. Specifically, this study examines the behavior of a SR-FSW formed between an AA 2014-T6 plate on the advancing side and an AA 2219-T87 plate on the retreating side and a SR-FSW (AA 2014-T6 to AA 2219-T87) with a 2219-T87 plug weld. This study presents the results of a characterization of the micro-hardness, joint strength, and strain field characterization of SR-FSW and FPW joints tested at room temperature and cryogenic temperatures.

Microstructure and Mechanical Properties of Welds of Al - Mg - Si Alloys After Different Modes of Impulse Friction Stir Welding

Science.gov (United States)

Kondrat'ev, S. Yu.; Morozova, Yu. N.; Golubev, Yu. A.; Hantelmann, C.; Naumov, A. A.; Mikhailov, V. G.

2018-03-01

Welded joints of aluminum alloy 6082-T6 formed by the method of impulse friction stir welding are studied. The effect of the power and frequency of the pulses on the microstructure and mechanical properties of the welded joints is determined. Application of an additional pulse during the welding affects the surface quality and the shape of the weld, the distribution of the oxide layer and of particles of the hardening phase, and the grain size in the zone of dynamic recrystallization.

Nondestructive online testing method for friction stir welding using acoustic emission

Science.gov (United States)

Levikhina, Anastasiya

2017-12-01

The paper reviews the possibility of applying the method of acoustic emission for online monitoring of the friction stir welding process. It is shown that acoustic emission allows the detection of weld defects and their location in real time. The energy of an acoustic signal and the median frequency are suggested to be used as informative parameters. The method of calculating the median frequency with the use of a short time Fourier transform is applied for the identification of correlations between the defective weld structure and properties of the acoustic emission signals received during welding.

Microstructure and mechanical properties of friction stir welded 18Cr–2Mo ferritic stainless steel thick plate

International Nuclear Information System (INIS)

Han, Jian; Li, Huijun; Zhu, Zhixiong; Barbaro, Frank; Jiang, Laizhu; Xu, Haigang; Ma, Li

2014-01-01

Highlights: • We focus on friction stir welding of 18Cr–2Mo ferritic stainless steel thick plate. • We produce high-quality joints with special tool and optimised welding parameters. • We compare microstructure and mechanical properties of steel and joint. • Friction stir welding is a method that can maintain the properties of joint. - Abstract: In this study, microstructure and mechanical properties of a friction stir welded 18Cr–2Mo ferritic stainless steel thick plate were investigated. The 5.4 mm thick plates with excellent properties were welded at a constant rotational speed and a changeable welding speed using a composite tool featuring a chosen volume fraction of cubic boron nitride (cBN) in a W–Re matrix. The high-quality welds were successfully produced with optimised welding parameters, and studied by means of optical microscopy (OM), scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) and standard hardness and impact toughness testing. The results show that microstructure and mechanical properties of the joints are affected greatly, which is mainly related to the remarkably fine-grained microstructure of equiaxed ferrite that is observed in the friction stir welded joint. Meanwhile, the ratios of low-angle grain boundary in the stir zone regions significantly increase, and the texture turns strong. Compared with the base material, mechanical properties of the joint are maintained in a comparatively high level

Friction stir welding - an alternative method for sealing nuclear waste storage canisters

Energy Technology Data Exchange (ETDEWEB)

Andrews, R.E. [TWI Ltd, Cambridge (United Kingdom)

2004-12-01

When welding 50 mm thick copper a very high heat input is required to combat the high thermal diffusivity and only the Electron Beam Welding (EBW) process had this capability when this copper canister concept was conceived. Despite the encouraging results achieved using EBW with thick section copper, SKB felt that it would be prudent to assess other joining methods. This assessment concluded that friction welding, could also provide very high quality welds to satisfy the service life requirements of the SKB canister design. A friction welding variant called Friction Stir Welding (FSW) was shown to have the capability of welding 3 mm thick copper sheet with excellent integrity and reproducibility. This later provided sufficient encouragement for SKB to consider the potential of FSW as a method for joining thick section copper, using relatively simple machine tool based technology. It was thought that FSW might provide an alternative or complementary method for welding lids, or bases to canisters. In 1997 an FSW development programme started at TWI, focussed on the feasibility of welding 10 mm thick copper plate. Once this task was successfully completed, work continued to demonstrate that progressively thicker plate, up to 50 mm thick, could be joined. At this stage, with process viability established, a full size experimental FSW canister machine was designed and built. Work with this machine finished in January 2003, when it had been shown that FSW could definitely be used to weld lids to full size canisters. This report summarises the TWI development of FSW for SKB from 1997 to January 2003. It also highlights the important aspects of the process and the project milestones that will help to ensure that SKB has a welding technology that can be used with confidence for production fabrication of copper waste storage canisters in the future. The overall conclusion to this FSW development is that there is no doubt that the FSW process could be used to produce full

Friction stir welding - an alternative method for sealing nuclear waste storage canisters

International Nuclear Information System (INIS)

Andrews, R.E.

2004-12-01

When welding 50 mm thick copper a very high heat input is required to combat the high thermal diffusivity and only the Electron Beam Welding (EBW) process had this capability when this copper canister concept was conceived. Despite the encouraging results achieved using EBW with thick section copper, SKB felt that it would be prudent to assess other joining methods. This assessment concluded that friction welding, could also provide very high quality welds to satisfy the service life requirements of the SKB canister design. A friction welding variant called Friction Stir Welding (FSW) was shown to have the capability of welding 3 mm thick copper sheet with excellent integrity and reproducibility. This later provided sufficient encouragement for SKB to consider the potential of FSW as a method for joining thick section copper, using relatively simple machine tool based technology. It was thought that FSW might provide an alternative or complementary method for welding lids, or bases to canisters. In 1997 an FSW development programme started at TWI, focussed on the feasibility of welding 10 mm thick copper plate. Once this task was successfully completed, work continued to demonstrate that progressively thicker plate, up to 50 mm thick, could be joined. At this stage, with process viability established, a full size experimental FSW canister machine was designed and built. Work with this machine finished in January 2003, when it had been shown that FSW could definitely be used to weld lids to full size canisters. This report summarises the TWI development of FSW for SKB from 1997 to January 2003. It also highlights the important aspects of the process and the project milestones that will help to ensure that SKB has a welding technology that can be used with confidence for production fabrication of copper waste storage canisters in the future. The overall conclusion to this FSW development is that there is no doubt that the FSW process could be used to produce full

The effect of laser surface melting on microstructure and corrosion behavior of friction stir welded aluminum alloy 2219

Science.gov (United States)

Ma, Shengchong; Zhao, Yong; Zou, Jiasheng; Yan, Keng; Liu, Chuan

2017-11-01

This study aimed to explore the electrochemical properties and microstructure of friction stir welds to understand the correlation between their properties and processing. Friction stir welding is a promising solid-state joining process for high-strength aluminum alloys (AA). Although friction stir welding (FSW) eliminates the problems of fusion welding due to the fact that it is performed below Tm, it causes severe plastic deformation in the material. Some AA welded by FSW exhibit relatively poor corrosion resistance. In this research, the corrosion resistance of such welds was enhanced through laser surface melting. A friction stir weld of AA 2219 was laser melted. The melt depth and microstructure were observed using optical and scanning electron microscopy. The melt zone exhibited epitaxially grown columnar grains. The redistribution of elemental composition was analyzed using energy-dispersive spectroscopy. The anticorrosion properties of both laser-melted and original welds were studied in aqueous 3.5% NaCl solution using cyclic potentiodynamic polarization. The results indicated a noticeable increase in the pitting corrosion resistance after the laser treatment on the surface. The repassivation potential was nobler than the corrosion potential after the laser treatment, confirming that the resistance to pitting growth improved.

Friction Stir Welding and Processing

Energy Technology Data Exchange (ETDEWEB)

Hovanski, Yuri; Carsley, John; Clarke, Kester D.; Krajewski, Paul E.

2015-05-01

With nearly twenty years of international research and collaboration in friction stir welding (FSW) and processing industrial applications have spread into nearly every feasible market. Currently applications exist in aerospace, railway, automotive, personal computers, technology, marine, cutlery, construction, as well as several other markets. Implementation of FSW has demonstrated diverse opportunities ranging from enabling new materials to reducing the production costs of current welding technologies by enabling condensed packaging solutions for traditional fabrication and assembly. TMS has sponsored focused instruction and communication in this technology area for more than fifteen years, with leadership from the Shaping and Forming Committee, which organizes a biannual symposium each odd year at the annual meeting. A focused publication produced from each of these symposia now comprises eight volumes detailing the primary research and development activities in this area over the last two decades. The articles assembled herein focus on both recent developments and technology reviews of several key markets from international experts in this area.

Development of niobium alloy/stainless steel joint by friction welding, (1)

International Nuclear Information System (INIS)

Kikuchi, Taiji; Kawamura, Hiroshi.

1988-08-01

The niobium alloy and stainless steel have been jointed by the nicrobrazing method generally. However the strength of the jointed part is weaker than that of the mother material. Therefore we developed the niobium alloy(Nb-1 % Zr)/stainless steel(SUS 304) transition joint by the friction welding method. As the tests for the development. We conducted the mechanical tests (tensile test at room temperature, 300 deg C, 500 deg C and 700 deg C, torsion fatigue test and burst test), metallographical observation and electron prove X-ray microanalysis observation. Those tests proved jointed part by the friction welding had enough properties for general uses. (author)

Investigation of Friction Stir Welding of Al Metal Matrix Composite Materials

Science.gov (United States)

Diwan, Ravinder M.

2003-01-01

The innovative process of Friction Stir Welding (FSW) has generated tremendous interest since its inception about a decade or so ago since the first patent in 1991 by TWI of Cambridge, England. This interest has been seen in many recent international conferences and publications on the subject and relevant published literature. Still the process needs both intensive basic study of deformation mechanisms during this FSW process and analysis and feasibility study to evaluate production methods that will yield high quality strong welds from the stirring action of the appropriate pin tool into the weld plate materials. Development of production processes is a complex task that involves effects of material thickness, materials weldability, pin tool design, pin height, and pin shoulder diameter and related control conditions. The frictional heating with rotational speeds of the pin tool as it plunges into the material and the ensuing plastic flow arising during the traverse of the welding faying surfaces provide the known special advantages of the FSW process in the area of this new advanced joining technology.

Characteristics of Laser Beam and Friction Stir Welded AISI 409M Ferritic Stainless Steel Joints

Science.gov (United States)

Lakshminarayanan, A. K.; Balasubramanian, V.

2012-04-01

This article presents the comparative evaluation of microstructural features and mechanical properties of friction stir welded (solid-state) and laser beam welded (high energy density fusion welding) AISI 409M grade ferritic stainless steel joints. Optical microscopy, microhardness testing, transverse tensile, and impact tests were performed. The coarse ferrite grains in the base material were changed to fine grains consisting duplex structure of ferrite and martensite due to the rapid cooling rate and high strain induced by severe plastic deformation caused by frictional stirring. On the other hand, columnar dendritic grain structure was observed in fusion zone of laser beam welded joints. Tensile testing indicates overmatching of the weld metal relative to the base metal irrespective of the welding processes used. The LBW joint exhibited superior impact toughness compared to the FSW joint.

Inverse Thermal Analysis of Ti-6Al-4V Friction Stir Welds Using Numerical-Analytical Basis Functions with Pseudo-Advection

Science.gov (United States)

Lambrakos, S. G.

2018-04-01

Inverse thermal analysis of Ti-6Al-4V friction stir welds is presented that demonstrates application of a methodology using numerical-analytical basis functions and temperature-field constraint conditions. This analysis provides parametric representation of friction-stir-weld temperature histories that can be adopted as input data to computational procedures for prediction of solid-state phase transformations and mechanical response. These parameterized temperature histories can be used for inverse thermal analysis of friction stir welds having process conditions similar those considered here. Case studies are presented for inverse thermal analysis of friction stir welds that use three-dimensional constraint conditions on calculated temperature fields, which are associated with experimentally measured transformation boundaries and weld-stir-zone cross sections.

Microstructural and mechanical properties of pure aluminum, 5083 and 7075 alloys joined by friction stir welding

Energy Technology Data Exchange (ETDEWEB)

Yilmaz, Selim Sarper [Celal Bayar Univ., Manisa, Muradiye (Turkey)

2012-07-01

In this study, microstructural and mechanical properties of pure aluminum, 5083 and 7075 alloys joined by friction stir welding were investigated. Hardness, tensile, bending and impact tests were applied to the welded samples. In addition, optical and SEM tests were carried out. The effects of welding speed on microstructure and mechanical properties were investigated in these materials. Then, the optimal conditions for friction stir welding were determined for pure aluminum, 5083 and 7075 alloys. The maximum hardness was observed for 7075 while the minimum hardness was observed for pure aluminum. (orig.)

An experimental study on joining of severe plastic deformed aluminium materials with friction welding method

Energy Technology Data Exchange (ETDEWEB)

Sahin, Mumin [Mechanical Engineering Department, Trakya University, 22030 Edirne (Turkey)], E-mail: mumins@trakya.edu.tr; Erol Akata, H.; Ozel, Kaan [Mechanical Engineering Department, Trakya University, 22030 Edirne (Turkey)

2008-07-01

In this study, 5083 aluminium alloys, which were exposed to severe plastic deformation, were joined with friction welding method and the variation in mechanical properties of the joints was experimentally investigated. Severe plastic deformation methods can be classified as equal channel angular pressing (ECAP) (in other words, equal cross section lateral extrusion - ECSLE) and cyclic extrusion-compression. Aluminium alloy as test material 5083 and square cross-sectional equal channel angular pressing die for severe plastic deformation were used in the study. Firstly 5083 alloys, as purchased, were joined with friction welding method. The optimum parameters for friction time, upset time, friction pressure and upset pressure, which are necessary for welding, were obtained. Afterwards, 5083 aluminium materials as purchased were prepared as square cross-section and then 1-pass severe plastic deformation was applied to specimen by equal channel angular pressing die. The obtained parts as square form were prepared as cylindrical form by machining and then the parts were joined by continuous drive friction welding equipment that was designed and produced in laboratory conditions before. Later, the tensile strengths of the parts, obtained at optimum conditions, were compared with those of the joined parts as purchased form. Then, hardness variations and microstructures of joints were examined. Finally, the obtained results were commented on.

Gas tungsten arc welding assisted hybrid friction stir welding of dissimilar materials Al6061-T6 aluminum alloy and STS304 stainless steel

International Nuclear Information System (INIS)

Bang, HanSur; Bang, HeeSeon; Jeon, GeunHong; Oh, IkHyun; Ro, ChanSeung

2012-01-01

Highlights: ► GTAW assisted hybrid friction stir welding (HFSW) has been carried out for dissimilar butt joint. ► Mechanical strength of dissimilar butt joint by HFSW and FSW has been investigated and compared. ► Microstructure of dissimilar butt joint by HFSW and FSW has been investigated and compared. -- Abstract: The aim of this research is to evaluate the potential for using the gas tungsten arc welding (GTAW) assisted hybrid friction stir welding (HFSW) process to join a stainless steel alloy (STS304) to an aluminum alloy (Al6061) in order to improve the weld strength. The difference in mechanical and microstructural characteristics of dissimilar joint by friction stir welding (FSW) and HFSW has been investigated and compared. Transverse tensile strength of approximately 93% of the aluminum alloy (Al6061) base metal tensile strength is obtained with HFSW, which is higher than the tensile strength of FSW welds. This may be due to the enhanced material plastic flow and partial annealing effect in dissimilar materials due to preheating of stainless steel surface by GTAW, resulting in significantly increased elongation of welds. The results indicate that HFSW that integrates GTAW preheating to FSW is advantageous in joining dissimilar combinations compared to conventional FSW.

Thermal Management in Friction-Stir Welding of Precipitation-Hardening Aluminum Alloys

Energy Technology Data Exchange (ETDEWEB)

Upadhyay, Piyush; Reynolds, Anthony

2015-05-25

Process design and implementation in FSW is mostly dependent on empirical information gathered through experience. Basic science of friction stir welding and processing can only be complete when fundamental interrelationships between process control parameters and response variables and resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters like tool rotation and translation rate and forge axis force have complicated and interactive relationships to the process response variables such as peak temperature, time at temperature etc. Of primary influence to the other process response parameters are temperature and its gradient at the deformation and heat affected zones. Through review of pertinent works in the literature and some experimental results from boundary condition work performed in precipitation hardening aluminum alloys this paper will partially elucidate the nature and effects of temperature transients caused by variation of thermal boundaries in Friction Stir Welding.

Spatially resolved positron annihilation spectroscopy on friction stir weld induced defects.

Science.gov (United States)

Hain, Karin; Hugenschmidt, Christoph; Pikart, Philip; Böni, Peter

2010-04-01

A friction stir welded (FSW) Al alloy sample was investigated by Doppler broadening spectroscopy (DBS) of the positron annihilation line. The spatially resolved defect distribution showed that the material in the joint zone becomes completely annealed during the welding process at the shoulder of the FSW tool, whereas at the tip, annealing is prevailed by the deterioration of the material due to the tool movement. This might be responsible for the increased probability of cracking in the heat affected zone of friction stir welds. Examination of a material pairing of steel S235 and the Al alloy Silafont36 by coincident Doppler broadening spectroscopy (CDBS) indicates the formation of annealed steel clusters in the Al alloy component of the sample. The clear visibility of Fe in the CDB spectra is explained by the very efficient trapping at the interface between steel cluster and bulk.

Investigation on dissimilar underwater friction stir lap welding of 6061-T6 aluminum alloy to pure copper

International Nuclear Information System (INIS)

Zhang, Jingqing; Shen, Yifu; Yao, Xin; Xu, Haisheng; Li, Bo

2014-01-01

Highlights: • 6061-T6 Al and pure Cu were successfully underwater friction stir lap welded. • The underwater weld was analyzed via comparing with the classical weld. • The oxidation of Cu was prevented via the external water. • The amount of Al–Cu intermetallic was decreased by the external water. • The thickness of Al–Cu diffusion interlayer was decreased by the external water. - Abstract: Friction stir welding (classical FSW) is considered to offer advantages over the traditional fusion welding techniques in terms of dissimilar welding. However, some challenges still exist in the dissimilar friction stir lap welding of the aluminum/copper (Al/Cu) metallic couple, among which the formation of the Al–Cu intermetallic compounds is the major problem. In the present research, due to the fact that the formation and growth of the intermetallic are significantly controlled by the thermal history, the underwater friction stir welding (underwater FSW) was employed for fabricating the weld, and the weld obtained by underwater FSW (underwater weld) was analyzed via comparing with the weld obtained under same parameters by classical FSW (classical weld). In order to investigate the effect of the external water on the thermal history, the K-type thermocouple was utilized to measure the weld temperature, and it is found that the water could decrease the peak temperature and shorten the thermal cycle time. The XRD results illustrate that the interface of the welds mainly consist of the Al–Cu intermetallic compounds such as CuAl 2 and Cu 9 Al 4 together with some amounts of Al and Cu, and it is also found that the amount of the intermetallic in the underwater weld is obvious less than in the classical weld. The SEM images and the EDS line scan results also illustrate that the Al–Cu diffusion interlayer at the Al–Cu interface of the underwater weld was obviously thinner than that of the classical weld

Effect of cryogenic cooling on corrosion of friction stir welded AA7010-T7651

DEFF Research Database (Denmark)

Jariyaboon, Manthana; Davenport, A. J.; Ambat, Rajan

2010-01-01

Purpose - The purpose of this paper is to study how cryogenic CO2 cooling during the welding process affects corrosion behaviour of friction stir welding (FSW) AA7010-T7651. Design/methodology/approach - Friction stir welded AA7010-17651 was produced with a rotation speed of 288 rpm and a travel...... speed of 58 mm/min. The liquid CO2 was sprayed onto the weld centre line immediately after the toolpiece. The microstructures of welds in different regions were observed using Field Emission Gun Scanning Electron Microscope (FEG-SEM). The effect on the corrosion susceptibility was investigated using...... a gel visualisation test and potentiodynamic polarisation measurements using a micro-electrochemical technique. Findings - The main corrosion region for both FSWs AA7010-T7651 produced with and without cryogenic CO2 cooling is in the HAZ region, which exhibited intergranular attack. Cryogenic cooling...

The study on defects in aluminum 2219-T6 thick butt friction stir welds with the application of multiple non-destructive testing methods

International Nuclear Information System (INIS)

Li, Bo; Shen, Yifu; Hu, Weiye

2011-01-01

Research highlights: → Friction stir weld-defect forming mechanisms of thick butt-joints. → Relationship between weld-defects and friction stir welding process parameters. → Multiple non-destructive testing methods applied to friction stir welds. → Empirical criterion basing on mass-conservation for inner material-loss defects. → Nonlinear correlation between weld strengths and root-flaw lengths. -- Abstract: The present study focused on the relationship between primary friction stir welding process parameters and varied types of weld-defect discovered in aluminum 2219-T6 friction stir butt-welds of thick plates, meanwhile, the weld-defect forming mechanisms were investigated. Besides a series of optical metallographic examinations for friction stir butt welds, multiple non-destructive testing methods including X-ray detection, ultrasonic C-scan testing, ultrasonic phased array inspection and fluorescent penetrating fluid inspection were successfully used aiming to examine the shapes and existence locations of different weld-defects. In addition, precipitated Al 2 Cu phase coarsening particles were found around a 'kissing-bond' defect within the weld stirred nugget zone by means of scanning electron microscope and energy dispersive X-ray analysis. On the basis of volume conservation law in material plastic deformation, a simple empirical criterion for estimating the existence of inner material-loss defects was proposed. Defect-free butt joints were obtained after process optimization of friction stir welding for aluminum 2219-T6 plates in 17-20 mm thickness. Process experiments proved that besides of tool rotation speed and travel speed, more other appropriate process parameter variables played important roles at the formation of high-quality friction stir welds, such as tool-shoulder target depth, spindle tilt angle, and fixture clamping conditions on the work-pieces. Furthermore, the nonlinear correlation between weld tensile strengths and weld crack

Experimental investigations of tungsten inert gas assisted friction stir welding of pure copper plates

Science.gov (United States)

Constantin, M. A.; Boșneag, A.; Nitu, E.; Iordache, M.

2017-10-01

Welding copper and its alloys is usually difficult to join by conventional fusion welding processes because of high thermal diffusivity of the copper, alloying elements, necessity of using a shielding gas and a clean surface. To overcome this inconvenience, Friction Stir Welding (FSW), a solid state joining process that relies on frictional heating and plastic deformation, is used as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (WIG) which generates and adds heat to the process. The aim of this paper is to identify the influence of the additional heat on the process parameters and on the welding joint properties (distribution of the temperature, hardness and roughness). The research includes two experiments for the FSW process and one experiment for tungsten inert gas assisted FSW process. The outcomes of the investigation are compared and analysed for both welding variants. Adding a supplementary heat source, the plates are preheated and are obtain some advantages such as reduced forces used in process and FSW tool wear, faster and better plasticization of the material, increased welding speed and a proper weld quality.

Thermo-Mechanical Calculations of Hybrid Rotary Friction Welding at Equal Diameter Copper Bars and Effects of Essential Parameters on Dependent Special Variables

International Nuclear Information System (INIS)

Parsa, M. H.; Davari, H.; Hadian, A. M.; Ahmadabadi, M. Nili

2007-01-01

Hybrid Rotary Friction Welding is a modified type of common rotary friction welding processes. In this welding method parameters such as pressure, angular velocity and time of welding control temperature, stress, strain and their variations. These dependent factors play an important rule in defining optimum process parameters combinations in order to improve the design and manufacturing of welding machines and quality of welded parts. Thermo-mechanical simulation of friction welding has been carried out and it has been shown that, simulation is an important tool for prediction of generated heat and strain at the weld interface and can be used for prediction of microstructure and evaluation of quality of welds. For simulation of Hybrid Rotary Friction Welding, a commercial finite element program has been used and the effects of pressure and rotary velocity of rotary part on temperature and strain variations have been investigated

Thermo-Mechanical Calculations of Hybrid Rotary Friction Welding at Equal Diameter Copper Bars and Effects of Essential Parameters on Dependent Special Variables

Science.gov (United States)

Parsa, M. H.; Davari, H.; Hadian, A. M.; Ahmadabadi, M. Nili

2007-05-01

Hybrid Rotary Friction Welding is a modified type of common rotary friction welding processes. In this welding method parameters such as pressure, angular velocity and time of welding control temperature, stress, strain and their variations. These dependent factors play an important rule in defining optimum process parameters combinations in order to improve the design and manufacturing of welding machines and quality of welded parts. Thermo-mechanical simulation of friction welding has been carried out and it has been shown that, simulation is an important tool for prediction of generated heat and strain at the weld interface and can be used for prediction of microstructure and evaluation of quality of welds. For simulation of Hybrid Rotary Friction Welding, a commercial finite element program has been used and the effects of pressure and rotary velocity of rotary part on temperature and strain variations have been investigated.

Effect of process parameters on the residual stresses in AA5083-H321 friction stir welds

Energy Technology Data Exchange (ETDEWEB)

Lombard, H. [NMMU, Gardham Avenue, PO Box 77000, 6031 Port Elizabeth (South Africa); University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Hattingh, D.G. [NMMU, Gardham Avenue, PO Box 77000, 6031 Port Elizabeth (South Africa); Steuwer, A. [NMMU, Gardham Avenue, PO Box 77000, 6031 Port Elizabeth (South Africa); FaME38 at the ILL-ESRF, 6 rue J Horowitz, 38042 Grenoble (France); University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)], E-mail: steuwer@ill.fr; James, M.N. [NMMU, Gardham Avenue, PO Box 77000, 6031 Port Elizabeth (South Africa); University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)

2009-02-15

This paper investigates the effect of varying welding parameters on the residual stress profiles in friction stir welds of aluminium alloy AA5083-H321, which were created on a fully instrumented friction welding machine. The residual stresses were determined non-destructively using synchrotron X-ray diffraction. The width and maximum of the residual stress profile show clear correlation with the heat input, and in particular feed rate, which was found to be the dominant parameter.

Improvement of Weldment Properties by Hot Forming Quenching of Friction Stir Welded TWB Sheet

Directory of Open Access Journals (Sweden)

Dae-Hoon Ko

2014-04-01

Full Text Available The purpose of this study is to improve the mechanical properties and formability of friction stir welded tailor-welded blanks (TWBs of Al6061 alloy with a new forming method called hot forming quenching (HFQ in which solid-solution heat-treated aluminum sheets are formed at elevated temperature. Forming and quenching during HFQ are simultaneously performed with the forming die for the solid-solution heat-treated sheet. In this study, specimens of aluminum TWBs were prepared by friction stir welding (FSW with a butt joint. The effectiveness of FSW joining was evaluated by observation of the macrostructure for different sheet thicknesses. In order to evaluate the formability of TWBs by HFQ, a hemisphere dome stretching test of the limit dome height achieved without specimen failure was performed with various tool temperatures. A Vickers test was also performed to measure weldment hardness as a function of position. The formability and mechanical properties of products formed by HFQ are compared with those formed by conventional forming methods, demonstrating the suitability of HFQ for sheet metal forming of friction stir welded TWBs.

Evaluation of interfacial bonding in dissimilar materials of YSZ-alumina composites to 6061 aluminium alloy using friction welding

International Nuclear Information System (INIS)

Uday, M.B.; Ahmad Fauzi, M.N.; Zuhailawati, H.; Ismail, A.B.

2011-01-01

Research highlights: → Friction-welding process. → Joining between ceramic composite and metal alloy. → Slip casting of the yttria stabilized zirconia/alumina composite samples. - Abstract: The interfacial microstructures characteristics of alumina ceramic body reinforced with yttria stabilized zirconia (YSZ) was evaluated after friction welding to 6061 aluminum alloy using optical and electron microscopy. Alumina rods containing 25 and 50 wt% yttria stabilized zirconia were fabricated by slip casting in plaster of Paris (POP) molds and subsequently sintered at 1600 deg. C. On the other hand, aluminum rods were machine down to the required dimension using a lathe machine. The diameter of the ceramic and the metal rods was 16 mm. Rotational speeds for the friction welding were varied between 900 and 1800 rpm. The friction pressure was maintained at 7 MPa for a friction time of 30 s. Optical and scanning electron microscopy was used to analyze the microstructure of the resultant joints, particularly at the interface. The joints were also examined with EDX line (energy dispersive X-ray) in order to determine the phases formed during the welding. The mechanical properties of the friction welded YSZ-Al 2 O 3 composite to 6061 alloy were determined with a four-point bend test and Vickers microhardness. The experimental results showed the degree of deformation varied significantly for the 6061 Al alloy than the ceramic composite part. The mechanical strength of friction-welded ceramic composite/6061 Al alloy components were obviously affected by joining rotational speed selected which decreases in strength with increasing rotational speed.

Friction stir welding (FSW) of AA 6061 T6

International Nuclear Information System (INIS)

Cabot, Pedro; Monglioni, Alberto; Carella, Eduardo

2002-01-01

The friction-stir process (FSW) developed by England's TWI in the last decade is a new concept in solid phase friction welding that is particularly appropriate for soldering aluminum and its alloys. It offers interesting aspects and can advantageously replace the usual arch processes. It is an automatic process that solders together long pieces by butt or lap welding and, therefore, overcomes the greater limitation of the conventional friction process that can be applied only to pieces with revolution symmetry. FSW is based essentially on the use of a cylindrical tool with a special profile, which is inserted between the surfaces where the materials meet to join them together at a certain rotation speed and under a specific force. The pieces must be rigidly butt bonded or overlapped to prevent movement when the tool moves forward along the joint producing the dispersion of oxides, local plastisizing of the material and the weld. Since its creation FSW has been the subject of many international publications, but until the present work there was no technologically relevant data about tools and procedures. For this reason, when its promising and novel nature was noticed, the CNEA began its own development project in 1997. The main characteristics of the tool are reviewed here and the results of tests carried out to evaluate the influence of the feed velocity on the mechanical properties of the butt joining of a 6.25 mm thick AA6061 T6 plate. Different accumulated aspects of the experience are discussed as well (cw)

Mechanical and Microstructural Properties of Friction Welded AISI 304 Stainless Steel to AISI 1060 Steel AISI 1060

Directory of Open Access Journals (Sweden)

Ates H.

2014-10-01

Full Text Available Rotary Friction welding is one of the most popular methods of joining similar and dissimilar materials. It is widely used with metals and thermoplastics in a wide variety of aviation, transport and aerospace industrial component designs. This study investigates the influence of friction and upsetting pressures on the hardness, tensile properties and microstructure of the welds. The experimental results showed that as the friction and upsetting pressures increased, the hardness and tensile strength values increased, as well. The tensile fracture of welded joint occurred in the AISI 1060 side. The friction processed joints were evaluated for their integrity and quality aspects by optical and scanning electron microscopy. For the perfect interfacial bonding, sufficient upsetting and friction pressures are necessary to reach the optimal temperature and severe plastic deformation to bring these materials within the attraction range.

Process optimization of friction stir welding based on thermal models

DEFF Research Database (Denmark)

Larsen, Anders Astrup

2010-01-01

This thesis investigates how to apply optimization methods to numerical models of a friction stir welding process. The work is intended as a proof-of-concept using different methods that are applicable to models of high complexity, possibly with high computational cost, and without the possibility...... information of the high-fidelity model. The optimization schemes are applied to stationary thermal models of differing complexity of the friction stir welding process. The optimization problems considered are based on optimizing the temperature field in the workpiece by finding optimal translational speed....... Also an optimization problem based on a microstructure model is solved, allowing the hardness distribution in the plate to be optimized. The use of purely thermal models represents a simplification of the real process; nonetheless, it shows the applicability of the optimization methods considered...

Use of Friction Stir Welding and Friction Stir Processing for Advanced Nuclear Fuels and Materials Joining Applications

International Nuclear Information System (INIS)

J. I. Cole; J. F. Jue

2006-01-01

Application of the latest developments in materials technology may greatly aid in the successful pursuit of next generation reactor and transmutation technologies. One such area where significant progress is needed is joining of advanced fuels and materials. Rotary friction welding, also referred to as friction stir welding (FSW), has shown great promise as a method for joining traditionally difficult to join materials such as aluminum alloys. This relatively new technology, first developed in 1991, has more recently been applied to higher melting temperature alloys such as steels, nickel-based and titanium alloys. An overview of the FSW technology is provided and two specific nuclear fuels and materials applications where the technique may be used to overcome limitations of conventional joining technologies are highlighted

Parameter design and analysis in continuous drive friction welding of Al6061/SiCp composites

Energy Technology Data Exchange (ETDEWEB)

Adalrasan, R. [Saveetha Engineering College, Chennai (India); Sundaram, A. Shanmuga [Sree Sastha Institute of Engineering and Technology, Chennai (India)

2015-02-15

Continuous drive friction welding (FW) had found profound industrial applications as an economical solid state joining process. The welding parameters such as frictional pressure, upset pressure, burn off length and rotational speed were found to influence the quality of joints. In the present study, Al6061/SiC{sub p} rods were joined by friction welding. The welding trials were designed by using Taguchi's L{sub 9} orthogonal array. Tensile strength and micro hardness of the joints were observed as the quality characteristics after each trial. The urge for parameter design had prompted the disclosure of a new integrated methodology based on technique for order of preference by similarity to ideal solution (TOPSIS) and grey relational analysis (GRA). The effectiveness of the proposed approach of T-GRA was validated by conducting a confirmation test and the field emission scanning electron microscope (FESEM) images of the fractured surface were also examined.

Evaluating location specific strain rates, temperatures, and accumulated strains in friction welds through microstructure modeling

Directory of Open Access Journals (Sweden)

Javed Akram

2018-04-01

Full Text Available A microstructural simulation method is adopted to predict the location specific strain rates, temperatures, grain evolution, and accumulated strains in the Inconel 718 friction welds. Cellular automata based 2D microstructure model was developed for Inconel 718 alloy using theoretical aspects of dynamic recrystallization. Flow curves were simulated and compared with experimental results using hot deformation parameter obtained from literature work. Using validated model, simulations were performed for friction welds of Inconel 718 alloy generated at three rotational speed i.e., 1200, 1500, and 1500 RPM. Results showed the increase in strain rates with increasing rotational speed. These simulated strain rates were found to match with the analytical results. Temperature difference of 150 K was noticed from center to edge of the weld. At all the rotational speeds, the temperature was identical implying steady state temperature (0.89Tm attainment. Keywords: Microstructure modeling, Dynamic recrystallization, Friction welding, Inconel 718, EBSD, Hot deformation, Strain map

Hybrid multi-response optimization of friction stir spot welds: failure ...

Indian Academy of Sciences (India)

O O OJO

2018-06-08

Jun 8, 2018 ... Friction stir spot welding; effective bonded size; failure load; expelled flash volume; hybrid multi- response ... eliminated with the application of FSSW process. Conse- ... design of experiment is generally applied in either single.

Implicit Geometry Meshing for the simulation of Rotary Friction Welding

Science.gov (United States)

Schmicker, D.; Persson, P.-O.; Strackeljan, J.

2014-08-01

The simulation of Rotary Friction Welding (RFW) is a challenging task, since it states a coupled problem of phenomena like large plastic deformations, heat flux, contact and friction. In particular the mesh generation and its restoration when using a Lagrangian description of motion is of significant severity. In this regard Implicit Geometry Meshing (IGM) algorithms are promising alternatives to the more conventional explicit methods. Because of the implicit description of the geometry during remeshing, the IGM procedure turns out to be highly robust and generates spatial discretizations of high quality regardless of the complexity of the flash shape and its inclusions. A model for efficient RFW simulation is presented, which is based on a Carreau fluid law, an Augmented Lagrange approach in mapping the incompressible deformations, a penalty contact approach, a fully regularized Coulomb-/fluid friction law and a hybrid time integration strategy. The implementation of the IGM algorithm using 6-node triangular finite elements is described in detail. The techniques are demonstrated on a fairly complex friction welding problem, demonstrating the performance and the potentials of the proposed method. The techniques are general and straight-forward to implement, and offer the potential of successful adoption to a wide range of other engineering problems.

Effect of Water Cooling on the Performances of Friction Stir Welding Heat-Affected Zone

Science.gov (United States)

Zhang, H. J.; Liu, H. J.; Yu, L.

2012-07-01

The heat-affected zone (HAZ) is generally the intrinsic weakest location of the normal friction stir welded precipitate hardened aluminum alloys. In order to improve the mechanical properties of the HAZ by controlling the temperature level, underwater friction stir welding (FSW) of an Al-Cu aluminum alloy was conducted in the present study. The results indicate that the hardness of the HAZ can be improved through underwater FSW. Microstructural analysis reveals that the hardness improvement is attributed to the lowering of precipitate coarsening level and the narrowing of precipitate free zone, which are essentially induced by the variations of welding thermal cycles under the cooling effect of water.

Effect of shoulder to pin ratio on magnesium alloy Friction Stir Welding

Science.gov (United States)

Othman, N. H.; Ishak, M.; Shah, L. H.

2017-09-01

This study focuses on the effect of shoulder to pin diameter ratio on friction stir welding of magnesium alloy AZ31. Two pieces of AZ31 alloy with thickness of 2 mm were friction stir welded by using conventional milling machine. The shoulder to pin diameter ratio used in this experiment are 2.25, 2.5, 2.75, 3, 3.33, 3.66, 4.5, 5 and 5.5. The rotational speed and welding speed used in this study are 1000 rpm and 100 mm/min, respectively. Microstructure observation of welded area was studied by using optical microscope. Equiaxed grains were observed at the TMAZ and stir zone indicating fully plastic deformation. The grain size of stir zone increased with decreasing shoulder to pin ratio from ratio 3.33 to 5.5 due to higher heat input. It is observed that, surface galling and faying surface defect is produced when excessive heat input is applied. To evaluate the mechanical properties of this specimen, tensile test was used in this study. Shoulder to pin ratio 5.5 shows lowest tensile strength while shoulder to pin diameter ratio 3.33 shows highest tensile strength with weld efficiency 91 % from based metal.

Influence of tool geometry and process parameters on macrostructure and static strength in friction stir spot welded polyethylene sheets

International Nuclear Information System (INIS)

Bilici, Mustafa Kemal; Yuekler, Ahmet Irfan

2012-01-01

Highlights: → All velding parameters and different tool geometries have demonstrated a different effects on weld strength. → Friction stir spot welding of polyethylene mechanical scission is very important. → Metric screw the tool has a great influence on the weld strength of FSSW. -- Abstract: The effect of important welding parameters and tool properties that are effective on static strength in friction stir spot welds of polyethylene sheets were studied. Six different tool pin profiles (straight cylindrical, tapered cylindrical, threaded cylindrical, triangular, square and hexagonal) with different shoulder geometries, different pin length, pin angle and concavity angle were used to fabricate the joints. The tool rotational speed, tool plunge depth and dwell time were determined welding parameters. All the welding operations were done at the room temperature. Welding force and welding zone material temperature measurements were also done. Lap-shear tests were carried out to find the weld static strength. Weld cross section appearance observations were also done. From the experiments, the effect of pin profile, pin length, pin angle, dwell time and tool rotational speed on friction stir spot welding formation and weld strength was determined.

Microstructure and mechanical properties of friction welded AISI 1040/AISI 304L steels before and after electrochemical corrosion

Energy Technology Data Exchange (ETDEWEB)

Sarsilmaz, Furkan [Firat Univ., Elazig (Turkey). Dept. of Mechatronics Engineering; Kirik, Ihsan [Batman Univ. (Turkey); Ozdemir, Niyazi [Firat Univ., Elazig (Turkey)

2018-03-01

The aim of the present study is to investigate the effect of welding parameters both on the electrochemical corrosion behavior and tensile strength of pre- and post-electrochemical corrosion of friction welded dissimilar steels. The microstructural changes of AISI 1040/AISI 304L friction welded couples and also parent materials were analyzed by using scanning electron microscopy. The electrochemical behaviors of AISI1040/AISI304L joints were comparatively investigated by potentiodynamic polarization curve test and by electrochemical impedance spectra. Moreover, tensile strength experiments were carried out determining the behavior of friction welded joints of pre- and post-electrochemical corrosion and results indicated that the maximum tensile test value of the dissimilar welded pre-electrochemical corrosion was higher than those of post-electrochemical corrosion and was also very close to AISI 1040 parent material value.

Friction welding; Magnesium; Finite element; Shear test.

Directory of Open Access Journals (Sweden)

Leonardo Contri Campanelli

2013-06-01

Full Text Available Friction spot welding (FSpW is one of the most recently developed solid state joining technologies. In this work, based on former publications, a computer aided draft and engineering resource is used to model a FSpW joint on AZ31 magnesium alloy sheets and subsequently submit the assembly to a typical shear test loading, using a linear elastic model, in order to conceive mechanical tests results. Finite element analysis shows that the plastic flow is concentrated on the welded zone periphery where yield strength is reached. It is supposed that “through the weld” and “circumferential pull-out” variants should be the main failure behaviors, although mechanical testing may provide other types of fracture due to metallurgical features.

Enhancement of mechanical properties and corrosion resistance of friction stir welded joint of AA2014 using water cooling

Energy Technology Data Exchange (ETDEWEB)

Sinhmar, S., E-mail: sinhmarsunil88@gmail.com; Dwivedi, D.K.

2017-01-27

An investigation on the microstructure, mechanical properties, and corrosion behavior of friction stir welded joint of AA2014 in natural cooled (NC) and water cooled (WC) conditions have been reported. Optical microscopy, field emission scanning electron microscopy (FESEM) with Energy dispersive X-ray spectroscopy (EDS), Vicker's microhardness, tensile testing, X-ray diffraction (XRD), and electrochemical potentiodynamic polarization corrosion test (Tafel curve) were carried out to characterize the friction stir weld joints in both the cooling conditions. Water cooling resulted in higher strength and microhardness of friction stir weld joint compared to the natural cooling. The width of heat affected zone was reduced by the use of water cooling during friction stir welding (FSW) and minimum hardness zone was shifted towards weld center. The corrosion test was performed in 3.5% NaCl solution. Corrosion resistance of water cooled joint was found higher than natural cooled FSW joint. The precipitation behavior of weld nugget and heat affected zone impacts the corrosion resistance of FSW joint of AA 2014. Hardness, tensile, and corrosion properties of FSW joints produced under NC and WC conditions have been discussed in the light of microstructure.

Enhancement of mechanical properties and corrosion resistance of friction stir welded joint of AA2014 using water cooling

International Nuclear Information System (INIS)

Sinhmar, S.; Dwivedi, D.K.

2017-01-01

An investigation on the microstructure, mechanical properties, and corrosion behavior of friction stir welded joint of AA2014 in natural cooled (NC) and water cooled (WC) conditions have been reported. Optical microscopy, field emission scanning electron microscopy (FESEM) with Energy dispersive X-ray spectroscopy (EDS), Vicker's microhardness, tensile testing, X-ray diffraction (XRD), and electrochemical potentiodynamic polarization corrosion test (Tafel curve) were carried out to characterize the friction stir weld joints in both the cooling conditions. Water cooling resulted in higher strength and microhardness of friction stir weld joint compared to the natural cooling. The width of heat affected zone was reduced by the use of water cooling during friction stir welding (FSW) and minimum hardness zone was shifted towards weld center. The corrosion test was performed in 3.5% NaCl solution. Corrosion resistance of water cooled joint was found higher than natural cooled FSW joint. The precipitation behavior of weld nugget and heat affected zone impacts the corrosion resistance of FSW joint of AA 2014. Hardness, tensile, and corrosion properties of FSW joints produced under NC and WC conditions have been discussed in the light of microstructure.

Microstructural evolution and properties of friction stir welded aluminium alloy AA2219

International Nuclear Information System (INIS)

Gupta, R. K.; Biju, S.; Ghosh, B. R.; Sinha, P. P.

2007-01-01

Low weld strength of fusion welded joints of aluminium alloy AA2219 is a concern in fabrication of pressure vessels and is attributable to the presence of weld defects, as well as various metallurgical factors. Friction stir welding (FSW), being a solid state joining process has obvious advantages over fusion welding. Results of preliminary FSW experiments conducted on 10 mm thick plate using a particular tool configuration are presented here. Microscopic studies show the presence of very fine equiaxed recrystallised grain at the weld nugget and a flow pattern of grains due to heavy deformation in defect-free weld coupons. Mechanical properties are correlated with the microstructure and process variables. Fractographic analysis complements the observations of optical microscopy and mechanical properties

Friction welded nonconsumable electrode assembly and use thereof for electrolytic production of metals and silicon

Science.gov (United States)

Byrne, Stephen C.; Ray, Siba P.; Rapp, Robert A.

1984-01-01

A nonconsumable electrode assembly suitable for use in the production of metal by electrolytic reduction of a metal compound dissolved in a molten salt, the assembly comprising a metal conductor and a ceramic electrode body connected by a friction weld between a portion of the body having a level of free metal or metal alloy sufficient to effect such a friction weld and a portion of the metal conductor.

Finite element modelling and characterization of friction welding on UNS S31803 duplex stainless steel joints

Directory of Open Access Journals (Sweden)

Mohammed Asif. M

2015-12-01

Full Text Available Solid state joining techniques are increasingly employed in joining duplex stainless steel materials due to their high integrity. Continuous drive friction welding is a solid state welding technique which is used to join similar and dissimilar materials. This joining technique is characterized by short cycle time, low heat input and narrow heat affected zones. The simulation becomes an important tool in friction welding because of short welding cycle. In the present work, a three dimensional non-linear finite element model was developed. The thermal history and axial shortening profiles were predicted using ANSYS, a software tool. This numerical model was validated using experimental results. The results show that the frictional heating stage of the process has more influence on temperature and upsetting stage has more impact on axial shortening. The knowledge of these parameters would lead to optimization of input parameters and improvement of design and machine tools.

Designing aluminium friction stir welded joints against multiaxial fatigue

Directory of Open Access Journals (Sweden)

L. Susmel

2016-07-01

Full Text Available The present paper investigates the accuracy of the Modified Wöhler Curve Method (MWCM in estimating multiaxial fatigue strength of aluminium friction stir (FS welded joints. Having developed a bespoke joining technology, circumferentially FS welded tubular specimens of Al 6082-T6 were tested under proportional and non-proportional tension and torsion, the effect of non-zero mean stresses being also investigated. The validation exercise carried out using the experimental results have demonstrated that the MWCM applied in terms of nominal stresses, notch stresses, and also the Point Method is accurate in predicting the fatigue lifetime of the tested FS welded joints, with its use resulting in life estimates that fall within the uniaxial and torsional calibration scatter bands.

Microstructure and mechanical properties of hard zone in friction stir welded X80 pipeline steel relative to different heat input

Energy Technology Data Exchange (ETDEWEB)

Aydin, Hakan, E-mail: hakanay@uludag.edu.tr [Engineering and Architecture Faculty, Mechanical Engineering Department, Uludag University, 16059 Gorukle-Bursa (Turkey); Nelson, Tracy W. [Mechanical Engineering Department, Brigham Young University, 435 CTB, Provo, UT 84602 (United States)

2013-12-01

The study was conducted to investigate the microstructure and mechanical properties of the hard zone in friction stir welded X80 pipeline steel at different heat inputs. Microstructural analysis of the welds was carried out using optical microscopy, transmission electron microscopy, and microhardness. Heat input during friction stir welding process had a significant influence on the microstructure and mechanical properties in the hard zone along the advancing side of the weld nugget. Based on the results, the linear relationships between heat input and post-weld microstructures and mechanical properties in the hard zone of friction stir welded X80 steels were established. It can be concluded that with decrease in heat input the bainitic structure in the hard zone becomes finer and so hard zone strength increases.

Microstructure and mechanical properties of hard zone in friction stir welded X80 pipeline steel relative to different heat input

International Nuclear Information System (INIS)

Aydin, Hakan; Nelson, Tracy W.

2013-01-01

The study was conducted to investigate the microstructure and mechanical properties of the hard zone in friction stir welded X80 pipeline steel at different heat inputs. Microstructural analysis of the welds was carried out using optical microscopy, transmission electron microscopy, and microhardness. Heat input during friction stir welding process had a significant influence on the microstructure and mechanical properties in the hard zone along the advancing side of the weld nugget. Based on the results, the linear relationships between heat input and post-weld microstructures and mechanical properties in the hard zone of friction stir welded X80 steels were established. It can be concluded that with decrease in heat input the bainitic structure in the hard zone becomes finer and so hard zone strength increases

Influence of Processing Parameters on the Flow Path in Friction Stir Welding

Science.gov (United States)

Schneider, J. A.; Nunes, A. C., Jr.

2006-01-01

Friction stir welding (FSW) is a solid phase welding process that unites thermal and mechanical aspects to produce a high quality joint. The process variables are rpm, translational weld speed, and downward plunge force. The strain-temperature history of a metal element at each point on the cross-section of the weld is determined by the individual flow path taken by the particular filament of metal flowing around the tool as influenced by the process variables. The resulting properties of the weld are determined by the strain-temperature history. Thus to control FSW properties, improved understanding of the processing parameters on the metal flow path is necessary.

Low cycle fatigue behavior of electron beam and friction welded joints of an α-β titanium alloy

International Nuclear Information System (INIS)

Mohandas, T.; Varma, V.K.; Banerjee, D.; Kutumbarao, V.V.

1996-01-01

Fusion welds in titanium alloys, with intermediate β stabilizing additions, show poor mechanical properties due to large fusion zone grain size coupled with a brittle plate martensitic microstructure and hydrogen induced microporosity. These problems, associated with fusion welding, have been reported to be overcome by friction welding. The alloy used in this study is a Soviet composition (VT9) of the α-β class with the nominal chemical composition Ti-6.5Al-3.3Mo-1.6Zr-0.3 Si (in weight percent), intended to be used as discs and blades in compressor stages of gas turbine engine where low cycle fatigue (LCF) loading is experienced. Electron beam welding of the alloy was largely unsuccessful for the reasons described above. Fatigue properties of such welds had large scatter due to the presence of microporosity. A continuous drive friction welding technique was investigated to overcome this problem These welds showed encouraging results in that microporosity, a problem in the electron beam welding, was not observed and the mechanical properties were at par or better than those of the base metal. This paper deals with the study of stress controlled LCF behavior of friction welds and electron beam welds of the α-β titanium alloy at ambient temperature and the results are compared with those of base metal

A Study on the Optimal Conditions of friction Welding for JLF and STS304 Using AE Technique

International Nuclear Information System (INIS)

Yoon, Han Ki; Lee, Sang Pil; Kong, Yu Sik; Lee, Jin Kyung

2003-01-01

Japanese low activation terrific steel(JLF) is a good material for the parts of heat exchanger such as blanket and diverter. At first, JLF was developed as a candidate for structural materials in nuclear fusion applications. However, the development of the jointing technique of JLF steel to other materials is important for wide applications of this material to the industry fields. Recently the jointing technologies including diffusion bonding, brazing, roll bonding, explosive bonding and hot iso-static pressing have been studied for the heterogeneous materials of JLF-1 steel(Fe-9Cr-2W-V-Ta) and stainless steel(STS304). Friction welding is one of the most popular welding methods for two different kinds of materials. In this paper, the JLF-1 steel was jointed to SIS304 by friction welding method and the optimal conditions of the friction welding discussed. Acoustic emission was used as a nondestructive technique to evaluate the weld quality in processing

Microstructural evolution during friction stir welding of AlSi1MgMn alloy

Directory of Open Access Journals (Sweden)

M. Janjić

2012-01-01

Full Text Available This paper provides the research of the infl uence of geometric and kinematic parameters on the microstructure and mechanical properties of welded joint of aluminum alloy AlSi1MgMn (6082-T6 obtained through the Friction Stir Welding (FSW process. The experiment parameters were welding speed, rotation speed, angle of pin slope, pin diameter and shoulder diameter. On the obtained welded workpieces the dynamic testing on the impact toughness, and determination of microstructural zones were carried out.

Evaluation of tensile strength and fracture behavior of friction welded ...

Indian Academy of Sciences (India)

In the present study an attempt was made to join austenitic stainless steel ... Experimental details ... This test was carried out on the friction welded samples of .... phenomenon was observed to be true if the rotational speed was increased up to ...

Microstructures and mechanical properties of friction stir welded dissimilar steel-copper joints

Energy Technology Data Exchange (ETDEWEB)

Jafari, M.; Abbasi, M.; Poursina, D.; Gheysarian, A. [University of Kashan, Kashan (Iran, Islamic Republic of); Bagheri, B. [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

2017-03-15

Welding dissimilar metals by fusion welding is challenging. It results in welding defects. Friction stir welding (FSW) as a solid-state joining method can overcome these problems. In this study, 304L stainless steel was joined to copper by FSW. The optimal values of the welding parameters traverse speed, rotational speed, and tilt angle were obtained through Response surface methodology (RSM). Under optimal welding conditions, the effects of welding pass number on the microstructures and mechanical properties of the welded joints were investigated. Results indicated that appropriate values of FSW parameters could be obtained by RSM and grain size refinement during FSW mainly affected the hardness in the weld regions. Furthermore, the heat from the FSW tool increased the grain size in the Heat-affected zones (HAZs), especially on the copper side. Therefore, the strength and ductility decreased as the welding pass number increased because of grain size enhancement in the HAZs as the welding pass number increased.

Improving the particle distribution and mechanical properties of friction-stir-welded composites by using a smooth pin tool

Science.gov (United States)

Liu, Huijie; Hu, Yanying; Zhao, Yunqiang; Fujii, Hidetoshi

2017-09-01

Friction stir welding (FSW) is a very promising technique for joining particle-reinforced aluminum-matrix composites (PRAMCs), but with increase in the volume fraction of reinforcing particles, their distribution in welds becomes inhomogeneous. This leads to an inconsistent deformation of welds and their destruction at low stresses. In order to improve the weld microstructure, a smooth pin tool was used for the friction stir welding of AC4A + 30 vol.% SiC particle-reinforced aluminum-matrix composites. The present work describes the effect of welding parameters on the characteristics of particle distribution and the mechanical properties of welds. The ultimate strength of weld reached, 309 MPa, was almost 190% of that of the basic material. The mechanism of SiC particle conglomeration is clearly illustrated by means of schematic illustrations.

The effect of welding parameters on the corrosion behaviour of friction stir welded AA2024-T351

DEFF Research Database (Denmark)

Jariyaboon, M; Davenport, A.J.; Ambat, Rajan

2007-01-01

The effect of welding parameters (rotation speed and travel speed) on the corrosion behaviour of friction stir welds in the high strength aluminium alloy AA2024-T351 was investigated. It was found that rotation speed plays a major role in controlling the location of corrosion attack. Localised...... intergranular attack was observed in the nugget region for low rotation speed welds, whereas for higher rotation speed welds, attack occurred predominantly in the heat-affected zone. The increase in anodic reactivity in the weld zone was due to the sensitisation of the grain boundaries leading to intergranular...... attack. Enhancement of cathodic reactivity was also found in the nugget as a result of the precipitation of S-phase. The results were compared with samples of AA2024-T351 that had been heat treated to simulate the thermal cycle associated with welding, and with samples that had been exposed to high...

Texture analysis of a friction stir welded ultrafine grained Al–Al2O3 composite produced by accumulative roll-bonding

International Nuclear Information System (INIS)

Shamanian, Morteza; Mohammadnezhad, Mahyar; Szpunar, Jerzy

2014-01-01

Highlights: • Aluminum matrix composite was successfully bonded using friction stir welding. • After welding process the fraction of low angle boundary area rapidly decreases. • The grain growth in the NZ is related the increase of temperature during the FSW. • The aluminum matrix composite has a strong Rotated Cube texture. • The weld nugget has a Rotated Cube and shear texture. - Abstract: In recent years, several studies have been focused on friction stir welding of aluminum alloys, and some researchers have also been reported on welding of aluminum-based composites. In the present research, ultrafine grained sheets of aluminum matrix composite (Al–Al 2 O 3 ) were produced by accumulative roll-bonding (ARB) technique. The aluminum composite sheets were then joined by friction stir welding. The present work describes the effect of the FSW process on the microstructure and crystallographic textures in the base metal and weld nugget. Electron backscattered diffraction (EBSD) results demonstrated the existence of different grain orientations within the weld nugget as compared to the base metal. Al composite plates have a Rotated Cube texture component. Moreover, in the nugget, grain structure with Rotated Cube and shear texture developed. Friction stir welding coarsened the grain size in the weld zone from the original grain size of 3–17 μm

Friction stir welding: multi-response optimisation using Taguchi-based GRA

Directory of Open Access Journals (Sweden)

Jitender Kundu

2016-01-01

Full Text Available In present experimental work, friction stir welding of aluminium alloy 5083- H321 is performed for optimisation of process parameters for maximum tensile strength. Taguchi’s L9 orthogonal array has been used for three parameters – tool rotational speed (TRS, traverse speed (TS, and tool tilt angle (TTA with three levels. Multi-response optimisation has been carried out through Taguchi-based grey relational analysis. The grey relational grade has been calculated for all three responses – ultimate tensile strength, percentage elongation, and micro-hardness. Analysis of variance is the tool used for obtaining grey relational grade to find out the significant process parameters. TRS and TS are the two most significant parameters which influence most of the quality characteristics of friction stir welded joint. Validation of predicted values done through confirmation experiments at optimum setting shows a good agreement with experimental values.

Microstructure examination and microhardness of friction stir welded joint of (AA7020-O after PWHT

Directory of Open Access Journals (Sweden)

Ghada M.F. Essa

2018-04-01

Full Text Available This paper studies the microstructure and microhardness of the welded joints of the annealed aluminum alloy AA7020-O produced by friction stir welding (FSW technique. The material was applied to post weld heat treatment (solution treatment and artificially aged, T6. The traverse speed and the rotational speed are the most important process parameters of FSW, and have great influence on the heat input of the welding operation which governs the welded joints quality. To investigate their effect, the welding operation was performed using three traverse speeds, 20, 40 and 60 mm/s with two rotational speeds of 1125 and 1400 rpm, and other welding parameters were kept constant to produce comparable joints. It was found that the two rotational speeds are accepted with lower traverse speeds to produce sound joints. Microstructure of the welded joints was significantly affected by the FSW process parameters, and slight effect was reported for the grain size. Microhardness examination showed high weld joint quality with respect to the base metal hardness, which proves the reprecipitation of the hardening phase in the weld zone. The microhardness profile was strongly dependant on the rotational speed, and the average values of the joints hardness have increased with the decrease in the rotational speed, where it have been slightly affected by the welding speed. Keywords: Friction stir welding, Aluminum alloy, Mechanical properties, Microstructures

High temperature corrosion studies on friction-welded dissimilar metals

International Nuclear Information System (INIS)

Arivazhagan, N.; Singh, Surendra; Prakash, Satya; Reddy, G.M.

2006-01-01

Understanding the behaviour of weldment at elevated temperatures and especially their corrosion behaviour has become an object of scientific investigation recently. Investigation has been carried out on friction-welded AISI 4140 and AISI 304 under molten salt of Na 2 SO 4 + V 2 O 5 (60%) environment at 500 and 550 deg. C under cyclic condition. The influences of welding parameters on the hot corrosion have been discussed. The resulting oxide scales in the weldment have been characterized systematically using surface analytical techniques. Scale thickness on low alloy steel side was found to be more and was prone to spalling. Weld region has been found to be more prone to degradation than base metals due to inter diffusion of element across the interface and the formation of intermetallic compound

High temperature corrosion studies on friction-welded dissimilar metals

Energy Technology Data Exchange (ETDEWEB)

Arivazhagan, N. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee (India)]. E-mail: arivadmt@iitr.ernet.in; Singh, Surendra [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee (India); Prakash, Satya [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee (India); Reddy, G.M. [Defense Metallurgical and Research Laboratory, Hyderabad (India)

2006-07-25

Understanding the behaviour of weldment at elevated temperatures and especially their corrosion behaviour has become an object of scientific investigation recently. Investigation has been carried out on friction-welded AISI 4140 and AISI 304 under molten salt of Na{sub 2}SO{sub 4} + V{sub 2}O{sub 5} (60%) environment at 500 and 550 deg. C under cyclic condition. The influences of welding parameters on the hot corrosion have been discussed. The resulting oxide scales in the weldment have been characterized systematically using surface analytical techniques. Scale thickness on low alloy steel side was found to be more and was prone to spalling. Weld region has been found to be more prone to degradation than base metals due to inter diffusion of element across the interface and the formation of intermetallic compound.

Predicting tensile strength of friction stir welded AA6061 aluminium alloy joints by a mathematical model

International Nuclear Information System (INIS)

Elangovan, K.; Balasubramanian, V.; Babu, S.

2009-01-01

AA6061 aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to weight ratio and good corrosion resistance. Compared to the fusion welding processes that are routinely used for joining structural aluminium alloys, friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a non-consumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force etc., and tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop a mathematical model to predict tensile strength of the friction stir welded AA6061 aluminium alloy by incorporating FSW process parameters. Four factors, five levels central composite design has been used to minimize number of experimental conditions. Response surface method (RSM) has been used to develop the model. Statistical tools such as analysis of variance (ANOVA), student's t-test, correlation co-efficient etc. have been used to validate the developed model. The developed mathematical model can be effectively used to predict the tensile strength of FSW joints at 95% confidence level

Multi-objective Optimization of Process Parameters in Friction Stir Welding

DEFF Research Database (Denmark)

Tutum, Cem Celal; Hattel, Jesper Henri

The objective of this paper is to investigate optimum process parameters in Friction Stir Welding (FSW) to minimize residual stresses in the work piece and maximize production efficiency meanwhile satisfying process specific constraints as well. More specifically, the choices of tool rotational...... speed and traverse welding speed have been sought in order to achieve the goals mentioned above using an evolutionary multi-objective optimization (MOO) algorithm, i.e. non-dominated sorting genetic algorithm (NSGA-II), integrated with a transient, 2- dimensional sequentially coupled thermo...

Microstructure and Mechanical Characterization of Friction-Stir-Welded Dual-Phase Brass

Science.gov (United States)

Ramesh, R.; Dinaharan, I.; Akinlabi, E. T.; Murugan, N.

2018-03-01

Friction stir welding (FSW) is an ideal process to join brass to avoid the evaporation of zinc. In the present investigation, 6-mm-thick dual-phase brass plates were joined efficiently using FSW at various tool rotational speeds. The microstructures were studied using optical microscopy, electron backscattered diffraction and transmission electron microscopy. The optical micrographs revealed the evolution of various zones across the joint line. The microstructure of the heat-affected zone was similar to that of base metal. The weld zone exhibited finer grains due to dynamic recrystallization. The recrystallization was inhomogeneous and the inhomogeneity reduced with increased tool rotational speed. The dual phase was preserved in the weld zone due to the retention of zinc. The severe plastic deformation created a lot of dislocations in the weld zone. The weld zone was strengthened after welding. The role of tool rotational speed on the joint strength is further reported.

Identifying Combination of Friction Stir Welding Parameters to Maximize Strength of Lap Joints of AA2014-T6 Aluminum Alloy

Directory of Open Access Journals (Sweden)

Rajendrana C.

2017-01-01

Full Text Available AA2014 aluminum alloy (Al-Cu alloy has been widely utilized in fabrication of lightweight structures like aircraft structures, demanding high strength to weight ratio and good corrosion resistance. The fusion welding of these alloys will lead to solidification problems such as hot cracking. Friction stir welding is a new solid state welding process, in which the material being welded does not melt and recast. Lot of research works have been carried out by many researchers to optimize process parameters and establish empirical relationships to predict tensile strength of friction stir welded butt joints of aluminum alloys. However, very few investigations have been carried out on friction stir welded lap joints of aluminum alloys. Hence, in this investigation, an attempt has been made to optimize friction stir lap welding (FSLW parameters to attain maximum tensile strength using statistical tools such as design of experiment (DoE, analysis of variance (ANOVA, response graph and contour plots. By this method, it is found that maximum tensile shear fracture load of 12.76 kN can be achieved if a joint is made using tool rotational speed of 900 rpm, welding speed of 110 mm/min, tool shoulder diameter of 12 mm and tool tilt angle of 1.5°.

Thermal analysis of friction stir welding process and investigation into affective parameters using simulation

Energy Technology Data Exchange (ETDEWEB)

Abbasi, Mahmoud [University of Kashan, Kashan (Iran, Islamic Republic of); Bagheri, Behrouz [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Keivani, Rasoul [Islamic Azad University, Tehran (Iran, Islamic Republic of)

2015-02-15

Friction stir welding (FSW) as an efficient solid state joining process has numerous applications in industries. Temperature distribution analysis through simulation not only brings the possibility to characterize the microstructure of different zones, but also enables one to save cost and energy as optimum welding variables are obtained with less concern. In the present study, the temperature distribution during the friction stir welding (FSW) process of AA6061-T6 was evaluated using finite element method (FEM). Since experimental measurements cannot be readily made in the weld region, it is difficult to understand physics in the stir zone of the welds without simulation. Abaqus software was applied to model the parts and simulate the process of welding, while Johnson-Cook law utilized to evaluate the effect of strain rate and generated heat. FE-results were verified by experimental results. The comparisons revealed a good compatibility between the results. The effect of probe shape on temperature distribution was also studied. It was found that spherical pins result in the highest temperatures at workpieces with respect to cylindrical and tapered pins. Additionally, it was concluded that more heat is generated in workpieces as pin angle increases.

Thermal analysis of friction stir welding process and investigation into affective parameters using simulation

International Nuclear Information System (INIS)

Abbasi, Mahmoud; Bagheri, Behrouz; Keivani, Rasoul

2015-01-01

Friction stir welding (FSW) as an efficient solid state joining process has numerous applications in industries. Temperature distribution analysis through simulation not only brings the possibility to characterize the microstructure of different zones, but also enables one to save cost and energy as optimum welding variables are obtained with less concern. In the present study, the temperature distribution during the friction stir welding (FSW) process of AA6061-T6 was evaluated using finite element method (FEM). Since experimental measurements cannot be readily made in the weld region, it is difficult to understand physics in the stir zone of the welds without simulation. Abaqus software was applied to model the parts and simulate the process of welding, while Johnson-Cook law utilized to evaluate the effect of strain rate and generated heat. FE-results were verified by experimental results. The comparisons revealed a good compatibility between the results. The effect of probe shape on temperature distribution was also studied. It was found that spherical pins result in the highest temperatures at workpieces with respect to cylindrical and tapered pins. Additionally, it was concluded that more heat is generated in workpieces as pin angle increases.

Multiobjective optimization of friction welding of UNS S32205 duplex stainless steel

Directory of Open Access Journals (Sweden)

P.M. Ajith

2015-06-01

Full Text Available The present study is to optimize the process parameters for friction welding of duplex stainless steel (DSS UNS S32205. Experiments were conducted according to central composite design. Process variables, as inputs of the neural network, included friction pressure, upsetting pressure, speed and burn-off length. Tensile strength and microhardness were selected as the outputs of the neural networks. The weld metals had higher hardness and tensile strength than the base material due to grain refinement which caused failures away from the joint interface during tensile testing. Due to shorter heating time, no secondary phase intermetallic precipitation was observed in the weld joint. A multi-layer perceptron neural network was established for modeling purpose. Five various training algorithms, belonging to three classes, namely gradient descent, genetic algorithm and Levenberg–Marquardt, were used to train artificial neural network. The optimization was carried out by using particle swarm optimization method. Confirmation test was carried out by setting the optimized parameters. In conformation test, maximum tensile strength and maximum hardness obtained are 822 MPa and 322 Hv, respectively. The metallurgical investigations revealed that base metal, partially deformed zone and weld zone maintain austenite/ferrite proportion of 50:50.

Effect of Friction Stir Welding Parameters on the Mechanical and Microstructure Properties of the Al-Cu Butt Joint

Directory of Open Access Journals (Sweden)

Sare Celik

2016-05-01

Full Text Available Friction Stir Welding (FSW is a solid-state welding process used for welding similar and dissimilar materials. FSW is especially suitable to join sheet Al alloys, and this technique allows different material couples to be welded continuously. In this study, 1050 Al alloys and commercially pure Cu were produced at three different tool rotation speeds (630, 1330, 2440 rpm and three different tool traverse speeds (20, 30, 50 mm/min with four different tool position (0, 1, 1.5, 2 mm by friction stir welding. The influence of the welding parameters on the microstructure and mechanical properties of the joints was investigated. Tensile and bending tests and microhardness measurements were used to determine the mechanical properties. The microstructures of the weld zone were investigated by optical microscope and scanning electron microscope (SEM and were analyzed in an energy dispersed spectrometer (EDS. Intermetallic phases were detected based on the X-ray diffraction (XRD analysis results that evaluated the formation of phases in the weld zone. When the welding performance of the friction stir welded butt joints was evaluated, the maximum value obtained was 89.55% with a 1330 rpm tool rotational speed, 20 mm/min traverse speed and a 1 mm tool position configuration. The higher tensile strength is attributed to the dispersion strengthening of the fine Cu particles distributed over the Al material in the stir zone region.

Aluminum 6060-T6 friction stir welded butt joints: fatigue resistance with different tools and feed rates

International Nuclear Information System (INIS)

Baragetti, S.; D'Urso, G.

2014-01-01

The fatigue behavior of AA6060-T6 friction stir welded butt joints was investigated. The joints were produced by using both a standard and a threaded tri-flute cylindrical-tool with flat shoulder. The friction stir welding process was carried out using different feed rates. Preliminary tensile tests, micrograph analyses and hardness profile measurements across the welds were carried out. Welded and unwelded fatigue samples were tested under axial loading (R = 0.1) with upper limits of 10 4 and 10 5 cycles, using threaded and unthreaded (standard) tools at different feed rates. The best tensile and fatigue performance was obtained using the standard tool at low feed rate.

Tensile strength and fatigue strength of 6061 aluminum alloy friction welded joints

Energy Technology Data Exchange (ETDEWEB)

Ochi, H.; Tsujino, R. [Osaka Inst. of Tech., Asahi-ku Osaka (Japan); Sawai, T. [Osaka Sangyo Univ., Daito (Japan); Yamamoto, Y. [Setsunan Univ., Neyagawa (Japan); Ogawa, K. [Osaka Prefecture Univ., Sakai (Japan); Suga, Y. [Keio Univ., Kohoku-ku, Yokohama (Japan)

2002-07-01

Friction welding of 6061 aluminum alloy was carried out in order to examine the relationship between deformation heat input in the upset stage and joint performance. The joint performance was evaluated by tensile testing and fatigue testing. Stabilized tensile strength was obtained when the deformation heat input in the upset stage exceeded 200 J/s. Weld condition at the weld interface and the width of softened area affected fatigue strength more than tensile strength. That is, when the weld condition at the weld interface is good and the softened area is wide, fatigue strength increases. On the other hand, when the weld condition at the weld interface is good and the softened area is narrow, and when the weld condition at the weld interface is somewhat poor in spite of the wide softened area, fatigue strength decreases. The fatigue limit obtained by the fatigue testing revealed that, when the deformation heat input in the upset stage exceeded a certain value, sound joints could be produced. (orig.)

Friction welding of a nickel free high nitrogen steel: influence of forge force on microstructure, mechanical properties and pitting corrosion resistance

Directory of Open Access Journals (Sweden)

Mrityunjoy Hazra

2014-01-01

Full Text Available In the present work, nickel free high nitrogen austenitic stainless steel specimens were joined by continuous drive friction welding process by varying the amount of forge (upsetting force and keeping other friction welding parameters such as friction force, burn-off, upset time and speed of rotation as constant at appropriate levels. The joint characterization studies include microstructural examination and evaluation of mechanical (micro-hardness, impact toughness and tensile and pitting corrosion behaviour. The integrity of the joint, as determined by the optical microscopy was very high and no crack and area of incomplete bonding were observed. Welds exhibited poor Charpy impact toughness than the parent material. Toughness for friction weld specimens decreased with increase in forge force. The tensile properties of all the welds were almost the same (irrespective of the value of the applied forge force and inferior to those of the parent material. The joints failed in the weld region for all the weld specimens. Weldments exhibited lower pitting corrosion resistance than the parent material and the corrosion resistance of the weld specimens was found to decrease with increase in forge force.

Special grain boundaries in the nugget zone of friction stir welded AA6061-T6 under various welding parameters

Energy Technology Data Exchange (ETDEWEB)

Tao, Wang [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Yong, Zou, E-mail: yzou@sdu.edu.cn [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Xuemei, Liu [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Matsuda, Kenji [Department of Materials Science and Technology, Faculty of Engineering, University of Toyama, Toyama 930-8555 (Japan)

2016-08-01

The age hardenable AA6061-T6 plate was butt welded by friction stir welding. The total heat input, generated by friction between the tool and work piece and plastic deformation, results in a consumption of meta-stable phases in the nugget zone. Precipitation phenomena were closely related to the diffusion of the solute atoms. The existence of special grain boundaries like Σ1a and Σ3 will increase the difficulty in diffusion, which will improve the hardness in the nugget zone. Furthermore, the formation of Σ3 grain boundaries can result from an impingement of re-crystallized grains coming from texture components in twin relationship already. An appropriate strain level may benefit the development of the twin components with a similar intensity. The welding parameters have an effect on heat source mode and the strain level. Then, the type of dynamic re-crystallization and distribution of the special grain boundaries was altered by changing the parameters.

Strain hardening and damage in 6xxx series aluminum alloy friction stir welds

DEFF Research Database (Denmark)

Simar, Aude; Nielsen, Kim Lau; de Meester, Bruno

2010-01-01

A friction stir weld in 6005A-T6 aluminum alloy has been prepared and analyzed by micro-hardness measurements, tensile testing and scanning electron microscopy (SEM). The locations of the various weld zones were determined by micro-hardness indentation measurements. The flow behavior of the various...... zones of the weld was extracted using micro-tensile specimens cut out parallel to the welding direction. The measured material properties and weld topology were then introduced in a fully coupled micro-mechanical finite element model, accounting for nucleation and growth of voids as well as void shape...... evolution. The model shows satisfactory preliminary results in predicting the tensile behaviour of the weld and the true strain at fracture....

Mechanical properties and microstructural evaluation of AA1100 to AZ31 dissimilar friction stir welds

Energy Technology Data Exchange (ETDEWEB)

Azizieh, M., E-mail: azizieh@gmail.com [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Sadeghi Alavijeh, A. [School of Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Avenue, Surrey, BC V3T 0A3 (Canada); Abbasi, M. [High Temperature Energy Materials, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Balak, Z. [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Kim, H.S. [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

2016-02-15

In this paper, microstructure and mechanical properties of dissimilar friction stir welds of AA1100 and AZ31 were investigated to understand the effects of rotational and travel speed as well as pin position. The tensile results of welded samples revealed that the sound welds were formed when the stirring pin deviated from the centreline to the AZ31 side. The X-ray diffraction shows that Al{sub 3}Mg{sub 2} and Al{sub 12}Mg{sub 17} intermetallics formation occurs in the stir zone during the welding process. High hardness of these intermetallic phases increased the hardness of the stir zone to 110 Hv. The best tensile results were obtained in the sample processed in the range of 28–32 (rev/mm) rotational to travel speed ratio. - Highlights: • For Al to Mg friction stir welding, tool offset must be to Mg side. • There is an optimum rotational speed for obtain the highest strength. • Intermetallics form in any welding condition. • The volume fraction of intermetallic is directly related to FSW peak temperature.

Eutectic structures in friction spot welding joint of aluminum alloy to copper

International Nuclear Information System (INIS)

Shen, Junjun; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; Santos, Jorge F. dos

2014-01-01

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl 2 eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting

Microscopic analysis of the morphology of seams in friction stir welded polypropylene

Directory of Open Access Journals (Sweden)

Z. Kiss

2012-01-01

Full Text Available Supermolecular structure of welded seams prepared by friction stir welding (FSW of polypropylene sheets has been studied by optical and electron microscopy. It has been shown that in the central parts of the seam spherulitic structures similar to that of the base material are formed, while at the borderline of the seam, a complex supermolecular structure could be identified. Lower welding rotation speed resulted in a border transition zone of more complex feature than the higher rotation speed during FSW. This was accompanied by reduced joint efficiency.

Numerical Simulation of Tension Properties for Al-Cu Alloy Friction Stir-Welded Joints with GTN Damage Model

Science.gov (United States)

Sun, Guo-Qin; Sun, Feng-Yang; Cao, Fang-Li; Chen, Shu-Jun; Barkey, Mark E.

2015-11-01

The numerical simulation of tensile fracture behavior on Al-Cu alloy friction stir-welded joint was performed with the Gurson-Tvergaard-Needleman (GTN) damage model. The parameters of the GTN model were studied in each region of the friction stir-welded joint by means of inverse identification. Based on the obtained parameters, the finite element model of the welded joint was built to predict the fracture behavior and tension properties. Good agreement can be found between the numerical and experimental results in the location of the tensile fracture and the mechanical properties.

An investigation on SA 213-Tube to SA 387-Tube plate using friction welding process

Energy Technology Data Exchange (ETDEWEB)

Rajan, S. Pandia; Kumaraswamidhas, L. A. [Indian Institute of Technology, Jharkhand (India); Kumaran, S. Senthil [RVS School of Engineering and Technology, Tamil Nadu (India); Muthukumaran, S. [National Institute of Technology, Tamil Nadu (India)

2016-01-15

Friction welding of tube to tube plate using an external tool (FWTPET) is a relatively newer solid state welding process used for joining tube to tube plate of either similar or dissimilar materials with enhanced mechanical and metallurgical properties. In the present study, FWTPET has been used to weld SA 213 (Grade T12) tube with SA 387 (Grade 22) tube plate. The welded samples are found to have satisfactory joint strength and the Energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) study showed that inter metallic compound is absent in the weld zone. The different weld joints have been identified and the phase composition is found using EDX and XRD. Microstructures have been analyzed using optical and Scanning electron microscopy (SEM). The mechanical properties such as hardness, compressive shear strength and peel test for different weld conditions are studied and the hardness survey revealed that there is increase in hardness at the weld interface due to grain refinement. The corrosion behavior for different weld conditions have been analyzed and the weld zone is found to have better corrosion resistance due to the influence of the grain refinement after FWTPET welding process. Hence, the present investigation is carried out to study the behavior of friction welded dissimilar joints of SA 213 tube and SA 387 tube plate joints and the results are presented. The present study confirms that a high quality tube to tube plate joint can be achieved using FWTPET process at 1120 rpm.

Friction Stir Welding of three dissimilar aluminium alloy used in aeronautics industry

Science.gov (United States)

Boşneag, A.; Constantin, M. A.; Niţu, E.; Iordache, M.

2017-10-01

Friction Stir Welding (FSW) is an innovative solid-state joining process. This process was, in first time, develop to join the similar aluminum plates but now the technology can be used to weld a large area of materials similar or dissimilar. Taking these into account FSW process, for dissimilar materials are increasingly required, more than traditional arc welding, in industrial environment. More than that FSW is used in aeronautics industry because of very good result and very good weldability between aluminum alloy used at building of airplanes, where the body of airplane are 20% aluminum alloy and this percent can be increaser in future. In this paper is presented an experimental study which includes welding three dissimilar aluminum alloy, with different properties, used in aeronautics industry, this materials are: AA 2024, AA6061 and AA7075. After welding with different parameters, the welding join and welding process will be analyzed considering process temperature, process vertical force, and roughnessof welding seams, visual aspect and microhardness.

Nondestructive Evaluation of the Friction Weld Process on 2195/2219 Grade Aluminum

Science.gov (United States)

Suits, Michael W.; Clark, Linda S.; Cox, Dwight E.

1999-01-01

In 1996, NASA's Marshall Space Flight Center began an ambitious program designed to find alternative methods of repairing conventional TIG (Tungsten Inert Gas) welds and VPPA (Variable Polarity Plasma Arc) welds on the Space Shuttle External Tank without producing additional heat-related anomalies or conditions. Therefore, a relatively new method, invented by The Welding Institute (TWI) in Cambridge, England, called Friction Stir Welding (FSW), was investigated for use in this application, as well as being used potentially as an initial weld process. As with the conventional repair welding processes, nondestructive evaluation (NDE) plays a crucial role in the verification of these repairs. Since it was feared that conventional NDE might have trouble with this type of weld structure (due to shape of nugget, grain structure, etc.) it was imperative that a complete study be performed to address the adequacy of the NDE process. This paper summarizes that process.

Remarks on manipulator classification and reversibility - deflection - backlash - inertia - balance and friction trade off

International Nuclear Information System (INIS)

Vertut, Jean.

1976-01-01

In a previous work the author proposed a time efficiency quotient based on time to perform a task for a man controlling a manipulator (RO MAN SY 73). This quotient is also a global evaluation of a man-manipulator system, and can be extended to teaching programmed manipulators. Classification based on this quotient emphasizes the importance of force feed-back to the operator, and enables to project the same concept to computer control. This paper concentrates on characteristics reflecting directly to the mechanics of the arm, to the actuators and to the control. They need delicate trade off: reversibility is key to force feed-back, deflection reflects on arm dynamics (oscillation) and precision, backlash allows lower friction but limits servo performances, inertia is high when limited deflection is required, friction is limiting the man in the loop performances, force transducers can compensate irreversibility and/or friction but lead to control sophistication. These trade offs are developed, and some proposed constants are given for force feed-back manipulators

Nonlinear Time Reversal Acoustic Method of Friction Stir Weld Assessment, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The goal of the project is demonstration of the feasibility of Friction Stir Weld (FSW) assessment by novel Nonlinear Time Reversal Acoustic (TRA) method. Time...

Dissimilar friction welding of 6061-T6 aluminum and AISI 1018 steel: Properties and microstructural characterization

International Nuclear Information System (INIS)

Taban, Emel; Gould, Jerry E.; Lippold, John C.

2010-01-01

Joining of dissimilar materials is of increasing interest for a wide range of industrial applications. The automotive industry, in particular, views dissimilar materials joining as a gateway for the implementation of lightweight materials. Specifically, the introduction of aluminum alloy parts into a steel car body requires the development of reliable, efficient and economic joining processes. Since aluminum and steel demonstrate different physical, mechanical and metallurgical properties, identification of proper welding processes and practices can be problematic. In this work, inertia friction welding has been used to create joints between a 6061-T6 aluminum alloy and a AISI 1018 steel using various parameters. The joints were evaluated by mechanical testing and metallurgical analysis. Microstructural analyses were done using metallography, microhardness testing, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray elemental mapping, focused ion beam (FIB) with ultra high resolution SEM and transmission electron microscopy (TEM) in TEM and STEM modes. Results of these analysis first suggested that joint strengths on the order of 250 MPa could be achieved. In addition, failures were seen in the plasticized layer on the aluminum side of the joint. Further, bond lines were characterized by a thin layer of formed Al-Fe intermetallic. This intermetallic layer averaged roughly 250 nm thick and compositionally appears related to the FeAl and Fe 2 Al 5 phases.

Interfacial microstructure and properties of copper clad steel produced using friction stir welding versus gas metal arc welding

Energy Technology Data Exchange (ETDEWEB)

Shen, Z.; Chen, Y. [Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo (Canada); Haghshenas, M., E-mail: mhaghshe@uwaterloo.ca [Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo (Canada); Nguyen, T. [Mechanical Systems Engineering, Conestoga College, Kitchener (Canada); Galloway, J. [Welding Engineering Technology, Conestoga College, Kitchener (Canada); Gerlich, A.P. [Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo (Canada)

2015-06-15

A preliminary study compares the feasibility and microstructures of pure copper claddings produced on a pressure vessel A516 Gr. 70 steel plate, using friction stir welding versus gas metal arc welding. A combination of optical and scanning electron microscopy is used to characterize the grain structures in both the copper cladding and heat affected zone in the steel near the fusion line. The friction stir welding technique produces copper cladding with a grain size of around 25 μm, and no evidence of liquid copper penetration into the steel. The gas metal arc welding of copper cladding exhibits grain sizes over 1 mm, and with surface microcracks as well as penetration of liquid copper up to 50 μm into the steel substrate. Transmission electron microscopy reveals that metallurgical bonding is produced in both processes. Increased diffusion of Mn and Si into the copper cladding occurs when using gas metal arc welding, although some nano-pores were detected in the FSW joint interface. - Highlights: • Cladding of steel with pure copper is possible using either FSW or GMAW. • The FSW yielded a finer grain structure in the copper, with no evidence of cracking. • The FSW joint contains some evidence of nano-pores at the interface of the steel/copper. • Copper cladding by GMAW contained surface cracks attributed to high thermal stresses. • The steel adjacent to the fusion line maintained a hardness value below 248 HV.

An investigation on thermal and friction effect produced by friction welding of SA 213 tube to SA 387 tube plate

Directory of Open Access Journals (Sweden)

S. Pandia Rajan

2016-03-01

Full Text Available The present study investigates the effect of thermal and friction produced in the tube to tube plate during the friction welding process by using a Tungsten carbide external tool. In this process, the fictional welding of SA 213 tube and SA 387 tube plate was done by using an external tool. Modeling of tool and wok piece is done by using Solid works and to study the thermal and frictional effect by using Ansys. In this research work, joining of SA 213 tube to SA 387 tube plate was done by using two different techniques such as with hole [WH] and without hole [WOH]. The stress value of with hole and without hole such as 18,782 MPa and 10,486 MPa respectively and the ultimate heat flux generated with hole and without hole such as 0.80475 W/mm2 and 1.1344 W/mm2 respectively were observed.

Influence of the welding temperature and the welding speed on the mechanical properties of friction stir welds in EN AW-2219-T87

Science.gov (United States)

Bachmann, A.; Krutzlinger, M.; Zaeh, M. F.

2018-06-01

Friction Stir Welding (FSW) is an innovative joining technique, which has proven to produce high quality joints in high strength aluminum alloys. Consequently, it is commonly used to manufacture lightweight aerospace structures with stringent requirements. For these structures, it is necessary to ensure a high ultimate tensile strength (UTS). Various studies have reported that the UTS is significantly influenced by the welding parameters. Samples welded with different parameter sets showed a considerably different UTS, despite being free from detectable welding defects (e.g. tunnel defect, voids, or lack of penetration). Based on the observations in the literature, a hypothesis was posed. The welding temperature along with the welding speed determine the UTS of the weld. This study aims to prove this hypothesis experimentally by using temperature-controlled FSW to join plates of EN AW-2219-T87 in butt joint configuration. The welded samples were examined using visual inspection, metallography, X-ray imaging, and uniaxial tensile tests. Finally, a statistical analysis was conducted. Hereby, the hypothesis was confirmed.

Fabrication of Aluminum Tubes Filled with Aluminum Alloy Foam by Friction Welding

Directory of Open Access Journals (Sweden)

Yoshihiko Hangai

2015-10-01

Full Text Available Aluminum foam is usually used as the core of composite materials by combining it with dense materials, such as in Al foam core sandwich panels and Al-foam-filled tubes, owing to its low tensile and bending strengths. In this study, all-Al foam-filled tubes consisting of ADC12 Al-Si-Cu die-cast aluminum alloy foam and a dense A1050 commercially pure Al tube with metal bonding were fabricated by friction welding. First, it was found that the ADC12 precursor was firmly bonded throughout the inner wall of the A1050 tube without a gap between the precursor and the tube by friction welding. No deformation of the tube or foaming of the precursor was observed during the friction welding. Next, it was shown that by heat treatment of an ADC12-precursor-bonded A1050 tube, gases generated by the decomposition of the blowing agent expand the softened ADC12 to produce the ADC12 foam interior of the dense A1050 tube. A holding time during the foaming process of approximately tH = 8.5 min with a holding temperature of 948 K was found to be suitable for obtaining a sound ADC12-foam-filled A1050 tube with sufficient foaming, almost uniform pore structures over the entire specimen, and no deformation or reduction in the thickness of the tube.

Counterrotating-Shoulder Mechanism for Friction Stir Welding

Science.gov (United States)

Nunes, Arthur C., Jr.

2007-01-01

A counterrotating-shoulder mechanism has been proposed as an alternative to the mechanism and fixtures used in conventional friction stir welding. The mechanism would internally react most or all of the forces and torques exerted on the workpiece, making it unnecessary to react the forces and torques through massive external fixtures. In conventional friction stir welding, a rotating pin tool is inserted into, and moved along, a weld seam. As the pin tool moves, it stirs together material from the opposite sides of the seam to form the weld. A large axial plunge force must be exerted upon the workpiece through and by the pin tool and a shoulder attached above the pin tool in order to maintain the pressure necessary for the process. The workpiece is secured on top of an anvil, which supports the workpiece against the axial plunge force and against the torque exerted by the pin tool and shoulder. The anvil and associated fixtures must be made heavy (and, therefore, are expensive) to keep the workpiece stationary. In addition, workpiece geometries must be limited to those that can be accommodated by the fixtures. The predecessor of the proposed counterrotating-shoulder mechanism is a second-generation, self-reacting tool, resembling a bobbin, that makes it possible to dispense with the heavy anvil. This tool consists essentially of a rotating pin tool with opposing shoulders. Although the opposing shoulders maintain the necessary pressure without need to externally apply or react a large plunge force, the torque exerted on the workpiece remains unreacted in the absence of a substantial external fixture. Depending on the RPM and the thickness of the workpiece, the torque can be large. The proposed mechanism (see figure) would include a spindle attached to a pin tool with a lower shoulder. The spindle would be coupled via splines to the upper one of three bevel gears in a differential drive. The middle bevel gear would be the power-input gear and would be coupled to the

Multiple Crack Growth Prediction in AA2024-T3 Friction Stir Welded Joints, Including Manufacturing Effects

DEFF Research Database (Denmark)

Carlone, Pierpaolo; Citarella, Roberto; Sonne, Mads Rostgaard

2016-01-01

A great deal of attention is currently paid by several industries toward the friction stir welding process to realize lightweight structures. Within this aim, the realistic prediction of fatigue behavior of welded assemblies is a key factor. In this work an integrated finite element method - dual...... boundary element method (FEM-DBEM) procedure, coupling the welding process simulation to the subsequent crack growth assessment, is proposed and applied to simulate multiple crack propagation, with allowance for manufacturing effects. The friction stir butt welding process of the precipitation hardened AA...... on a notched specimen. The whole procedure was finally tested comparing simulation outcomes with experimental data. The good agreement obtained highlights the predictive capability of the method. The influence of the residual stress distribution on crack growth and the mutual interaction between propagating...

Evolution of microstructure and mechanical properties in naturally aged 7050 and 7075 Al friction stir welds

Energy Technology Data Exchange (ETDEWEB)

Fuller, Christian B., E-mail: christian.fuller@yahoo.com [Rockwell Scientific, 1049 Camino Dos Rios, Thousand Oaks, CA 93021 (United States); Mahoney, Murray W., E-mail: murraymahoney@comcast.net [Rockwell Scientific, 1049 Camino Dos Rios, Thousand Oaks, CA 93021 (United States); Calabrese, Mike [Rockwell Scientific, 1049 Camino Dos Rios, Thousand Oaks, CA 93021 (United States); Micona, Leanna [The Boeing Company, P.O. Box 3707 MC 19-HP, Seattle, WA 98124 (United States)

2010-04-15

The microstructural and mechanical property evolution of friction stir welded 7050-T7651 and 7075-T651 Al alloys were examined as a function of room temperature (natural) aging for up to 67,920 h. During the range of aging times studied, transverse tensile strengths continuously increased, and are still increasing, with improvements of 24% and 29% measured for the 7050-T7651 and 7075-T651 Al alloy friction stir welds, respectively. Microstructural evolution within the weld nugget and heat-affected zone was evaluated with both transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). Formation of a high volume fraction of GP(II) zones produced a majority of the strength improvement within the weld nugget and HAZ regions. The rational for the microstructural changes are discussed in light of the mechanical properties.

Effect of microstructure on properties of friction stir welded Inconel Alloy 600

International Nuclear Information System (INIS)

Sato, Y.S.; Arkom, P.; Kokawa, H.; Nelson, T.W.; Steel, R.J.

2008-01-01

Friction stir welding (FSW) has been widely used to metals with moderate melting temperatures, primarily Al alloys. Recently, tool materials that withstand high stresses and temperatures necessary for FSW of materials with high melting temperatures have been developed. In the present study, polycrystalline cubic boron nitride (PCBN) tool was used for partially penetrated FSW of Inconel Alloy 600, and a defect-free weld was successfully produced. Microstructural characteristics, mechanical and corrosion properties in the weld were examined. The weld had better mechanical properties than the base material due to formation of fine grain structure in the stir zone, but exhibited slightly the lower corrosion resistance in a part of the stir zone and heat-affected zone (HAZ)

Friction stir welding of dissimilar AA2024 and AA7075 aluminum alloys

International Nuclear Information System (INIS)

Khodir, Saad Ahmed; Shibayanagi, Toshiya

2008-01-01

The present study focuses on the microstructure and mechanical properties of dissimilar joints of 2024-T3 Al alloy to 7075-T6 Al alloy produced by friction stir welding. Effects of welding speed and fixed location of base metals on microstructures, hardness distributions, and tensile properties of the welded joints were investigated. SEM-EDS analysis revealed that the stir zone contains a mixed structure and onion ring pattern with a periodic change of grain size as well as a heterogeneous distribution of alloying elements. The maximum tensile strength of 423.0 MPa was achieved for the joint produced at welding speed of 1.67 mm/s when 2024 Al alloy was located on the advancing side

Effect of process parameters on microstructure and mechanical behaviors of friction stir linear welded aluminum to magnesium

International Nuclear Information System (INIS)

Rao, H.M.; Ghaffari, B.; Yuan, W.; Jordon, J.B.; Badarinarayan, H.

2016-01-01

The microstructure and lap-shear behaviors of friction stir linear welded wrought Al alloy AA6022-T4 to cast Mg alloy AM60B joints were examined. A process window was developed to initially identify the potential process conditions. Multitudes of welds were produced by varying the tool rotation rate and tool traverse speed. Welds produced at 1500 revolutions per minute (rpm) tool rotation rate and either 50 mm/min or 75 mm/min tool traverse speed displayed the highest quasi-static failure load of ~3.3 kN per 30 mm wide lap-shear specimens. Analysis of cross sections of untested coupons indicated that the welds made at these optimum welding parameters had negligible microvoids and displayed a favorable weld geometry for the cold lap and hook features at the faying surface, compared to welds produced using other process parameters. Cross sections of the tested coupons indicated that the dominant crack initiated on the advancing side and progressed through the weld nugget, which consists of intermetallic compounds (IMC). This study demonstrates the feasibility of welding wrought Al and cast Mg alloy via friction stir linear welding with promising lap-shear strength results.

Effect of process parameters on microstructure and mechanical behaviors of friction stir linear welded aluminum to magnesium

Energy Technology Data Exchange (ETDEWEB)

Rao, H.M. [Research & Development Division, Hitachi America Ltd., Farmington Hills, MI 48335 (United States); Ghaffari, B. [Research and Advanced Engineering, Ford Motor Company, Dearborn, MI 48121 (United States); Yuan, W., E-mail: wei.yuan@hitachi-automotive.us [Research & Development Division, Hitachi America Ltd., Farmington Hills, MI 48335 (United States); Jordon, J.B. [Department of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); Badarinarayan, H. [Research & Development Division, Hitachi America Ltd., Farmington Hills, MI 48335 (United States)

2016-01-10

The microstructure and lap-shear behaviors of friction stir linear welded wrought Al alloy AA6022-T4 to cast Mg alloy AM60B joints were examined. A process window was developed to initially identify the potential process conditions. Multitudes of welds were produced by varying the tool rotation rate and tool traverse speed. Welds produced at 1500 revolutions per minute (rpm) tool rotation rate and either 50 mm/min or 75 mm/min tool traverse speed displayed the highest quasi-static failure load of ~3.3 kN per 30 mm wide lap-shear specimens. Analysis of cross sections of untested coupons indicated that the welds made at these optimum welding parameters had negligible microvoids and displayed a favorable weld geometry for the cold lap and hook features at the faying surface, compared to welds produced using other process parameters. Cross sections of the tested coupons indicated that the dominant crack initiated on the advancing side and progressed through the weld nugget, which consists of intermetallic compounds (IMC). This study demonstrates the feasibility of welding wrought Al and cast Mg alloy via friction stir linear welding with promising lap-shear strength results.

Mechanical properties and fracture behaviour of ODS steel friction stir welds at variable temperatures

Energy Technology Data Exchange (ETDEWEB)

Dawson, H., E-mail: huwdawson@gmail.com [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Serrano, M.; Hernandez, R. [Structural Materials Division, Technology Department, CIEMAT, Avda de la Complutense 40, 28040 Madrid (Spain); Cater, S. [Friction and Forge Processes Department, Joining Technologies Group, TWI Technology Centre (Yorkshire), Advanced Manufacturing Park, Wallis Way, Catcliffe, Rotherham S60 5TZ (United Kingdom); Jimenez-Melero, E. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom)

2017-05-02

We have assessed the microstructure and the temperature-dependent mechanical behaviour of five bead-on-plate friction stir welds of Oxide Dispersion Strengthened (ODS) steel, produced using systematic changes to the tool rotation and traverse speed. Friction stir welding can potentially retain the fine dispersion of nanoparticles, and therefore also the high-temperature strength and radiation damage resistance of these materials. Tensile testing was carried out on the MA956 base material at a range of temperatures, from room temperature up to 750 °C. The mechanical properties of the welds were investigated via tensile testing at room temperature and at 500 °C, together with micro-hardness testing. The welds exhibited similar strength and ductility to the base material at both testing temperatures as welding caused a partial loss of particle strengthening, alongside an increase in grain boundary strengthening due to a greatly refined grain size in the stir zones. The micro-hardness data revealed a trend of increasing hardness with increasing tool traverse speed or decreasing rotation speed. This was attributed to the smaller grain size and lower nanoparticle number density in the welds created with these parameters. At 500 °C, the yield stress and ultimate tensile stress of the base material and the welds decreased, due to a progressive reduction in both the Orowan-type particle strengthening and the grain boundary strengthening.

Linear friction welding for constructing and repairing rail for high speed and intercity passenger service rail : final report.

Science.gov (United States)

2016-08-01

This project developed a solid-state welding process based on linear friction welding (LFW) technology. While resistance flash welding or : thermite techniques are tried and true methods for joining rails and performing partial rail replacement repai...

A Finite Element Model to Simulate Defect Formation during Friction Stir Welding

Directory of Open Access Journals (Sweden)

Zhi Zhu

2017-07-01

Full Text Available In this study, a 3D coupled thermo-mechanical finite element model is developed to predict and analyze the defect formation during friction stir welding based on coupled Eulerian Lagrangian method. The model is validated by comparing the estimated welding temperature, processed zone shape and void size with those obtained experimentally. The results compared indicate that the simulated temperature and the data measured are in good agreement with each other. In addition, the model can predict the plasticized zone shape and the presence of a void in the weld quite accurately. However, the void size is overestimated. The effects of welding parameters and tool pin profile are also analyzed. The results reveal that welding at low welding speed or high tool rotational speed could produce a smaller void. Moreover, compared to a smooth tool pin, a featured tool pin can enhance plastic flow in the weld and achieve defect-free weldment. The results are helpful for the optimization of the welding process and the design of welding tools.

Microstructure and mechanical characterization of friction stir welded high strength low alloy steels

Energy Technology Data Exchange (ETDEWEB)

Ramesh, R., E-mail: rameshsmit@gmail.com [Department of Mechanical Engineering, PSG College of Technology, Coimbatore 641004, Tamilnadu (India); Dinaharan, I., E-mail: dinaweld2009@gmail.com [Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park Kingsway Campus, Johannesburg 2006, Gauteng (South Africa); Kumar, Ravi, E-mail: nvrk@iitm.ac.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamilnadu (India); Akinlabi, E.T., E-mail: etakinlabi@uj.ac.za [Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park Kingsway Campus, Johannesburg 2006, Gauteng (South Africa)

2017-02-27

Friction stir welding (FSW) is a promising technique to join HSLA steels without the problems encountered during fusion based welding processes. In the present work, 3 mm thick HSLA plates were successfully welded using FSW. A tool made of tungsten-rhenium alloy was used in this work. The relationship between microstructure and tensile strength was studied under various welding conditions i.e. change in traverse speed (57–97 mm/min). The microstructure of the weld nugget revealed the presence of upper bainite and fine ferrite phases. The amount of upper bainite reduced with increase in traverse speed. EBSD images showed a reducing trend for grain size. The details of hardness, tensile strength and bending test were reported.

Microstructure and mechanical characterization of friction stir welded high strength low alloy steels

International Nuclear Information System (INIS)

Ramesh, R.; Dinaharan, I.; Kumar, Ravi; Akinlabi, E.T.

2017-01-01

Friction stir welding (FSW) is a promising technique to join HSLA steels without the problems encountered during fusion based welding processes. In the present work, 3 mm thick HSLA plates were successfully welded using FSW. A tool made of tungsten-rhenium alloy was used in this work. The relationship between microstructure and tensile strength was studied under various welding conditions i.e. change in traverse speed (57–97 mm/min). The microstructure of the weld nugget revealed the presence of upper bainite and fine ferrite phases. The amount of upper bainite reduced with increase in traverse speed. EBSD images showed a reducing trend for grain size. The details of hardness, tensile strength and bending test were reported.

Mechanical Property Analysis in the Retracted Pin-Tool (RPT) Region of Friction Stir Welded (FSW) Aluminum Lithium 2195

Science.gov (United States)

Ding, R. Jeffrey; Oelgoetz, Peter A.

1999-01-01

The "Auto-Adjustable Pin Tool for Friction Stir Welding", was developed at The Marshall Space Flight Center to address process deficiencies unique to the FSW process. The auto-adjustable pin tool, also called the retractable pin-tool (R.PT) automatically withdraws the welding probe of the pin-tool into the pin-tool's shoulder. The primary function of the auto-adjustable pin-tool is to allow for keyhole closeout, necessary for circumferential welding and localized weld repair, and, automated pin-length adjustment for the welding of tapered material thickness. An overview of the RPT hardware is presented. The paper follows with studies conducted using the RPT. The RPT was used to simulate two capabilities; welding tapered material thickness and closing out the keyhole in a circumferential weld. The retracted pin-tool regions in aluminum- lithium 2195 friction stir weldments were studied through mechanical property testing and metallurgical sectioning. Correlation's can be =de between retractable pin-tool programmed parameters, process parameters, microstructure, and resulting weld quality.

Effect of post weld heat treatment on tensile properties and microstructure characteristics of friction stir welded armour grade AA7075-T651 aluminium alloy

Directory of Open Access Journals (Sweden)

P. Sivaraj

2014-03-01

Full Text Available This paper reports the effects of post weld heat treatments, namely artificial ageing and solution treatment followed by artificial ageing, on microstructure and mechanical properties of 12 mm thick friction stir welded joints of precipitation hardenable high strength armour grade AA7075-T651 aluminium alloy. The tensile properties, such as yield strength, tensile strength, elongation and notch tensile strength, are evaluated and correlated with the microhardness and microstructural features. The scanning electron microscope is used to characterie the fracture surfaces. The solution treatment followed by ageing heat treatment cycle is found to be marginally beneficial in improving the tensile properties of friction stir welds of AA7075-T651 aluminium alloy.

Microstructure Characterization and Stress Corrosion Evaluation of Autogenous and Hybrid Friction Stir Welded Al-Cu-Li 2195 Alloy

Science.gov (United States)

Li, Zhixian; Arbegast, William J.; Meletis, Efstathios I.

1997-01-01

Friction stir welding process is being evaluated for application on the Al-Cu-Li 2195 Super-Light Weight External Tank of the Space Transportation System. In the present investigation Al-Cu-Li 2195 plates were joined by autogenous friction stir welding (FSW) and hybrid FSW (friction stir welding over existing variable polarity plasma arc weld). Optical microscopy and transmission electron microscopy (TEM) were utilized to characterize microstructures of the weldments processed by both welding methods. TEM observations of autogenous FSW coupons in the center section of the dynamically-recrystallized zone showed an equiaxed recrystallized microstructure with an average grain size of approx. 3.8 microns. No T(sub 1), precipitates were present in the above-mentioned zone. Instead, T(sub B) and alpha precipitates were found in this zone with a lower population. Alternate immersion, anodic polarization, constant load, and slow strain tests were carried out to evaluate the general corrosion and stress-corrosion properties of autogenous and hybrid FSW prepared coupons. The experimental results will be discussed.

Micro friction stir lap welding of AISI 430 ferritic stainless steel: a study on the mechanical properties, microstructure, texture and magnetic properties

Science.gov (United States)

Mostaan, Hossein; Safari, Mehdi; Bakhtiari, Arash

2018-04-01

In this study, the effect of friction stir welding of AISI 430 (X6Cr17, material number 1.4016) ferritic stainless steel is examined. Two thin sheets with dimensions of 0.4 × 50 × 200 mm3 are joined in lap configuration. Optical microscopy and field emission electron microscopy were used in order to microstructural evaluations and fracture analysis, respectively. Tensile test and microhardness measurements are employed in order to study the mechanical behaviors of welds. Also, vibrational sample magnetometry (VSM) is employed for characterizing magnetic properties of welded samples. Texture analysis is carried out in order to clarify the change mechanism of magnetic properties in the welded area. The results show that AISI 430 sheets are successfully joined considering both, the appearance of the welding bead and the strength of the welded joint. It is found that by friction stir welding of AISI 430 sheets, texture components with easy axes magnetization have been replaced by texture components with harder magnetization axes. VSM analysis showed that friction stir welding leads to increase in residual induction (Br) and coercivity (Hc). This increase is attributed to the grain refining due the friction stir welding and formation of texture components with harder axes of magnetizations.

Heat input effect of friction stir welding on aluminum alloy AA 6061-T6 welded joint

Czech Academy of Sciences Publication Activity Database

Sedmak, A.; Kumar, R.; Chattopadhyaya, S.; Hloch, Sergej; Tadić, S.; Djurdjević, A. A.; Čeković, I. R.; Dončeva, E.

2016-01-01

Roč. 20, č. 2 (2016), s. 637-641 ISSN 0354-9836 Institutional support: RVO:68145535 Keywords : friction stir welding * defect * heat input * maximum temperature Subject RIV: JQ - Machines ; Tools Impact factor: 1.093, year: 2016 http://www.doiserbia.nb.rs/img/doi/0354-9836/2016/0354-98361500147D.pdf

Ductile damage development in friction stir welded aluminum (AA2024) joints

DEFF Research Database (Denmark)

Nielsen, Kim Lau

2008-01-01

Ductile damage development in a friction stir welded aluminum joint subjected to tension is analyzed numerically by FE-analysis, based on a total Lagrangian formulation. An elastic-viscoplastic constitutive relation that accounts for nucleation and growth of microvoids is applied. Main focus...

Effect of tool rotational speed and penetration depth on dissimilar aluminum alloys friction stir spot welds

Directory of Open Access Journals (Sweden)

Joaquín M. Piccini

2017-03-01

Full Text Available In the last years, the automotive industry is looking for the use of aluminum parts in replace of steel parts in order to reduce the vehicles weight. These parts have to be joined, for instance, by welding processes. The more common welding process in the automotive industry is the Resistance Spot Welding (RSW technique. However, RSW of aluminum alloys has many disadvantages. Regarding this situation, a variant of the Friction Stir Welding process called Friction Stir Spot Welding (FSSW has been developed, showing a strong impact in welding of aluminum alloys and dissimilar materials in thin sheets. Process parameters affect the characteristics of the welded joints. However, the information available on this topic is scarce, particularly for dissimilar joints and thin sheets. The aim of this work was to study the effect of the rotational speed and the tool penetration depth on the characteristics of dissimilar FSS welded joints. Defects free joints have been achieved with higher mechanical properties than the ones reported. The maximum fracture load was 5800 N. It was observed that the effective joint length of the welded spots increased with the tool penetration depth, meanwhile the fracture load increased and then decreased. Finally, welding at 1200 RPM produced welded joints with lower mechanical properties than the ones achieved at 680 and 903 RPM.

Experimental and numerical investigation on under-water friction stir welding of armour grade AA2519-T87 aluminium alloy

OpenAIRE

Sree Sabari, S.; Malarvizhi, S.; Balasubramanian, V.; Madusudhan Reddy, G.

2016-01-01

Friction stir welding (FSW) is a promising welding process that can join age hardenable aluminium alloys with high joint efficiency. However, the thermal cycles experienced by the material to be joined during FSW resulted in the deterioration of mechanical properties due to the coarsening and dissolution of strengthening precipitates in the thermo-mechanical affected zone (TMAZ) and heat affected zone (HAZ). Under water friction stir welding (UWFSW) is a variant of FSW process which can maint...

High-Speed Friction Stir Welding of AA7075-T6 Sheet: Microstructure, Mechanical Properties, Micro-texture, and Thermal History

Science.gov (United States)

Zhang, Jingyi; Upadhyay, Piyush; Hovanski, Yuri; Field, David P.

2018-01-01

Friction stir welding (FSW) is a cost-effective and high-quality joining process for aluminum alloys (especially heat-treatable alloys) that is historically operated at lower joining speeds (up to hundreds of millimeters per minute). In this study, we present a microstructural analysis of friction stir welded AA7075-T6 blanks with high welding speeds up to 3 M/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. The higher welding speed results in narrower, stronger heat-affected zones (HAZs) and also higher hardness in the nugget zones. The material flow direction in the nugget zone is found to be leaning towards the welding direction as the welding speed increases. Results are coupled with welding parameters and thermal history to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high-speed processing.

Mechanical Behaviour Investigation Of Aluminium Alloy Tailor Welded Blank Developed By Using Friction Stir Welding Technique

Science.gov (United States)

Dwi Anggono, Agus; Sugito, Bibit; Hariyanto, Agus; Subroto; Sarjito

2017-10-01

The objective on the research was to investigate the mechanical properties and microstructure of tailor welded blank (TWB) made from AA6061-T6 and AA1100 using friction stir welding (FSW) process. Due to the dissimilar mechanical properties of the two aluminium alloys, microhardness test was conducted to measure the hardness distribution across the weld nugget. The mixing of two distinct materials was influenced by tool rotation speed. Therefore, microstructure analysis was carried out to investigate the grain size and shape. The grain size of AA6061-T6 has increased in the heat affected zone (HAZ) while for AA1100 has decreased. In the weld nugget, it has found a hook defects in the dissimilar aluminium joining. By using monotonic tensile load, the different weld line direction was observed with the expansion in tool rotation. The joints failure were consistently on the area of AA1100 series. Furthermore, two specimens were investigated, one through the dissimilar aluminium and the other through similiar material. Inspection of the weld nugget hardness was shown that nonhomogen material intermixing during the stiring process as confirmed by microhardness measurement.

On use of weld zone temperatures for online monitoring of weld quality in friction stir welding of naturally aged aluminium alloys

International Nuclear Information System (INIS)

Imam, Murshid; Biswas, Kajal; Racherla, Vikranth

2013-01-01

Highlights: • FSWs for 6063-T4 AA are done at different process parameters and sheet thicknesses. • Weld nugget zone and heat affected zone temperatures are monitored for each case. • Microstructural and mechanical characterisation of welds is done in all cases. • Weld ductility is found to be particularly sensitive to weld zone temperatures. • Strong correlation is found between WNZ and HAZ temperatures and weld properties. - Abstract: 6063-T4 aluminium alloy sheets of 3 and 6 mm thicknesses were friction stir butt welded using a square tool pin at a wide range of tool rotational speeds. Properties of obtained welds were characterised using tensile tests, optical micrographs, X-ray diffraction, and transmission electron microscopy. Shape, size, and distribution of precipitates in weld zones, and strength and ductility of welds were seen to directly correlate with peak temperatures in weld nugget and heat affected zones, independent of sheet thickness. In addition, fluctuations in measured temperature profiles, for 3 mm sheets, were seen to correlate with an increase in scatter of weld nugget zone properties for 3 mm sheets. Optimal weld strength and ductility were obtained for peak weld nugget zone temperatures of around 450 °C and corresponding peak heat affected zone temperatures of around 360–380 °C. Results obtained suggest that, at least for naturally aged aluminium alloys, nature of temperature evolution and magnitudes of peak temperatures in weld nugget and heat affected zones provide information on uniformity of properties in weld zones, overaging of heat affected zones, and formation of tunnel defects from improper material mixing at low weld zone temperatures

Effect of Pin Geometry on the Mechanical Strength of Friction-Stir-Welded Polypropylene Composite Plates

Science.gov (United States)

Kordestani, F.; Ashenai Ghasemi, F.; Arab, N. B. M.

2017-09-01

Friction stir welding (FSW) is a solid-state welding process, which has successfully been applied in aerospace and automotive industries for joining materials. The friction stir tool is the key element in the FSW process. In this study, the effect of four different tool pin geometries on the mechanical properties of two types of polypropylene composite plates, with 30% glass and carbon fiber, respectively, were investigated. For this purpose, four pins of different geometry, namely, a threaded-tapered pin, square pin, four-flute threaded pin, and threaded-tapered pin with a chamfer were made and used to carry out the butt welding of 5-mm-thick plates. The standard tensile and Izod impact tests were performed to evaluate the tensile strength and impact toughness of welded specimens. The results indicated that the threaded-tapered pin with a chamfer produced welds with a better surface appearance and higher tensile and impact strengths. The tests also showed that, with the threaded-tapered pin with a chamfer, the impact strength of the glass- and carbon-fiber composite welds were about 40 and 50%, respectively, of that of the base materials.

Microstructure and anisotropic mechanical behavior of friction stir welded AA2024 alloy sheets

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhihan [State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Li, Wenya, E-mail: liwy@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Li, Jinglong [State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Chao, Y.J. [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Vairis, A. [Mechanical Engineering Department, TEI of Crete, Heraklion, Crete 71004 (Greece)

2015-09-15

The anisotropic mechanical properties of friction stir welded (FSW) AA2024-T3 alloy joints were investigated based on the uniaxial tensile tests. The joint microstructure was examined by using electron back-scattered diffraction and transmission electron microscope. Results show that the evident anisotropic failure and yielding are present in the FSW joints. With the increase of loading angle from 0° to 90° the ultimate tensile strength and elongation of the specimens consistently decrease, or at first decrease and then increase, depending on the FSW process parameters. The specimen cut from the weld direction, i.e. a loading angle of 0°, exhibits the highest strength and elongation. - Highlights: • Microstructure and anisotropy of friction stir welded joints were studied. • The evident anisotropic failure and yielding are present in joints. • The lowest yield stress and UTS are at 45° and 60° loadings, respectively. • Rotation speed heavily impact on the anisotropy of joints.

Microstructure and anisotropic mechanical behavior of friction stir welded AA2024 alloy sheets

International Nuclear Information System (INIS)

Zhang, Zhihan; Li, Wenya; Li, Jinglong; Chao, Y.J.; Vairis, A.

2015-01-01

The anisotropic mechanical properties of friction stir welded (FSW) AA2024-T3 alloy joints were investigated based on the uniaxial tensile tests. The joint microstructure was examined by using electron back-scattered diffraction and transmission electron microscope. Results show that the evident anisotropic failure and yielding are present in the FSW joints. With the increase of loading angle from 0° to 90° the ultimate tensile strength and elongation of the specimens consistently decrease, or at first decrease and then increase, depending on the FSW process parameters. The specimen cut from the weld direction, i.e. a loading angle of 0°, exhibits the highest strength and elongation. - Highlights: • Microstructure and anisotropy of friction stir welded joints were studied. • The evident anisotropic failure and yielding are present in joints. • The lowest yield stress and UTS are at 45° and 60° loadings, respectively. • Rotation speed heavily impact on the anisotropy of joints

A study on microstructure and strain-hardening rate of friction stir welded Al-Mg-Si alloys using a weak beam technique

International Nuclear Information System (INIS)

Sukedai, E; Yokoyama, T

2012-01-01

Mechanical properties of a friction stir welded Al-Mg-Si (6061-T6Al) alloy are evaluated by a tensile test. It is found that the strain-hardening rate is higher than that of a base material. In order to investigate the origin, TEM observations have been performed about 4 kinds of materials; base- and friction stir welded-materials, and both materials deformed to 5 % strain by tension. There are not so large differences about dislocation density, size and density of precipitates and crystal defects between the base material and the friction stir welded-materials, but a significant decrease of grain-size in the friction stir welded-materials is recognized. These results suggest a dynamic recovery occurs during FSW process, and it is speculated that the recovery leads to the differences of yield stress and strain-hardening rate between both materials.

Effect of microstructural variation on the Cu/CK45 carbon steel friction weld joint

Energy Technology Data Exchange (ETDEWEB)

Lee, W.B.; Jung, S.B. [Advanced Materials and Process Research Center for IT, Sungkyunkwan Univ., Gyounggi-do (Korea)

2003-12-01

The mechanical properties of friction-welded pure Cu/CK45 carbon steel joints have been studied. The joint strength increased with increasing upset pressure till it reached a critical value. However, the joint strength was fixed at a low strength with increasing friction time, compared to that of the Cu base metal. The hardness near the interface at the Cu side was softer than that of the base metal due to the dynamically recrystallized and annealed grain. The width of the softened region became wider with increasing friction time and decreasing upset pressure. But the hardness of the CK45 carbon steel side showed a slightly higher value than that of the base metal. This result was explained by the formation of martensite structure at the CK45 carbon steel side during the welding process. (orig.)

Texture analysis of a friction stir welded ultrafine grained Al–Al{sub 2}O{sub 3} composite produced by accumulative roll-bonding

Energy Technology Data Exchange (ETDEWEB)

Shamanian, Morteza, E-mail: shamanian@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Mohammadnezhad, Mahyar [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Szpunar, Jerzy [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK S7N5A9 (Canada)

2014-12-05

Highlights: • Aluminum matrix composite was successfully bonded using friction stir welding. • After welding process the fraction of low angle boundary area rapidly decreases. • The grain growth in the NZ is related the increase of temperature during the FSW. • The aluminum matrix composite has a strong Rotated Cube texture. • The weld nugget has a Rotated Cube and shear texture. - Abstract: In recent years, several studies have been focused on friction stir welding of aluminum alloys, and some researchers have also been reported on welding of aluminum-based composites. In the present research, ultrafine grained sheets of aluminum matrix composite (Al–Al{sub 2}O{sub 3}) were produced by accumulative roll-bonding (ARB) technique. The aluminum composite sheets were then joined by friction stir welding. The present work describes the effect of the FSW process on the microstructure and crystallographic textures in the base metal and weld nugget. Electron backscattered diffraction (EBSD) results demonstrated the existence of different grain orientations within the weld nugget as compared to the base metal. Al composite plates have a Rotated Cube texture component. Moreover, in the nugget, grain structure with Rotated Cube and shear texture developed. Friction stir welding coarsened the grain size in the weld zone from the original grain size of 3–17 μm.

The Effect of Tool Profiles on Mechanical Properties of Friction Stir Welded Al5052 T-Joints.

Science.gov (United States)

Kim, Byeong-Jin; Bang, Hee-Seon; Bang, Han-Sur

2018-03-01

Al5052 T butt joints with two skins (5 mm) and one stringer (3 mm) has been successfully welded by friction stir welding (FSW). Notably, this paper has been investigated the effect of tool shape on welded formation mechanism and mechanical properties. The used shapes of tool pin are two types which are cylinder (type 1) and frustum (type 2). Dimension on two types of tool pin shape is respectively pin length of 4.7 mm and pin diameter of frustum type of top (5 mm) and bottom (3 mm). The results of experiment show that inner defects in FSWed T-joints increase significantly in accordance with traverse speed. The maximum tensile strength of welded joint fabricated using type 1 is equivalent to 85% that of the base metal, which is approximately 10% higher than that of type 2. Because welded joint of type 1 has more smoothly plastic flow in comparison with type 2. Consequently, the results show that type 1 is better appropriate for friction stir welded Al5052 T butt joints than type 2.

Optimizing friction stir weld parameters of aluminum and copper using conventional milling machine

Science.gov (United States)

Manisegaran, Lohappriya V.; Ahmad, Nurainaa Ayuni; Nazri, Nurnadhirah; Noor, Amirul Syafiq Mohd; Ramachandran, Vignesh; Ismail, Muhammad Tarmizizulfika; Ahmad, Ku Zarina Ku; Daruis, Dian Darina Indah

2018-05-01

The joining of two of any particular materials through friction stir welding (FSW) are done by a rotating tool and the work piece material that generates heat which causes the region near the FSW tool to soften. This in return will mechanically intermix the work pieces. The first objective of this study is to join aluminum plates and copper plates by means of friction stir welding process using self-fabricated tools and conventional milling machine. This study also aims to investigate the optimum process parameters to produce the optimum mechanical properties of the welding joints for Aluminum plates and Copper plates. A suitable tool bit and a fixture is to be fabricated for the welding process. A conventional milling machine will be used to weld the aluminum and copper. The most important parameters to enable the process are speed and pressure of the tool (or tool design and alignment of the tool onto the work piece). The study showed that the best surface finish was produced from speed of 1150 rpm and tool bit tilted to 3°. For a 200mm × 100mm Aluminum 6061 with plate thickness of 2 mm at a speed of 1 mm/s, the time taken to complete the welding is only 200 seconds or equivalent to 3 minutes and 20 seconds. The Copper plates was successfully welded using FSW with tool rotation speed of 500 rpm, 700 rpm, 900 rpm, 1150 rpm and 1440 rpm and with welding traverse rate of 30 mm/min, 60 mm/min and 90 mm/min. As the conclusion, FSW using milling machine can be done on both Aluminum and Copper plates, however the weld parameters are different for the two types of plates.

Friction stir weld-bonding defect inspection using phased array ultrasonic testing

NARCIS (Netherlands)

Fortunato, J.; Anand, C.; Braga, Daniel F.O.; Groves, R.M.; Moreira, P. M.G.P.; Infante, V

2017-01-01

Weight reduction is an important driver of the aerospace industry, which encourages the development of lightweight joining techniques to substitute rivet joints. Friction stir welding (FSW) is a solid-state process that enables the production of lighter joints with a small performance reduction

TEM analysis of a friction stir-welded butt joint of Al-Si-Mg alloys

International Nuclear Information System (INIS)

Cabibbo, M.; Meccia, E.; Evangelista, E.

2003-01-01

The microstructure evolution of a joint of Al-Si-Mg alloys A6056-T4 and A6056-T6 has been characterized by transmission electron microscopy (TEM). Metallurgical investigations, hardness and mechanical tests were also performed to correlate the TEM investigations to the mechanical properties of the produced friction stir-welded butt joint. After friction stir-welding thermal treatment has been carried out at 530 deg. C followed by ageing at 160 deg. C (T6). The base material (T4) and the heat-treated one (T6) were put in comparison showing a remarkable ductility reduction of the joint after T6 treatment

Nondestructive Evaluation of Friction Stir-Welded Aluminum Alloy to Coated Steel Sheet Lap Joint

Science.gov (United States)

Das, H.; Kumar, A.; Rajkumar, K. V.; Saravanan, T.; Jayakumar, T.; Pal, Tapan Kumar

2015-11-01

Dissimilar lap joints of aluminum sheet (AA 6061) of 2 mm thickness and zinc-coated steel sheet of 1 mm thickness were produced by friction stir welding with different combinations of rotational speed and travel speed. Ultrasonic C- and B-scanning, and radiography have been used in a complementary manner for detection of volumetric (cavity and flash) and planar (de bond) defects as the defects are in micron level. Advanced ultrasonic C-scanning did not provide any idea about the defects, whereas B-scanning cross-sectional image showed an exclusive overview of the micron-level defects. A digital x-ray radiography methodology is proposed for quality assessment of the dissimilar welds which provide three-fold increase in signal-to-noise ratio with improved defect detection sensitivity. The present study clearly shows that the weld tool rotational speed and travel speed have a decisive role on the quality of the joints obtained by the friction stir welding process. The suitability of the proposed NDE techniques to evaluate the joint integrity of dissimilar FSW joints is thus established.

Impact of friction stir welding on the microstructure of ODS steel

Energy Technology Data Exchange (ETDEWEB)

Dawson, H., E-mail: huwdawson@gmail.com [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Serrano, M. [Structural Materials Division, Technology Department, CIEMAT, Avda de la Complutense 40, 28040 Madrid (Spain); Cater, S.; Iqbal, N. [Friction and Forge Processes Department, Joining Technologies Group, TWI Technology Centre, Advanced Manufacturing Park, Wallis Way, Catcliffe, Rotherham S60 5TZ (United Kingdom); Almásy, L. [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, P.O. Box 49, H-1525 Budapest (Hungary); Tian, Q. [Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, P.O. Box 49, H-1525 Budapest (Hungary); Jimenez-Melero, E. [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Dalton Cumbrian Facility, The University of Manchester, Moor Row CA24 3HA (United Kingdom)

2017-04-01

We have assessed the impact of the welding parameters on the nano-sized oxide dispersion and the grain size in the matrix of an ODS steel after friction stir welding. Our results, based on combined small angle neutron scattering and electron microscopy, reveal a decrease in the volume fraction of the particles smaller than 80 nm in the welds, mainly due to particle agglomeration. The increase in tool rotation speed or decrease in transverse speed leads to a higher reduction in nano-sized particle fraction, and additionally to the occurrence of particle melting. The dependence of the average grain size in the matrix on the particle volume fraction follows a Zener pinning-type relationship. This result points to the principal role that the particles have in pinning grain boundary movement, and consequently in controlling the grain size during welding.

Impact of friction stir welding on the microstructure of ODS steel

Science.gov (United States)

Dawson, H.; Serrano, M.; Cater, S.; Iqbal, N.; Almásy, L.; Tian, Q.; Jimenez-Melero, E.

2017-04-01

We have assessed the impact of the welding parameters on the nano-sized oxide dispersion and the grain size in the matrix of an ODS steel after friction stir welding. Our results, based on combined small angle neutron scattering and electron microscopy, reveal a decrease in the volume fraction of the particles smaller than 80 nm in the welds, mainly due to particle agglomeration. The increase in tool rotation speed or decrease in transverse speed leads to a higher reduction in nano-sized particle fraction, and additionally to the occurrence of particle melting. The dependence of the average grain size in the matrix on the particle volume fraction follows a Zener pinning-type relationship. This result points to the principal role that the particles have in pinning grain boundary movement, and consequently in controlling the grain size during welding.

Joining of hybrid AA6063-6SiCp-3Grp composite and AISI 1030 steel by friction welding

Directory of Open Access Journals (Sweden)

N. Rajesh Jesudoss Hynes

2017-10-01

Full Text Available Joining of metals and aluminium hybrid metal matrix composites has significant applications in aviation, ship building and automotive industries. In the present work, investigation is carried out on Friction Welding of AISI 1030 steel and hybrid AA6063-6SiCp-3Grpcomposite, that are difficult to weld by fusion welding technique. Silicon carbide and graphite particle reinforced AA6063 matrix hybrid composite was developed successfully using stir casting method and the joining feasibility of AISI1030 steel with AA6063-6SiCp-3Grp hybrid composite was tried out by friction stud welding technique. During friction stage of welding process, the particulates (SiC & Graphite used for reinforcement, tend to increase the viscosity and lead to improper mixing of matrix and reinforcement. This eventually results in lower strength in dissimilar joints. To overcome this difficulty AA1100 interlayer is used while joining hybrid composite to AISI 1030 steel. Experimentation was carried out using Taguchi based design of experiments (DOE technique. Multiple regression methods were applied to understand the relationship between process parameters of the friction stud welding process. Micro structural examination reveals three separate zones namely fully plasticized zone, partially deformed zone and unaffected base material zone. Ultra fine dynamically recrystallized grains of about 341 nm were observed at the fully plasticized zone. EDX analysis confirms the presence of intermetallic compound Fe2Al5 at the joint interface. According to the experimental analysis using DOE, rotational speed and interlayer sheet thickness contribute about 39% and 36% respectively in determining the impact strength of the welded joints. It is found that joining with 0.5 mm interlayer sheet provides efficient joints. Developed regression model could be used to predict the axial shortening distance and impact strength of the welded joint with reasonable accuracy.

Global and Local Mechanical Properties and Microstructure of Friction Stir Welds with Dissimilar Materials and/or Thicknesses

NARCIS (Netherlands)

Zadpoor, A.A.; Sinke, J.; Benedictus, R.

2010-01-01

This article studies the properties of a wide range of friction-stir-welded joints with dissimilar aluminum alloys or thicknesses. Two aluminum alloys, namely, 2024-T3 and 7075-T6, are selected for the study and are welded in ten different combinations of alloys and thicknesses. The welding

Potential Applications of Friction Stir Welding to the Hydrogen Economy. Hydrogen Regional Infrastructure Program In Pennsylvania, Materials Task

Energy Technology Data Exchange (ETDEWEB)

Brendlinger, Jennifer [Concurrent Technologies Corporation, Johnstown, PA (United States)

2009-07-17

Friction Stir Welding (FSW) is a solid-state welding technique developed by The Welding Institute (TWI) of Cambridge, UK in the early 1990’s. The process uses a non-consumable rotating tool to develop frictional heat and plastically deform workpieces to be joined, resulting in a solid-state weld on the trailing side of the advancing tool. Since the materials to be joined are not melted, FSW results in a finer grain structure and therefore enhanced properties, relative to fusion welds. And unlike fusion welding, a relatively small number of key process parameters exist for FSW: tool rotational speed, linear weld velocity and force perpendicular to the joining surface. FSW is more energy efficient than fusion welding and can be accomplished in one or two passes, versus many more passes required of fusion welding thicker workpieces. Reduced post-weld workpiece distortion is another factor that helps to reduce the cost of FSW relative to fusion welding. Two primary areas have been identified for potential impact on the hydrogen economy: FSW of metallic pipes for hydrogen transmission and FSW of aluminum pressure vessels for hydrogen storage. Both areas have been under active development and are explored in this paper.

Friction Stir Welding: Standards and Specifications in Today's U.S. Manufacturing and Fabrication

Science.gov (United States)

Ding, Robert Jeffrey

2008-01-01

New welding and technology advancements are reflected in the friction stir welding (FSW) specifications used in the manufacturing sector. A lack of publicly available specifications as one of the reasons that the FSW process has not propagate through the manufacturing sectors. FSW specifications are an integral supporting document to the legal agreement written between two entities for deliverable items. Understanding the process and supporting specifications is essential for a successful FSW manufacturing operation. This viewgraph presentation provides an overview of current FSW standards in the industry and discusses elements common to weld specifications.

Anodising and corrosion resistance of AA 7050 friction stir welds

International Nuclear Information System (INIS)

Atz Dick, Pedro; Knörnschild, Gerhard H.; Dick, Luís F.P.

2017-01-01

Highlights: • Sulphuric Anodizing films of AA7050 friction stir welds are 25% thinner on the nugget zone. • Semicoherent MgZn_2 precipitates locally pin the formation of anodic oxide film. • Coarse Al_7Cu_2Fe precipitates anodize irregularly and produces locally thicker films. • Localized corrosion occurs preferentially on the nugget zone and is related to the thinner oxide film and irregular anodizing on stirring voids. - Abstract: The influence of friction stir welding on the sulphuric anodising and corrosion of AA7050 was studied in 0.1 M NaCl by the scanning vibrating electrode technique under simultaneous polarization. The oxide films obtained were characterized by scanning electron microscopy. The porous oxide films are up to 25% thicker on the thermomechanically and heat affected zones and 25% thinner on the nugget. This thinner defective oxide film explains the lower pitting resistance of the nugget zone. Individual pit current transients were indirectly determined from current maps. However, the calculated values are lower than expected, due to underestimation of electrolyte conductivity near pits.

Metallurgical examination of powder metallurgy uranium alloy welds

International Nuclear Information System (INIS)

Morrison, A.G.M.; Dobbins, A.G.; Holbert, R.K.; Doughty, M.W.

1986-01-01

Inertia welding provided a successful technique for joining full density, powder metallurgy uranium-6 wt pct niobium alloy. Initial joining attempts concentrated on the electron beam method, but this method failed to produce a sound weld. The electron beam welds and the inertia welds were evaluated by radiography and metallography. Electron beam welds were attempted on powder metallurgy plates which contained various levels of oxygen and nitrogen. All welds were porous. Sixteen inertia welds were made and all welds were radiographically sound. The tensile properties of the joints were found to be equivalent to the p/m base metal properties

A Microstructural Evaluation of Friction Stir Welded 7075 Aluminum Rolled Plate Heat Treated to the Semi-Solid State

Directory of Open Access Journals (Sweden)

Ava Azadi Chegeni

2018-01-01

Full Text Available Two rolled plates of 7075 aluminum alloy were used as starting material. The plates were welded using a simultaneous double-sided friction stir welding (FSW process. One way of obtaining feedstock materials for Semi-solid processing or thixoforming is via deformation routes followed by partial melting in the semi-solid state. As both the base plate materials and the friction weld area have undergone extensive deformation specimens were subjected to a post welding heat-treatment in the semi-solid range at a temperature of 628 °C, for 3 min in order to observe the induced microstructural changes. A comparison between the microstructural evolution and mechanical properties of friction stir welded plates was performed before and after the heat-treatment in the Base Metal (BM, the Heat Affected Zone (HAZ, the Thermomechanically Affected Zone (TMAZ and the Nugget Zone (NZ using optical microscopy, Scanning Electron microscopy (SEM and Vickers hardness tests. The results revealed that an extremely fine-grained structure, obtained in the NZ after FSW, resulted in a rise of hardness from the BM to the NZ. Furthermore, post welding heat-treatment in the semi-solid state gave rise to a consistent morphology throughout the material which was similar to microstructures obtained by the thixoforming process. Moreover, a drop of hardness was observed after heat treatment in all regions as compared to that in the welded microstructure.

Process Model for Friction Stir Welding

Science.gov (United States)

Adams, Glynn

1996-01-01

Friction stir welding (FSW) is a relatively new process being applied for joining of metal alloys. The process was initially developed by The Welding Institute (TWI) in Cambridge, UK. The FSW process is being investigated at NASA/MSEC as a repair/initial weld procedure for fabrication of the super-light-weight aluminum-lithium shuttle external tank. The FSW investigations at MSFC were conducted on a horizontal mill to produce butt welds of flat plate material. The weldment plates are butted together and fixed to a backing plate on the mill bed. A pin tool is placed into the tool holder of the mill spindle and rotated at approximately 400 rpm. The pin tool is then plunged into the plates such that the center of the probe lies at, one end of the line of contact, between the plates and the shoulder of the pin tool penetrates the top surface of the weldment. The weld is produced by traversing the tool along the line of contact between the plates. A lead angle allows the leading edge of the shoulder to remain above the top surface of the plate. The work presented here is the first attempt at modeling a complex phenomenon. The mechanical aspects of conducting the weld process are easily defined and the process itself is controlled by relatively few input parameters. However, in the region of the weld, plasticizing and forging of the parent material occurs. These are difficult processes to model. The model presented here addresses only variations in the radial dimension outward from the pin tool axis. Examinations of the grain structure of the weld reveal that a considerable amount of material deformation also occurs in the direction parallel to the pin tool axis of rotation, through the material thickness. In addition, measurements of the axial load on the pin tool demonstrate that the forging affect of the pin tool shoulder is an important process phenomenon. Therefore, the model needs to be expanded to account for the deformations through the material thickness and the

Characterization of Residual Stress as a Function of Friction Stir Welding Parameters in ODS Steel MA956

Science.gov (United States)

2013-06-01

dispersion strengthened - Eurofer steel ,” J. Nucl. Mater., vol. 416 , pp. 2229, Sep 1, 2011. [10] H. J. K. Lemmen and K. J. Sudmeijer, I, “Laser beam...Reynolds and W. Tang, “Structure, properties, and residual stress of 304L stainless steel friction stir welds,” Scr. Mater., vol. 48, pp. 12891294...OF RESIDUAL STRESS AS A FUNCTION OF FRICTION STIR WELDING PARAMETERS IN ODS STEEL MA956 by Martin S. Bennett June 2013 Thesis Advisor

Effect of water-cooling treatment times on properties of friction stir welded joints of 7N01-T4 aluminum alloy

Science.gov (United States)

Zhang, T. H.; Wang, Y.; Fang, X. F.; Liang, P.; Zhao, Y.; Li, Y. H.; Liu, X. M.

2018-02-01

Due to the deformation caused by residual stress in the welding process, welded components need treatment to reduce welding distortion. In this paper, several different times of flame-heating and water-cooling treatment were subjected to the friction stir welding joints of 15mm thick 7N01P-T4 aluminum alloy sheets to study the microstructure variation of friction stir welding joints of 7N01P-T4 aluminum alloy, and to analyze the effect on micro-hardness, tensile and fracture mechanical properties. This investigation will be helpful to optimize treatment methods and provide instruction on industrial production.

Very High Cycle Fatigue Crack Initiation Mechanism in Nugget Zone of AA 7075 Friction Stir Welded Joint

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Chao He

2017-01-01

Full Text Available Very high cycle fatigue behavior of nugget zone in AA 7075 friction stir welded joint was experimentally investigated using ultrasonic fatigue testing system (20 kHz to clarify the crack initiation mechanism. It was found that the fatigue strength of nugget zone decreased continuously even beyond 107 cycles with no traditional fatigue limits. Fatigue cracks initiated from the welding defects located at the bottom side of the friction stir weld. Moreover, a special semicircular zone could be characterized around the crack initiation site, of which the stress intensity factor approximately equaled the threshold of fatigue crack propagation rate. Finally, a simplified model was proposed to estimate the fatigue life by correlating the welding defect size and applied stress. The predicted results are in good agreement with the experimental results.

A preliminary investigation on microstructure and mechanical properties of dissimilar Al to Cu friction stir welds prepared using silver interlayer

Directory of Open Access Journals (Sweden)

Shailesh N. Pandya

2018-04-01

Full Text Available Due to its solid-state nature, friction stir welding (FSW process can be considered a better alternative for dissimilar welding metals. However, like fusion welding techniques, in friction stir welding growth of thick layers of brittle intermetallics - Cu9Al4 and CuAl2 is a significant issue. One solution to this problem is the use of the suitable interlayer material. Use of interlayer material modifies the joint microstructure with the replacement of thick, brittle intermetallics by more ductile intermetallics in a thin layer or particle form. The present study is a preliminary investigation about joining of AA6082-O to pure copper joints with and without silver (Ag wire interlayer. Friction stir welded joints were characterized regarding optical microscopy, X-Ray Diffraction (XRD analysis, microhardness measurement, tensile testing and Scanning Electron Microscopy (SEM based fractography. The Al-Cu weld prepared using silver interlayer was stronger than without it. The higher strength of the weld with silver interlayer is attributed to the formation of a composite type of structure with intercalation of more ductile Ag2Al intermetallics along with dispersion of Ag particles in stir zone.

High-Speed Friction Stir Welding of AA7075-T6 Sheet: Microstructure, Mechanical Properties, Micro-texture, and Thermal History

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jingyi; Upadhyay, Piyush; Hovanski, Yuri; Field, David P.

2017-11-20

Friction-stir-welding (FSW) is a cost-effective and high quality joining process for aluminum alloys (especially heat-treatable allo ys) that has been applied successfully in the aerospace industry. However, the full potential of FSW on more cost-sensitive applications is still limited by the production rate, namely the welding speed of the process. The majority of literature evaluating FSW of aluminum alloys is based on welds made in the range of welding speeds around hundreds of millimeters per minute, and only a handful are at a moderate speed of 1 m/min. In this study we present a microstructural analysis of friction stir welded AA7075-T6 blanks with welding speeds up to 3 m/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. Results are coupled with welding parameters to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high speed processing.

A study on friction welding of localized SPS5 spring steel

Energy Technology Data Exchange (ETDEWEB)

Jeong, S. U. [Gyeongsang National Univ., Jinju (Korea, Republic of)

2000-07-01

This thesis studied whether friction welding of SPS5, localized torsion bar material could be accomplished or not. And then optimum welding conditions were examined and leaded through tensile, impact, torsion and hardness test after postweld heat treatment of the actual field condition. Obtained results were as follows; linear relationship was existed between heating time and total upset, and a quadratic equation model could be made between tensile strength and heating time. Optimum welding conditions with fine structure were as follows in case total upset(U)= 8.5mm; the number of rotations(n)= 2,000 rpm, heating pressure(p{sub 1})= 80 MPa, upset pressure(P{sub 2})200 MPa, heating time(t{sub 1})= 4 sec, upset time(t{sub 2})= 3 sec.

Microstructure Stability During Creep of Friction Stir Welded AA2024-T3 Alloy

Science.gov (United States)

Regev, Michael; Rashkovsky, Tal; Cabibbo, Marcello; Spigarelli, Stefano

2018-01-01

The poor weldability of the AA2024 aluminum alloy limits its use in industrial applications. Because friction stir welding (FSW) is a non-fusion welding process, it seems to be a promising solution for welding this alloy. In the current study, FSW was applied to butt weld AA2024-T3 aluminum alloy plates. Creep tests were conducted at 250 and at 315 °C on both the parent material and the friction stir welded specimens. The microstructures of the welded and non-welded AA2024-T3 specimens before and after the creep tests were studied and compared. A comprehensive transmission electron microscopy study together with a high-resolution scanning electron microscopy study and energy-dispersive x-ray spectroscopy analysis was conducted to investigate the microstructure stability. The parent material seems to contain two kinds of Cu-rich precipitates—coarse precipitates of a few microns each and uniformly dispersed fine nanosized precipitates. Unlike the parent material, the crept specimens were found to contain the two kinds of precipitates mentioned above together with platelet-like precipitates. In addition, extensive decoration of the grain boundaries with precipitates was clearly observed in the crept specimens. Controlled aging experiments for up to 280 h at the relevant temperatures were conducted on both the parent material and the welded specimens in order to isolate the contribution of exposure to high temperatures to the microstructure changes. TEM study showed the development of dislocation networks into a cellular dislocation structure in the case of the parent metal. Changes in the dislocation structure as a function of the creep strain and the FSW process were recorded. A detailed creep data analysis was conducted, taking into account the instability of the microstructure.

Heat generation during plunge stage in friction stir welding

Directory of Open Access Journals (Sweden)

Veljić Darko M.

2013-01-01

Full Text Available This paper deals with the heat generation in the Al alloy Al2024-T3 plate under different rotating speeds and plunge speeds during the plunge stage of friction stir welding (FSW. A three-dimensional finite element model (FEM is developed in the commercial code ABAQUS/Explicit using the arbitrary Lagrangian-Eulerian formulation, the Johnson-Cook material law and Coulomb’s Law of friction. The heat generation in FSW can be divided into two parts: frictional heat generated by the tool and heat generated by material deformation near the pin and the tool shoulder region. Numerical results obtained in this work indicate a more prominent influence from the friction-generated heat. The slip rate of the tool relative to the workpiece material is related to this portion of heat. The material velocity, on the other hand, is related to the heat generated by plastic deformation. Increasing the plunging speed of the tool decreases the friction-generated heat and increases the amount of deformation-generated heat, while increasing the tool rotating speed has the opposite influence on both heat portions. Numerical results are compared with the experimental ones, in order to validate the numerical model, and a good agreement is obtained.

On the feasibility of BLISK produced by linear friction welding

Directory of Open Access Journals (Sweden)

Mateo, Antonio

2014-09-01

Full Text Available Friction welding technologies are solid-state processes that convert mechanical energy into heat at the joint to be welded. In the case of linear friction, interatomic diffusion takes place under compressive contact by rubbing one component across the face of the other. It is a relatively recent technology which has found important applications in the aeronautical sector. Specifically, it is applied by world leading aero-engine manufacturers for the fabrication of BLISK, a design where disk and blades are a single component. It is obvious that for such a critical function the reliability of linear friction welds must be totally guaranteed. The present work displays results concerning the characterization, both microstructural and mechanical, of a BLISK demonstrator designed for the intermediate pressure compressor of an aero-engine. Moreover, considering that the design constrains for disks and blades on the compressors are quite different, dissimilar titanium alloys were selected for each part in order to improve the BLISK in-service performance. The results establish that linear friction welding is a reliable process which can produce joints free of defects and with mechanical properties comparable to those of the corresponding base materials.Las técnicas de soldadura por fricción son procesos en estado sólido que convierten la energía mecánica en calor en la junta a soldar. En el caso de la soldadura por fricción lineal, la coalescencia tiene lugar bajo un contacto compresivo producido rozando un componente contra otro. Se trata de una tecnología relativamente reciente que ha encontrado importantes aplicaciones en el sector aeronáutico. En concreto, los mayores fabricantes mundiales de motores de aviones la emplean para la fabricación de BLISK, un diseño en que disco y álabes son una única pieza. Es obvio que para una función tan crítica la fiabilidad de las soldaduras debe estar totalmente garantizada. El presente trabajo

Rotary Friction Welding of Weight Heavy Alloy with Wrought AlMg3 Alloy for Subcaliber Ammunition

OpenAIRE

Olgierd Janusz Goroch; Zbigniew Gulbinowicz

2017-01-01

The results of studies concerning friction welding of Weight Heavy Alloy (WHA) with AlMg3 alloy are presented. The friction welding of density 17,5 Mg/m3 with aluminum alloy showed that it is possible to reach the joints with the strength exceeding the yield strength of wrought AlMg3 alloy. This strength looks to be promising from point of view of condition which have to be fulfilled in case of armor subcaliber ammunition, where WHA rods play the role Kinetic Energy Penetrators and aluminum i...

Mechanical evaluation of linear friction welds in titanium alloys through indentation experiments

International Nuclear Information System (INIS)