Weld Nugget Temperature Control in Thermal Stir Welding

Science.gov (United States)

Ding, R. Jeffrey (Inventor)

2014-01-01

A control system for a thermal stir welding system is provided. The control system includes a sensor and a controller. The sensor is coupled to the welding system's containment plate assembly and generates signals indicative of temperature of a region adjacent and parallel to the welding system's stir rod. The controller is coupled to the sensor and generates at least one control signal using the sensor signals indicative of temperature. The controller is also coupled to the welding system such that at least one of rotational speed of the stir rod, heat supplied by the welding system's induction heater, and feed speed of the welding system's weld material feeder are controlled based on the control signal(s).

Frequency response function (FRF) based updating of a laser spot welded structure

Science.gov (United States)

Zin, M. S. Mohd; Rani, M. N. Abdul; Yunus, M. A.; Sani, M. S. M.; Wan Iskandar Mirza, W. I. I.; Mat Isa, A. A.

2018-04-01

The objective of this paper is to present frequency response function (FRF) based updating as a method for matching the finite element (FE) model of a laser spot welded structure with a physical test structure. The FE model of the welded structure was developed using CQUAD4 and CWELD element connectors, and NASTRAN was used to calculate the natural frequencies, mode shapes and FRF. Minimization of the discrepancies between the finite element and experimental FRFs was carried out using the exceptional numerical capability of NASTRAN Sol 200. The experimental work was performed under free-free boundary conditions using LMS SCADAS. Avast improvement in the finite element FRF was achieved using the frequency response function (FRF) based updating with two different objective functions proposed.

STUDY OF ARC IMPULSE FREQUENCY EFFECT ON THE STRUCTURE AND PROPERTIES OF WELDED CONNECTION ELEMENTS IN ALUMINIUM PIPELINE SYSTEMS, MADE WITH MASTERTIG 3500

Directory of Open Access Journals (Sweden)

Mr. Pavel V. Bakhmatov

2016-06-01

Full Text Available Summary . The article focuses on the arc impulse frequency effect on the structure and properties of welded connections in aluminum pipeline systems hand-operated with argon-arc welding nonconsumable rod on MasterTig3500. It was revealed that the frequency of the welding current impulses plays an important role in the forming of the welded connection. The authors determined the optimal value of the welding current frequency significantly accelerating the welding process to ensure consistent quality of the weld. The authors detailed some features of cleaning assembly parts with a wire brush prior to welding process.

Micro-Welding of Copper Plate by Frequency Doubled Diode Pumped Pulsed Nd:YAG Laser

Science.gov (United States)

Nakashiba, Shin-Ichi; Okamoto, Yasuhiro; Sakagawa, Tomokazu; Takai, Sunao; Okada, Akira

A pulsed laser of 532 nm wavelength with ms range pulse duration was newly developed by second harmonic generation of diode pumped pulsed Nd:YAG laser. High electro-optical conversion efficiency more than 13% could be achieved, and 1.5 kW peak power green laser pulse was put in optical fiber of 100 μm in diameter. In micro- welding of 1.0 mm thickness copper plate, a keyhole welding was successfully performed by 1.0 kW peak power at spot diameter less than 200 μm. The frequency doubled pulsed laser improved the processing efficiency of copper welding, and narrow and deep weld bead was stably obtained.

Thermal Stir Welding: A New Solid State Welding Process

Science.gov (United States)

Ding, R. Jeffrey

2003-01-01

Thermal stir welding is a new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating, stirring and forging elements of the process are all independent of each other and are separately controlled. Furthermore, the heating element of the process can be either a solid-state process (such as a thermal blanket, induction type process, etc), or, a fusion process (YG laser, plasma torch, etc.) The separation of the heating, stirring, forging elements of the process allows more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

Welding method, and welding device for use therein, and method of analysis for evaluating welds

NARCIS (Netherlands)

Aendenroomer, A.J.; Den Ouden, G.; Xiao, Y.H.; Brabander, W.A.J.

1995-01-01

Described is a method of automatically welding pipes, comprising welding with a pulsation welding current and monitoring, by means of a sensor, the variations occurring in the arc voltage caused by weld pool oscillations. The occurrence of voltage variations with only frequency components below 100

Flaw-size measurement in a weld samples by ultrasonic frequency analysis

International Nuclear Information System (INIS)

Adler, L.; Cook, K.V.; Whaley, H.L. Jr.; McClung, R.W.

1975-01-01

An ultrasonic frequency-analysis technique was developed and applies to characterize flaws in an 8-in. (203-mm) thick heavy-section steel weld specimen. The technique applies a multitransducer system. The spectrum of the received broad-band signal is frequency analyzed at two different receivers for each of the flaws. From the two spectra, the size and orientation of the flaw are determined by the use of an analytic model proposed earlier. (auth)

High frequency electromagnetic processes in induction motors supplied from PWM inverters

Directory of Open Access Journals (Sweden)

Ioan Ţilea

2010-12-01

Full Text Available The paper presents the electromagnetic interference between induction motors and inverters when at high frequency electromagnetic process appears in induction motors having a parallel resonant effect because of parasitic capacitive coupling between windings and ground, using a numerical model in simulink and a high frequency induction motor equivalent circuit model this effect is shown.

Residual stress improvement for pipe weld by means of induction heating pre-flawed pipe

International Nuclear Information System (INIS)

Umemoto, T.; Yoshida, K.; Okamoto, A.

1980-01-01

The intergranular stress corrosion cracking (IGSCC) has been found in type 304 stainless steel piping of several BWR plants. It is already well known that IGSCC is most likely to occur when three essential factors, material sensitization, high tensile stress and corrosive environment, are present. If the welding residual stress is sufficiently high (200 to approximately 400 MPa) in the inside piping surface near the welded joint, then it may be one of the biggest contributors to IGSCC. If the residual stress is reduced or reversed by some way, the IGSCC will be effectively mitigated. In this paper a method to improve the residual stress named IHSI (Induction Heating Stress Improvement) is explained. IHSI aims to improve the condition of residual stress in the inside pipe surface using the thermal stress induced by the temperature difference in pipe wall, that is produced when the pipe is heated from the outside surface by an induction heating coil and cooled on the inside surface by water simultaneously. This method becomes more attractive when it can be successfully applied to in-service piping which might have some pre-flaw. In order to verify the validity of IHSI for such piping, some experiments and calculations using finite element method were conducted. These results are mainly discussed in this paper from the view-points of residual stress, flaw behaviour during IHSI and material deterioration. (author)

MODELLING AND SIMULATION OF HIGH FREQUENCY INVERTER FOR INDUCTION HEATING APPLICATION

OpenAIRE

SACHIN S. BANKAR; Dr. PRASAD M. JOSHI

2016-01-01

This paper presents modelling and simulation of high frequency inverter for induction heating applications. Induction heating has advantages like higher efficiency, controlled heating, safety and pollution free therefore this technology is used in industrial, domestic and medical applications. The high frequency full bridge inverter is used for induction heating, also MOSFET is used as a switching device for inverter and the control strategy used for inverter is Bipolar PWM control. The size ...

Laser welding engineering

International Nuclear Information System (INIS)

Bhieh, N. M.; El Eesawi, M. E.; Hashkel, A. E.

2007-01-01

Laser welding was in its early life used mainly for unusual applications where no other welding process would be suitable that was twenty five years ago. Today, laser welding is a fully developed part of the metal working industry, routinely producing welds for common items such as cigarette lighters, which springs, motor/transformer lamination, hermetic seals, battery and pacemaker cans and hybrid circuit packages. Yet very few manufacturing engineering have seriously considers employing lasers in their own operations. Why? There are many reasons, but a main one must be not acquainted with the operation and capabilities of a laser system. Other reasons, such as a relatively high initial cost and a concern about using lasers in the manufacturing environment, also are frequently cited, and the complexity of the component and flexibility of the light delivery system. Laser welding could be used in place of many different standard processes, such as resistance (spot or seam), submerged arc, RF induction, high-frequency resistance, ultrasonic and electronic and electron-beam. while each of these techniques has established an independent function in the manufacturing world, the flexible laser welding approach will operate efficiently and economically in many different applications. Its flexibility will even permit the welding system to be used for other machining function, such as drilling, scribing, sealing and serializing. In this article, we will look at how laser welding works and what benefits it can offer to manufacturing engineers. Some industry observers state that there are already 2,000 laser machine tools being used for cutting, welding and drilling and that the number could reach 30,000 over the next 15 years as manufacturing engineers become more aware of the capabilities of lasers [1). While most laser applications are dedicated to one product or process that involves high-volume, long-run manufacturing, the flexibility of a laser to supply energy to hard

Development of weld plugging for steam generator tubes of FBR

International Nuclear Information System (INIS)

Shimoyama, T.; Matsuyama, T.; Matsumoto, O.; Nagura, Y.; Nakamura, H.; Tohguchi, Y.; Kurokawa, M.; Fukada, T.

2002-01-01

This study was undertaken to develop a method of weld plugging of the heat-exchanger tubes of steam generator of Prototype FBR 'MONJU' in case these tubes are damaged for some reason. We studied mainly the shape of plug, welding procedure and effect of postweld heat treatment (PWHT). Evaporator tube sheet, tube and plug are made of 2-1/4Cr-1Mo steel and usually preheating and PWHT will be required for welding of this steel. The results of this study is as follows. 1) Plug was designed to make butt joint welding with grooved tube sheet around the tube hole to satisfy the requirements of plug designing, stress analysis, and good weldability. 2) TIG welding process was selected and certified its good weldability and good performance. 3) PWHT can be done by using high frequency induction heating method locally and also designing the plug to weld joint with tube sheet which was grooved around the tube hole. 4) Mock up test was done and it was certified that this plugging procedure has good weldability and good performance ability for Non Destructive Inspection. (author)

Influence of shielding gas pressure on welding characteristics in CO2 laser-MIG hybrid welding process

Science.gov (United States)

Chen, Yanbin; Lei, Zhenglong; Li, Liqun; Wu, Lin

2006-01-01

The droplet transfer behavior and weld characteristics have been investigated under different pressures of shielding gas in CO2 laser and metal inert/active gas (laser-MIG) hybrid welding process. The experimental results indicate that the inherent droplet transfer frequency and stable welding range of conventional MIG arc are changed due to the interaction between CO2 laser beam and MIG arc in laser-MIG hybrid welding process, and the shielding gas pressure has a crucial effect on welding characteristics. When the pressure of shielding gas is low in comparison with MIG welding, the frequency of droplet transfer decreases, and the droplet transfer becomes unstable in laser-MIG hybrid welding. So the penetration depth decreases, which shows the characteristic of unstable hybrid welding. However, when the pressure of shielding gas increases to a critical value, the hybrid welding characteristic is changed from unstable hybrid welding to stable hybrid welding, and the frequency of droplet transfer and the penetration depth increase significantly.

Enhanced UXO Discrimination Using Frequency-Domain Electromagnetic Induction

National Research Council Canada - National Science Library

Nelson, H. H; Steinhurst, D. A; Barrow, B; Bell, T; Khadar, N; SanFilipo, B; Won, I. J

2007-01-01

.... With support from the Environmental Security Technology Certification Program, we have developed a frequency-domain electromagnetic induction sensor array to extend the discrimination capabilities of the MTADS...

Grain refinement control in TIG arc welding

Science.gov (United States)

Iceland, W. F.; Whiffen, E. L. (Inventor)

1975-01-01

A method for controlling grain size and weld puddle agitation in a tungsten electrode inert gas welding system to produce fine, even grain size and distribution is disclosed. In the method the frequency of dc welding voltage pulses supplied to the welding electrode is varied over a preselected frequency range and the arc gas voltage is monitored. At some frequency in the preselected range the arc gas voltage will pass through a maximum. By maintaining the operating frequency of the system at this value, maximum weld puddle agitation and fine grain structure are produced.

Experience of Using Domestic High-Frequency Electric Welding Technology in Surgical Treatment of Patients with Abdominal Pathology

Directory of Open Access Journals (Sweden)

A.M. Babiy

2014-04-01

Full Text Available The article presents the experience of using electric welding technology of biological tissues with domestic high-frequency electrical generator EC 300 M1 in 176 patients at open and laparoscopic surgery for abdominal pathology. The analysis of findings showed that electric welding of living tissue provides reliable hemostasis, promotes tissue repair after their separation.

High resolution switching mode inductance-to-frequency converter with temperature compensation.

Science.gov (United States)

Matko, Vojko; Milanović, Miro

2014-10-16

This article proposes a novel method for the temperature-compensated inductance-to-frequency converter with a single quartz crystal oscillating in the switching oscillating circuit to achieve better temperature stability of the converter. The novelty of this method lies in the switching-mode converter, the use of additionally connected impedances in parallel to the shunt capacitances of the quartz crystal, and two inductances in series to the quartz crystal. This brings a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 10 and 40 °C. The oscillator switching method and the switching impedances connected to the quartz crystal do not only compensate for the crystal's natural temperature characteristics but also any other influences on the crystal such as ageing as well as from other oscillating circuit elements. In addition, the method also improves frequency sensitivity in inductance measurements. The experimental results show that through high temperature compensation improvement of the quartz crystal characteristics, this switching method theoretically enables a 2 pH resolution. It converts inductance to frequency in the range of 85-100 µH to 2-560 kHz.

High Resolution Switching Mode Inductance-to-Frequency Converter with Temperature Compensation

Directory of Open Access Journals (Sweden)

Vojko Matko

2014-10-01

Full Text Available This article proposes a novel method for the temperature-compensated inductance-to-frequency converter with a single quartz crystal oscillating in the switching oscillating circuit to achieve better temperature stability of the converter. The novelty of this method lies in the switching-mode converter, the use of additionally connected impedances in parallel to the shunt capacitances of the quartz crystal, and two inductances in series to the quartz crystal. This brings a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 10 and 40 °C. The oscillator switching method and the switching impedances connected to the quartz crystal do not only compensate for the crystal’s natural temperature characteristics but also any other influences on the crystal such as ageing as well as from other oscillating circuit elements. In addition, the method also improves frequency sensitivity in inductance measurements. The experimental results show that through high temperature compensation improvement of the quartz crystal characteristics, this switching method theoretically enables a 2 pH resolution. It converts inductance to frequency in the range of 85–100 µH to 2–560 kHz.

MFDC - technological improvement in resistance welding controls

Energy Technology Data Exchange (ETDEWEB)

Somani, A.K.; Naga Bhaskar, V.; Chandramouli, J.; Rameshwara Rao, A. [Nuclear Fuel Complex, Dept. of Atomic Energy, Hyderabad (India)

2008-07-01

Among the various Resistance Welding operations carried out in the production line of a fuel bundle end plug welding is the most critical operation. Welding controllers play a very vital role in obtaining consistent weld quality by regulating and controlling the weld current. Conventional mains synchronized welding controllers are at best capable of controlling the weld current at a maximum speed of the mains frequency. In view of the very short welding durations involved in the various stages of a fuel bundle fabrication, a need was felt for superior welding controllers. Medium Frequency Welding Controllers offer a solution to these limitations in addition to offering other advantages. Medium Frequency power sources offer precise welding current control as they regulate and correct the welding current faster, typically twenty times faster when operated at 1000Hz. An MFDC was employed on one of the welding machines and its performance was studied. This paper discusses about the various advantages of MFDCs with other controllers employed at NFC to end plug welding operation. (author)

Development of laser welded appendages to Zircaloy-4 fuel tubing (sheath/cladding)

Energy Technology Data Exchange (ETDEWEB)

Livingstone, S., E-mail: steve.livingstone@cnl.ca [Canadian Nuclear Laboratories Limited, Chalk River, ON, Canada K0J 1J0 (Canada); Xiao, L. [Canadian Nuclear Laboratories Limited, Chalk River, ON, Canada K0J 1J0 (Canada); Corcoran, E.C.; Ferrier, G.A.; Potter, K.N. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, Canada K7K 7B4 (Canada)

2015-04-01

Highlights: • Examines feasibility of laser welding appendages to Zr-4 tubing. • Laser welding minimizes the HAZ and removes toxic Be. • Mechanical properties of laser welds appear competitive with induction brazed joints. • Work appears promising and lays the foundation for further investigations. - Abstract: Laser welding is a potential alternative to the induction brazing process commonly used for appendage attachment in CANDU{sup ®} fuel fabrication that uses toxic Be as a filler metal, and creates multiple large heat affected zones in the sheath. For this work, several appendages were laser welded to tubing using different laser heat input settings and then examined with a variety of techniques: visual examination, metallography, shear strength testing, impact testing, and fracture surface analysis. Where possible, the examination results are contrasted against production induction brazed joints. The work to date looks promising for laser welded appendages. Further work on joint optimization, corrosion testing, irradiation testing, and post-irradiation examination will be performed in the future.

Modernization of gas-turbine engines with high-frequency induction motors

Science.gov (United States)

Abramovich, B. N.; Sychev, Yu A.; Kuznetsov, P. A.

2018-03-01

Main tendencies of growth of electric energy consumption in general and mining industries were analyzed in the paper. A key role of electric drive in this process was designated. A review about advantages and disadvantages of unregulated gearboxes with mechanical units that are commonly used in domestically produced gas-turbine engines was made. This review allows one to propose different gas-turbine engines modernization schemes with the help of PWM-driven high-frequency induction motors. Induction motors with the double rotor winding were examined. A simulation of high-frequency induction motors with double rotor windings in Matlab-Simulink software was carried out based on equivalent circuit parameters. Obtained characteristics of new motors were compared with serially produced analogues. After the simulation, results were implemented in the real prototype.

High-Precision Hysteresis Sensing of the Quartz Crystal Inductance-to-Frequency Converter.

Science.gov (United States)

Matko, Vojko; Milanović, Miro

2016-06-28

A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter hysteresis, as well as the temperature compensation of the quartz crystal and any other circuit element. Also used is the programmable timing control device that allows the selection of different oscillating frequencies. In the proposed programmable method two different inductances connected in series to the quartz crystal are switched in a short time sequence, compensating the crystal's natural temperature characteristics (in the temperature range between 0 and 50 °C). The procedure allows for the measurement of the converter hysteresis at various values of capacitance connected in parallel with the quartz crystal for the converter sensitivity setting at selected inductance. It, furthermore, enables the measurement of hysteresis at various values of inductance at selected parallel capacitance (sensitivity) connected to the quartz crystal. The article shows that the proposed hysteresis measurement of the converter, which converts the inductance in the range between 95 and 100 μH to a frequency in the range between 1 and 200 kHz, has only 7 × 10(-13) frequency instability (during the temperature change between 0 and 50 °C) with a maximum 1 × 10(-11) hysteresis frequency difference.

High-Precision Hysteresis Sensing of the Quartz Crystal Inductance-to-Frequency Converter

Directory of Open Access Journals (Sweden)

Vojko Matko

2016-06-01

Full Text Available A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter hysteresis, as well as the temperature compensation of the quartz crystal and any other circuit element. Also used is the programmable timing control device that allows the selection of different oscillating frequencies. In the proposed programmable method two different inductances connected in series to the quartz crystal are switched in a short time sequence, compensating the crystal’s natural temperature characteristics (in the temperature range between 0 and 50 °C. The procedure allows for the measurement of the converter hysteresis at various values of capacitance connected in parallel with the quartz crystal for the converter sensitivity setting at selected inductance. It, furthermore, enables the measurement of hysteresis at various values of inductance at selected parallel capacitance (sensitivity connected to the quartz crystal. The article shows that the proposed hysteresis measurement of the converter, which converts the inductance in the range between 95 and 100 μH to a frequency in the range between 1 and 200 kHz, has only 7 × 10−13 frequency instability (during the temperature change between 0 and 50 °C with a maximum 1 × 10−11 hysteresis frequency difference.

Numerical analysis of weld pool oscillation in laser welding

Energy Technology Data Exchange (ETDEWEB)

Cho, Jung Ho [Chungbuk National University, Cheongju (Korea, Republic of); Farson, Dave F [The Ohio State University, Columbus (United States); Hollis, Kendall; Milewski, John O. [Los Alamos National Laboratory, Los Alamos (United States)

2015-04-15

Volume of fluid (VOF) numerical simulation was used to investigate melt flow and volumetric oscillation of conduction-mode pulsed laser weld pools. The result is compared to high speed video stream of titanium laser spot welding experiment. The total simulation time is 10ms with the first 5 ms being heating and melting under constant laser irradiation and the remaining 5 ms corresponding to resolidification of the weld pool. During the melting process, the liquid pool did not exhibit periodic oscillation but was continually depressed by the evaporation recoil pressure. After the laser pulse, the weld pool was excited into volumetric oscillation by the release of pressure on its surface and oscillation of the weld pool surface was analyzed. The simulation model suggested adjusting thermal diffusivity to match cooling rate and puddle diameter during solidification which is distinguishable from previous weld pool simulation. The frequency continuously increased from several thousand cycles per second to tens of thousands of cycles per second as the weld pool solidified and its diameter decreased. The result is the first trial of investigation of small weld pool oscillation in laser welding although there have been several reports about arc welding.

Effects of induction heating parameters on controlling residual stress in intermediate size pipes

International Nuclear Information System (INIS)

Rybicki, E.F.; McGuire, P.A.

1981-01-01

Induction heating for stress improvement (IHSI) is a method for reducing the tensile weld induced stresses on the inner surfaces of the girth welded pipes. The process entails inductively heating the outside of a welded pipe while cooling the inner surface with flowing water. A 10-inch schedule 80 Type 304 stainless steel pipe was selected for this study. Residual stresses due to welding were first determined using a finite element computational model. 26 refs

Use of servo controlled weld head for end closure welding

Energy Technology Data Exchange (ETDEWEB)

Pathak, S.K.; Setty, D.S.; Rameswara Rao, A.; Hemantha Rao, G.V.S.; Jayaraj, R.N. [Nuclear Fuel Complex, Dept. of Atomic Energy, Hyderabad (India)

2010-07-01

In the PHWR fuel fabrication line resistance welding processes are used for joining various zirconium based alloy components to fuel tube of similar material. The quality requirement of these welding processes is very stringent and has to meet all the product requirements. At present these welding processes are being carried out by using standard resistance welding machines. In the resistance welding process in addition to current and time, force is one of the critical and important parameter, which influences the weld quality. At present advanced feed back type fast response medium frequency weld controllers are being used. This has upslope/down slope, constant and repetitive weld pattern selection features makes this critical welding process more reliable. Compared to weld controllers, squeeze force application devices are limited and normally standard high response pneumatic cylinders are used in the welding process. With this type of devices the force is constant during welding process and cannot be varied during welding process as per the material deformation characteristics. Similarly due to non-availability of feed back systems in the squeeze force application systems restricts the accuracy and quality of the welding process. In the present paper the influence of squeeze force pattern on the weld quality using advanced feed back type servo based force control system was studied. Different squeeze forces were used during pre and post weld heat periods along with constant force and compared with the weld quality. (author)

Measurement of flaw size in a weld sample by ultrasonic frequency analysis

International Nuclear Information System (INIS)

Whaley, H.L. Jr.; Adler, L.; Cook, K.V.; McClung, R.W.

1975-05-01

An ultrasonic frequency analysis technique has been developed and applied to the measurement of flaws in an 8-in.-thick heavy-section steel specimen belonging to the Pressure Vessel Research Committee program. Using the technique the flaws occurring in the weld area were characterized in quantitative terms of both dimension and orientation. Several modifications of the technique were made during the study to include the application of several transducers and to consider ultrasonic mode conversion. (U.S.)

Determination of High-Frequency d- and q-axis Inductances for Surface-Mounted Permanent-Magnet Synchronous Machines

DEFF Research Database (Denmark)

Lu, Kaiyuan; Vetuschi, M.; Rasmussen, Peter Omand

2010-01-01

This paper presents a reliable method for the experimental determination of high-frequency d- and q -axis inductances for surface-mounted permanent-magnet synchronous machines (SMPMSMs). Knowledge of the high-frequency d- and q-axis inductances plays an important role in the efficient design...... of sensorless controllers using high-frequency signal injection techniques. The proposed method employs a static locked-rotor test using an ac +dc power supply. By injecting a high-frequency rotating voltage vector into the machine, the d- and q-axis inductances may simultaneously be determined with no need...

Frequency Splitting Analysis and Compensation Method for Inductive Wireless Powering of Implantable Biosensors.

Science.gov (United States)

Schormans, Matthew; Valente, Virgilio; Demosthenous, Andreas

2016-08-04

Inductive powering for implanted medical devices, such as implantable biosensors, is a safe and effective technique that allows power to be delivered to implants wirelessly, avoiding the use of transcutaneous wires or implanted batteries. Wireless powering is very sensitive to a number of link parameters, including coil distance, alignment, shape, and load conditions. The optimum drive frequency of an inductive link varies depending on the coil spacing and load. This paper presents an optimum frequency tracking (OFT) method, in which an inductive power link is driven at a frequency that is maintained at an optimum value to ensure that the link is working at resonance, and the output voltage is maximised. The method is shown to provide significant improvements in maintained secondary voltage and system efficiency for a range of loads when the link is overcoupled. The OFT method does not require the use of variable capacitors or inductors. When tested at frequencies around a nominal frequency of 5 MHz, the OFT method provides up to a twofold efficiency improvement compared to a fixed frequency drive. The system can be readily interfaced with passive implants or implantable biosensors, and lends itself to interfacing with designs such as distributed implanted sensor networks, where each implant is operating at a different frequency.

Frequency Splitting Analysis and Compensation Method for Inductive Wireless Powering of Implantable Biosensors

Directory of Open Access Journals (Sweden)

Matthew Schormans

2016-08-01

Full Text Available Inductive powering for implanted medical devices, such as implantable biosensors, is a safe and effective technique that allows power to be delivered to implants wirelessly, avoiding the use of transcutaneous wires or implanted batteries. Wireless powering is very sensitive to a number of link parameters, including coil distance, alignment, shape, and load conditions. The optimum drive frequency of an inductive link varies depending on the coil spacing and load. This paper presents an optimum frequency tracking (OFT method, in which an inductive power link is driven at a frequency that is maintained at an optimum value to ensure that the link is working at resonance, and the output voltage is maximised. The method is shown to provide significant improvements in maintained secondary voltage and system efficiency for a range of loads when the link is overcoupled. The OFT method does not require the use of variable capacitors or inductors. When tested at frequencies around a nominal frequency of 5 MHz, the OFT method provides up to a twofold efficiency improvement compared to a fixed frequency drive. The system can be readily interfaced with passive implants or implantable biosensors, and lends itself to interfacing with designs such as distributed implanted sensor networks, where each implant is operating at a different frequency.

[New welding processes and health effects of welding].

Science.gov (United States)

La Vecchia, G Marina; Maestrelli, Piero

2011-01-01

This paper describes some of the recent developments in the control technology to enhance capability of Pulse Gas Metal Arc Welding. Friction Stir Welding (FSW) processing has been also considered. FSW is a new solid-state joining technique. Heat generated by friction at the rotating tool softens the material being welded. FSW can be considered a green and energy-efficient technique without deleterious fumes, gas, radiation, and noise. Application of new welding processes is limited and studies on health effects in exposed workers are lacking. Acute and chronic health effects of conventional welding have been described. Metal fume fever and cross-shift decline of lung function are the main acute respiratory effects. Skin and eyes may be affected by heat, electricity and UV radiations. Chronic effects on respiratory system include chronic bronchitis, a benign pneumoconiosis (siderosis), asthma, and a possible increase in the incidence of lung cancer. Pulmonary infections are increased in terms of severity, duration, and frequency among welders.

Ultrasonic Stir Welding

Science.gov (United States)

Nabors, Sammy

2015-01-01

NASA Marshall Space Flight Center (MSFC) developed Ultrasonic Stir Welding (USW) to join large pieces of very high-strength metals such as titanium and Inconel. USW, a solid-state weld process, improves current thermal stir welding processes by adding high-power ultrasonic (HPU) energy at 20 kHz frequency. The addition of ultrasonic energy significantly reduces axial, frictional, and shear forces; increases travel rates; and reduces wear on the stir rod, which results in extended stir rod life. The USW process decouples the heating, stirring, and forging elements found in the friction stir welding process allowing for independent control of each process element and, ultimately, greater process control and repeatability. Because of the independent control of USW process elements, closed-loop temperature control can be integrated into the system so that a constant weld nugget temperature can be maintained during welding.

Energy saving work of frequency controlled induction cage machine

Energy Technology Data Exchange (ETDEWEB)

Gnacinski, P. [Gdynia Maritime University, Department of Ship Electrical Power Engineering, Morska Str. 8, 81-225 Gdynia (Poland)]. E-mail: piotrg@am.gdynia.pl

2007-03-15

Energy saving work, understood as lowering the supply voltage when load torque is much less than rated, is one way of reducing power losses in an induction cage machine working with a variable load. Reduction in power losses also affects the thermal properties of an induction machine because the energy saving work allows the temperature rise of the windings to decrease. Thanks to a lower temperature of the windings, the same load torque can be carried by a machine of less rated power. The ability of energy saving work to reduce the temperature of windings depends on the thermal properties of an induction machine, which are different in the case of a machine with foreign ventilation and its own ventilation. This paper deals with the thermal effect of energy saving work on a frequency controlled induction cage machine. A comparison of the properties of a machine with its own and outside ventilation is presented. The results of the investigations are shown for a 3 kW induction cage machine with the two previously mentioned ways of ventilation: one provided with a fan placed on a shaft and the other provided with a fan driven by an auxiliary motor.

Energy saving work of frequency controlled induction cage machine

International Nuclear Information System (INIS)

Gnacinski, P.

2007-01-01

Energy saving work, understood as lowering the supply voltage when load torque is much less than rated, is one way of reducing power losses in an induction cage machine working with a variable load. Reduction in power losses also affects the thermal properties of an induction machine because the energy saving work allows the temperature rise of the windings to decrease. Thanks to a lower temperature of the windings, the same load torque can be carried by a machine of less rated power. The ability of energy saving work to reduce the temperature of windings depends on the thermal properties of an induction machine, which are different in the case of a machine with foreign ventilation and its own ventilation. This paper deals with the thermal effect of energy saving work on a frequency controlled induction cage machine. A comparison of the properties of a machine with its own and outside ventilation is presented. The results of the investigations are shown for a 3 kW induction cage machine with the two previously mentioned ways of ventilation: one provided with a fan placed on a shaft and the other provided with a fan driven by an auxiliary motor

MAGNETIC ARC WELDING STABILIZATION USING NON-CONSUMABLE ELECTRODE

Directory of Open Access Journals (Sweden)

Павло Юрійович Сидоренко

2017-06-01

Full Text Available Results of development torch to magnetically operated   welding arc are defined. Changing the design of the electrode unit is provided the ability to create within the area of the arc magnetic field and induction given configuration without additional equipment. The features of the arc in an axial magnetic field which make it possible to avoid the welding process of unsteady abnormalities resulted in the inappropriate formation of defects in welds. Significant increase in the depth of  weld penetration is connected with the more concentrated magnetically operated   welding arc transmission energy to the product. It is concluded about the feasibility of using a designed torch for the implementation of modern technological processes non-consumable electrode welding.

Building Quakes: Detection of Weld Fractures in Buildings using High-Frequency Seismic Techniques

Science.gov (United States)

Heckman, V.; Kohler, M. D.; Heaton, T. H.

2009-12-01

Catastrophic fracture of welded beam-column connections in buildings was observed in the Northridge and Kobe earthquakes. Despite the structural importance of such connections, it can be difficult to locate damage in structural members underneath superficial building features. We have developed a novel technique to locate fracturing welds in buildings in real time using high-frequency information from seismograms. Numerical and experimental methods were used to investigate an approach for detecting the brittle fracture of welds of beam-column connections in instrumented steel moment-frame buildings through the use of time-reversed Green’s functions and wave propagation reciprocity. The approach makes use of a prerecorded catalogue of Green’s functions for an instrumented building to detect high-frequency failure events in the building during a later earthquake by screening continuous data for the presence of one or more of the events. This was explored experimentally by comparing structural responses of a small-scale laboratory structure under a variety of loading conditions. Experimentation was conducted on a polyvinyl chloride frame model structure with data recorded at a sample rate of 2000 Hz using piezoelectric accelerometers and a 24-bit digitizer. Green’s functions were obtained by applying impulsive force loads at various locations along the structure with a rubber-tipped force transducer hammer. We performed a blind test using cross-correlation techniques to determine if it was possible to use the catalogue of Green’s functions to pinpoint the absolute times and locations of subsequent, induced failure events in the structure. A finite-element method was used to simulate the response of the model structure to various source mechanisms in order to determine the types of elastic waves that were produced as well as to obtain a general understanding of the structural response to localized loading and fracture.

Electromagnetic induction imaging with a radio-frequency atomic magnetometer

Energy Technology Data Exchange (ETDEWEB)

Deans, Cameron; Marmugi, Luca, E-mail: l.marmugi@ucl.ac.uk; Hussain, Sarah; Renzoni, Ferruccio [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2016-03-07

We report on a compact, tunable, and scalable to large arrays imaging device, based on a radio-frequency optically pumped atomic magnetometer operating in magnetic induction tomography modality. Imaging of conductive objects is performed at room temperature, in an unshielded environment and without background subtraction. Conductivity maps of target objects exhibit not only excellent performance in terms of shape reconstruction but also demonstrate detection of sub-millimetric cracks and penetration of conductive barriers. The results presented here demonstrate the potential of a future generation of imaging instruments, which combine magnetic induction tomography and the unmatched performance of atomic magnetometers.

Welding abilities of UFG metals

Science.gov (United States)

Morawiński, Łukasz; Chmielewski, Tomasz; Olejnik, Lech; Buffa, Gianluca; Campanella, Davide; Fratini, Livan

2018-05-01

Ultrafine Grained (UFG) metals are characterized by an average grain size of welded joints with similar properties to the base of UFG material are crucial for the production of finished engineering components. Conventional welding methods based on local melting of the joined edges cannot be used due to the UFG microstructure degradation caused by the heat occurrence in the heat affected zone. Therefore, the possibility of obtaining UFG materials joints with different shearing plane (SP) positions by means of friction welded processes, which do not exceed the melting temperature during the process, should be investigated. The article focuses on the Linear Friction Welding (LFW) method, which belongs to innovative welding processes based on mixing of the friction-heated material in the solid state. LFW is a welding process used to joint bulk components. In the process, the friction forces work due to the high frequency oscillation and the pressure between the specimens is converted in thermal energy. Character and range of recrystallization can be controlled by changing LFW parameters. Experimental study on the welded UFG 1070 aluminum alloy by means of FLW method, indicates the possibility of reducing the UFG structure degradation in the obtained joint. A laboratory designed LFW machine has been used to weld the specimens with different contact pressure and oscillation frequency.

Measuring weld heat to evaluate weld integrity

Energy Technology Data Exchange (ETDEWEB)

Schauder, V., E-mail: schauder@hks-prozesstechnik.de [HKS-Prozesstechnik GmbH, Halle (Germany)

2015-11-15

Eddy current and ultrasonic testing are suitable for tube and pipe mills and have been used for weld seam flaw detection for decades, but a new process, thermography, is an alternative. By measuring the heat signature of the weld seam as it cools, it provides information about weld integrity at and below the surface. The thermal processes used to join metals, such as plasma, induction, laser, and gas tungsten arc welding (GTAW), have improved since they were developed, and they get better with each passing year. However, no industrial process is perfect, so companies that conduct research in flaw detection likewise continue to develop and improve the technologies used to verify weld integrity: ultrasonic testing (UT), eddy current testing (ET), hydrostatic, X-ray, magnetic particle, and liquid penetrant are among the most common. Two of these are used for verifying the integrity of the continuous welds such as those used on pipe and tube mills: UT and ET. Each uses a transmitter to send waves of ultrasonic energy or electrical current through the material and a receiver (probe) to detect disturbances in the flow. The two processes often are combined to capitalize on the strengths of each. While ET is good at detecting flaws at or near the surface, UT penetrates the material, detecting subsurface flaws. One drawback is that sound waves and electrical current waves have a specific direction of travel, or an alignment. A linear defect that runs parallel to the direction of travel of the ultrasonic sound wave or a flaw that is parallel to the coil winding direction of the ET probe can go undetected. A second drawback is that they don't detect cold welds. An alternative process, thermography, works in a different fashion: It monitors the heat of the material as the weld cools. Although it measures the heat at the surface, the heat signature provides clues about cooling activity deep in the material, resulting in a thorough assessment of the weld's integrity It

Solid State Welding Development at Marshall Space Flight Center

Science.gov (United States)

Ding, Robert J.; Walker, Bryant

2012-01-01

What is TSW and USW? TSW is a solid state weld process consisting of an induction coil heating source, a stir rod, and non-rotating containment plates Independent heating, stirring and forging controls Decouples the heating, stirring and forging process elements of FSW. USW is a solid state weld process consisting of an induction coil heating source, a stir rod, and a non-rotating containment plate; Ultrasonic energy integrated into non-rotating containment plate and stir rod; Independent heating, stirring and forging controls; Decouples the heating, stirring and forging process elements of FSW.

Optimization of vibratory welding process parameters using response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Singh, Pravin Kumar; Kumar, S. Deepak; Patel, D.; Prasad, S. B. [National Institute of Technology Jamshedpur, Jharkhand (India)

2017-05-15

The current investigation was carried out to study the effect of vibratory welding technique on mechanical properties of 6 mm thick butt welded mild steel plates. A new concept of vibratory welding technique has been designed and developed which is capable to transfer vibrations, having resonance frequency of 300 Hz, into the molten weld pool before it solidifies during the Shielded metal arc welding (SMAW) process. The important process parameters of vibratory welding technique namely welding current, welding speed and frequency of the vibrations induced in molten weld pool were optimized using Taguchi’s analysis and Response surface methodology (RSM). The effect of process parameters on tensile strength and hardness were evaluated using optimization techniques. Applying RSM, the effect of vibratory welding parameters on tensile strength and hardness were obtained through two separate regression equations. Results showed that, the most influencing factor for the desired tensile strength and hardness is frequency at its resonance value, i.e. 300 Hz. The micro-hardness and microstructures of the vibratory welded joints were studied in detail and compared with those of conventional SMAW joints. Comparatively, uniform and fine grain structure has been found in vibratory welded joints.

Estimation and control of droplet size and frequency in projected spray mode of a gas metal arc welding (GMAW) process.

Science.gov (United States)

Anzehaee, Mohammad Mousavi; Haeri, Mohammad

2011-07-01

New estimators are designed based on the modified force balance model to estimate the detaching droplet size, detached droplet size, and mean value of droplet detachment frequency in a gas metal arc welding process. The proper droplet size for the process to be in the projected spray transfer mode is determined based on the modified force balance model and the designed estimators. Finally, the droplet size and the melting rate are controlled using two proportional-integral (PI) controllers to achieve high weld quality by retaining the transfer mode and generating appropriate signals as inputs of the weld geometry control loop. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Determination of the High Frequency Inductance Profile of Surface Mounted Permanent Magnet Synchronous Motors

DEFF Research Database (Denmark)

Lu, Kaiyuan; Rasmussen, Peter Omand; Ritchie, Ewen

2008-01-01

) synchronous motors. This paper presents an AC+DC measurement method for determination of the d-axis and q-axis high frequency inductance profiles of SMPM synchronous motors. This method uses DC currents to set a desired magnetic working point on the motor laminations, and then superimpose balanced small AC......Accurate knowledge of the high frequency inductance profile plays an important role in many designs of sensorless controllers for Surface inductance. A special algorithm is used to decouple the cross-coupling effects between the d-axis and the q-axis, which allows Mounted Permanent Magnet (SMPM...... signals to measure the incremental a separate determination of the d, q inductance profiles as functions of the d, q currents. Experimental results on a commercial SMPM motor using the proposed method are presented in this paper....

Feedback control of laser welding based on frequency analysis of light emissions and adaptive beam shaping

Czech Academy of Sciences Publication Activity Database

Mrňa, Libor; Šarbort, Martin; Řeřucha, Šimon; Jedlička, Petr

2012-01-01

Roč. 39, NOV (2012), s. 784-791 ISSN 1875-3892. [LANE 2012. Laser Assisted Net Shape Engineering /7./ International Conference on Photonic Technologies. Fürth, 12.11.2012-15.12.2012] Institutional support: RVO:68081731 Keywords : laser welding * feedback control * frequency analysis * adaptive beam shaping Subject RIV: BH - Optics, Masers, Lasers

Model of inductive plasma production assisted by radio-frequency wave in tokamaks

International Nuclear Information System (INIS)

Hasegawa, Makoto; Hanada, Kazuaki; Sato, Kohnosuke

2007-01-01

For initial plasma production, an induction electric field generated by applying voltage to a poloidal field (PF) coil system is used to produce a Townsend avalanche breakdown. When the avalanche margins are small, as for the International Thermonuclear Experimental Reactor (ITER) in which the induction electric field is about 0.3 V/m, the assistance of radio-frequency waves (RF) is provided to reduce the induction electric field required for reliable breakdown. However, the conditions of RF-assisted breakdown are not clear. Here, the effects of both RF and induction electric field on the RF-assisted breakdown are evaluated considering the electron loss. When traveling loss is the dominant loss, a simple model of an extended Townsend avalanche is proposed. In this model, the induction electric field required for RF-assisted breakdown can be decreased to half that required for induction breakdown. (author)

State-space modeling of the radio frequency inductively-coupled plasma generator

International Nuclear Information System (INIS)

Dewangan, Rakesh Kumar; Punjabi, Sangeeta B; Mangalvedekar, H A; Lande, B K; Joshi, N K; Barve, D N

2010-01-01

Computational fluid dynamics models of RF-ICP are useful in understanding the basic transport phenomenon in an ICP torch under a wide variety of operating conditions. However, these models lack the ability to evaluate the effects of the plasma condition on the RF generator. In this paper, simulation of an induction plasma generator has been done using state space modelling by considering inductively coupled plasma as a part of RF network .The time dependent response of the RF-ICP generator circuit to given input excitation has been computed by extracting the circuit's state-space variables and their constraint matrices. MATLAB 7.1 software has been used to solve the state equations. The values of RF coil current, frequency and plasma power has been measured experimentally also at different plate bias voltage. The simulated model is able to predict RF coil current, frequency, plasma power, overall efficiency of the generator. The simulated and measured values are in agreement with each other. This model can prove useful as a design tool for the Induction plasma generator.

A study of weld quality in ultrasonic spot welding of similar and dissimilar metals

International Nuclear Information System (INIS)

Al-Sarraf, Z; Lucas, M

2012-01-01

Several difficulties are faced in joining thinner sheets of similar and dissimilar materials from fusion welding processes such as resistance welding and laser welding. Ultrasonic metal welding overcomes many of these difficulties by using high frequency vibration and applied pressure to create a solid-state weld. Ultrasonic metal welding is an effective technique in joining small components, such as in wire bonding, but is also capable of joining thicker sheet, depending on the control of welding conditions. This study presents the design, characterisation and test of a lateral-drive ultrasonic metal welding device. The ultrasonic welding horn is modelled using finite element analysis and its vibration behaviour is characterised experimentally to ensure ultrasonic energy is delivered to the weld coupon. The welding stack and fixtures are then designed and mounted on a test machine to allow a series of experiments to be conducted for various welding and ultrasonic parameters. Weld strength is subsequently analysed using tensile-shear tests. Control of the vibration amplitude profile through the weld cycle is used to enhance weld strength and quality, providing an opportunity to reduce part marking. Optical microscopic examination and scanning electron microscopy (SEM) were employed to investigate the weld quality. The results show how the weld quality is particularly sensitive to the combination of clamping force and vibration amplitude of the welding tip.

Ultrasonic testing of austenitic stainless steel welds

International Nuclear Information System (INIS)

Nishino, Shunichi; Hida, Yoshio; Yamamoto, Michio; Ando, Tomozumi; Shirai, Tasuku.

1982-05-01

Ultrasonic testing of austenitic stainless steel welds has been considered difficult because of the high noise level and remarkable attenuation of ultrasonic waves. To improve flaw detectability in this kind of steel, various inspection techniques have been studied. A series of tests indicated: (1) The longitudinal angle beam transducers newly developed during this study can detect 4.8 mm dia. side drilled holes in dissimilar metal welds (refraction angle: 55 0 from SUS side, 45 0 from CS side) and in cast stainless steel welds (refraction angle: 45 0 , inspection frequency: 1 MHz). (2) Cracks more than 5% t in depth in the heat affected zones of fine-grain stainless steel pipe welds can be detected by the 45 0 shear wave angle beam method (inspection frequency: 2 MHz). (3) The pattern recognition method using frequency analysis technology was presumed useful for discriminating crack signals from spurious echoes. (author)

Instant centre frequency at anaesthetic induction--a new way to analyse sympathovagal balance.

Science.gov (United States)

de Souza Neto, Edmundo Pereira; Cerutti, Catherine; Loufoua, Joseph; Saroul, Christine; Chiari, Pascal; Custaud, Marc-Antoine; Lehot, Jean-Jacques

2003-02-01

The instant centre frequency (ICF) of RR interval has been proposed as a global index to analyse the sympathovagal interaction in the heart. The aim of this study was to assess the ICF during anaesthesia to test if it can reliably capture the neural control of the cardiovascular system. Twenty-four ASA II or III patients scheduled for cardiac surgery were included in the study. They were allocated in two groups: control, no treatment (group 1, n = 12), and beta-adrenergic blockade by atenolol (group 2, n = 12). Spectra of pulse interval series were computed with a time-frequency method and they were divided into: very low frequency (VLF, 0.000-0.040 Hz), low frequency (LF, 0.050-0.150 Hz) and high frequency (HF, 0.160-0.500 Hz). Normalized power was obtained by dividing the cumulative power within each frequency band (LF or HF) by the sum of LF and HF; the ratio of LF/HF was also calculated. Instant centre frequency is a time-varying parameter that the evolution along time of the gravity centrum of a local spectrum. All spectral indexes were recorded at the following time points: before induction, after induction and before intubation, during intubation, and after intubation. The atenolol group had lower normalized LF and the LF/HF ratio (P ICF was higher in atenolol group at all times. The ICF shifted towards HF frequency after induction and before intubation and shifted towards LF during intubation in both groups. The autonomic nervous system control on the heart through the interaction of sympathetic and parasympathetic reflex mechanisms could be studied by the ICF. The ICF may assess the autonomic cardiac modulation and may provide useful information for anaesthetic management.

Determination of Elements and Carbon Content of Stainless Steel Welded Pipeline

Directory of Open Access Journals (Sweden)

Pavel Hudeček

2016-01-01

Full Text Available Find out defects or problems of welds are not so simple from time to time. Specially, if weld has been made in rough environmental conditions like high temperature, dusty wind and humidity. It is important to assure have good conditions to realize basic step of welding. For welding, have been used welding procedures specification and procedure qualification record. However, difficult conditions, documentations rightness or human errors are always here. Common weld defects like cracks, porosity, lack of penetration and distortion can compromise the strength of the base metal, as well as the integrity of the weld. According of site inspection, there were suspicion of inclusions, leaker or segregation in root of weld. Surface treatment after welding and keep the intervals between single welds to not overheat the pipes. To recognize those suspicions, mechanical testing around weld joint, determination of carbon content and inductively coupled plasma atomic emission spectroscopy will be done.

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.

Welding of Aluminum Alloys to Steels: An Overview

Science.gov (United States)

2013-08-01

and deformations are a few examples of the unwanted consequences which somehow would lead to brittle fracture, fatigue fracture, shape instability...was made under the copper tips of the spot welding machine. The fatigue results showed higher fatigue strength of the joints with transition layer...kHz ultrasonic butt welding system with a vibration source applying eight bolt-clamped Langevin type PZT transducers and a 50 kW static induction

The evaluation of different environments in ultra-high frequency induction sintered powder metal compacts

International Nuclear Information System (INIS)

Cavdar, P. S.; Cavdar, U.

2015-01-01

The application of the iron based Powder Metal (PM) compacts in Ultra-High Frequency Induction Sintering (UHFIS) was reviewed for different environments. The three different environments: atmosphere, argon and vacuum were applied to the PM compacts. Iron based PM compacts were sintered at 1120 degree centigrade for a total of 550 seconds by using induction sintering machines with 2.8 kW power and 900 kHz frequency. Micro structural properties, densities, roughness and micro hardness values were obtained for all environments. The results were compared with each other. (Author)

The effects of extremely low frequency magnetic fields on mutation induction in mice

Energy Technology Data Exchange (ETDEWEB)

Wilson, James W. [Department of Genetics, University of Leicester, Leicester LE1 7RH (United Kingdom); Haines, Jackie; Sienkiewicz, Zenon [Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot, Oxfordshire OX11 0RQ (United Kingdom); Dubrova, Yuri E., E-mail: yed2@le.ac.uk [Department of Genetics, University of Leicester, Leicester LE1 7RH (United Kingdom)

2015-03-15

Highlights: • The effects of 50 Hz magnetic fields on mutation induction in mice were analyzed. • The frequency of ESTR mutation was established in sperm and blood. • Exposure to 10–300 μT for 2 and 15 h did not result in mutation induction. • Mutagenic effects of 50 Hz magnetic fields are likely to be negligible. - Abstract: The growing human exposure to extremely low frequency (ELF) magnetic fields has raised a considerable concern regarding their genotoxic effects. The aim of this study was to evaluate the in vivo effects of ELF magnetic fields irradiation on mutation induction in the germline and somatic tissues of male mice. Seven week old BALB/c × CBA/Ca F{sub 1} hybrid males were exposed to 10, 100 or 300 μT of 50 Hz magnetic fields for 2 or 15 h. Using single-molecule PCR, the frequency of mutation at the mouse Expanded Simple Tandem Repeat (ESTR) locus Ms6-hm was established in sperm and blood samples of exposed and matched sham-treated males. ESTR mutation frequency was also established in sperm and blood samples taken from male mice exposed to 1 Gy of acute X-rays. The frequency of ESTR mutation in DNA samples extracted from blood of mice exposed to magnetic fields did not significantly differ from that in sham-treated controls. However, there was a marginally significant increase in mutation frequency in sperm but this was not dose-dependent. In contrast, acute exposure X-rays led to significant increases in mutation frequency in sperm and blood of exposed males. The results of our study suggest that, within the range of doses analyzed here, the in vivo mutagenic effects of ELF magnetic fields are likely to be minor if not negligible.

The effects of extremely low frequency magnetic fields on mutation induction in mice

International Nuclear Information System (INIS)

Wilson, James W.; Haines, Jackie; Sienkiewicz, Zenon; Dubrova, Yuri E.

2015-01-01

Highlights: • The effects of 50 Hz magnetic fields on mutation induction in mice were analyzed. • The frequency of ESTR mutation was established in sperm and blood. • Exposure to 10–300 μT for 2 and 15 h did not result in mutation induction. • Mutagenic effects of 50 Hz magnetic fields are likely to be negligible. - Abstract: The growing human exposure to extremely low frequency (ELF) magnetic fields has raised a considerable concern regarding their genotoxic effects. The aim of this study was to evaluate the in vivo effects of ELF magnetic fields irradiation on mutation induction in the germline and somatic tissues of male mice. Seven week old BALB/c × CBA/Ca F 1 hybrid males were exposed to 10, 100 or 300 μT of 50 Hz magnetic fields for 2 or 15 h. Using single-molecule PCR, the frequency of mutation at the mouse Expanded Simple Tandem Repeat (ESTR) locus Ms6-hm was established in sperm and blood samples of exposed and matched sham-treated males. ESTR mutation frequency was also established in sperm and blood samples taken from male mice exposed to 1 Gy of acute X-rays. The frequency of ESTR mutation in DNA samples extracted from blood of mice exposed to magnetic fields did not significantly differ from that in sham-treated controls. However, there was a marginally significant increase in mutation frequency in sperm but this was not dose-dependent. In contrast, acute exposure X-rays led to significant increases in mutation frequency in sperm and blood of exposed males. The results of our study suggest that, within the range of doses analyzed here, the in vivo mutagenic effects of ELF magnetic fields are likely to be minor if not negligible

High frequency induction of mitotic recombination by ionizing radiation in Mlh1 null mouse cells

International Nuclear Information System (INIS)

Wang Qi; Ponomareva, Olga N.; Lasarev, Michael; Turker, Mitchell S.

2006-01-01

Mitotic recombination in somatic cells involves crossover events between homologous autosomal chromosomes. This process can convert a cell with a heterozygous deficiency to one with a homozygous deficiency if a mutant allele is present on one of the two homologous autosomes. Thus mitotic recombination often represents the second mutational step in tumor suppressor gene inactivation. In this study we examined the frequency and spectrum of ionizing radiation (IR)-induced autosomal mutations affecting Aprt expression in a mouse kidney cell line null for the Mlh1 mismatch repair (MMR) gene. The mutant frequency results demonstrated high frequency induction of mutations by IR exposure and the spectral analysis revealed that most of this response was due to the induction of mitotic recombinational events. High frequency induction of mitotic recombination was not observed in a DNA repair-proficient cell line or in a cell line with an MMR-independent mutator phenotype. These results demonstrate that IR exposure can initiate a process leading to mitotic recombinational events and that MMR function suppresses these events from occurring

Development of Weld Metal Microstructures in Pulsed Laser Welding of Duplex Stainless Steel

Science.gov (United States)

Mirakhorli, F.; Malek Ghaini, F.; Torkamany, M. J.

2012-10-01

The microstructure of the weld metal of a duplex stainless steel made with Nd:YAG pulsed laser is investigated at different travel speeds and pulse frequencies. In terms of the solidification pattern, the weld microstructure is shown to be composed of two distinct zones. The presence of two competing heat transfer channels to the relatively cooler base metal and the relatively hotter previous weld spot is proposed to develop two zones. At high overlapping factors, an array of continuous axial grains at the weld centerline is formed. At low overlapping factors, in the zone of higher cooling rate, a higher percentage of ferrite is transformed to austenite. This is shown to be because with extreme cooling rates involved in pulsed laser welding with low overlapping, the ferrite-to-austenite transformation can be limited only to the grain boundaries.

The mechanical properties of high speed GTAW weld and factors of nonlinear multiple regression model under external transverse magnetic field

Science.gov (United States)

Lu, Lin; Chang, Yunlong; Li, Yingmin; He, Youyou

2013-05-01

A transverse magnetic field was introduced to the arc plasma in the process of welding stainless steel tubes by high-speed Tungsten Inert Gas Arc Welding (TIG for short) without filler wire. The influence of external magnetic field on welding quality was investigated. 9 sets of parameters were designed by the means of orthogonal experiment. The welding joint tensile strength and form factor of weld were regarded as the main standards of welding quality. A binary quadratic nonlinear regression equation was established with the conditions of magnetic induction and flow rate of Ar gas. The residual standard deviation was calculated to adjust the accuracy of regression model. The results showed that, the regression model was correct and effective in calculating the tensile strength and aspect ratio of weld. Two 3D regression models were designed respectively, and then the impact law of magnetic induction on welding quality was researched.

High-frequency current application in industry for heating of non-metallic materials. Session 4 N. 4. 2

Energy Technology Data Exchange (ETDEWEB)

Bezmenov, F V; Dashkevich, I P; Dobrovolskaya, V I; Fedorova, I G; Shamov, A N; Vasiliev, A S

1984-01-01

Large scale industrial development of induction heating requires high operating efficiencies. This resulted in extending the research and development in the fiels of static frequency inverters and its circuits. Medium frequency sub-stations for centralized feeding of heating units are widely introduced into industry. Techno-economical parameters of induction heating strongly depend of proper choice and monitoring of heating conditions. Systems of analog and digital control for electro-heat processes and for power source operational conditions are considered. Large attention is drawn to the development of high capacity radio frequency power source for welding. Some questions arising from the computer design techniques adopted for industrial heating uits and power sources are described. Modes of combined solution of two and three-dimensional systems as well as hydrodynamic problems are presented.

The impact of a stress induction task on tic frequencies in youth with Tourette Syndrome.

Science.gov (United States)

Conelea, Christine A; Woods, Douglas W; Brandt, Bryan C

2011-08-01

Tourette Syndrome (TS) is a neuropsychiatric disorder characterized by motor and vocal tics. Tic fluctuations are common and thought to be attributable in part, to contextual variables. Stress is one such variable, but its effects and mechanism of action are poorly understood. The current study measured the effects of a stress induction task on tic frequencies during periods of suppression and non-suppression of tics. Ten youth with TS between the ages of 9 and 17 were exposed to four conditions in random sequence: free-to-tic baseline (BL), reinforced tic suppression (SUP), reinforced tic suppression plus a stress induction task (SUP + STRESS), and a stress induction task alone (STRESS). Tic frequencies did not differ during STRESS and BL. Tic frequencies were greater in SUP + STRESS than SUP. Stress may impact tics through disrupting suppression efforts. Clinically, results suggest that interventions designed to improve tic inhibition in the presence of acute stressors may be beneficial. Copyright © 2011 Elsevier Ltd. All rights reserved.

Design Optimization and Fatigue Analysis of Laser Stake Welded Connections

Science.gov (United States)

2008-06-01

is ultimately envisioned that laser welding will be as common in the shipyard as other processes such -- as MIG, TIG and SMAW. Laser stake- welding of...input from conventional welding techniques can be detrimental to the polymer matrix composite material. In comparison, the laser welding process allows...more discrete frequencies. In the laser welding process , the photons are targeted on the work piece surface which needs to be welded . Highly

Comparison of computer codes for evaluation of double-supply-frequency pulsations in linear induction pumps

International Nuclear Information System (INIS)

Kirillov, Igor R.; Obukhov, Denis M.; Ogorodnikov, Anatoly P.; Araseki, Hideo

2004-01-01

The paper describes and compares three computer codes that are able to estimate the double-supply-frequency (DSF) pulsations in annular linear induction pumps (ALIPs). The DSF pulsations are the result of interaction of the magnetic field and induced in liquid metal currents both changing with supply-frequency. They may be of some concern for electromagnetic pumps (EMP) exploitation and need to be evaluated at their design. The results of computer simulation are compared with experimental ones for annular linear induction pump ALIP-1

Special Features of Induction Annealing of Friction Stir Welded Joints of Medium-Alloy Steels

Science.gov (United States)

Priymak, E. Yu.; Stepanchukova, A. V.; Bashirova, E. V.; Fot, A. P.; Firsova, N. V.

2018-01-01

Welded joints of medium-alloy steels XJY750 and 40KhN2MA are studied in the initial condition and after different variants of annealing. Special features of the phase transformations occurring in the welded steels are determined. Optimum modes of annealing are recommended for the studied welded joints of drill pipes, which provide a high level of mechanical properties including the case of impact loading.

High-cycle fatigue properties of small-bore socket-welded pipe joint

International Nuclear Information System (INIS)

Maekawa, Akira; Noda, Michiyasu; Suzuki, Michiaki

2009-01-01

Piping and equipment in nuclear power plants are structures including many welded joints. Reliability of welded joints is one of high-priority issues to improve the safety of nuclear power plants. However, occurrence of fatigue failures in small-bore socket-welded pipe joints by high-cycle vibrations is still reported. In this study, fatigue experiments on a socket-welded joint of austenitic stainless steel pipe was conducted under excitation conditions similar to those in actual plants to investigate vibration characteristics and fatigue strength. It was found that the natural frequency of pipe with socket-welded joint gradually decreased as fatigue damage developed, according to the Miner rule for fatigue life evaluation. The results indicate that the fatigue life of the welded pipe joint could be estimated by monitoring the decreasing ratio of the natural frequency of the pipe. The evaluation of decreasing ratio of the natural frequency in addition to fatigue damage evaluation by the Miner rule could enhance the accuracy of fatigue life evaluation. (author)

Comparison of single and consecutive dual frequency induction surface hardening of gear wheels

Science.gov (United States)

Barglik, J.; Ducki, K.; Kukla, D.; Mizera, J.; Mrówka-Nowotnik, G.; Sieniawski, J.; Smalcerz, A.

2018-05-01

Mathematical modelling of single and consecutive dual - frequency induction surface hardening systems are presented and compared. The both models are solved by the 3D FEM-based professional software supported by a number of own numerical procedures. The methodology is illustrated with some examples of surface induction hardening of a gear wheel made of steel 41Cr4. The computations are in a good accordance with experiments provided on the laboratory stand.

Analysis of Pulsed Laser Welding Parameters Effect on Weld Geometry of 316L Stainless Steel using DOE

Directory of Open Access Journals (Sweden)

M. R. Pakmanesh

2018-03-01

Full Text Available In the present study, the optimization of pulsed Nd:YAG laser welding parameters was done on a lap-joint of a 316L stainless steel foil in order to predict the weld geometry through response surface methodology. For this purpose, the effects of laser power, pulse duration, and frequency were investigated. By presenting a second-order polynomial, the above-mentioned statistical method was managed to be well employed to evaluate the effect of welding parameters on weld width. The results showed that the weld width at the upper, middle and lower surfaces of weld cross section increases by increasing pulse durationand laser power; however, the effects of these parameters on the mentioned levels are different. The effect of pulse duration in the models of weld upper, middle and lower widths was calculated as 76, 73 and 68%, respectively. Moreover, the effect of power on theses widths was determined as 18, 24 and 28%, respectively. Finally, by superimposing these models, optimum conditions were obtained to attain a full penetration weld and the weld with no defects.

Experimental observation of the inductive electric field and related plasma nonuniformity in high frequency capacitive discharge

International Nuclear Information System (INIS)

Ahn, S. K.; Chang, H. Y.

2008-01-01

To elucidate plasma nonuniformity in high frequency capacitive discharges, Langmuir probe and B-dot probe measurements were carried out in the radial direction in a cylindrical capacitive discharge driven at 90 MHz with argon pressures of 50 and 400 mTorr. Through the measurements, a significant inductive electric field (i.e., time-varying magnetic field) was observed at the radial edge, and it was found that the inductive electric field creates strong plasma nonuniformity at high pressure operation. The plasma nonuniformity at high pressure operation is physically similar to the E-H mode transition typically observed in inductive discharges. This result agrees well with the theories of electromagnetic effects in large area and/or high frequency capacitive discharges

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.

The effect of gas tungsten arc welding and pulsed-gas tungsten arc welding processes’ parameters on the heat affected zone-softening behavior of strain-hardened Al–6.7Mg alloy

International Nuclear Information System (INIS)

Hadadzadeh, Amir; Ghaznavi, Majid Mahmoudi; Kokabi, Amir Hossein

2014-01-01

Highlights: • The strain-hardened Al–6.7Mg alloy was welded using GTAW and PGTAW processes. • The HAZ softening behavior of the welding joint was characterized. • Employing pulsed current in GTAW process eliminated the HAZ softening. • Duration ratio did not affect the weld strength while the frequency influenced it. - Abstract: The heat affected zone (HAZ) softening behavior of strain-hardened Al–6.7Mg alloy welded by gas tungsten arc welding (GTAW) process was investigated. Increasing the heat input during welding led to formation of a wider HAZ. Moreover, the size of the precipitates was increased at higher heat inputs. Consequently, by increasing the heat input, lower strength was obtained for the welding joints. At the second stage of the study, pulsed-GTAW (PGTAW) process was employed to improve the strength of the joints. It was observed that the overall strength of the welding joints was improved and the fracture during tensile test was moved from the HAZ to the fusion zone. Moreover, the effect of duration ratio and pulse frequency was studied. For the current study, the duration ratio did not have a significant effect on the strength and microstructure of the weld, but increasing the frequency led to higher strength of the weld and finer microstructure

Voltage and frequency control of wind-powered islanded microgrids based on induction generator and STATCOM

DEFF Research Database (Denmark)

Bouzid, Allal; Sicard, Pierre; Guerrero, Josep M.

2015-01-01

This paper presents a comprehensive modeling of a three-phase cage induction machine used as a self-excited squirrel-cage induction generator (SEIG), and discusses the regulation of the voltage and frequency of a self-excited SEIG based on the action of the static synchronous Compensator (STATCOM......). The STATCOM with the proposed controller consists of a three-phase voltage-sourced inverter and a DC voltage. The compensator can provide the active and reactive powers and regulate AC system bus voltage and the frequency, but also may enhance the load stability. Moreover, a feed forward control method...

Use of pulsed arc welding for butt joint fabrication

International Nuclear Information System (INIS)

Merkulov, B.A.

1977-01-01

A technology of pulsed-arc butt welding with periodic wire feed to the welding zone has been developed. The pulsed arc is suitable both for submerged and gas-shielded weldings. The technology proposed has some advantages over the stationary-arc welding. Control of the amplitude-frequency characteristics of the process enables one to affect melting and crystallization conditions of the welding crater, weld shape, relation between melting and deposited metal section areas, etc., as well as to reduce heat contribution to the base metal. The new process is shown to be applicable in power engineering. Automatic submerged welding conditions are given for low-carbon and pearlitic heat-resistant steels

Effects of switching frequency and leakage inductance on slow-scale stability in a voltage controlled flyback converter

International Nuclear Information System (INIS)

Wang Fa-Qiang; Ma Xi-Kui

2013-01-01

The effects of both the switching frequency and the leakage inductance on the slow-scale stability in a voltage controlled flyback converter are investigated in this paper. Firstly, the system description and its mathematical model are presented. Then, the improved averaged model, which covers both the switching frequency and the leakage inductance, is established, and the effects of these two parameters on the slow-scale stability in the system are analyzed. It is found that the occurrence of Hopf bifurcation in the system is the main reason for losing its slow-scale stability and both the switching frequency and the leakage inductance have an important effect on this slow-scale stability. Finally, the effectiveness of the improved averaged model and that of the corresponding theoretical analysis are confirmed by the simulation results and the experimental results. (general)

Subminiature eddy-current transducers designed to study welded joints of titanium alloys

Science.gov (United States)

Malikov, V. N.; Dmitriev, S. F.; Katasonov, A. O.; Sagalakov, A. M.; Ishkov, A. V.

2017-12-01

Eddy current transducers (ECT) are used to construct a sensor for investigating titanium sheets connected by a welded joint. The paper provides key technical information about the eddy current transducer used and describes the procedure of measurements that makes it possible to control defects in welded joints of titanium alloys. It is capable of automatically changing the filtering cutoff frequency and operating frequency of the device. Experiments were conducted on welded VT1-0 titanium plates. The paper contains the results of these measurements. The dependence data facilitates the assessment of the quality of the welded joints and helps make an educated conclusion about welding quality.

Vibration stress relief of DH 36 rectangle welded plates

Science.gov (United States)

Li, Shuqi; Fang, Hongyuan

2018-03-01

Vibration stress relief (VSR) is widely used in reducing residual stress in welded structures. However, the effectiveness of this method is still instable in some circumstance. In this study, a covert negative treatment phenomenon was investigated, i.e. natural frequency of welded structures decreased after VSR but residual stress in one direction increased. When the alteration of natural frequency after VSR is significant, the residual stresses in both the longitudinal and transversal directions shall decrease. Otherwise, residual stresses may increase on one direction. Thus, sufficient power shall be applied to the welded structures to avoid negative results.

Diamond deposition using a planar radio frequency inductively coupled plasma

Science.gov (United States)

Bozeman, S. P.; Tucker, D. A.; Stoner, B. R.; Glass, J. T.; Hooke, W. M.

1995-06-01

A planar radio frequency inductively coupled plasma has been used to deposit diamond onto scratched silicon. This plasma source has been developed recently for use in large area semiconductor processing and holds promise as a method for scale up of diamond growth reactors. Deposition occurs in an annulus which coincides with the area of most intense optical emission from the plasma. Well-faceted diamond particles are produced when the substrate is immersed in the plasma.

Measurement of Dynamic Resistance in Resistance Spot Welding

DEFF Research Database (Denmark)

Wu, Pei; Lu, J.; Zhang, Wenqi

2007-01-01

is influenced by inductive noise caused by the high welding current. In this study, the dynamic resistance is determined by measuring the voltage at primary side and current at secondary side. This increases the accuracy of measurement because of higher signal-noise ratio, and allows to apply to in-process......The conventional methods of determining the dynamic resistance were mostly done by measuring the voltage and current at secondary side of transformer in resistance welding machines, in which the measuring set-up normally interferes with the movement of electrode, and the measuring precision...

Identification of the Quality Spot Welding used Non Destructive Test-Ultrasonic Testing: (Effect of Welding Time)

Science.gov (United States)

Sifa, A.; Endramawan, T.; Badruzzaman

2017-03-01

Resistance Spot Welding (RSW) is frequently used as one way of welding is used in the manufacturing process, especially in the automotive industry [4][5][6][7]. Several parameters influence the process of welding points. To determine the quality of a welding job needs to be tested, either by damaging or testing without damage, in this study conducted experimental testing the quality of welding or identify quality of the nugget by using Non-Destructive Test (NDT) -Ultrasonic Testing (UT), in which the identification of the quality of the welding is done with parameter thickness of worksheet after welding using NDT-UT with use same material worksheet and have more thickness of worksheet, the thickness of the worksheet single plate 1mm, with the capability of propagation Ultrasonic Testing (UT) standard limited> 3 mm [1], welding process parameters such as the time difference between 1-10s and the welding current of 8 KV, visually Heat Affected Zone ( HAZ ) have different results due to the length of time of welding. UT uses a probe that is used with a frequency of 4 MHz, diameter 10 mm, range 100 and the couplant used is oil. Identification techniques using drop 6dB, with sound velocity 2267 m / s of Fe, with the result that the effect of the Welding time affect the size of the HAZ, identification with the lowest time 1s show results capable identified joined through NDT - UT.

High Power Laser Beam Welding of Thick-walled Ferromagnetic Steels with Electromagnetic Weld Pool Support

Science.gov (United States)

Fritzsche, André; Avilov, Vjaceslav; Gumenyuk, Andrey; Hilgenberg, Kai; Rethmeier, Michael

The development of modern high power laser systems allows single pass welding of thick-walled components with minimal distortion. Besides the high demands on the joint preparation, the hydrostatic pressure in the melt pool increases with higher plate thicknesses. Reaching or exceeding the Laplace pressure, drop-out or melt sagging are caused. A contactless electromagnetic weld support system was used for laser beam welding of thick ferromagnetic steel plates compensating these effects. An oscillating magnetic field induces eddy currents in the weld pool which generate Lorentz forces counteracting the gravity forces. Hysteresis effects of ferromagnetic steels are considered as well as the loss of magnetization in zones exceeding the Curie temperature. These phenomena reduce the effective Lorentz forces within the weld pool. The successful compensation of the hydrostatic pressure was demonstrated on up to 20 mm thick plates of duplex and mild steel by a variation of the electromagnetic power level and the oscillation frequency.

A new inductive method for measuring the RRR-value of niobium

International Nuclear Information System (INIS)

Bolore, M.; Bonin, B.; Boudigou, Y.; Heuveline, S.; Jacques, E.; Jaidane, S.; Koechlin, F.; Safa, H.

1996-01-01

A new method for measuring the RRR-value of niobium is presented. The principle of the measurement uses low frequency induction in a niobium sheet placed close to a pair of coils. In contrast with the usual resistive method, the present one gives information on the local value of the RRR, with a spatial resolution of the order of 1 cm. In addition, it is non destructive, thus opening the way to mapping RRR measurements on cavities. This tool will permit the measure of RRR inhomogeneities in cavities due to sheet forming or heat treatments, and the systematic check of the quality of weld seams. (author)

Thermal Stir Welding Development at Marshall Space Flight Center

Science.gov (United States)

Ding, Robert J.

2008-01-01

Solid state welding processes have become the focus of welding process development at NASA's Marshall Space Flight Center. Unlike fusion weld processes such as tungsten inert gas (TIG), variable polarity plasma arc (VPPA), electron beam (EB), etc., solid state welding processes do not melt the material during welding. The resultant microstructure can be characterized as a dynamically recrystallized morphology much different than the casted, dentritic structure typical of fusion weld processes. The primary benefits of solid state processes over fusion weld processes include superior mechanic properties and the elimination of thermal distortion and residual stresses. These solid state processes attributes have profoundly influenced the direction of advanced welding research and development within the NASA agency. Thermal Stir Welding (TSW) is a new solid state welding process being developed at the Marshall Space Flight Center. Unlike friction stir welding, the heating, stirring and forging elements of the weld process can be decoupled for independent control. An induction coil induces energy into a workpiece to attain a desired plastic temperature. An independently controlled stir rod, captured within non-rotating containment plates, then stirs the plasticized material followed by forging plates/rollers that work the stirred weld joint. The independent control (decoupling) of heating, stirring and forging allows, theoretically, for the precision control of microstructure morphology. The TSW process is being used to evaluate the solid state joining of Haynes 230 for ARES J-2X applications. It is also being developed for 500-in (12.5 mm) thick commercially pure grade 2 titanium for navy applications. Other interests include Inconel 718 and stainless steel. This presentation will provide metallurgical and mechanical property data for these high melting temperature alloys.

Modelling grain-scattered ultrasound in austenitic stainless-steel welds: A hybrid model

International Nuclear Information System (INIS)

Nowers, O.; Duxbury, D. J.; Velichko, A.; Drinkwater, B. W.

2015-01-01

The ultrasonic inspection of austenitic stainless steel welds can be challenging due to their coarse grain structure, charaterised by preferentially oriented, elongated grains. The anisotropy of the weld is manifested as both a ‘steering’ of the beam and the back-scatter of energy due to the macroscopic granular structure of the weld. However, the influence of weld properties, such as mean grain size and orientation distribution, on the magnitude of scattered ultrasound is not well understood. A hybrid model has been developed to allow the study of grain-scatter effects in austenitic welds. An efficient 2D Finite Element (FE) method is used to calculate the complete scattering response from a single elliptical austenitic grain of arbitrary length and width as a function of the specific inspection frequency. A grain allocation model of the weld is presented to approximate the characteristic structures observed in austenitic welds and the complete scattering behaviour of each grain calculated. This model is incorporated into a semi-analytical framework for a single-element inspection of a typical weld in immersion. Experimental validation evidence is demonstrated indicating excellent qualitative agreement of SNR as a function of frequency and a minimum SNR difference of 2 dB at a centre frequency of 2.25 MHz. Additionally, an example Monte-Carlo study is presented detailing the variation of SNR as a function of the anisotropy distribution of the weld, and the application of confidence analysis to inform inspection development

Measurement of Dynamic Resistance in Resistance Spot Welding

DEFF Research Database (Denmark)

Wu, Pei; Zhang, Wenqi; Bay, Niels

Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side of the transfo......Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side...... of the transformer in resistance welding machines, implying defects from induction noise and interference with the leads connected to the electrodes for measuring the voltage. In this study, the dynamic resistance is determined by measuring the voltage on the primary side and the current on the secondary side...

Process Stability of Ultrasonic-Wave-Assisted Gas Metal Arc Welding

Science.gov (United States)

Fan, Chenglei; Xie, Weifeng; Yang, Chunli; Lin, Sanbao; Fan, Yangyang

2017-10-01

As a newly developed arc welding method, ultrasonic-wave-assisted arc welding successfully introduced power ultrasound into the arc and weld pool, during which the ultrasonic acts on the top of the arc in the coaxial alignment direction. The advanced process for molten metals can be realized by using an additional ultrasonic field. Compared with the conventional gas metal arc welding (GMAW), the welding arc is compressed, the droplet size is decreased, and the droplet transfer frequency is increased significantly in ultrasonic-wave-assisted GMAW (U-GMAW). However, the stability of the metal transfer has deep influence on the welding quality equally, and the ultrasonic wave effect on the stability of the metal transfer is a phenomenon that is not completely understood. In this article, the stabilities of the short-circuiting transfer process and globular transfer process are studied systematically, and the effect of ultrasonic wave on the metal transfer is analyzed further. The transfer frequency and process stability of the U-GMAW process are much higher than those of the conventional GMAW. Analytical results show that the additional ultrasonic wave is helpful for improving welding stability.

Characterisation of fume from hyperbaric welding operations

Energy Technology Data Exchange (ETDEWEB)

Ross, John A S; Semple, Sean [Environmental and Occupational Medicine, University of Aberdeen (United Kingdom); Duffin, Rodger [ELEGI Colt Laboratory, University of Edinburgh (United Kingdom); Kelly, Frank [Lung Biology Group, Kings College, University of London (United Kingdom); Seldmann, Joerg; Raab, Andrea, E-mail: j.a.ross@abdn.ac.u [Trace Element Speciation Laboratory, University of Aberdeen (United Kingdom)

2009-02-01

We report preliminary work characterising dust from hyperbaric welding trials carried out at increased pressure in a helium and oxygen atmosphere. Particle size and concentration were measured during welding. Samples for quartz and metal analysis and toxicity assessment were taken from a filter in the local fume extraction system. The residue of dust after metal extraction by nitric acid in hydrogen peroxide predominantly a non-metallic white powder assumed to be dust from welding rod coatings and thermal insulation material. Metallic analysis showed predominantly calcium, from the welding rod coating, and period 4 transition metals such as iron, manganese, magnesium and titanium (inductively coupled mass spectrometry, Agilent 7500c). The presence of zirconium indicated a contribution from grinding. The fume was nanoparticulate in nature with a mean particle diameter of 20-30 nm (MSI Inc WPS 1000XP). It showed an intermediate level of oxidative potential regarding the low-molecular weight respiratory tract lining fluid antioxidants ascorbate and glutathione and caused release of the inflammatory marker IL-8 in a human lung A 549 epithelial cell culture with no indication of cytotoxicity. The study findings have strong implications for the measurement techniques needed to assess fume exposure in hyperbaric welding and the provision of respiratory protection.

Quality status display for a vibration welding process

Science.gov (United States)

Spicer, John Patrick; Abell, Jeffrey A.; Wincek, Michael Anthony; Chakraborty, Debejyo; Bracey, Jennifer; Wang, Hui; Tavora, Peter W.; Davis, Jeffrey S.; Hutchinson, Daniel C.; Reardon, Ronald L.; Utz, Shawn

2017-11-28

A method includes receiving, during a vibration welding process, a set of sensory signals from a collection of sensors positioned with respect to a work piece during formation of a weld on or within the work piece. The method also includes receiving control signals from a welding controller during the process, with the control signals causing the welding horn to vibrate at a calibrated frequency, and processing the received sensory and control signals using a host machine. Additionally, the method includes displaying a predicted weld quality status on a surface of the work piece using a status projector. The method may include identifying and display a quality status of a suspect weld. The laser projector may project a laser beam directly onto or immediately adjacent to the suspect welds, e.g., as a red, green, blue laser or a gas laser having a switched color filter.

Inertia and friction welding of aluminum alloy 1100 to type 316 stainless steel

International Nuclear Information System (INIS)

Perkins, M.A.

1979-01-01

The inertia and friction-welding processes were evaluated for joining aluminum alloy 1100-H14 and Type 316 vacuum-induction melted, vacuum-arc remelted (VIM VAR) stainless steel. While both processes consistently produced joints in which the strength exceeded the strength of the aluminum base metal, 100 percent bonding was not reliably achieved with inertia welding. The deficiency points out the need for development of nondestructive testing techniques for this type of joint. Additionally, solid-state volume diffusion did not appear to be a satisfactory explanation for the inertia and friction-welding bonding mechanism

TIG welding power supply with improved efficiency

Directory of Open Access Journals (Sweden)

Сергій Володимирович Гулаков

2015-03-01

Full Text Available In the article, the influence of the DC component of the welding current during TIG (Tungsten Inert Gas welding is discussed. Known methods of DC current cancellation are reviewed, such as capacitor bank or diode/thyristor network insertion in the secondary circuit of the welding transformer. A new method of controlling the magnitude and shape of the TIG welding current is proposed. The idea is to insert a controlled voltage source in the secondary circuit of the welding transformer. This controlled voltage source is realized using a full-bridge voltage source inverter (VSI. VSI control system design issues are discussed. VSI is controlled by a three-level hysteretic current controller, while current reference is generated using lookup table driven by PLL (Phase Locked Loop locked to the mains frequency. Simulation results are shown. The proposed topology of TIG power supply allows to provide magnitude and shape control of the welding current, with the limitation that its DC component must be zero. Thus, some capabilities of professional AC-TIG welders are obtained using substantially lower cost components: VSI built using high-current low voltage MOSFETs with control system based on 32-bit ARM microcontroller. The use of proposed TIG welding power supply will eliminate the DC component of the welding current, improve welding transformer’s power factor and improve welding technology by increasing the welding arc stability

IMITATION MODEL OF A HIGH-SPEED INDUCTION MOTOR WITH FREQUENCY CONTROL

Directory of Open Access Journals (Sweden)

V. E. Pliugin

2017-12-01

Full Text Available Purpose. To develop the imitation model of the frequency converter controlled high-speed induction motor with a squirrel-cage rotor in order to determine reasons causes electric motor vibrations and noises in starting modes. Methodology. We have applied the mathematical simulation of electromagnetic field in transient mode and imported obtained field model as an independent object in frequency converter circuit. We have correlated the simulated result with the experimental data obtained by means of the PID regulator factors. Results. We have made the simulation model of the high-speed induction motor with a squirrel-cage rotor speed control in AnsysRMxprt, Ansys Maxwell and Ansys Simplorer, approximated to their physical prototype. We have made models modifications allows to provide high-performance computing (HPC in dedicated server and computer cluster to reduce the simulation time. We have obtained motor characteristics in starting and rated modes. This allows to make recommendations on determination of high-speed electric motor optimal deign, having minimum indexes of vibrations and noises. Originality. For the first time, we have carried out the integrated research of induction motor using simultaneously simulation models both in Ansys Maxwell (2D field model and in Ansys Simplorer (transient circuit model with the control low realization for the motor soft start. For the first time the correlation between stator and rotor slots, allows to obtain minimal vibrations and noises, was defined. Practical value. We have tested manufactured high-speed motor based on the performed calculation. The experimental studies have confirmed the adequacy of the model, which allows designing such motors for new high-speed construction, and upgrade the existing ones.

Soldadura (Welding). Spanish Translations for Welding.

Science.gov (United States)

Hohhertz, Durwin

Thirty transparency masters with Spanish subtitles for key words are provided for a welding/general mechanical repair course. The transparency masters are on such topics as oxyacetylene welding; oxyacetylene welding equipment; welding safety; different types of welds; braze welding; cutting torches; cutting with a torch; protective equipment; arc…

Microwave heating for thermoplastic composites - Could the technology be used for welding applications?

Science.gov (United States)

Barasinski, Anaïs; Tertrais, Hermine; Bechtel, Stéphane; Chinesta, Francisco

2018-05-01

Welding primary structure thermoplastic composites parts is still an issue today, many technologies have been extensively studied: induction, ultrasonic, resistive welding, none is today entirely viable for this application due to various implementation reasons. On the other hand, microwave solutions are not very common in composites forming process, although being widespread in homes. Microwave (MW) technology relies on volumetric heating. Thermal energy is transferred from an electromagnetic field to materials that can absorb it at specific frequencies. Volumetric heating enables better process temperature control and less overall energy losses, which can results in shorter processing cycles and higher process efficiency. Nowadays, the main drawback of this technology is that the complex physics involved in the conversion of electromagnetic energy in thermal energy (heating) is not entirely understood and controlled for complex materials. In that work, the authors propose to look deeper in that way, first proposing a simulation tool, based on a coupling between a commercial code and a home made one, allowing the following of the electromagnetic field very precisely in the thickness of a laminate composite part, the last consisting of a stack of layers with different orientations, each layer made of a resin matrix and carbon fibers. Thermal fields are then computed and validated by experimental measurements. In a second part, the authors propose to look at a common welding case of a stringer, on a skin.

Austenitic stainless steel weld inspection

International Nuclear Information System (INIS)

Mech, S.J.; Emmons, J.S.; Michaels, T.E.

1978-01-01

Analytical techniques applied to ultrasonic waveforms obtained from inspection of austenitic stainless steel welds are described. Experimental results obtained from a variety of geometric and defect reflectors are presented. Specifically, frequency analyses parameters, such as simple moments of the power spectrum, cross-correlation techniques, and adaptive learning network analysis, all represent improvements over conventional time domain analysis of ultrasonic waveforms. Results for each of these methods are presented, and the overall inspection difficulties of austenitic stainless steel welds are discussed

Investigation of mixing and diffusion processes in hybrid spot laser-MIG keyhole welding

International Nuclear Information System (INIS)

Zhou, J; Tsai, H L

2009-01-01

In hybrid laser-MIG keyhole welding, anti-crack elements can be added into the weld pool through a filler metal in anticipation of compensating mass loss, preventing porosity formation and improving compositional and mechanical properties of the welds. Understanding the mixing and diffusion of the filler metal in the molten pool is vital to achieve these desired objectives. In this study, mathematical models and associated numerical techniques have been developed to investigate the mixing and diffusion processes in hybrid laser-MIG keyhole welding. The transient interactions between droplets and weld pool and dynamics of the melt flow are studied. The effects of key process parameters, such as droplet size (wire diameter), droplet generation frequency (wire feed speed) and droplet impinging speed, on mixing/diffusion are systematically investigated. It was found that compositional homogeneity of the weld pool is determined by the competition between the mixing rate and the solidification rate. A small-size filler droplet together with high generation frequency can increase the latitudinal diffusion of the filler metal into the weld pool, while the large-size droplet along with the low generation frequency helps to get more uniform longitudinal diffusion. Increasing the impinging velocity of the filler droplet can improve the latitudinal diffusion of the filler metal. However, a high impinging velocity can cause a lower diffusion zone in the upper part of the welds. This study provides a good foundation for optimizing the hybrid laser-MIG keyhole welding process to achieve quality welds with desired properties.

Comparative Study of Time-Frequency Decomposition Techniques for Fault Detection in Induction Motors Using Vibration Analysis during Startup Transient

Directory of Open Access Journals (Sweden)

Paulo Antonio Delgado-Arredondo

2015-01-01

Full Text Available Induction motors are critical components for most industries and the condition monitoring has become necessary to detect faults. There are several techniques for fault diagnosis of induction motors and analyzing the startup transient vibration signals is not as widely used as other techniques like motor current signature analysis. Vibration analysis gives a fault diagnosis focused on the location of spectral components associated with faults. Therefore, this paper presents a comparative study of different time-frequency analysis methodologies that can be used for detecting faults in induction motors analyzing vibration signals during the startup transient. The studied methodologies are the time-frequency distribution of Gabor (TFDG, the time-frequency Morlet scalogram (TFMS, multiple signal classification (MUSIC, and fast Fourier transform (FFT. The analyzed vibration signals are one broken rotor bar, two broken bars, unbalance, and bearing defects. The obtained results have shown the feasibility of detecting faults in induction motors using the time-frequency spectral analysis applied to vibration signals, and the proposed methodology is applicable when it does not have current signals and only has vibration signals. Also, the methodology has applications in motors that are not fed directly to the supply line, in such cases the analysis of current signals is not recommended due to poor current signal quality.

Assessment of Crack Detection in Heavy-Walled Cast Stainless Steel Piping Welds Using Advanced Low-Frequency Ultrasonic Methods

Energy Technology Data Exchange (ETDEWEB)

Anderson, Michael T.; Crawford, Susan L.; Cumblidge, Stephen E.; Denslow, Kayte M.; Diaz, Aaron A.; Doctor, Steven R.

2007-03-01

Studies conducted at the Pacific Northwest National Laboratory in Richland, Washington, have focused on assessing the effectiveness and reliability of novel approaches to nondestructive examination (NDE) for inspecting coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the U.S. Nuclear Regulatory Commission on the effectiveness and reliability of advanced NDE methods as related to the inservice inspection of safety-related components in pressurized water reactors (PWRs). This report provides progress, recent developments, and results from an assessment of low frequency ultrasonic testing (UT) for detection of inside surface-breaking cracks in cast stainless steel reactor piping weldments as applied from the outside surface of the components. Vintage centrifugally cast stainless steel piping segments were examined to assess the capability of low-frequency UT to adequately penetrate challenging microstructures and determine acoustic propagation limitations or conditions that may interfere with reliable flaw detection. In addition, welded specimens containing mechanical and thermal fatigue cracks were examined. The specimens were fabricated using vintage centrifugally cast and statically cast stainless steel materials, which are typical of configurations installed in PWR primary coolant circuits. Ultrasonic studies on the vintage centrifugally cast stainless steel piping segments were conducted with a 400-kHz synthetic aperture focusing technique and phased array technology applied at 500 kHz, 750 kHz, and 1.0 MHz. Flaw detection and characterization on the welded specimens was performed with the phased array method operating at the frequencies stated above. This report documents the methodologies used and provides results from laboratory studies to assess baseline material noise, crack detection, and length-sizing capability for low-frequency UT in cast stainless steel piping.

Calculation of temperature fields formed in induction annealing of closing welded joint of jacket of steam generator for WWER 440 type nuclear power plant using ICL 2960 computer

International Nuclear Information System (INIS)

Sajnar, P.; Fiala, J.

1983-01-01

The problems are discussed of the mathematical description and simulation of temperature fields in annealing the closing weld of the steam generator jacket of the WWER 440 nuclear power plant. The basic principles are given of induction annealing, the method of calculating temperature fields is indicated and the mathematical description is given of boundary conditions on the outer and inner surfaces of the steam generator jacket for the computation of temperature fields arising during annealing. Also described are the methods of determining the temperature of exposed parts of heat exchange tubes inside the steam generator and the technical possibilities are assessed of the annealing equipment from the point of view of its computer simulation. Five alternatives are given for the computation of temperature fields in the area around the weld for different boundary conditions. The values are given of maximum differences in the temperatures of the metal in the annealed part of the steam generator jacket which allow the assessment of individual computation variants, this mainly from the point of view of observing the course of annealing temperature in the required width of the annealed jacket of the steam generator along both sides of the closing weld. (B.S.)

Real-time ultrasonic weld evaluation system

Science.gov (United States)

Katragadda, Gopichand; Nair, Satish; Liu, Harry; Brown, Lawrence M.

1996-11-01

Ultrasonic testing techniques are currently used as an alternative to radiography for detecting, classifying,and sizing weld defects, and for evaluating weld quality. Typically, ultrasonic weld inspections are performed manually, which require significant operator expertise and time. Thus, in recent years, the emphasis is to develop automated methods to aid or replace operators in critical weld inspections where inspection time, reliability, and operator safety are major issues. During this period, significant advances wee made in the areas of weld defect classification and sizing. Very few of these methods, however have found their way into the market, largely due to the lack of an integrated approach enabling real-time implementation. Also, not much research effort was directed in improving weld acceptance criteria. This paper presents an integrated system utilizing state-of-the-art techniques for a complete automation of the weld inspection procedure. The modules discussed include transducer tracking, classification, sizing, and weld acceptance criteria. Transducer tracking was studied by experimentally evaluating sonic and optical position tracking techniques. Details for this evaluation are presented. Classification is obtained using a multi-layer perceptron. Results from different feature extraction schemes, including a new method based on a combination of time and frequency-domain signal representations are given. Algorithms developed to automate defect registration and sizing are discussed. A fuzzy-logic acceptance criteria for weld acceptance is presented describing how this scheme provides improved robustness compared to the traditional flow-diagram standards.

Recent studies on the welding of austenitic stainless steel piping for BWR service

International Nuclear Information System (INIS)

Childs, W.J.

1986-01-01

The incidence of intergranular stress corrosion cracking (IGSCC) in stainless steel piping in BWR power plants has led to the development of various countermeasures. Replacement of the susceptible Type 304 stainless steel with Type 316 nuclear grade stainless steel has been done by a number of plants. In order to minimize radiation exposure to welding personnel, automatic GTA welding has been used wherever possible when we make the field welds. Studies have shown that the residual stresses in the welded butt joints are affected by the welding process, weld joint design and welding procedures. A new weld joint design has been developed which minimizes the volume of deposited metal while providing adequate access for welding. It also minimizes axial and radial shrinkage and the resulting residual stresses. Other countermeasures, which have been used, include stress modifications such as induction heating stress improvement (IHSI) and last pass heat sink welding (LPHSW). It has been shown that these remedies must be process adjusted to account for the welding process employed. In some cases where UT cracking indication have been detected or where through wall cracking has occurred, weld surfacing has been used to extend life. A further approach to preventing IGSCC in the weld HAZ has been through improvement of the water chemistry by injecting hydrogen to reduce the oxygen level and by keeping the impurity level low

New And Existing Bridge Constructions - Increase of Fatigue Strength of Welded Joints by High Frequency Mechanical Impact Treatment

Directory of Open Access Journals (Sweden)

Ummenhofer Thomas

2013-07-01

Full Text Available Numerous studies at KIT prove that high frequency mechanical impact (HFMI treatment is an efficient method for increasing the fatigue strength of welded steel structures. Within different research projects it was found that HFMI-methods can be used successfully for new and existing structures in order to extend the fatigue life. This paper gives an overview of the current status of existing steel bridges in Germany regarding aspects like bridge age distributions and traffic loads. Based on that overview welded joints susceptible to fatigue failure are identified. Using component-like small scale specimens, HFMI-methods were investigated within the objective of implementing an effective application for new and existing structures. Applying the fatigue test data observed, existing design proposals are evaluated and design recommendations for HFMI-treated joints are given. As a result of the research work, a transfer into practice has been realized and different applications are illustrated using the example of bridge constructions made of steel.

Electron backscattering for process control in electron beam welding

International Nuclear Information System (INIS)

Ardenne, T. von; Panzer, S.

1983-01-01

A number of solutions to the automation of electron beam welding is presented. On the basis of electron backscattering a complex system of process control has been developed. It allows an enlarged imaging of the material's surface, improved adjustment of the beam focusing and definite focus positioning. Furthermore, both manual and automated positioning of the electron beam before and during the welding process has become possible. Monitoring of the welding process for meeting standard welding requirements can be achieved with the aid of a control quantity derived from the results of electronic evaluation of the high-frequency electron backscattering

Radio frequency induction plasma spraying of molybdenum

International Nuclear Information System (INIS)

Jiang Xianliang

2003-01-01

Radio frequency (RF) induction plasma was used to make free-standing deposition of molybdenum (Mo). The phenomena of particle melting, flattening, and stacking were investigated. The effect of process parameters such as plasma power, chamber pressure, and spray distance on the phenomena mentioned above was studied. Scanning electron microscopy (SEM) was used to analyze the plasma-processed powder, splats formed, and deposits obtained. Experimental results show that less Mo particles are spheroidized when compared to the number of spheroidized tungsten (W) particles at the same powder feed rate under the same plasma spray condition. Molten Mo particles can be sufficiently flattened on substrate. The influence of the process parameters on the flattening behavior is not significant. Mo deposit is not as dense as W deposit, due to the splash and low impact of molten Mo particles. Oxidation of the Mo powder with a large particle size is not evident under the low pressure plasma spray

Efficiency optimization of class-D biomedical inductive wireless power transfer systems by means of frequency adjustment.

Science.gov (United States)

Schormans, Matthew; Valente, Virgilio; Demosthenous, Andreas

2015-01-01

Inductive powering for implanted medical devices is a commonly employed technique, that allows for implants to avoid more dangerous methods such as the use of transcutaneous wires or implanted batteries. However, wireless powering in this way also comes with a number of difficulties and conflicting requirements, which are often met by using designs based on compromise. In particular, one aspect common to most inductive power links is that they are driven with a fixed frequency, which may not be optimal depending on factors such as coupling and load. In this paper, a method is proposed in which an inductive power link is driven by a frequency that is maintained at an optimum value f(opt), to ensure that the link is in resonance. In order to maintain this resonance, a phase tracking technique is employed at the primary side of the link; this allows for compensation of changes in coil separation and load. The technique is shown to provide significant improvements in maintained secondary voltage and efficiency for a range of loads when the link is overcoupled.

Reflection of illumination laser from gas metal arc weld pool surface

International Nuclear Information System (INIS)

Ma, Xiaoji; Zhang, YuMing

2009-01-01

The weld pool is the core of the welding process where complex welding phenomena originate. Skilled welders acquire their process feedback primarily from the weld pool. Observation and measurement of the three-dimensional weld pool surface thus play a fundamental role in understanding and future control of complex welding processes. To this end, a laser line is projected onto the weld pool surface in pulsed gas metal arc welding (GMAW) and an imaging plane is used to intercept its reflection from the weld pool surface. Resultant images of the reflected laser are analyzed and it is found that the weld pool surface in GMAW does specularly reflect the projected laser as in gas tungsten arc welding (GTAW). Hence, the weld pool surface in GMAW is also specular and it is in principle possible that it may be observed and measured by projecting a laser pattern and then intercepting and imaging the reflection from it. Due to high frequencies of surface fluctuations, GMAW requires a relatively short time to image the reflected laser

Vibration stress relief treatment in welded samples of ST-3 steel

International Nuclear Information System (INIS)

Suarez, J.C.; Fernandez, L.M.; Echevarria, J.F.; Estevez, A.; Perez, A.; Aragon, B.

1996-01-01

The presented work is aimed to find the optimal vibration frequency and treatment duration for ST-3 steel welded test pieces. In the experiment transversal stresses were not virtually relieved by the application of vibrations at the three natural frecuencies. With regard to the optimal frequency for our system, the firths natural frequency appears to be most effective one, wherewith a maximum 35-70 % longitudinal stress relief was obtained. The influence of the propagation direction (transversal or longitudinal) of vibrations on stress relief in a welded joint was confirmed

The rating of element closure welds and its influence on fuel reliability

International Nuclear Information System (INIS)

Sejnoha, R.; Ceccotti, G.; Magnoli, L.

1986-10-01

A high performance standard of CANDU fuel, and similarly of CIRENE fuel is possible only if the frequency of fuel element failures due to incomplete welds is kept very low. Weld rating, i.e. the relative length of sound weld line, is used to characterize the weld completeness. Metallography is used for quantative determination of the weld rating. The nature of the metallographic inspection method, together with the affordable sample size and the very low acceptable weld failure rate, make a statistical approach to the evaluation of the weld ratings necessary. The paper outlines a statistical method of weld rating assessment. The method links the probability of finding discontinuities in metallographic sections, with the distribution of discontinuities in a statistical sample of welds. It presents the results in the form of a weld rating distribution graph. Applications of the method are discussed. Its use is shown for three batches of CIRENE development welds

Quality evaluation of PHWR fuel element end cap weld joints by ultrasonic testing technique

Energy Technology Data Exchange (ETDEWEB)

Singh, J L; Nair, V R; Ramadasan, E; Majumdar, S; Sahoo, K C [Bhabha Atomic Research Centre, Bombay (India). Radiometallurgy Div.; Kumar, Arun [Atomic Fuel Fabrication Facility, Tarapur (India)

1994-12-31

An ultrasonic testing technique has been developed for effective quality evaluation of Pressurised Heavy Water Reactor (PHWR) fuel end plug welds. A focused high frequency shear wave is directed to the weld zone from half skip distance to detect lack of fusion, porosities and wall cracks in the weld zone. A tentative select/reject level has been evolved to sort out the defective weld by examining more than 700 PHWR fuel pin welds. (author). 5 refs., 5 figs.

Magnetic fields and uniformity of radio frequency power deposition in low-frequency inductively coupled plasmas with crossed internal oscillating currents

International Nuclear Information System (INIS)

Tsakadze, E.L.; Ostrikov, K.; Tsakadze, Z.L.; Vladimirov, S.V.; Xu, S.

2004-01-01

Radial and axial distributions of magnetic fields in a low-frequency (∼460 kHz) inductively coupled plasma source with two internal crossed planar rf current sheets are reported. The internal antenna configuration comprises two orthogonal sets of eight alternately reconnected parallel and equidistant copper litz wires in quartz enclosures and generates three magnetic (H z , H r , and H φ ) and two electric (E φ and E r ) field components at the fundamental frequency. The measurements have been performed in rarefied and dense plasmas generated in the electrostatic (E) and electromagnetic (H) discharge modes using two miniature magnetic probes. It is shown that the radial uniformity and depth of the rf power deposition can be improved as compared with conventional sources of inductively coupled plasmas with external flat spiral ('pancake') antennas. Relatively deeper rf power deposition in the plasma source results in more uniform profiles of the optical emission intensity, which indicates on the improvement of the plasma uniformity over large chamber volumes. The results of the numerical modeling of the radial magnetic field profiles are found in a reasonable agreement with the experimental data

Scaling of spiking and humping in keyhole welding

Energy Technology Data Exchange (ETDEWEB)

Wei, P S; Chuang, K C [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); DebRoy, T [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Ku, J S, E-mail: pswei@mail.nsysu.edu.tw, E-mail: cielo.zhuang@gmail.com, E-mail: rtd1@psu.edu, E-mail: jsku@mail.nsysu.edu.tw [Institute of Materials Science and Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China)

2011-06-22

Spiking, rippling and humping seriously reduce the strength of welds. The effects of beam focusing, volatile alloying element concentration and welding velocity on spiking, coarse rippling and humping in keyhole mode electron-beam welding are examined through scale analysis. Although these defects have been studied in the past, the mechanisms for their formation are not fully understood. This work relates the average amplitudes of spikes to fusion zone depth for the welding of Al 6061, SS 304 and carbon steel, and Al 5083. The scale analysis introduces welding and melting efficiencies and an appropriate power distribution to account for the focusing effects, and the energy which is reflected and escapes through the keyhole opening to the surroundings. The frequency of humping and spiking can also be predicted from the scale analysis. The analysis also reveals the interrelation between coarse rippling and humping. The data and the mechanistic findings reported in this study are useful for understanding and preventing spiking and humping during keyhole mode electron and laser beam welding.

Experimental diagnostics and modeling of inductive phenomena at low frequencies in impedance spectra of proton exchange membrane fuel cells

Science.gov (United States)

Pivac, Ivan; Šimić, Boris; Barbir, Frano

2017-10-01

Representation of fuel cell processes by equivalent circuit models, involving resistance and capacitance elements representing activation losses on both anode and cathode in series with resistance representing ohmic losses, cannot capture and explain the inductive loop that may show up at low frequencies in Nyquist diagram representation of the electrochemical impedance spectra. In an attempt to explain the cause of the low-frequency inductive loop and correlate it with the processes within the fuel cell electrodes, a novel equivalent circuit model of a Proton Exchange Membrane (PEM) fuel cell has been proposed and experimentally verified here in detail. The model takes into account both the anode and the cathode, and has an additional resonant loop on each side, comprising of a resistance, capacitance and inductance in parallel representing the processes within the catalyst layer. Using these additional circuit elements, more accurate and better fits to experimental impedance data in the wide frequency range at different current densities, cell temperatures, humidity of gases, air flow stoichiometries and backpressures were obtained.

Influence of laser hardening with weld penetration onto mechanical and fatigue properties of 40H steel

International Nuclear Information System (INIS)

Napadlek, W.; Przetakiewicz, W.

2003-01-01

In the article were described investigations results of mechanical properties (hardness, R 0.2 , R m , A 5 , Z) and fatigue properties (rotary bending) of the 40H steel samples, being quenched and tempered, induction and laser hardened. In the laser hardened samples with weld penetration of top layer cracking process in fatigue strength is started mainly in weld penetration area as structural notch. (author)

Prediction of Weld Residual Stress of Narrow Gap Welds

International Nuclear Information System (INIS)

Yang, Jun Seog; Huh, Nam Su

2010-01-01

The conventional welding technique such as shield metal arc welding has been mostly applied to the piping system of the nuclear power plants. It is well known that this welding technique causes the overheating and welding defects due to the large groove angle of weld. On the other hand, the narrow gap welding(NGW) technique has many merits, for instance, the reduction of welding time, the shrinkage of weld and the small deformation of the weld due to the small groove angle and welding bead width comparing with the conventional welds. These characteristics of NGW affect the deformation behavior and the distribution of welding residual stress of NGW, thus it is believed that the residual stress results obtained from conventional welding procedure may not be applied to structural integrity evaluation of NGW. In this paper, the welding residual stress of NGW was predicted using the nonlinear finite element analysis to simulate the thermal and mechanical effects of the NGW. The present results can be used as the important information to perform the flaw evaluation and to improve the weld procedure of NGW

High-Powered, Ultrasonically Assisted Thermal Stir Welding

Science.gov (United States)

Ding, Robert

2013-01-01

This method is a solid-state weld process capable of joining metallic alloys without melting. The weld workpieces to be joined by thermal stir welding (TSW) are drawn, by heavy forces, between containment plates past the TSW stir tool that then causes joining of the weld workpiece. TSW is similar to friction stir welding (FSW) in that material is heated into a plastic state (not melted) and stirred using a stir rod. The FSW pin tool is an integrated geometrical structure consisting of a large-diameter shoulder, and a smaller-diameter stir pin protruding from the shoulder. When the pin is plunged into a weld workpiece, the shoulder spins on the surface of the weld workpiece, thus inducing frictional heat into the part. The pin stirs the fraying surfaces of the weld joint, thus joining the weld workpiece into one structure. The shoulder and stir pin of the FSW pin tool must rotate together at a desired rotational speed. The induced frictional energy control and stir pin control of the pin tool cannot be de-coupled. The two work as one integrated unit. TSW, on the other hand, de-couples the heating and stirring of FSW, and allows for independent control of each process element. A uniquely designed induction coil heats the weld workpiece to a desired temperature, and once heated, the part moves into a stir rod whose RPM is also independently controlled. As the weld workpiece moves into the stir rod, the piece is positioned, or sandwiched, between upper and lower containment plates. The plate squeezes together, thus compressing the upper and lower surfaces of the weld workpiece. This compressive force, also called consolidation force, consolidates the plastic material within the weld nugget material as it is being stirred by the stir rod. The stir rod is positioned through the center of the top containment plate and protrudes midway through the opposite lower containment plate where it is mechanically captured. The upper and lower containment plates are separated by a

Low-frequency, self-sustained oscillations in inductively coupled plasmas used for optical pumping

Energy Technology Data Exchange (ETDEWEB)

Coffer, J.; Encalada, N.; Huang, M.; Camparo, J. [Physical Sciences Laboratories, The Aerospace Corporation 2310, E. El Segundo Blvd., El Segundo, California 90245 (United States)

2014-10-28

We have investigated very low frequency, on the order of one hertz, self-pulsing in alkali-metal inductively-coupled plasmas (i.e., rf-discharge lamps). This self-pulsing has the potential to significantly vary signal-to-noise ratios and (via the ac-Stark shift) resonant frequencies in optically pumped atomic clocks and magnetometers (e.g., the atomic clocks now flying on GPS and Galileo global navigation system satellites). The phenomenon arises from a nonlinear interaction between the atomic physics of radiation trapping and the plasma's electrical nature. To explain the effect, we have developed an evaporation/condensation theory (EC theory) of the self-pulsing phenomenon.

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.

Mathematical Model and Computational Analysis of Selected Transient States of Cylindrical Linear Induction Motor Fed via Frequency Converter

Directory of Open Access Journals (Sweden)

Andrzej Rusek

2008-01-01

Full Text Available The mathematical model of cylindrical linear induction motor (C-LIM fed via frequency converter is presented in the paper. The model was developed in order to analyze numerically the transient states. Problems concerning dynamics of ac-machines especially linear induction motor are presented in [1 – 7]. Development of C-LIM mathematical model is based on circuit method and analogy to rotary induction motor. The analogy between both: (a stator and rotor windings of rotary induction motor and (b winding of primary part of C-LIM (inductor and closed current circuits in external secondary part of C-LIM (race is taken into consideration. The equations of C-LIM mathematical model are presented as matrix together with equations expressing each vector separately. A computational analysis of selected transient states of C-LIM fed via frequency converter is presented in the paper. Two typical examples of C-LIM operation are considered for the analysis: (a starting the motor at various static loads and various synchronous velocities and (b reverse of the motor at the same operation conditions. Results of simulation are presented as transient responses including transient electromagnetic force, transient linear velocity and transient phase current.

Investigation on mechanical properties of welded material under different types of welding filler (shielded metal arc welding)

Science.gov (United States)

Tahir, Abdullah Mohd; Lair, Noor Ajian Mohd; Wei, Foo Jun

2018-05-01

The Shielded Metal Arc Welding (SMAW) is (or the Stick welding) defined as a welding process, which melts and joins metals with an arc between a welding filler (electrode rod) and the workpieces. The main objective was to study the mechanical properties of welded metal under different types of welding fillers and current for SMAW. This project utilized the Design of Experiment (DOE) by adopting the Full Factorial Design. The independent variables were the types of welding filler and welding current, whereas the other welding parameters were fixed at the optimum value. The levels for types of welding filler were by the models of welding filler (E6013, E7016 and E7018) used and the levels for welding current were 80A and 90A. The responses were the mechanical properties of welded material, which include tensile strength and hardness. The experiment was analyzed using the two way ANOVA. The results prove that there are significant effects of welding filler types and current levels on the tensile strength and hardness of the welded metal. At the same time, the ANOVA results and interaction plot indicate that there are significant interactions between the welding filler types and the welding current on both the hardness and tensile strength of the welded metals, which has never been reported before. This project found that when the amount of heat input with increase, the mechanical properties such as tensile strength and hardness decrease. The optimum tensile strength for welded metal is produced by the welding filler E7016 and the optimum of hardness of welded metal is produced by the welding filler E7018 at welding current of 80A.

Use of eddy current mixes to solve a weld examination application

International Nuclear Information System (INIS)

Ward, R.C.; LaBoissonniere, A.

1995-01-01

The augmentation of typical nondestructive (i.e., ultrasound) weld inspection techniques by the use of eddy current tools may significantly enhance the quality and reliability of weld inspections. One recent example is the development of an eddy current technique for use in the examination of BWR core shroud welds, where multi-frequency mixes are used to eliminate signals coming from the weld material so that the examination of the heat affected zone is enhanced. An analysis tool most commonly associated with ultrasound examinations, the C-Scan based on gated information, may be implemented with eddy current data to enhance analysis

Reduction method for residual stress of welded joint using harmonic vibrational load

International Nuclear Information System (INIS)

Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro; Hirai, Seiji

2007-01-01

Welding is widely used for construction of many structures. Since welding is a process using locally given heat, residual stress is generated near the bead. Tensile residual stress degrades fatigue strength. Some reduction methods of residual stress have been presented and, for example, heat treatment and shot peening are practically used. However, those methods need special tools and are time consuming. In this paper, a new method for reduction of residual stress using harmonic vibrational load during welding is proposed. The proposed method is examined experimentally for some conditions. Two thin plates are supported on the supporting device and butt-welded using an automatic CO 2 gas shielded arc welding machine. Residual stress in the direction of the bead is measured by using a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. First, the welding of rolled steel for general structure for some excitation frequencies is examined. Specimens are welded along the groove on both sides. For all frequencies, tensile residual stress near the bead is significantly reduced. Second, welding of the specimen made of high tensile strength steel is examined. In this case, tensile residual stress near the bead is also reduced. Finally, the proposed method is examined by an analytical method. An analytical model which consists of mass and preloaded springs with elasto-plastic characteristic is used. Reduction of residual stress is demonstrated using this model

Optimized design on condensing tubes high-speed TIG welding technology magnetic control based on genetic algorithm

Science.gov (United States)

Lu, Lin; Chang, Yunlong; Li, Yingmin; Lu, Ming

2013-05-01

An orthogonal experiment was conducted by the means of multivariate nonlinear regression equation to adjust the influence of external transverse magnetic field and Ar flow rate on welding quality in the process of welding condenser pipe by high-speed argon tungsten-arc welding (TIG for short). The magnetic induction and flow rate of Ar gas were used as optimum variables, and tensile strength of weld was set to objective function on the base of genetic algorithm theory, and then an optimal design was conducted. According to the request of physical production, the optimum variables were restrained. The genetic algorithm in the MATLAB was used for computing. A comparison between optimum results and experiment parameters was made. The results showed that the optimum technologic parameters could be chosen by the means of genetic algorithm with the conditions of excessive optimum variables in the process of high-speed welding. And optimum technologic parameters of welding coincided with experiment results.

Defects detection on the welded reinforcing steel with self-shielded wires by vibration tests

Directory of Open Access Journals (Sweden)

Crâştiu Ion

2017-01-01

Full Text Available The aim of this paper is the development and validation of a vibroacustic technique to welding defects detection, especially for welded reinforcing structures. In welded structures subjected to dynamic cyclic loads may appear and propagate fatigue cracks due to local structural damage. These cracks may initiate due to the technological parameters used in welding process, or due to environmental operating conditions. By the means of Finite Element Method (FEM, the natural frequencies and shape modes of more welded steel specimens are determined. The analysis is carried out in undamaged condition as well as damaged one, after artificially induced damages. The experimental measurement of the vibroacustic response is carried out by using a condenser microphone, which is suitable for high-fidelity acoustic measurements in the frequency range of 20 – 20.000 Hz. The vibration responses of the welded specimens, in free-free conditions, are carried out using algorithms based on Fast Fourier Transform (FFT, and Prony's series. The results are compared to modal parameters estimated using FE Analysis.

[Study on the arc spectral information for welding quality diagnosis].

Science.gov (United States)

Li, Zhi-Yong; Gu, Xiao-Yan; Li, Huan; Yang, Li-Jun

2009-03-01

Through collecting the spectral signals of TIG and MIG welding arc with spectrometer, the arc light radiations were analyzed based on the basic theory of plasma physics. The radiation of welding arc distributes over a broad range of frequency, from infrared to ultraviolet. The arc spectrum is composed of line spectra and continuous spectra. Due to the variation of metal density in the welding arc, there is great difference between the welding arc spectra of TIG and MIG in both their intensity and distribution. The MIG welding arc provides more line spectra of metal and the intensity of radiation is greater than TIG. The arc spectrum of TIG welding is stable during the welding process, disturbance factors that cause the spectral variations can be reflected by the spectral line related to the corresponding element entering the welding arc. The arc spectrum of MIG welding will fluctuate severely due to droplet transfer, which produces "noise" in the line spectrum aggregation zone. So for MIG welding, the spectral zone lacking spectral line is suitable for welding quality diagnosis. According to the characteristic of TIG and MIG, special spectral zones were selected for welding quality diagnosis. For TIG welding, the selected zone is in ultraviolet zone (230-300 nm). For MIG welding, the selected zone is in visible zone (570-590 nm). With the basic theory provided for welding quality diagnosis, the integral intensity of spectral signal in the selected zone of welding process with disturbing factor was studied to prove the theory. The results show that the welding quality and disturbance factors can be diagnosed with good signal to noise ratio in the selected spectral zone compared with signal in other spectral zone. The spectral signal can be used for real-time diagnosis of the welding quality.

A Study Regarding the Efficiency of the Electromagnetic Induction Thermal Treatment Process Depending to the Work Frequency

Directory of Open Access Journals (Sweden)

MICH-VANCEA Claudiu

2011-05-01

Full Text Available The paper is focused on the induction heating for thermal treatments to make more efficient this process, using the numerical simulation. In the first part we analyze the parameters that can changethe dept penetration of the electromagnetic field in the hardened piece. The frequency of the electromagnetic field can be imposed, and by this parameter we can control the hardened layer in piece. In second part of the paper, is presented the numerical simulation in 1Dfor the induction heating process for hardening. The results obtained are helping the designer and the enduser to choose the best configuration of the induction heating and cooling systems that fulfils the most stringent requirements needed for hardened piece.

Transition welds in welding of two-ply steels

International Nuclear Information System (INIS)

Fartushnyj, V.G.; Evsyukov, Yu.G.

1977-01-01

Studied were physico-mechanical properties of welds made by various welding wires of chromium-nickel and nickel-chromium steels in submerged arc welding of double-layer steels with main layer of the VSt.3sp. carbon steel. It is shown that service-reliable structures welded of two-layer steels are obtained by providing the content from 11 to 20 % Ni in the automatically welded transition layer

Optimization of the Closure-Weld Region of cylindrical Containers for Long-Term Corrosion Resistance

International Nuclear Information System (INIS)

Zekai Ceylan; Mohamed B. Trabia

2001-01-01

Welded cylindrical containers are susceptible to stress corrosion cracking (SCC) in the closure-weld area. An induction coil heating technique may be used to relieve the residual stresses in the closure-weld. This technique involves localized heating of the material by the surrounding coils. The material is then cooled to room temperature by quenching. A two-dimensional axisymmetric finite element model is developed to study the effects of induction coil heating and subsequent quenching. The finite element results are validated through an experimental test. The parameters of the design are tuned to maximize the compressive stress from the outer surface to a depth that is equal to the long-term general corrosion rate of Alloy 22 (Appendix A) multiplied by the desired container lifetime. The problem is subject to geometrical and stress constraints. Two different solution methods are implemented for this purpose. First, off-the-shelf optimization software is used to obtain an optimum solution. These results are not satisfactory because of the highly nonlinear nature of the problem. The paper proposes a novel alternative: the Successive Heuristic Quadratic Approximation (SHQA) technique. This algorithm combines successive quadratic approximation with an adaptive random search. Examples and discussion are included

An Experimental Investigation on APR1400 Penetration Weld Failure by Metallic Melt

International Nuclear Information System (INIS)

An, Sang Mo; Ha, Kwang Soon; Kim, Hwan Yeol

2014-01-01

The penetrations are considered as the most vulnerable parts with respect to the reactor vessel failure when a core melt severe accident occurs and the corium reaches the lower head. Penetration tube failure modes can be divided into two categories; tube ejection out of the vessel lower head and rupture of the penetration tube outside the vessel. Tube ejection begins with degrading the penetration tube weld strength to zero as the weld is exposed to temperatures as high as the weld melting temperature, which is called weld failure, and then overcoming any binding force in the hole in the vessel wall that results from differential thermal expansion of the tube and vessel wall. Tube rupture assumes that the debris bed has melted the instrument tube inside the reactor and melt migrates down into the tube to a location outside the vessel wall where a pressure rupture can occur, thus breaching the pressure boundary. In the present paper, we have a focus on the tube ejection failure mode, specifically on the APR1400 weld failure by direct contact with a metallic melt. The objective is to investigate experimentally the ablation kinetics of an APR1400 penetration weld during the interactions with a metallic melt and to suggest the modification of the existing weld failure model. This paper involves the interaction experiments of two different metallic melts (metallic corium and stainless steel melts) with a weld specimen, and rough estimation of weld failure time. The interaction experiments between the metallic melts and an APR1400 penetration weld were performed to investigate the ablation kinetics of the penetration weld. Metallic corium and stainless steel melts were generated using an induction heating technique and interacted with a penetration weld specimen. The ablation rate of the weld specimen showed a range from 0.109 to 0..244 mm/s and thus the APR1400 penetration weld was estimated to be failed at hundreds of times after the interaction with the melt

Spatially resolved ultrasonic attenuation in resistance spot welds: implications for nondestructive testing.

Science.gov (United States)

Mozurkewich, George; Ghaffari, Bita; Potter, Timothy J

2008-09-01

Spatial variation of ultrasonic attenuation and velocity has been measured in plane parallel specimens extracted from resistance spot welds. In a strong weld, attenuation is larger in the nugget than in the parent material, and the region of increased attenuation is surrounded by a ring of decreased attenuation. In the center of a stick weld, attenuation is even larger than in a strong weld, and the low-attenuation ring is absent. These spatial variations are interpreted in terms of differences in grain size and martensite formation. Measured frequency dependences indicate the presence of an additional attenuation mechanism besides grain scattering. The observed attenuations do not vary as commonly presumed with weld quality, suggesting that the common practice of using ultrasonic attenuation to indicate weld quality is not a reliable methodology.

Weld controller for automated nuclear service welding

International Nuclear Information System (INIS)

Barfield, K.L.; Strubhar, P.M.; Green, D.I.

1995-01-01

B and W Nuclear Technologies (BWNT) uses many different types of weld heads for automated welding in the commercial nuclear service industry. Some weld heads are purchased as standard items, while others are custom designed and fabricated by BWNT requiring synchronized multiaxis motion control. BWNT recently completed a development program to build a common weld controller that interfaces to all types of weld heads used by BWNT. Their goal was to construct a system that had the flexibility to add different modules to increase the capability of the controller as different application needs become necessary. The benefits from having a common controller are listed. This presentation explains the weld controller system and the types of applications to which it has been applied

Welding hazards

International Nuclear Information System (INIS)

Khan, M.A.

1992-01-01

Welding technology is advancing rapidly in the developed countries and has converted into a science. Welding involving the use of electricity include resistance welding. Welding shops are opened in residential area, which was causing safety hazards, particularly the teenagers and children who eagerly see the welding arc with their naked eyes. There are radiation hazards from ultra violet rays which irritate the skin, eye irritation. Welding arc light of such intensity could damage the eyes. (Orig./A.B.)

Optimization of process parameters of pulsed TIG welded maraging steel C300

Science.gov (United States)

Deepak, P.; Jualeash, M. J.; Jishnu, J.; Srinivasan, P.; Arivarasu, M.; Padmanaban, R.; Thirumalini, S.

2016-09-01

Pulsed TIG welding technology provides excellent welding performance on thin sections which helps to increase productivity, enhance weld quality, minimize weld costs, and boost operator efficiency and this has drawn the attention of the welding society. Maraging C300 steel is extensively used in defence and aerospace industry and thus its welding becomes an area of paramount importance. In pulsed TIG welding, weld quality depends on the process parameters used. In this work, Pulsed TIG bead-on-plate welding is performed on a 5mm thick maraging C300 plate at different combinations of input parameters: peak current (Ip), base current (Ib) and pulsing frequency (HZ) as per box behnken design with three-levels for each factor. Response surface methodology is utilized for establishing a mathematical model for predicting the weld bead depth. The effect of Ip, Ib and HZ on the weld bead depth is investigated using the developed model. The weld bead depth is found to be affected by all the three parameters. Surface and contour plots developed from regression equation are used to optimize the processing parameters for maximizing the weld bead depth. Optimum values of Ip, Ib and HZ are obtained as 259 A, 120 A and 8 Hz respectively. Using this optimum condition, maximum bead depth of the weld is predicted to be 4.325 mm.

Identification of Damaged Spot Welds in a Complicated Joined Structure

International Nuclear Information System (INIS)

Yunus, M A; Rani, M N Abdul; Ouyang, H; Deng, H; James, S

2011-01-01

In automotive engineering, spot welds on assembled structures such as Body in White (BiW) have a significant effect on the vehicles' dynamic characteristics. Understandably, imperfections in the spot welds will cause variations in the dynamic properties such as natural frequencies and mode shapes of the structure. In this paper, a complicated welded structure which is a simplified Natural Gas Vehicle (NGV) platform is investigated. The structure fabricated from thin metal sheets consists of ten components. They are jointed together by a number of scattered spot welds. NASTRAN Solution 200 based on sensitivity analysis is used to identify the most sensitive parameters to natural frequencies. The numerical model of the undamaged structure is initially updated in order to minimise the discrepancies between the measured and numerical data using NASTRAN optimisation code. The initial updated model serves as a benchmark for the subsequent structural damage identification. The numerical data of the benchmark model is then compared with the measured data obtained from the damaged structure. The same updating procedure is applied to the benchmark model in order to bring the numerical data as close as possible to the measured data of the damaged structure. The disparity in certain parameter values from the parameter values used in the benchmark model shows a fault or damage in the location of a particular joint, depending on the severity of this disparity. The challenge in this work is to localise damaged area and quantify the damage of the complicated structure with multiple spot welds in the presence of uncertainty in the location and material properties of the welds.

Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

Energy Technology Data Exchange (ETDEWEB)

Trushnikov, D. N., E-mail: trdimitr@yandex.ru [The department for Applied Physics, Perm National Research Polytechnic University, Perm, 614990 (Russian Federation); Mladenov, G. M., E-mail: gmmladenov@abv.bg; Koleva, E. G., E-mail: eligeorg@abv.bg [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Shose, 1784, Sofia (Bulgaria); Technology Centre of Electron Beam and Plasma Technologies and Techniques, 68-70 Vrania, ap.10, Banishora,1309, Sofia (Bulgaria); Belenkiy, V. Ya., E-mail: mtf@pstu.ru; Varushkin, S. V., E-mail: stepan.varushkin@mail.ru [The department for Welding Production and Technology of Constructional Materials, Perm National Research Polytechnic University, Perm, 614990 (Russian Federation)

2014-04-15

Many papers have sought correlations between the parameters of secondary particles generated above the beam/work piece interaction zone, dynamics of processes in the keyhole, and technological processes. Low- and high-frequency oscillations of the current, collected by plasma have been observed above the welding zone during electron beam welding. Low-frequency oscillations of secondary signals are related to capillary instabilities of the keyhole, however; the physical mechanisms responsible for the high-frequency oscillations (>10 kHz) of the collected current are not fully understood. This paper shows that peak frequencies in the spectra of the collected high-frequency signal are dependent on the reciprocal distance between the welding zone and collector electrode. From the relationship between current harmonics frequency and distance of the collector/welding zone, it can be estimated that the draft velocity of electrons or phase velocity of excited waves is about 1600 m/s. The dispersion relation with the properties of ion-acoustic waves is related to electron temperature 10 000 K, ion temperature 2 400 K and plasma density 10{sup 16} m{sup −3}, which is analogues to the parameters of potential-relaxation instabilities, observed in similar conditions. The estimated critical density of the transported current for creating the anomalous resistance state of plasma is of the order of 3 A·m{sup −2}, i.e. 8 mA for a 3–10 cm{sup 2} collector electrode. Thus, it is assumed that the observed high-frequency oscillations of the current collected by the positive collector electrode are caused by relaxation processes in the plasma plume above the welding zone, and not a direct demonstration of oscillations in the keyhole.

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.

Advanced Welding Concepts

Science.gov (United States)

Ding, Robert J.

2010-01-01

Four advanced welding techniques and their use in NASA are briefly reviewed in this poster presentation. The welding techniques reviewed are: Solid State Welding, Friction Stir Welding (FSW), Thermal Stir Welding (TSW) and Ultrasonic Stir Welding.

Resistance seam welding

International Nuclear Information System (INIS)

Schueler, A.W.

1977-01-01

The advantages and disadvantages of the resistance seam welding process are presented. Types of seam welds, types of seam welding machines, seam welding power supplies, resistance seam welding parameters and seam welding characteristics of various metals

Effect of vibration on microstructures and mechanical properties of 304 stainless steel GTA welds

Science.gov (United States)

Hsieh, Chih-Chun; Lai, Chien-Hong; Wu, Weite

2013-07-01

This study investigates the microstructures and mechanical properties of 304 stainless steel at various vibration frequencies during simultaneous vibration welding. The experimental results demonstrated that simultaneous vibration welding could accelerate the nucleation and grain refinement of the microstructures. The effect of the grain refinement was more evident at the resonant frequency (375 Hz) and a minimum content of residual δ-ferrite (4.0%). The γ phase grew in the preferential orientation of the (111) direction with and without vibration. The full width at half maximum of the diffraction peak widened after the vibration, which was attributed to the grain refinement. The residual stress could be efficiently removed through simultaneous vibration welding when the amplitude of the vibration was increased. Furthermore, the lowest residual stress (139 MPa) was found when the vibration frequency was 375 Hz. The hardness and Young's modulus exhibited slight increases with low and medium frequencies. The hardness values were increased by 7.6% and Young's modulus was increased by 15% when the vibration frequency was resonant (375 Hz).

Inductance loop and partial

CERN Document Server

Paul, Clayton R

2010-01-01

"Inductance is an unprecedented text, thoroughly discussing "loop" inductance as well as the increasingly important "partial" inductance. These concepts and their proper calculation are crucial in designing modern high-speed digital systems. World-renowned leader in electromagnetics Clayton Paul provides the knowledge and tools necessary to understand and calculate inductance." "With the present and increasing emphasis on high-speed digital systems and high-frequency analog systems, it is imperative that system designers develop an intimate understanding of the concepts and methods in this book. Inductance is a much-needed textbook designed for senior and graduate-level engineering students, as well as a hands-on guide for working engineers and professionals engaged in the design of high-speed digital and high-frequency analog systems."--Jacket.

Comparison of Welding Residual Stresses of Hybrid Laser-Arc Welding and Submerged Arc Welding in Offshore Steel Structures

DEFF Research Database (Denmark)

Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

2016-01-01

In the offshore industry, welding-induced distortion and tensile residual stresses have become a major concern in relation to the structural integrity of a welded structure. Particularly, the continuous increase in size of welded plates and joints needs special attention concerning welding induced...... residual stresses. These stresses have a negative impact on the integrity of the welded joint as they promote distortion, reduce fatigue life, and contribute to corrosion cracking and premature failure in the weld components. This paper deals with the influence and impact of welding method on the welding...... induced residual stresses. It is also investigated whether the assumption of residual stresses up to yield strength magnitude are present in welded structures as stated in the design guidelines. The fatigue strength for welded joints is based on this assumption. The two welding methods investigated...

Welding technology transfer task/laser based weld joint tracking system for compressor girth welds

Science.gov (United States)

Looney, Alan

1991-01-01

Sensors to control and monitor welding operations are currently being developed at Marshall Space Flight Center. The laser based weld bead profiler/torch rotation sensor was modified to provide a weld joint tracking system for compressor girth welds. The tracking system features a precision laser based vision sensor, automated two-axis machine motion, and an industrial PC controller. The system benefits are elimination of weld repairs caused by joint tracking errors which reduces manufacturing costs and increases production output, simplification of tooling, and free costly manufacturing floor space.

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 promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

Frequency Calculation For Loss Coolant Accident In The Nuclear Reactor

International Nuclear Information System (INIS)

Sony, DT

1996-01-01

LOCA as initiating event is engineering judgement, because it is rare condition. So, to determine LOCA frequency used be probability and statistic method. By probability and statistic method was estimated from size, weld, age, learning curve and quality, etc. it has been calculated for LOCA frequency in the simplified piping system model, especially estimates from size and weld factors. From calculation, LOCA frequency is 9,82.10 - 6/year

Alternate Welding Processes for In-Service Welding

Science.gov (United States)

2009-04-24

Conducting weld repairs and attaching hot tap tees onto pressurized pipes has the advantage of avoiding loss of service and revenue. However, the risks involved with in-service welding need to be managed by ensuring that welding is performed in a rep...

Pulsed Nd-YAG laser welding of Prototype Fast Breeder Reactor fuel elements

International Nuclear Information System (INIS)

Suresh Varma, P.V.; Gupta, Amit; Amit, K.; Bhatt, R.B.; Afzal, Mohd.; Panakkal, J.P.; Kamath, H.S.

2009-02-01

End plug welding of Prototype Fast Breeder Reactor (PFBR) fuel elements involves welding of fully Austenitic Stainless Steel (ASS) of grade D9 clad tube with 316M end plug. Pulsed Gas Tungsten Arc Welding (GTAW) is being used for the production of PFBR fuel elements at Advanced Fuel Fabrication Facility (AFFF). GTAW is an established process for end plug welding and hence adopted by many countries. GTAW has got certain limitations like heat input, arc gap sensitivity and certain sporadic defects like tungsten inclusion. Experiments have been carried out at AFFF to use Laser Beam Welding (LBW) technique as LBW offers a number of advantages over the former process. This report mainly deals with the optimization of laser parameters for welding of PFBR fuel elements. To facilitate pulsed Nd-YAG laser spot welding, parameters like peak power, pulse duration, pulse energy, frequency and defocusing of laser beam on to the work piece have been optimized. On the basis of penetration requirement laser welding parameters have been optimized. (author)

Hybrid laser-TIG welding, laser beam welding and gas tungsten arc welding of AZ31B magnesium alloy

International Nuclear Information System (INIS)

Liu Liming; Wang Jifeng; Song Gang

2004-01-01

Welding of AZ31B magnesium alloy was carried out using hybrid laser-TIG (LATIG) welding, laser beam welding (LBW) and gas tungsten arc (TIG) welding. The weldability and microstructure of magnesium AZ31B alloy welded using LATIG, LBW and TIG were investigated by OM and EMPA. The experimental results showed that the welding speed of LATIG was higher than that of TIG, which was caught up with LBW. Besides, the penetration of LATIG doubles that of TIG, and was four times that of LBW. In addition, arc stability was improved in hybrid of laser-TIG welding compared with using the TIG welding alone, especially at high welding speed and under low TIG current. It was found that the heat affect zone of joint was only observed in TIG welding, and the size of grains in it was evidently coarse. In fusion zone, the equiaxed grains exist, whose size was the smallest welded by LBW, and was the largest by TIG welding. It was also found that Mg concentration of the fusion zone was lower than that of the base one by EPMA in three welding processes

IR-based spot weld NDT in automotive applications

Science.gov (United States)

Chen, Jian; Feng, Zhili

2015-05-01

utilizes the relative IR intensity change, so that the influence of surface reflection and environment interference can be reduced. Second, for the post-processing inspection, a special induction heater is used to replace the flash lamp, resulting in temperature changes on the order of 10°C. As a result, the signal-to-noise ratio increased by several orders of magnitudes with no surface painting needed, and the inspection results are more accurate and reliable. For real-time inspection, the heat from welding (with temperature exceeding 1000°C) was utilized. Third, "thermal signatures" were identified to uniquely correlate to different weld quality attributes through computational modeling of heat transfer and extensive testing of specially designed ranges of welding conditions. Novel IR image analysis algorithms that automatically and intelligently identify the "thermal signatures" from the IR images and positively determine the weld quality in less than a second were developed.

Closing the weld gap with laser/mig hybrid welding process

DEFF Research Database (Denmark)

Bagger, Claus; Olsen, Flemming Ove; Wiwe, Bjarne David

2003-01-01

In this article, laboratory tests are demonstrated that systematically accesses the critical gap distance when welding CMn 2.13 mm steel with a 2.6 kW CO2 laser, combined with a MIG energy source. In the work, the welding speed is varied at gap distances from 0 to 0.8 mm such that the limits...... for obtaining sound welds are identified. The welds are quality assessed according to ISO 13.919-1 and EN25817, transversal hardness measurements are made and the heat input to the workpiece is calculated. The results show that the critical gap is 0.1 mm for a laser weld alone. With hybrid welding, this can...... be increased to 0.6 mm, even at a welding speed of 3.5 m/min. The maximum welding speed with the hybrid process is comparable to laser welding alone, 4.5 m/min. The measured hardness is comparable to MIG welding, and this corresponds to a 33 percent reduction compared to laser welding alone. The heat input...

Induction heating using induction coils in series-parallel circuits

Science.gov (United States)

Matsen, Marc Rollo; Geren, William Preston; Miller, Robert James; Negley, Mark Alan; Dykstra, William Chet

2017-11-14

A part is inductively heated by multiple, self-regulating induction coil circuits having susceptors, coupled together in parallel and in series with an AC power supply. Each of the circuits includes a tuning capacitor that tunes the circuit to resonate at the frequency of AC power supply.

Laser welding parameters for manufacturing iridium-192 (Ir-192) source

International Nuclear Information System (INIS)

Anung Pujiyanto; Moch Subechi; Hotman Lubis; Diandono KY

2013-01-01

Number of cervical cancer patients in Indonesia is growing every year. One of cervical cancer treatment was fairly effective use brachytherapy treatment with radioisotope sources of iridium-192. Manufacturing of iridium sources for brachytherapy can be done by incorporating the iridium-192 into stainless steel microcapsules then welding using laser welder which the quality of the welding of iridium source (Ir-192) was determined by the welding parameters such as full power, energy frequency, average power and speed. Based on the result of leakage test using pressure -20 inch Hg and tensile test 2.5 bar showed the welding parameters III and IV did not have leakage and damaged. So that parameters III and IV are recommended to be applied to Ir-192 HDR's source. (author)

Investigations on a Novel Inductive Concept Frequency Technique for the Grading of Oil Palm Fresh Fruit Bunches

Directory of Open Access Journals (Sweden)

Kunihisa Tashiro

2013-02-01

Full Text Available From the Malaysian harvester’s perspective, the determination of the ripeness of the oil palm (FFB is a critical factor to maximize palm oil production. A preliminary study of a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunches is presented. To optimize the functionality of the sensor, the frequency characteristics of air coils of various diameters are investigated to determine their inductance and resonant characteristics. Sixteen samples from two categories, namely ripe oil palm fruitlets and unripe oil palm fruitlets, are tested from 100 Hz up to 100 MHz frequency. The results showed the inductance and resonant characteristics of the air coil sensors display significant changes among the samples of each category. The investigations on the frequency characteristics of the sensor air coils are studied to observe the effect of variations in the coil diameter. The effect of coil diameter yields a significant 0.02643 MHz difference between unripe samples to air and 0.01084 MHz for ripe samples to air. The designed sensor exhibits significant potential in determining the maturity of oil palm fruits.

LASER WELDING WITH MICRO-JET COOLING FOR TRUCK FRAME WELDING

Directory of Open Access Journals (Sweden)

Jan PIWNIK

2017-12-01

Full Text Available The aim of this paper is to analyse the mechanical properties of the weld steel structure of car body truck frames after laser welding. The best welding conditions involve the use of proper materials and alloy elements in steel and filer materials, in addition to welding technology, state of stress and temperature of exploitation. We present for the first time the properties of steel track structures after laser welding with micro-jet cooling. Therefore, good selection of both welding parameters and micro-jet cooling parameters is very important to achieve a proper steel structure. In this study, the metallographic structure, tensile results and impact toughness of welded joints have been analysed in terms of welding parameters.

Forming Completely Penetrated Welded T-joints when Pulsed Arc Welding

Science.gov (United States)

Krampit, N. Yu; Krampit, M. A.; Sapozhkov, A. S.

2016-04-01

The paper is focused on revealing the influence of welding parameters on weld formation when pulsed arc welding. As an experimental sample a T-joint over 10 mm was selected. Welding was carried out in flat position, which required no edge preparation but provided mono-directional guaranteed root penetration. The following parameters of welding were subjected to investigation: gap in the joint, wire feed rate and incline angles of the torch along and across the weld axis. Technological recommendations have been made with respect to pulsed arc welding; the cost price of product manufacturing can be reduced on their basis due to reduction of labor input required by machining, lowering consumption of welding materials and electric power.

Resistance welding

DEFF Research Database (Denmark)

Bay, Niels; Zhang, Wenqi; Rasmussen, Mogens H.

2003-01-01

Resistance welding comprises not only the well known spot welding process but also more complex projection welding operations, where excessive plastic deformation of the weld point may occur. This enables the production of complex geometries and material combinations, which are often not possible...... to weld by traditional spot welding operations. Such joining processes are, however, not simple to develop due to the large number of parameters involved. Development has traditionally been carried out by large experimental investigations, but the development of a numerical programme system has changed...... this enabling prediction of the welding performance in details. The paper describes the programme in short and gives examples on industrial applications. Finally investigations of causes for failure in a complex industrial joint of two dissimilar metals are carried out combining numerical modelling...

Increased risk of parkinsonism associated with welding exposure.

Science.gov (United States)

Racette, Brad A; Criswell, Susan R; Lundin, Jessica I; Hobson, Angela; Seixas, Noah; Kotzbauer, Paul T; Evanoff, Bradley A; Perlmutter, Joel S; Zhang, Jing; Sheppard, Lianne; Checkoway, Harvey

2012-10-01

Manganese (Mn), an established neurotoxicant, is a common component of welding fume. The neurological phenotype associated with welding exposures has not been well described. Prior epidemiologic evidence linking occupational welding to parkinsonism is mixed, and remains controversial. This was a cross-sectional and nested case-control study to investigate the prevalence and phenotype of parkinsonism among 811 shipyard and fabrication welders recruited from trade unions. Two reference groups included 59 non-welder trade workers and 118 newly diagnosed, untreated idiopathic PD patients. Study subjects were examined by a movement disorders specialist using the Unified Parkinson Disease Rating Scale motor subsection 3 (UPDRS3). Parkinsonism cases were defined as welders with UPDRS3 score ≥15. Normal was defined as UPDRS3welding. Adjusted prevalence ratios for parkinsonism were calculated in relation to quartiles of welding years. The overall prevalence estimate of parkinsonism was 15.6% in welding exposed workers compared to 0% in the reference group. Among welders, we observed a U-shaped dose-response relation between weighted welding exposure-years and parkinsonism. UPDRS3 scores for most domains were similar between welders and newly diagnosed idiopathic Parkinson disease (PD) patients, except for greater frequency of rest tremor and asymmetry in PD patients. This work-site based study among welders demonstrates a high prevalence of parkinsonism compared to nonwelding-exposed workers and a clinical phenotype that overlaps substantially with PD. Copyright © 2012 Elsevier Inc. All rights reserved.

Cu-Fe welding techniques by electromagnetic and electron beam welding processes

International Nuclear Information System (INIS)

Kumar, Satendra; Saroj, P.C.; Kulkarni, M.R.; Sharma, A.; Rajawat, R.K.; Saha, T.K.

2015-01-01

Electromagnetic welding being a solid state welding process has been found suitable for welding Copper and Iron which are conventionally very tricky. Owing to good electrical conductivity of both copper and iron, they are best suited combination for EM welding. For the experimental conditions presented above, 1.0 mm wall thickness of Cu tube was lap welded to Fe disc. A heavy duty four disc stainless steel coil was used for electromagnetic welding of samples. MSLD of the welded samples indicated leak proof joints. Metallographic examination of the welds also revealed defect free interfaces. Electron beam welding is also a non-conventional welding process used for joining dissimilar materials. Autogenous welding of the above specimen was carried out by EBW method for the sake of comparison. A characterization analysis of the above mentioned joining processes will be discussed in the paper. (author)

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.

Identification of Damaged Spot Welds in a Complicated Joined Structure

Energy Technology Data Exchange (ETDEWEB)

Yunus, M A; Rani, M N Abdul; Ouyang, H; Deng, H; James, S, E-mail: h.ouyang@liverpool.ac.uk [Department of Engineering, Harrison Hughes Building, University of Liverpool, Brownlow Hill, Liverpool L69 3GH (United Kingdom)

2011-07-19

In automotive engineering, spot welds on assembled structures such as Body in White (BiW) have a significant effect on the vehicles' dynamic characteristics. Understandably, imperfections in the spot welds will cause variations in the dynamic properties such as natural frequencies and mode shapes of the structure. In this paper, a complicated welded structure which is a simplified Natural Gas Vehicle (NGV) platform is investigated. The structure fabricated from thin metal sheets consists of ten components. They are jointed together by a number of scattered spot welds. NASTRAN Solution 200 based on sensitivity analysis is used to identify the most sensitive parameters to natural frequencies. The numerical model of the undamaged structure is initially updated in order to minimise the discrepancies between the measured and numerical data using NASTRAN optimisation code. The initial updated model serves as a benchmark for the subsequent structural damage identification. The numerical data of the benchmark model is then compared with the measured data obtained from the damaged structure. The same updating procedure is applied to the benchmark model in order to bring the numerical data as close as possible to the measured data of the damaged structure. The disparity in certain parameter values from the parameter values used in the benchmark model shows a fault or damage in the location of a particular joint, depending on the severity of this disparity. The challenge in this work is to localise damaged area and quantify the damage of the complicated structure with multiple spot welds in the presence of uncertainty in the location and material properties of the welds.

Structure–property relationship in a 960 MPa grade ultrahigh strength low carbon niobium–vanadium microalloyed steel: The significance of high frequency induction tempering

International Nuclear Information System (INIS)

Xie, Z.J.; Fang, Y.P.; Han, G.; Guo, H.; Misra, R.D.K.; Shang, C.J.

2014-01-01

The present study describes the microstructure and precipitation behavior in an ultra-high strength low carbon niobium–vanadium microalloyed steel that was processed by quenching and high frequency induction tempering. Ultrahigh yield strength of ∼1000 MPa with high elongation of ∼15% and high low temperature toughness of 55 J (half thickness) at −40 °C was obtained after quenching from austenitization at 900 °C for 30 min, and tempering at 600 °C for 15 min by induction reheating with a reheating rate of ∼50 °C/s. While the yield strength increase on tempering was similar for both induction reheating and conventional reheating (electrical resistance reheating), there was ∼100% increase in low temperature toughness in induction reheated steel compared to the conventional reheating process. The underlying reason for the increase in toughness was attributed to the transformation of cementite film observed in conventional reheating and tempering to nanoscale cementite in induction reheating and tempering. The precipitation of nanoscale carbides is believed to significantly contribute to ultra-high strength, good ductility, and high toughness in the high frequency induction reheating and tempering process

Effects of Fusion Tack Welds on Self-Reacting Friction Stir Welds

Science.gov (United States)

Nunes, A. C., Jr.; Pendleton, M. L.; Brooke, S. A.; Russell, C. K.

2012-01-01

In order to know whether fusion tack welds would affect the strength of self-reacting friction stir seam welds in 2195-T87 aluminum alloy, the fracture stresses of 144 tensile test coupons cut from 24 welded panels containing segments of friction stir welds were measured. Each of the panels was welded under unique processing conditions. A measure of the effect of the tack welds for each panel was devised. An analysis of the measures of the tack weld effect supported the hypothesis that fusion tack welds do not affect the strength of self-reacting friction stir welds to a 5% level of confidence.

Residual stress reduction in the penetration nozzle weld joint by overlay welding

International Nuclear Information System (INIS)

Jiang, Wenchun; Luo, Yun; Wang, B.Y.; Tu, S.T.; Gong, J.M.

2014-01-01

Highlights: • Residual stress reduction in penetration weld nozzle by overlay welding was studied. • The overlay weld can decrease the residual stress in the weld root. • Long overlay welding is proposed in the actual welding. • Overlay weld to decrease residual stress is more suitable for thin nozzle. - Abstract: Stress corrosion cracking (SCC) in the penetration nozzle weld joint endangers the structural reliability of pressure vessels in nuclear and chemical industries. How to decrease the residual stress is very critical to ensure the structure integrity. In this paper, a new method, which uses overlay welding on the inner surface of nozzle, is proposed to decrease the residual stresses in the penetration joint. Finite element simulation is used to study the change of weld residual stresses before and after overlay welding. It reveals that this method can mainly decrease the residual stress in the weld root. Before overlay welding, large tensile residual stresses are generated in the weld root. After overlay weld, the tensile hoop stress in weld root has been decreased about 45%, and the radial stress has been decreased to compressive stress, which is helpful to decrease the susceptibility to SCC. With the increase of overlay welding length, the residual stress in weld root has been greatly decreased, and thus the long overlay welding is proposed in the actual welding. It also finds that this method is more suitable for thin nozzle rather than thick nozzle

Welding processes handbook

CERN Document Server

Weman, Klas

2011-01-01

Offers an introduction to the range of available welding technologies. This title includes chapters on individual techniques that cover principles, equipment, consumables and key quality issues. It includes material on such topics as the basics of electricity in welding, arc physics, and distortion, and the weldability of particular metals.$bThe first edition of Welding processes handbook established itself as a standard introduction and guide to the main welding technologies and their applications. This new edition has been substantially revised and extended to reflect the latest developments. After an initial introduction, the book first reviews gas welding before discussing the fundamentals of arc welding, including arc physics and power sources. It then discusses the range of arc welding techniques including TIG, plasma, MIG/MAG, MMA and submerged arc welding. Further chapters cover a range of other important welding technologies such as resistance and laser welding, as well as the use of welding techniqu...

Welding Curriculum.

Science.gov (United States)

Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

This competency-based curriculum guide is a handbook for the development of welding trade programs. Based on a survey of Alaskan welding employers, it includes all competencies a student should acquire in such a welding program. The handbook stresses the importance of understanding the principles associated with the various elements of welding.…

Energy Efficiency of Induction Motors Running Off Frequency Converters with Pulse-Width Voltage Modulation{sup 1}

Energy Technology Data Exchange (ETDEWEB)

Shvetsov, N. K., E-mail: elmash@em.ispu.ru [V. I. Lenin Ivanovo State Power University (Russian Federation)

2016-11-15

The results of calculations of the increase in losses in an induction motor with frequency control and different forms of the supply voltage are presented. The calculations were performed by an analytic method based on harmonic analysis of the supply voltage as well as numerical calculation of the electromagnetic processes by the finite-element method.

Two-Phase Induction Motor Drives

Directory of Open Access Journals (Sweden)

Gholam Reza Arab Markadeh

2010-10-01

Full Text Available The lack of variable-speed drives for two (single induction motor is a reality. This article attempts mainly to investigate the reasons for this lack of variable – speed drives. This paper deals with literature survey of various existing converter topologies, which have been proposed for adjustable speed single phase induction motor drives. Various converter topologies have been compared in this paper. Among these converter topologies, the adjustable frequency PWM inverter is the best choice for single-phase induction motor drives. However, adjustable-frequency drives have not been widely used with single-phase Induction motors. The open-loop constant V/F control law cannot be used with the single-phase induction motor drives as it is used with three phase motors. The variation of the operating frequency at lower speed range with constant load torque causes variation in motor's slip. A constant V/F control is suitable only over the upper speed range.

LASER WELDING WITH MICRO-JET COOLING FOR TRUCK FRAME WELDING

OpenAIRE

Jan PIWNIK; Bożena SZCZUCKA-LASOTA; Tomasz WĘGRZYN; Wojciech MAJEWSKI

2017-01-01

The aim of this paper is to analyse the mechanical properties of the weld steel structure of car body truck frames after laser welding. The best welding conditions involve the use of proper materials and alloy elements in steel and filer materials, in addition to welding technology, state of stress and temperature of exploitation. We present for the first time the properties of steel track structures after laser welding with micro-jet cooling. Therefore, good selection of both welding paramet...

Sturdy on Orbital TIG Welding Properties for Nuclear Fuel Test Rod

International Nuclear Information System (INIS)

Joung, Changyoung; Hong, Jintae; Kim, Kahye; Huh, Sungho

2014-01-01

We developed a precision TIG welding system that is able to weld the seam between end-caps and a fuel cladding tube for the nuclear fuel test rod and rig. This system can be mainly classified into an orbital TIG welder (AMI, M-207A) and a pressure chamber. The orbital TIG welder can be independently used, and it consists of a power supply unit, a microprocessor, water cooling unit, a gas supply unit and an orbital weld head. In this welder, the power supply unit mainly supplies GTAW power for a welding specimen and controls an arc starting of high frequency, supping of purge gas, arc rotation through the orbital TIG welding head, and automatic timing functions. In addition, the pressure chamber is used to make the welded surface of the cladding specimen clean with the inert gas filled inside the chamber. To precisely weld the cladding tube, a welding process needs to establish a schedule program for an orbital TIG welding. Therefore, the weld tests were performed on a cladding tube and dummy rods under various conditions. This paper describes not only test results on parameters of the purge gas flow rates and the chamber gas pressures for the orbital TIG welding, but also test results on the program establishment of an orbital TIG welding system to weld the fuel test rods. Various welding tests were performed to develop the orbital TIG welding techniques for the nuclear fuel test rod. The width of HAZ of a cladding specimen welded with the identical power during an orbital TIG welding cycle was continuously increased from a welded start-point to a weld end-point because of heat accumulation. The welding effect of the PGFR and CGP shows a relatively large difference for FSS and LSS. Each hole on the cladding specimens was formed in the 1bar CGP with the 20L/min PGFR but not made in the case of the PGFR of 10L/min in the CGP of 2bar. The optimum schedule program of the orbital TIG welding system to weld the nuclear fuel test rod was established through the program

Sturdy on Orbital TIG Welding Properties for Nuclear Fuel Test Rod

Energy Technology Data Exchange (ETDEWEB)

Joung, Changyoung; Hong, Jintae; Kim, Kahye; Huh, Sungho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

We developed a precision TIG welding system that is able to weld the seam between end-caps and a fuel cladding tube for the nuclear fuel test rod and rig. This system can be mainly classified into an orbital TIG welder (AMI, M-207A) and a pressure chamber. The orbital TIG welder can be independently used, and it consists of a power supply unit, a microprocessor, water cooling unit, a gas supply unit and an orbital weld head. In this welder, the power supply unit mainly supplies GTAW power for a welding specimen and controls an arc starting of high frequency, supping of purge gas, arc rotation through the orbital TIG welding head, and automatic timing functions. In addition, the pressure chamber is used to make the welded surface of the cladding specimen clean with the inert gas filled inside the chamber. To precisely weld the cladding tube, a welding process needs to establish a schedule program for an orbital TIG welding. Therefore, the weld tests were performed on a cladding tube and dummy rods under various conditions. This paper describes not only test results on parameters of the purge gas flow rates and the chamber gas pressures for the orbital TIG welding, but also test results on the program establishment of an orbital TIG welding system to weld the fuel test rods. Various welding tests were performed to develop the orbital TIG welding techniques for the nuclear fuel test rod. The width of HAZ of a cladding specimen welded with the identical power during an orbital TIG welding cycle was continuously increased from a welded start-point to a weld end-point because of heat accumulation. The welding effect of the PGFR and CGP shows a relatively large difference for FSS and LSS. Each hole on the cladding specimens was formed in the 1bar CGP with the 20L/min PGFR but not made in the case of the PGFR of 10L/min in the CGP of 2bar. The optimum schedule program of the orbital TIG welding system to weld the nuclear fuel test rod was established through the program

Ion energy distributions in a pulsed dual frequency inductively coupled discharge of Ar/CF4 and effect of duty ratio

International Nuclear Information System (INIS)

Mishra, Anurag; Seo, Jin Seok; Kim, Tae Hyung; Yeom, Geun Young

2015-01-01

Controlling time averaged ion energy distribution (IED) is becoming increasingly important in many plasma material processing applications for plasma etching and deposition. The present study reports the evolution of ion energy distributions with radio frequency (RF) powers in a pulsed dual frequency inductively discharge and also investigates the effect of duty ratio. The discharge has been sustained using two radio frequency, low (P 2 MHz  = 2 MHz) and high (P 13.56 MHz  = 13.56 MHz) at a pressure of 10 mTorr in argon (90%) and CF 4 (10%) environment. The low frequency RF powers have been varied from 100 to 600 W, whereas the high frequency powers from 200 to 1200 W. Typically, IEDs show bimodal structure and energy width (energy separation between the high and low energy peaks) increases with increasing P 13.56 MHz ; however, it shows opposite trends with P 2 MHz . It has been observed that IEDs bimodal structure tends to mono-modal structure and energy peaks shift towards low energy side as duty ratio increases, keeping pulse power owing to mode transition (capacitive to inductive) constant

INVESTIGATION ON ESTABLISHED OPERATIONAL MODES OF FREQUENCY-CONTROLLED INDUCTION GENERATOR OF WIND POWER PLANTS

Directory of Open Access Journals (Sweden)

R. I. Mustafayev

2014-01-01

Full Text Available The paper proposes an analytical expression for calculating a manipulated variable of stator voltage in a frequency-controlled induction generator with a cage rotor of a wind power plant while regulating a constant value of the absolute slip of the generator. Comparison of the calculated results by the proposed expression and full differential equations of the generator (an equation of state at steady state has confirmed a high accuracy of the analytical expression.

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.

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.

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.

Automatic orbital GTAW welding: Highest quality welds for tomorrow's high-performance systems

Science.gov (United States)

Henon, B. K.

1985-01-01

Automatic orbital gas tungsten arc welding (GTAW) or TIG welding is certain to play an increasingly prominent role in tomorrow's technology. The welds are of the highest quality and the repeatability of automatic weldings is vastly superior to that of manual welding. Since less heat is applied to the weld during automatic welding than manual welding, there is less change in the metallurgical properties of the parent material. The possibility of accurate control and the cleanliness of the automatic GTAW welding process make it highly suitable to the welding of the more exotic and expensive materials which are now widely used in the aerospace and hydrospace industries. Titanium, stainless steel, Inconel, and Incoloy, as well as, aluminum can all be welded to the highest quality specifications automatically. Automatic orbital GTAW equipment is available for the fusion butt welding of tube-to-tube, as well as, tube to autobuttweld fittings. The same equipment can also be used for the fusion butt welding of up to 6 inch pipe with a wall thickness of up to 0.154 inches.

Influence of Welding Process and Post Weld Heat Treatment on Microstructure and Pitting Corrosion Behavior of Dissimilar Aluminium Alloy Welds

Science.gov (United States)

Venkata Ramana, V. S. N.; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

2018-03-01

Welding of dissimilar Aluminum alloy welds is becoming important in aerospace, shipbuilding and defence applications. In the present work, an attempt has been made to weld dissimilar aluminium alloys using conventional gas tungsten arc welding (GTAW) and friction stir welding (FSW) processes. An attempt was also made to study the effect of post weld heat treatment (T4 condition) on microstructure and pitting corrosion behaviour of these welds. Results of the present investigation established the differences in microstructures of the base metals in T4 condition and in annealed conditions. It is evident that the thickness of the PMZ is relatively more on AA2014 side than that of AA6061 side. In FS welds, lamellar like shear bands are well noticed on the top of the stir zone. The concentration profile of dissimilar friction stir weld in T4 condition revealed that no diffusion has taken place at the interface. Poor Hardness is observed in all regions of FS welds compared to that of GTA welds. Pitting corrosion resistance of the dissimilar FS welds in all regions was improved by post weld heat treatment.

A control system for uniform bead in fillet arc welding on tack welds

International Nuclear Information System (INIS)

Kim, Jae Woong; Lee, Jun Young

2008-01-01

Positioning a workpiece accurately and preventing weld distortion, tack welding is often adopted before main welding in the construction of welded structures. However, this tack weld deteriorates the final weld bead profile, so that the grinding process is usually performed for a uniform weld bead profile. In this study, a control system for uniform weld bead is proposed for the fillet arc welding on tack welds. The system consists of GMA welding machine, torch manipulator, laser vision sensor for measuring the tack weld size and the database for optimal welding conditions. Experiments have been performed for constructing the database and for evaluating the control capability of the system. It has been shown that the system has the capability to smooth the bead at the high level of quality

Torque Measurement of Welding of Endplug-Endplate using Multi-pin Remote Welding System

Energy Technology Data Exchange (ETDEWEB)

Koo, Dae-Seo; Kim, Soo-Sung; Park, Geun-Il; Lee, Jung-Won; Song, Kee-Chan [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2006-07-01

As fuel bundles in PHWR irradiates, inner pressure in claddings of fuel rods increases owing to outer pressure and fission products of nuclear fissions. Because of leak possibility of welding between cladding and end plug, this welding part connects with safety of nuclear fuel rods. Because of importance of this welding part, weldability of end plug-cladding of nuclear fuel rods is continually researched. Welding method for research and commercialization is classified as melting, solid type welding or resistance welding. End plug cladding welding of nuclear fuel rods in PHWR takes advantage of resistance upset butt welding using multicycle mode. This method makes weld flash and shapes re-entrant corner owing to welding heat due to resistivity, contact resistance of cladding-end plug, and inelasticity deformation due to pressure. Welding part between cladding and end plug receives stresses and makes small cracks. In this study, remote welding system for multi-pin assembly was designed, fabricated and welding specimens of end plug-endplate were made using electrical resistance method. The torques of welding between end plug and endplate were measured. These results on welding current, pressure of main electrode and pressure of branch electrode were analyzed. Weldability between end plug and endplate was confirmed through metallographic examinations. In the future, optimal welding examinations due to welding current, welding pressure and welding time will be performed to improve weldability of end plug-endplate.

Advantages of new micro-jet welding technology on weld microstructure control

Directory of Open Access Journals (Sweden)

Jan PIWNIK

2013-01-01

Full Text Available An innovative apparatus to welding process with micro-jet cooling of the weld made it possible to carry out technological tests, which have proved theoretical considerations about this problem. This project gives real opportunities for professional development in the field of welding with controlling the parameters of weld structure. These tests have proved that the new micro-jet technology has the potential for growth. It may be great achievement of welding technology in order to increase weld metal strength. The new technology with micro-jet cooling may have many practical applications in many fields, for example such as in the transport industry or to repair damaged metal elements. The advantages of the new device over the traditional system are the ability to control the structure of the weld, the weld mechanical performance increases and improve the quality of welded joints.

Optimization of hybrid laser - TIG welding of 316LN steel using response surface methodology (RSM)

Science.gov (United States)

Ragavendran, M.; Chandrasekhar, N.; Ravikumar, R.; Saxena, Rajesh; Vasudevan, M.; Bhaduri, A. K.

2017-07-01

In the present study, the hybrid laser - TIG welding parameters for welding of 316LN austenitic stainless steel have been investigated by combining a pulsed laser beam with a TIG welding heat source at the weld pool. Laser power, pulse frequency, pulse duration, TIG current were presumed as the welding process parameters whereas weld bead width, weld cross-sectional area and depth of penetration (DOP) were considered as the process responses. Central composite design was used to complete the design matrix and welding experiments were conducted based on the design matrix. Weld bead measurements were then carried out to generate the dataset. Multiple regression models correlating the process parameters with the responses have been developed. The accuracy of the models were found to be good. Then, the desirability approach optimization technique was employed for determining the optimum process parameters to obtain the desired weld bead profile. Validation experiments were then carried out from the determined optimum process parameters. There was good agreement between the predicted and measured values.

TECHNOLOGICAL ISSUES IN MECHANISED FEED WIG/TIG WELDING SURFACING OF WELDING

Directory of Open Access Journals (Sweden)

BURCA Mircea

2016-09-01

manual welding tests in the light of using the process for welding surfacing being known that in such applications mechanised operations are recommended whenever possible given the latter strengths i.e. increased productivity and quality deposits. The research also aims at achieving a comparative a study between wire mechanised feed based WIG manual welding and the manual rod entry based manual welding in terms of geometry deposits, deposits aesthetics, operating technique, productivity, etc . In this regard deposits were made by means of two welding procedures, and subsequently welding surfacing was made with the optimum values of the welding parameters in this case.

In situ post-weld heat treatment on martensitic stainless steel turbine runners using a robotic induction heating process to control temperature distribution

Science.gov (United States)

Boudreault, E.; Hazel, B.; Côté, J.; Godin, S.

2014-03-01

A new robotic heat treatment process is developed. Using this solution it is now possible to perform local heat treatment on large steel components. Crack, cavitation and erosion repairs on turbine blades and Pelton buckets are among the applications of this technique. The proof of concept is made on a 13Cr-4Ni stainless steel designated "CA6NM". This alloy is widely used in the power industry for modern system components. Given the very tight temperature tolerance (600 to 630 °C) for post-weld heat treatment on this alloy, 13Cr-4Ni stainless steel is very well suited for demonstrating the possibilities of this process. To achieve heat treatment requirements, an induction heating system is mounted on a compact manipulator named "Scompi". This robot moves a pancake coil in order to control the temperature distribution. A simulator using thermal finite element analysis is first used for path planning. A feedback loop adjusts parameters in function of environmental conditions.

In situ post-weld heat treatment on martensitic stainless steel turbine runners using a robotic induction heating process to control temperature distribution

International Nuclear Information System (INIS)

Boudreault, E; Hazel, B; Côté, J; Godin, S

2014-01-01

A new robotic heat treatment process is developed. Using this solution it is now possible to perform local heat treatment on large steel components. Crack, cavitation and erosion repairs on turbine blades and Pelton buckets are among the applications of this technique. The proof of concept is made on a 13Cr-4Ni stainless steel designated C A6NM . This alloy is widely used in the power industry for modern system components. Given the very tight temperature tolerance (600 to 630 °C) for post-weld heat treatment on this alloy, 13Cr-4Ni stainless steel is very well suited for demonstrating the possibilities of this process. To achieve heat treatment requirements, an induction heating system is mounted on a compact manipulator named S compi . This robot moves a pancake coil in order to control the temperature distribution. A simulator using thermal finite element analysis is first used for path planning. A feedback loop adjusts parameters in function of environmental conditions

Welding Penetration Control of Fixed Pipe in TIG Welding Using Fuzzy Inference System

Science.gov (United States)

Baskoro, Ario Sunar; Kabutomori, Masashi; Suga, Yasuo

This paper presents a study on welding penetration control of fixed pipe in Tungsten Inert Gas (TIG) welding using fuzzy inference system. The welding penetration control is essential to the production quality welds with a specified geometry. For pipe welding using constant arc current and welding speed, the bead width becomes wider as the circumferential welding of small diameter pipes progresses. Having welded pipe in fixed position, obviously, the excessive arc current yields burn through of metals; in contrary, insufficient arc current produces imperfect welding. In order to avoid these errors and to obtain the uniform weld bead over the entire circumference of the pipe, the welding conditions should be controlled as the welding proceeds. This research studies the intelligent welding process of aluminum alloy pipe 6063S-T5 in fixed position using the AC welding machine. The monitoring system used a charge-coupled device (CCD) camera to monitor backside image of molten pool. The captured image was processed to recognize the edge of molten pool by image processing algorithm. Simulation of welding control using fuzzy inference system was constructed to simulate the welding control process. The simulation result shows that fuzzy controller was suitable for controlling the welding speed and appropriate to be implemented into the welding system. A series of experiments was conducted to evaluate the performance of the fuzzy controller. The experimental results show the effectiveness of the control system that is confirmed by sound welds.

Fatigue evaluation for the socket weld in nuclear power plants

International Nuclear Information System (INIS)

Choi, Young Hwan; Choi, Sun Yeong; Huh, Nam Soo

2004-01-01

The operating experience showed that the fatigue is one of the major piping failure mechanisms in nuclear power plants (NPPs). The pressure and/or temperature loading transients, the vibration, and the mechanical cyclic loading during the plant operation may induce the fatigue failure in the nuclear piping. Recently, many fatigue piping failure occurred at the socket weld area have been widely reported. Many failure cases showed that the gap requirement between the pipe and fitting in the socket weld was not satisfied though the ASME Code Sec. Requires 1/16 inch gap in the socket weld. The ASME Code OM also limits the vibration level of the piping system, but some failure cases showed the limitation was not satisfied during the plant operation. In this paper, the fatigue behavior of the socket weld in the nuclear piping was estimated by using the three dimensional finite element method. The results are as follows. The socket weld is susceptible to the vibration if the vibration levels exceed the requirement in the ASME Code OM. The effect of the pressure or temperature transient load on the socket weld in NPPs is not significant because of the very low frequency of the transient during the plant lifetime operation. 'No gap' is very risky to the socket weld integrity for the specific systems having the vibration condition to exceed the requirement in the ASME OM Code and/or the transient loading condition. The reduction of the weld leg size from 1.09 * t 1 to 0.75 * t 1 can affect severely on the socket weld integrity

Versatile Friction Stir Welding/Friction Plug Welding System

Science.gov (United States)

Carter, Robert

2006-01-01

A proposed system of tooling, machinery, and control equipment would be capable of performing any of several friction stir welding (FSW) and friction plug welding (FPW) operations. These operations would include the following: Basic FSW; FSW with automated manipulation of the length of the pin tool in real time [the so-called auto-adjustable pin-tool (APT) capability]; Self-reacting FSW (SRFSW); SR-FSW with APT capability and/or real-time adjustment of the distance between the front and back shoulders; and Friction plug welding (FPW) [more specifically, friction push plug welding] or friction pull plug welding (FPPW) to close out the keyhole of, or to repair, an FSW or SR-FSW weld. Prior FSW and FPW systems have been capable of performing one or two of these operations, but none has thus far been capable of performing all of them. The proposed system would include a common tool that would have APT capability for both basic FSW and SR-FSW. Such a tool was described in Tool for Two Types of Friction Stir Welding (MFS- 31647-1), NASA Tech Briefs, Vol. 30, No. 10 (October 2006), page 70. Going beyond what was reported in the cited previous article, the common tool could be used in conjunction with a plug welding head to perform FPW or FPPW. Alternatively, the plug welding head could be integrated, along with the common tool, into a FSW head that would be capable of all of the aforementioned FSW and FPW operations. Any FSW or FPW operation could be performed under any combination of position and/or force control.

Effect of Welding Parameters on Dilution and Weld Bead Geometry in Cladding

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The effect of pulsed gas metal arc welding (GMAW) variables on the dilution and weld bead geometry in cladding X65 pipeline steel with 316L stainless steel was studied. Using a full factorial method, a series of experiments were carried out to know the effect of wire feed rate, welding speed, distance between gas nozzle and plate, and the vertical angle of welding on dilution and weld bead geometry. The findings indicate that the dilution of weld metal and its dimension i.e. width, height and depth increase with the feed rate, but the contact angle of the bead decreases first and then increases. Meantime, welding speed has an opposite effect except for dilution. There is an interaction effect between welding parameters at the contact angle. The results also show forehand welding or decreasing electrode extension decrease the angle of contact. Finally,a mathematical model is contrived to highlight the relationship between welding variables with dilution and weld bead geometry.

Research of the multipolar induction traction frequency regulated motor

Directory of Open Access Journals (Sweden)

V. Ia. Bespalov

2014-01-01

Full Text Available The paper considers the application features of traction induction electric motors in transmissions of vehicles. It shows that one of important stages in their designing is to choose the number of poles. In traction electric drives engines with the raised number of poles without comprehensive assessment of such solution are often applied. The paper investigates dynamic and power characteristics of the multi-polar traction asynchronous engine (TAE designed and made for using in the individual electric drive of heavy-load wheeled cars. The basic functional elements of the model to simulate the electric drive in Matlab environment with the Simulink and SimPower Systems applications in the structure with vector control are described, and the simulation modeling results of its dynamic mechanical characteristics are provided. It is established that because of increased alternating frequency of currents of the multi-polar engine in the range of high speeds there is an excessive decrease in the torque and the requirement for constancy of the target capacity, corresponding to the specified traction characteristic is not fulfilled. It is a consequence of the waveform distortion of engine phase current in the range of high speeds because of incapability of the power source to compensate an increasing EMF of movement as the speed continues to grow.The paper studies the influence of increased current frequencies on the additional losses in the engine. The analysis of electromagnetic field penetration depth in the copper conductor of stator winding at high frequency allowed us to establish a significant skin – effect. The quantitative assessment is given to this phenomenon by results of numerical calculation of electromagnetic field distribution in a stator groove. Significant increase in additional losses in the engine is established, and estimates of flow loss extent because of damping actions of eddy currents in the laminated steel of stator at

Modeling of welded bead profile for rapid prototyping by robotic MAG welding

Institute of Scientific and Technical Information of China (English)

CAO Yong; ZHU Sheng; WANG Tao; WANG Wanglong

2009-01-01

As a deposition technology, robotic metal active gas(MAG) welding has shown new promise for rapid prototyping (RP) of metallic parts. During the process of metal forming using robotic MAG welding, sectional profile of single-pass welded bead is critical to formed accuracy and quality of metal pans. In this paper, the experiments of single-pass welded bead for rapid prototyping using robotic MAG welding were carried out. The effect of some edge detectors on the cross-sectional edge of welded bead was discussed and curve fitting was applied using leat square fitting. Consequently, the mathematical model of welded bead profile was developed. The experimental results show that good shape could be obtained under suitable welding parameters. Canny operawr is suitable to edge detection of welded bead profile, and the mathematical model of welded bead profile developed is approximately parabola.

Fusion welding process

Science.gov (United States)

Thomas, Kenneth C.; Jones, Eric D.; McBride, Marvin A.

1983-01-01

A process for the fusion welding of nickel alloy steel members wherein a ferrite containing pellet is inserted into a cavity in one member and melted by a welding torch. The resulting weld nugget, a fusion of the nickel containing alloy from the members to be welded and the pellet, has a composition which is sufficiently low in nickel content such that ferrite phases occur within the weld nugget, resulting in improved weld properties. The steel alloys encompassed also include alloys containing carbon and manganese, considered nickel equivalents.

MAG narrow gap welding - an economic way to minimize welding expenses

International Nuclear Information System (INIS)

Kast, W.; Scholz, E.; Weyland, F.

1982-01-01

The thicker structural components are, the more important it is to take measures to reduce the volume of the weld. The welding process requiring the smallest possible weld section is the so-called narrow gap process. In submerged arc narrow gap welding as well as in MAG narrow gap welding different variants are imaginable, some of them already in practical use. With regard to efficiency and weld quality an optimum variant of the MAG narrow gap welding process is described. It constitutes a two wire system in which two wire electrodes of 1.2 mm diameter are arranged one behind the other. In order to avoid lack of fusion, the wire guides are slightly pointed towards each groove face. Thus, by inclining the two arcs burning one behind the other in the direction of weld progress, it is achieved that two separately solidifying weld pools and two beads per layer are simultaneously formed. Welding parameters are selected in such a way that a heat input of 16-20 kJ/cm and a deposition rate of 11-16 kgs/h are obtained. In spite of this comparatively high deposition rate, good impact values are found both in the weld and HAZ (largely reduced coarse-grain zone) which is due to an optimum weld build-up. With the available welding equipment the process can be applied to structural members having a thickness of 40-400 mm. The width of gap is 13 mm (root section) with a bevel angle of 1 0 . As filler metal, basic flux-cored wires are used which, depending on the base metal to be welded and the required tensile properties, can be of the Mn-, MnMo-, MnCrMo-, MnNi-, or MnNiMo-alloyed types. (orig.)

Study on the Relationship Between Emission Signals and Weld Defect for In-Process Monitoring in CO{sub 2} Laser Welding of Zn-Coated Steel

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Do; Lee, Chang Je [Korea Maritime University, Busan (Korea, Republic of)

2010-10-15

In this study, the plasma induced by CO{sub 2} laser lap welding of 6t Zn coated steel used for ship building was measured using photodiodes and a microphone. Then, the welding phenomenon with gap clearance of lap joint was compared with RMS-treated signal. Thus, we found that intensity of the RMS-treated signal increased with Zn vaporization; further, the presence of defects results in rapid variations with the RMS value as a function of lap-joint parameters. Besides, the FFT value of the raw signal with variations of changing welding parameters was calculated, and then the calculated FFT frequency value was set as the bandwidth of digital filter for a more accurate in-process monitoring. The RMS values were acquired by filtering the raw signal. By matching the weld beads and the calculated RMS values, we confirmed that there is a strong relationship between the signals and the defects.

Advanced Welding Applications

Science.gov (United States)

Ding, Robert J.

2010-01-01

Some of the applications of advanced welding techniques are shown in this poster presentation. Included are brief explanations of the use on the Ares I and Ares V launch vehicle and on the Space Shuttle Launch vehicle. Also included are microstructural views from four advanced welding techniques: Variable Polarity Plasma Arc (VPPA) weld (fusion), self-reacting friction stir welding (SR-FSW), conventional FSW, and Tube Socket Weld (TSW) on aluminum.

WELDING METHOD

Science.gov (United States)

Cornell, A.A.; Dunbar, J.V.; Ruffner, J.H.

1959-09-29

A semi-automatic method is described for the weld joining of pipes and fittings which utilizes the inert gasshielded consumable electrode electric arc welding technique, comprising laying down the root pass at a first peripheral velocity and thereafter laying down the filler passes over the root pass necessary to complete the weld by revolving the pipes and fittings at a second peripheral velocity different from the first peripheral velocity, maintaining the welding head in a fixed position as to the specific direction of revolution, while the longitudinal axis of the welding head is disposed angularly in the direction of revolution at amounts between twenty minutas and about four degrees from the first position.

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.

Syllabus in Trade Welding.

Science.gov (United States)

New York State Education Dept., Albany. Bureau of Secondary Curriculum Development.

The syllabus outlines material for a course two academic years in length (minimum two and one-half hours daily experience) leading to entry-level occupational ability in several welding trade areas. Fourteen units covering are welding, gas welding, oxyacetylene welding, cutting, nonfusion processes, inert gas shielded-arc welding, welding cast…

Latest MIG, TIG arc-YAG laser hybrid welding systems for various welding products

Science.gov (United States)

Ishide, Takashi; Tsubota, Shuho; Watanabe, Masao

2003-03-01

Laser welding is capable of high-efficiency low-strain welding, and so its applications are started to various products. We have also put the high-power YAG laser of up to 10 kW to practical welding use for various products. On the other hand the weakest point of this laser welding is considered to be strict in the welding gap aiming allowance. In order to solve this problem, we have developed hybrid welding of TIG, MIG arc and YAG laser, taking the most advantages of both the laser and arc welding. Since the electrode is coaxial to the optical axis of the YAG laser in this process, it can be applied to welding of various objects. In the coaxial MIG, TIG-YAG welding, in order to make irradiation positions of the YAG laser beams having been guided in a wire or an electrode focused to the same position, the beam transmitted in fibers is separated to form a space between the separated beams, in which the laser is guided. With this method the beam-irradiating area can be brought near or to the arc-generating point. This enables welding of all directions even for the member of a three-dimensional shape. This time we carried out welding for various materials and have made their welding of up to 1 mm or more in welding groove gap possible. We have realized high-speed 1-pass butt welding of 4m/min in welding speed with the laser power of 3 kW for an aluminum alloy plate of approximately 4 mm thick. For a mild steel plate also we have realized butt welding of 1m/min with 5 kW for 6 mm thick. Further, in welding of stainless steel we have shown its welding possibility, by stabilizing the arc with the YAG laser in the welding atmosphere of pure argon, and shown that this welding is effective in high-efficiency welding of various materials. Here we will report the fundamental welding performances and applications to various objects for the coaxial MIG, TIG-YAG welding we have developed.

Ultrasonic testing of austenitic welds and its dependency on the welding process

International Nuclear Information System (INIS)

Tabatabaeipour, S.M.; Honarvar, F.

2009-01-01

This paper describes the ultrasonic testing of austenitic welds prepared by two different welding processes. The tests were carried out by the ultrasonic Time-of-Flight Diffraction (ToFD) technique. Shielded Metal Arc Welding (SMAW) and Gas Tungsten Arc Welding (GTAW) are the welding processes used for preparing the specimens. Identical artificial defects were implanted in both welds during the welding process. Both specimens were examined by the ToFD technique under similar conditions. Metallographic images were also obtained from the cross sectional plane of both the SMA and GTA welds. These images show that the grain orientation in the two welded specimens are different. D-scan images obtained by the ToFD technique from these welds indicates that inspecting the specimens prepared by the SMAW process is easier than the one made by the GTAW process. The results also show that the D-scan images cannot reveal the small vertical drilled holes implanted in the specimens. (author)

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.

The technology and welding joint properties of hybrid laser-tig welding on thick plate

Science.gov (United States)

Shenghai, Zhang; Yifu, Shen; Huijuan, Qiu

2013-06-01

The technologies of autogenous laser welding and hybrid laser-TIG welding are used on thick plate of high strength lower alloy structural steel 10CrNiMnMoV in this article. The unique advantages of hybrid laser-TIG welding is summarized by comparing and analyzing the process parameters and welding joints of autogenous laser welding laser welding and hybrid laser-TIG welding. With the optimal process parameters of hybrid welding, the good welding joint without visible flaws can be obtained and its mechanical properties are tested according to industry standards. The results show that the hybrid welding technology has certain advantages and possibility in welding thick plates. It can reduce the demands of laser power, and it is significant for lowering the aspect ratio of weld during hybrid welding, so the gas in the molten pool can rise and escape easily while welding thick plates. Therefore, the pores forming tendency decreases. At the same time, hybrid welding enhances welding speed, and optimizes the energy input. The transition and grain size of the microstructure of hybrid welding joint is better and its hardness is higher than base material. Furthermore, its tensile strength and impact toughness is as good as base material. Consequently, the hybrid welding joint can meet the industry needs completely.

Effects of post weld heat treatment and weld overlay on the residual stress and mechanical properties in dissimilar metal weld

International Nuclear Information System (INIS)

Campos, Wagner R.C.; Ribeiro, Vladimir S.; Vilela, Alisson H.F.; Almeida, Camila R.O.; Rabello, Emerson G.

2017-01-01

The object of this work is a dissimilar metal weld (DMW) pipe joint between carbon steel (A-106 Gr B) and stainless steel (A-312 TP316L) pipes and filler metals of Nickel alloy (82/182), which find wide application in the field of chemical, oil, petroleum industries, fossil fuel and nuclear power plant. A lot of the failures that have occurred in dissimilar metal welded are affected greatly by residual stresses. Residual stress is often a cause of premature failure of critical components under normal operation of welded components. Several methods have been tested and developed for removing the tensile residual stresses. The aim of the methods is to reduce the tensile stress state or to create compressive stresses at a predefined area, such as the inner surface of a welded pipe joint. Post weld heat treatment (PWHT) and weld overlay (WOL) are two of the residual stress mitigation methods which reduce the tensile residual stress, create compressive stresses and arrest crack initiation and crack growth. The technique used to substantially minimized or eliminated this failure development in the root weld is the post weld heat treatments (stress relief heat treatment) or the weld overlay. In this work was studied the effectiveness in reducing internal residual stress in dissimilar metal welded pipe joints subjected to post weld heat treatment and weld overlay, measurement by hole-drilling strain-gage method of stress relaxation. Also held was mechanical characterization of the welded pipe joint itself. (author)

Effects of post weld heat treatment and weld overlay on the residual stress and mechanical properties in dissimilar metal weld

Energy Technology Data Exchange (ETDEWEB)

Campos, Wagner R.C.; Ribeiro, Vladimir S.; Vilela, Alisson H.F.; Almeida, Camila R.O.; Rabello, Emerson G., E-mail: wrcc@cdtn.br, E-mail: camilarezende.cr@gmail.com, E-mail: egr@cdtn.br, E-mail: vladimirsoler@hotmail.com, E-mail: ahfv02@outlook.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

The object of this work is a dissimilar metal weld (DMW) pipe joint between carbon steel (A-106 Gr B) and stainless steel (A-312 TP316L) pipes and filler metals of Nickel alloy (82/182), which find wide application in the field of chemical, oil, petroleum industries, fossil fuel and nuclear power plant. A lot of the failures that have occurred in dissimilar metal welded are affected greatly by residual stresses. Residual stress is often a cause of premature failure of critical components under normal operation of welded components. Several methods have been tested and developed for removing the tensile residual stresses. The aim of the methods is to reduce the tensile stress state or to create compressive stresses at a predefined area, such as the inner surface of a welded pipe joint. Post weld heat treatment (PWHT) and weld overlay (WOL) are two of the residual stress mitigation methods which reduce the tensile residual stress, create compressive stresses and arrest crack initiation and crack growth. The technique used to substantially minimized or eliminated this failure development in the root weld is the post weld heat treatments (stress relief heat treatment) or the weld overlay. In this work was studied the effectiveness in reducing internal residual stress in dissimilar metal welded pipe joints subjected to post weld heat treatment and weld overlay, measurement by hole-drilling strain-gage method of stress relaxation. Also held was mechanical characterization of the welded pipe joint itself. (author)

Investigation on the Mechanism and Failure Mode of Laser Transmission Spot Welding Using PMMA Material for the Automotive Industry

Science.gov (United States)

Wang, Xiao; Liu, Baoguang; Liu, Wei; Zhong, Xuejiao; Jiang, Yingjie; Liu, Huixia

2017-01-01

To satisfy the need of polymer connection in lightweight automobiles, a study on laser transmission spot welding using polymethyl methacrylate (PMMA) is conducted by using an Nd:YAG pulse laser. The influence of three variables, namely peak voltages, defocusing distances and the welding type (type I (pulse frequency and the duration is 25 Hz, 0.6 s) and type II (pulse frequency and the duration is 5 Hz, 3 s)) to the welding quality was investigated. The result showed that, in the case of the same peak voltages and defocusing distances, the number of bubbles for type I was obviously more than type II. The failure mode of type I was the base plate fracture along the solder joint, and the connection strength of type I was greater than type II. The weld pool diameter:depth ratio for type I was significantly greater than type II. It could be seen that there was a certain relationship between the weld pool diameter:depth ratio and the welding strength. By the finite element simulation, the weld pool for type I was more slender than type II, which was approximately the same as the experimental results. PMID:28772383

Investigation on the Mechanism and Failure Mode of Laser Transmission Spot Welding Using PMMA Material for the Automotive Industry.

Science.gov (United States)

Wang, Xiao; Liu, Baoguang; Liu, Wei; Zhong, Xuejiao; Jiang, Yingjie; Liu, Huixia

2017-01-01

To satisfy the need of polymer connection in lightweight automobiles, a study on laser transmission spot welding using polymethyl methacrylate (PMMA) is conducted by using an Nd:YAG pulse laser. The influence of three variables, namely peak voltages, defocusing distances and the welding type (type I (pulse frequency and the duration is 25 Hz, 0.6 s) and type II (pulse frequency and the duration is 5 Hz, 3 s)) to the welding quality was investigated. The result showed that, in the case of the same peak voltages and defocusing distances, the number of bubbles for type I was obviously more than type II. The failure mode of type I was the base plate fracture along the solder joint, and the connection strength of type I was greater than type II. The weld pool diameter:depth ratio for type I was significantly greater than type II. It could be seen that there was a certain relationship between the weld pool diameter:depth ratio and the welding strength. By the finite element simulation, the weld pool for type I was more slender than type II, which was approximately the same as the experimental results.

Investigation on the Mechanism and Failure Mode of Laser Transmission Spot Welding Using PMMA Material for the Automotive Industry

Directory of Open Access Journals (Sweden)

Xiao Wang

2017-01-01

Full Text Available To satisfy the need of polymer connection in lightweight automobiles, a study on laser transmission spot welding using polymethyl methacrylate (PMMA is conducted by using an Nd:YAG pulse laser. The influence of three variables, namely peak voltages, defocusing distances and the welding type (type I (pulse frequency and the duration is 25 Hz, 0.6 s and type II (pulse frequency and the duration is 5 Hz, 3 s to the welding quality was investigated. The result showed that, in the case of the same peak voltages and defocusing distances, the number of bubbles for type I was obviously more than type II. The failure mode of type I was the base plate fracture along the solder joint, and the connection strength of type I was greater than type II. The weld pool diameter:depth ratio for type I was significantly greater than type II. It could be seen that there was a certain relationship between the weld pool diameter:depth ratio and the welding strength. By the finite element simulation, the weld pool for type I was more slender than type II, which was approximately the same as the experimental results.

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

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....

Nitrogen And Oxygen Amount In Weld After Welding With Micro-Jet Cooling

Directory of Open Access Journals (Sweden)

Węgrzyn T.

2015-06-01

Full Text Available Micro-jet cooling after welding was tested only for MIG welding process with argon, helium and nitrogen as a shielded gases. A paper presents a piece of information about nitrogen and oxygen in weld after micro-jet cooling. There are put down information about gases that could be chosen both for MIG/MAG welding and for micro-jet process. There were given main information about influence of various micro-jet gases on metallographic structure of steel welds. Mechanical properties of weld was presented in terms of nitrogen and oxygen amount in WMD (weld metal deposit.

Prophage induction by ultraviolet light in Acinetobacter calcoaceticus

Energy Technology Data Exchange (ETDEWEB)

Berenstein, D.

1986-09-01

UV-induction of prophage P78 of Acinetobacter calcoaceticus increased with the UV-dose given to the lysogenic strain from the spontaneous induction frequency of about 0.8% to a maximal frequency of 10%. This 10- to 20-fold increase of induction frequency, as measured by the number of infective centres, was accompanied by a 1000-fold increase in the yield of free phage. This effect was probably due to an increase in burst size under the conditions of lysogenic induction. Unusually, the lysogen was more resistant to UV-irradiation than the corresponding non-lysogenic strain.

Prophage Induction by Ultraviolet Light in Acinetobacter calcoaceticus

DEFF Research Database (Denmark)

Berenstein, D.

1986-01-01

UV-induction of prophage P78 of Acinetobacter calcoaceticus increased with the UV-dose given to the lysogenic strain from the spontaneous induction frequency of about 0.8% to a maximal frequency of 10%. This 10- to 20-fold increase of induction frequency, as measured by the number of infective...... centres, was accompanied by a 1000-fold increase in the yield of free phage. This effect was probably due to an increase in burst size under the conditions of lysogenic induction. Unusually, the lysogen was more resistant to UV-irradiation than the corresponding non-lysogenic strain....

Complexity of the ultraviolet mutation frequency response curve in Escherichia coli B/r: SOS induction, one-lesion and two-lesion mutagenesis

International Nuclear Information System (INIS)

Doudney, C.O.

1976-01-01

Three distinct sections of the ultraviolet mutation frequency response (MFR) curve toward tryptophan prototrophy have been demonstrated in Escherichia coli B/r WP2 trp thy and its uvrA derivative in log-phase growth in minimal medium. The initial section, which appears fluence-squared, may reflect the necessity, if mutation is to result, for induction of two lesions, one located within the potentially mutated genetic locus and the other damaging deoxyribonucleic acid replication and resulting in induction of the error-prone SOS repair function. A second linear section is ascribed to the continued induction, after exposure above that sufficient for complete SOS expression, of isolated lesions which lead to mutation in potentially mutated loci. The third section demonstrates an increased rate of mutagenesis and suggests the induction of two lesions in proximity which result in additional mutations. Split-exposure studies support the inducible nature of the SOS function and suggest that mutation frequency decline (MFD) is due to excision resulting from or related to the prevention of SOS induction by inhibition of protein synthesis. Preirradiation tryptophan starvation of the uvr + strain for 30 min decreases MFR in the first and second sections of the curve. Reduction of MFR in the third section requires more prestarvation time and is blocked by nalidixic acid. The decreased MFR of the first and second sections is ascribed to promotion of postirradiation MFD based on excision and that of the third section to completion of the chromosome during the prestarvation period

Optimization of pulsed laser welding process parameters in order to attain minimum underfill and undercut defects in thin 316L stainless steel foils

Science.gov (United States)

Pakmanesh, M. R.; Shamanian, M.

2018-02-01

In this study, the optimization of pulsed Nd:YAG laser welding parameters was done on the lap-joint of a 316L stainless steel foil with the aim of reducing weld defects through response surface methodology. For this purpose, the effects of peak power, pulse-duration, and frequency were investigated. The most important weld defects seen in this method include underfill and undercut. By presenting a second-order polynomial, the above-mentioned statistical method was managed to be well employed to balance the welding parameters. The results showed that underfill increased with the increased power and reduced frequency, it first increased and then decreased with the increased pulse-duration; and the most important parameter affecting it was the power, whose effect was 65%. The undercut increased with the increased power, pulse-duration, and frequency; and the most important parameter affecting it was the power, whose effect was 64%. Finally, by superimposing different responses, improved conditions were presented to attain a weld with no defects.

Welding and cutting

International Nuclear Information System (INIS)

Drews, P.; Schulze Frielinghaus, W.

1978-01-01

This is a survey, with 198 literature references, of the papers published in the fields of welding and cutting within the last three years. The subjects dealt with are: weldability of the materials - Welding methods - Thermal cutting - Shaping and calculation of welded joints - Environmental protection in welding and cutting. (orig.) [de

Simplified welding distortion analysis for fillet welding using composite shell elements

Directory of Open Access Journals (Sweden)

Mingyu Kim

2015-05-01

Full Text Available This paper presents the simplified welding distortion analysis method to predict the welding deformation of both plate and stiffener in fillet welds. Currently, the methods based on equivalent thermal strain like Strain as Direct Boundary (SDB has been widely used due to effective prediction of welding deformation. Regarding the fillet welding, however, those methods cannot represent deformation of both members at once since the temperature degree of freedom is shared at the intersection nodes in both members. In this paper, we propose new approach to simulate deformation of both members. The method can simulate fillet weld deformations by employing composite shell element and using different thermal expansion coefficients according to thickness direction with fixed temperature at intersection nodes. For verification purpose, we compare of result from experiments, 3D thermo elastic plastic analysis, SDB method and proposed method. Compared of experiments results, the proposed method can effectively predict welding deformation for fillet welds.

Welding Technician

Science.gov (United States)

Smith, Ken

2009-01-01

About 95% of all manufactured goods in this country are welded or joined in some way. These welded products range in nature from bicycle handlebars and skyscrapers to bridges and race cars. The author discusses what students need to know about careers for welding technicians--wages, responsibilities, skills needed, career advancement…

Introduction to Welding.

Science.gov (United States)

Fortney, Clarence; Gregory, Mike

This curriculum guide provides six units of instruction on basic welding. Addressed in the individual units of instruction are the following topics: employment opportunities for welders, welding safety and first aid, welding tools and equipment, basic metals and metallurgy, basic math and measuring, and procedures for applying for a welding job.…

Orbital welding technique

International Nuclear Information System (INIS)

Hoeschen, W.

2003-01-01

The TIG (Tungsten-inert gas) orbital welding technique is applied in all areas of pipe welding. The process is mainly used for austenitic and ferritic materials but also for materials like aluminium, nickel, and titanium alloys are commonly welded according to this technique. Thin-walled as well as thick-walled pipes are welded economically. The application of orbital welding is of particular interest in the area of maintenance of thick-walled pipes that is described in this article. (orig.) [de

Metal Droplet Formation in Gas Metal Arc Welding

International Nuclear Information System (INIS)

Haidar, J.

2000-01-01

A two-dimensional dynamic treatment has been developed for description of arc and electrode properties in gas metal arc welding (GMAW). The theory is a unified treatment of the arc the welding wire anode and the cathode, and includes a detailed account of sheath effects near the anode. The wire anode is included as a dynamic entity and the volume of fluid method is used to handle the movement of the free surface of the molten metal at the tip of the wire, accounting for effects of surface tension, inertia, gravity, arc pressure, viscous drag force of the plasma, magnetic forces and Marangoni effect, and also for the effects of wire feed rate in GMAW. Results of calculations made for a mild steel wire of diameter 0.16 cm are in good agreement with experimental measurements of droplet diameter and droplet detachment frequency at currents between 150 and 330 A, which includes the transition between ''globular'' and ''spray'' transfer. Quantitative predictions are also made of the amount of metal vapour that is generated from the welding droplets at the tip of the welding wire. (author)

Welding stresses

International Nuclear Information System (INIS)

Poirier, J.; Barbe, B.; Jolly, N.

1976-01-01

The aim is to show how internal stresses are generated and to fix the orders of magnitude. A realistic case, the vertical welding of thick plates free to move one against the other, is described and the deformations and stresses are analyzed. The mathematical model UEDA, which accounts for the elastic modulus, the yield strength and the expansion coefficient of the metal with temperature, is presented. The hypotheses and results given apply only to the instantaneous welding of a welded plate and to a plate welded by a moving electrode [fr

Reduction of Biomechanical and Welding Fume Exposures in Stud Welding.

Science.gov (United States)

Fethke, Nathan B; Peters, Thomas M; Leonard, Stephanie; Metwali, Mahmoud; Mudunkotuwa, Imali A

2016-04-01

The welding of shear stud connectors to structural steel in construction requires a prolonged stooped posture that exposes ironworkers to biomechanical and welding fume hazards. In this study, biomechanical and welding fume exposures during stud welding using conventional methods were compared to exposures associated with use of a prototype system that allowed participants to weld from an upright position. The effect of base material (i.e. bare structural beam versus galvanized decking) on welding fume concentration (particle number and mass), particle size distribution, and particle composition was also explored. Thirty participants completed a series of stud welding simulations in a local apprenticeship training facility. Use of the upright system was associated with substantial reductions in trunk inclination and the activity levels of several muscle groups. Inhalable mass concentrations of welding fume (averaged over ~18 min) when using conventional methods were high (18.2 mg m(-3) for bare beam; 65.7 mg m(-3) for through deck), with estimated mass concentrations of iron (7.8 mg m(-3) for bare beam; 15.8 mg m(-3) for through deck), zinc (0.2 mg m(-3) for bare beam; 15.8 mg m(-3) for through deck), and manganese (0.9 mg m(-3) for bare beam; 1.5 mg m(-3) for through deck) often exceeding the American Conference of Governmental Industrial Hygienists Threshold Limit Values (TLVs). Number and mass concentrations were substantially reduced when using the upright system, although the total inhalable mass concentration remained above the TLV when welding through decking. The average diameters of the welding fume particles for both bare beam (31±17 nm) through deck conditions (34±34 nm) and the chemical composition of the particles indicated the presence of metallic nanoparticles. Stud welding exposes ironworkers to potentially high levels of biomechanical loading (primarily to the low back) and welding fume. The upright system used in this study improved exposure

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.

Estimation of weld nugget temperature by thermography method in resistance projection welding process

International Nuclear Information System (INIS)

Setty, D.S.; Rameswara Roa, A.; Hemantha Rao, G.V.S.; Jaya Raj, R.N.

2008-01-01

In the Pressurized Heavy Water Reactor (PHWR) fuel manufacturing, zirconium alloy appendages like spacer and bearing pads are welded to the thin wall zirconium alloy fuel tubes by using resistance projection welding process. Out of many joining processes available, resistance-welding process is reliable, environment friendly and best suitable for mass production applications. In the fuel assembly, spacer pads are used to get the required inter-element spacing and Bearing pads are used to get the required load-bearing surface for the fuel assembly. Performance of the fuel assembly in the reactor is greatly influenced by these weld joint's quality. Phase transformation from α to β phase is not acceptable while welding these tiny appendages. At present only destructive metallography test is available for this purpose. This can also be achieved by measuring weld nugget temperature where in the phase transformation temperature for zirconium alloy material is 853 o C. The temperature distribution during resistance welding of tiny parts cannot be measured by conventional methods due to very small space and short weld times involved in the process. Shear strength, dimensional accuracy and weld microstructures are some of the key parameters used to measure the quality of appendage weld joints. Weld parameters were optimized with the help of industrial experimentation methodology. Individual projection welding by split electrode concept, and during welding on empty tube firm support is achieved on inner side of the tube by using expandable pneumatic mandrel. In the present paper, an attempt was made to measure the weld nugget temperature by thermography technique and is correlated with standard microstructures of zirconium alloy material. The temperature profiles in the welding process are presented for different welding conditions. This technique has helped in measuring the weld nugget temperature more accurately. It was observed that in the present appendage welding

Influence of Loading Direction and Weld Reinforcement on Fatigue Performance of TIG Weld Seam

Directory of Open Access Journals (Sweden)

HUI Li

2018-02-01

Full Text Available The influence of loading direction and weld reinforcement on fatigue performance of TC2 titanium alloy TIG weld seam was investigated via fatigue experiments and SEM fracture observation. The results show that the fatigue life of retaining weld reinforcement specimens is lower than that of removing one in the same weld direction. The fatigue life of oblique weld specimens is higher than that of straight one with the same weld reinforcement treatment. The initiation of removing weld reinforcement specimens' fatigue crack sources is in the hole defect, but the weld reinforcement specimen initiate at the weld toes. During the early stage of fatigue crack propagation, the cracks all grow inside the weld seam metal with obvious fatigue striation. And the fatigue cracks of oblique weld specimens pass through the weld seam into the base with a typical toughness fatigue striation during the last stage of fatigue crack propagation. The dimple of straight weld specimens is little and shallow in the final fracture zone. The oblique weld specimens broke in the base metal area, and the dimple is dense.

Nitrogen And Oxygen Amount In Weld After Welding With Micro-Jet Cooling

OpenAIRE

Węgrzyn T.; Piwnik J.

2015-01-01

Micro-jet cooling after welding was tested only for MIG welding process with argon, helium and nitrogen as a shielded gases. A paper presents a piece of information about nitrogen and oxygen in weld after micro-jet cooling. There are put down information about gases that could be chosen both for MIG/MAG welding and for micro-jet process. There were given main information about influence of various micro-jet gases on metallographic structure of steel welds. Mechanical properties of weld was pr...

Frequency characteristics of geomagnetic induction anomalies in ...

Indian Academy of Sciences (India)

P V Vijaya Kumar

2017-10-07

Oct 7, 2017 ... characteristics of electrical conductivity distribution are presented in the form of induction arrows. From ... High resistive block related to underplating mantle material has .... Recent seismic tomography studies indicate low.

Influence of weld structure on cross-weld creep behavior in P23 steel

Energy Technology Data Exchange (ETDEWEB)

Allen, D.J.; Degnan, C.C. [E.ON Engineering (United Kingdom); Brett, S.J. [RWE npower (United Kingdom); Buchanan, L.W. [Doosan Babcock (United Kingdom)

2010-07-01

A thick section pipe weld in low alloy steel P23 has been characterised by cross-weld creep rupture testing at a range of stresses, together with all-weld-metal and parent material testing, under the auspices of the UK High Temperature Power Plant Forum. The results generally show that the weld metal can be weak when tested in the transverse (cross-weld) orientation, and can fail with limited overall ductility by cracking in the zone of refined weld metal beneath the fusion boundary of the superposed weld bead. However, one specimen showed a much superior performance, which could be understood in terms of its locally more creep resistant weld macrostructure. The implications for P23 performance and weld manufacture are discussed. (orig.)

Two high-frequency mutual inductance bridges with high resolution

NARCIS (Netherlands)

Flokstra, Jakob; Gerritsma, G.J.; Kreuwel, H.J.M.; van der Marel, L.C.

1980-01-01

Two mutual inductance bridges are described for operation up to about 100 kHz. Special attention is paid to the sensitivity and resolution of the bridges. Both bridges can be used to measure variations of about 10 pH in the mutual inductance. The first bridge consists of passive elements only

Welded joints integrity analysis and optimization for fiber laser welding of dissimilar materials

Science.gov (United States)

Ai, Yuewei; Shao, Xinyu; Jiang, Ping; Li, Peigen; Liu, Yang; Liu, Wei

2016-11-01

Dissimilar materials welded joints provide many advantages in power, automotive, chemical, and spacecraft industries. The weld bead integrity which is determined by process parameters plays a significant role in the welding quality during the fiber laser welding (FLW) of dissimilar materials. In this paper, an optimization method by taking the integrity of the weld bead and weld area into consideration is proposed for FLW of dissimilar materials, the low carbon steel and stainless steel. The relationships between the weld bead integrity and process parameters are developed by the genetic algorithm optimized back propagation neural network (GA-BPNN). The particle swarm optimization (PSO) algorithm is taken for optimizing the predicted outputs from GA-BPNN for the objective. Through the optimization process, the desired weld bead with good integrity and minimum weld area are obtained and the corresponding microstructure and microhardness are excellent. The mechanical properties of the optimized joints are greatly improved compared with that of the un-optimized welded joints. Moreover, the effects of significant factors are analyzed based on the statistical approach and the laser power (LP) is identified as the most significant factor on the weld bead integrity and weld area. The results indicate that the proposed method is effective for improving the reliability and stability of welded joints in the practical production.

Ultrasonic Spot and Torsion Welding of Aluminum to Titanium Alloys: Process, Properties and Interfacial Microstructure

Science.gov (United States)

Balle, Frank; Magin, Jens

Hybrid lightweight structures shape the development of future vehicles in traffic engineering and the aerospace industry. For multi-material concepts made out of aluminum and titanium alloys, the ultrasonic welding technique is an alternative effective joining technology. The overlapped structures can be welded in the solid state, even without gas shielding. In this paper the conventional ultrasonic spot welding with longitudinal oscillation mode is compared to the recent ultrasonic torsion welding with a torsional mode at 20 kHz working frequency. For each technique the process parameters welding force, welding energy and oscillation amplitude were optimized for the hybrid joints using design of experiments. Relationships between the process parameters, mechanical properties and related welding zone should be understood. Central aspects of the research project are microscopic studies of the joining zone in cross section and extensive fracture surface analysis. Detailed electron microscopy and spectroscopy of the hybrid interface help to understand the interfacial formation during ultrasonic welding as well as to transfer the gained knowledge for further multi-metal joints.

Joint formation of dissimilar steels in pressure welding with superposition of ultrasonic oscillations

Energy Technology Data Exchange (ETDEWEB)

Surovtsev, A P; Golovanenko, S A; Sukhanov, V E; Kazantsev, V F

1983-12-01

Investigation results of kinetics and quality of carbon steel joints with the steel 12Kh18N10T, obtained by pressure welding with superposition of ultrasonic oscillations with the frequency 16.5-18.0 kHz are given. The effect of ultrasonic oscillations on the process of physical contact development of the surfaces welded, formation of microstructure and impact viscosity of the compound, is shown.

The use of extraction and electronic diffraction replicas for precipitates characterization in welded Cr-Mo Steels

International Nuclear Information System (INIS)

Gutierrez de Saiz-Solabarria, S.; San Juan Nunez, J.M.

1997-01-01

The precipitates and phases found in the structure of welded joints of Heat Interchanges Tubes were studied and identified. The base material satisfied the requirements of ASME Sec II, SA 213 Gr T22 (2 1/4 Cr 1 Mo). Compositions of Filler Metals were: 2 1/4 Cr 1 Mo and 2 1/4 Cr 1 Mo 1/4 Nb. The chemical composition of base and weld materials were analyzed by atomic emission spectroscopy in high vacuum electric discharge and by inductive plasma coupled. For the constituents characterization extraction and diffraction microscopy replicas were used. (Author) 65 refs

Fabrication Flaw Density and Distribution in Weld Repairs

International Nuclear Information System (INIS)

Doctor, Steven R.

2009-01-01

The Pacific Northwest National Laboratory (PNNL) is developing a generalized flaw distribution for the population of nuclear reactor pressure vessels and for piping welds in the U. S. operating reactors. The purpose of the generalized flaw distribution is to predict component-specific flaw densities. The estimates of fabrication flaws are intended for use in fracture mechanics structural integrity assessments. Structural integrity assessments, such as estimating the frequency of loss-of-coolant accidents, are performed by computer codes that require, as input, accurate estimates of flaw densities. Welds from four different cancelled reactor pressure vessels and a collection of archived pipes have been studied to develop empirical estimates of fabrication flaw densities. This paper describes the fabrication flaw distribution and characterization in the repair weld metal of vessels and piping. This work indicates that large flaws occur in these repairs which are complex in composition and sometimes include cracks on the ends of the repair cavities. Parametric analysis using an exponential fit is performed on the data. Construction records where available were reviewed. It is difficult to make conclusions due to the limited number of construction records reviewed. However, the records reviewed to date show a significant change in repair frequency over the years when the components in this study were fabricated. A description of repair flaw morphology is provided with a discussion of fracture mechanics significance.

Laser Welding Test Results with Gas Atmospheres in Welding Chamber

Energy Technology Data Exchange (ETDEWEB)

Joung, Chang-Young; Hong, Jin-Tae; Ahn, Sung-Ho; Heo, Sung-Ho; Jang, Seo-Yun; Yang, Tae-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

The weld beads of specimens welded under identical conditions in the helium and argon gas were cleaner, more regular, and steadier than those in a vacuum. The penetration depth of the FZ in the vacuum was much deeper than those in the helium and argon gas. To measure the irradiation properties of nuclear fuel in a test reactor, a nuclear fuel test rod instrumented with various sensors must be fabricated with assembly processes. A laser welding system to assemble the nuclear fuel test rod was designed and fabricated to develop various welding technologies of the fuel test rods to joint between a cladding tube and end-caps. It is an air-cooling optical fiber type and its emission modes are a continuous (CW) mode of which the laser generates continuous emission, and pulse (QCW) mode in which the laser internally generates sequences of pulses. We considered the system welding a sample in a chamber that can weld a specimen in a vacuum and inert gas atmosphere, and the chamber was installed on the working plate of the laser welding system. In the chamber, the laser welding process should be conducted to have no defects on the sealing area between a cladding tube and an end-cap.

Welding of Thin Steel Plates by Hybrid Welding Process Combined TIG Arc with YAG Laser

Science.gov (United States)

Kim, Taewon; Suga, Yasuo; Koike, Takashi

TIG arc welding and laser welding are used widely in the world. However, these welding processes have some advantages and problems respectively. In order to improve problems and make use of advantages of the arc welding and the laser welding processes, hybrid welding process combined the TIG arc with the YAG laser was studied. Especially, the suitable welding conditions for thin steel plate welding were investigated to obtain sound weld with beautiful surface and back beads but without weld defects. As a result, it was confirmed that the shot position of the laser beam is very important to obtain sound welds in hybrid welding. Therefore, a new intelligent system to monitor the welding area using vision sensor is constructed. Furthermore, control system to shot the laser beam to a selected position in molten pool, which is formed by TIG arc, is constructed. As a result of welding experiments using these systems, it is confirmed that the hybrid welding process and the control system are effective on the stable welding of thin stainless steel plates.

Hybrid laser-arc welding

DEFF Research Database (Denmark)

Hybrid laser-arc welding (HLAW) is a combination of laser welding with arc welding that overcomes many of the shortfalls of both processes. This important book gives a comprehensive account of hybrid laser-arc welding technology and applications. The first part of the book reviews...... the characteristics of the process, including the properties of joints produced by hybrid laser-arc welding and ways of assessing weld quality. Part II discusses applications of the process to such metals as magnesium alloys, aluminium and steel as well as the use of hybrid laser-arc welding in such sectors as ship...... building and the automotive industry. With its distinguished editor and international team of contributors, Hybrid laser-arc welding, will be a valuable source of reference for all those using this important welding technology. Professor Flemming Ove Olsen works in the Department of Manufacturing...

Plug-welding of ODS cladding tube for BOR-60 irradiation. Welding condition setting. Device remodeling and welding

International Nuclear Information System (INIS)

Seki, Masayuki; Ishibashi, Fujio; Kono, Syusaku; Hirako, Kazuhito; Tsukada, Tatsuya

2003-04-01

Irradiation test in BOR-60 at RIAR to judge practical use prospect of ODS cladding tube at early stage is planned as Japan-Russia a joint research. RIAR does fuel design of fuel pin used for this joint research. JNC manufactures ODS cladding tube and bar materials (two steel kind of martensite and ferrite), upper endplug production. They are welded by pressurized resistance welding, and are inspected in JNC Tokai, transported to RIAR. And RIAR manufactures vibration packing fuel pin. On the upper endplug welding by pressurized resistance welding method, we worded on the problems such as decision of welding condition by changing the size and crystallization of cladding tube and the design of endplug, and the chucking device remodeling to correspond to the long scale cladding tube welding system (included handling) and of quality assurance method. Especially, use of long scale cladding tube caused problem that bending transformation occurred in cladding tube by welding pressure. However, we solved this problem by shortening the distance of cladding tube colette chuck and pressure receiving, and by putting the sleeve in an internal space of welding machine, losing the bending of cladding tube. Moreover, welding defects were occurred by the difference of an inside state, an inside defect and recrystallization of cladding tube. We solved the problem by inside grinding for the edge of tube, angle beam method by ultrasonic wave, and ultrasonic wave form confirmation. Manufacturing process with long scale cladding tube including heat-treatment to remove combustion return and remaining stress was established besides, Afterwards, welding of ODS cladding tube and upper endplug. As the quality assurance system, we constructed [Documented procedure (referred to JOYO)] based on [Document of the QA plan] by OEC. Welding and inspection were executed by the document procedure. It is thought that the quality assurance method become references for the irradiation test in JOYO in the

Modification of the grain structure of austenitic welds for improved ultrasonic inspectability

International Nuclear Information System (INIS)

Wagner, Sabine; Dugan, Sandra; Stubenrauch, Steffen; Jacobs, Oliver

2013-01-01

Welding is an essential part of the fabrication of austenitic stainless steel components used in industrial plants, such as those designed for nuclear power generation, chemical processing, conventional power generation and, increasingly, for production of renewable energy. The welded austenitic material presents major challenges for ultrasonic inspection due to the grain structure of the weld metal. The typically coarse grain structure, in combination with the elastic anisotropy of the material, leads to increased scattering and affects sound wave propagation in the weld. These effects result in a reduced signal-to-noise ratio, and complicate the interpretation of signals and the localisation of defects by ultrasonic inspection. This paper presents the results of a research project dealing with efforts to influence grain growth in the weld during the welding process, in particular during the solidification process, in order to produce smaller grains. The objective was to achieve improved sound propagation through the weld, so that inspectability can be improved. The welding process was modified by the application of alternating magnetic fields at different frequencies, as well as different temperature cycles and pulsed arc technology. Metallographic sections of the test welds show that modification of the grain structure can be achieved by the use of these techniques. For further optimisation, test blocks for ultrasonic testing were manufactured with testflaws to study sound propagation through the modified weld and to assess the detectability of test flaws. The results of this investigation are of importance in assessing the integrity of highly stressed components in industrial installations, particularly for those components with stringent requirements on safety and quality.

Weld analysis and control system

Science.gov (United States)

Kennedy, Larry Z. (Inventor); Rodgers, Michael H. (Inventor); Powell, Bradley W. (Inventor); Burroughs, Ivan A. (Inventor); Goode, K. Wayne (Inventor)

1994-01-01

The invention is a Weld Analysis and Control System developed for active weld system control through real time weld data acquisition. Closed-loop control is based on analysis of weld system parameters and weld geometry. The system is adapted for use with automated welding apparatus having a weld controller which is capable of active electronic control of all aspects of a welding operation. Enhanced graphics and data displays are provided for post-weld analysis. The system provides parameter acquisition, including seam location which is acquired for active torch cross-seam positioning. Torch stand-off is also monitored for control. Weld bead and parent surface geometrical parameters are acquired as an indication of weld quality. These parameters include mismatch, peaking, undercut, underfill, crown height, weld width, puddle diameter, and other measurable information about the weld puddle regions, such as puddle symmetry, etc. These parameters provide a basis for active control as well as post-weld quality analysis and verification. Weld system parameters, such as voltage, current and wire feed rate, are also monitored and archived for correlation with quality parameters.

Dry hyperbaric gas metal arc welding of subsea pipelines: experiments and modeling

Energy Technology Data Exchange (ETDEWEB)

Azar, Amin S.

2012-07-01

welding parameters. The datasets are representing the effects of using pure argon under 14 incrementally increased pressure levels. Fast Fourier Transformation (FFT) is used to characterize the frequency domain of the waveforms. Auto-correlation Function (AF) and Power Spectral Density (PSD) were calculated assuming the Wiener-Khinchin theorem. Considering the AF, it is possible to visualize the deteriorating stability of the arc. The rate of stability degradation is quite gentle after 20 bar, though, huge differences were observed from 1 to 20 bar. The characteristic frequencies of 100-150 Hz and 350-400 Hz were observed. The first range can be associated with the mass transfer or molten droplet launch frequency and the latter range is representative of the rectified mains. The spread of large low-frequency peaks at higher pressures is illustrating the mass transfer deterioration. The aforementioned peaks were found above 125 bar where the range of the characteristic frequency peaks in voltage and current waveforms started to deviate. The calculated arc power is higher at high-pressure range while the weld bead geometry was barely varied. It implies that the arc efficiency factor decreases at high pressures.The heat source dimensions and heat efficiency factor are two major inputs for finite element (FE) simulations of the weld. However, a systematic classification of these factors was hardly available prior to this work. Additionally, to the best of author's knowledge, the direct high-speed observation of the arc inside the hyperbaric welding chamber has not been investigated in detail by far due to several technological issues. The varying bead-on-plate welds including the end crater appearance can possibly be good candidates to categorize the FE heat source dimensions. Double-ellipsoidal heat source (Goldak's Model) was implemented in WeldSimS R FE code that is used in this study. Since the model incorporates two superimposed reference heat sources, the

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

Optimum welding condition of 2017 aluminum similar alloy friction welded joints

Energy Technology Data Exchange (ETDEWEB)

Tsujino R.; Ochi, H. [Osaka Inst. of Tech., Osaka (Japan); Morikawa, K. [Osaka Sangyo Univ., Osaka (Japan); Yamaguchi, H.; Ogawa, K. [Osaka Prefecture Univ., Osaka (Japan); Fujishiro, Y.; Yoshida, M. [Sumitomo Metal Technology Ltd., Hyogo (Japan)

2002-07-01

Usefulness of the statistical analysis for judging optimization of the friction welding conditions was investigated by using 2017 aluminum similar alloy, where many samples under fixed welding conditions were friction welded and analyzed statistically. In general, selection of the optimum friction welding conditions for similar materials is easy. However, it was not always the case for 2017 aluminum alloy. For optimum friction welding conditions of this material, it is necessary to apply relatively larger upset pressure to obtain high friction heating. Joint efficiencies obtained under the optimum friction welding conditions showed large shape parameter (m value) of Weibull distribution as well as in the dissimilar materials previously reported. The m value calculated on the small number of data can be substituted for m value on the 30 data. Therefore, m value is useful for practical use in the factory for assuming the propriety of the friction welding conditions. (orig.)

Dual wire welding torch and method

Science.gov (United States)

Diez, Fernando Martinez; Stump, Kevin S.; Ludewig, Howard W.; Kilty, Alan L.; Robinson, Matthew M.; Egland, Keith M.

2009-04-28

A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

TIG welding method and TIG welding device

International Nuclear Information System (INIS)

Yoneda, Eishi

1998-01-01

The present invention provides a method of TIG welding for members having different heat capacities including a cladding tube and an end plug of a fuel rod to be used, for example, in a reactor, and a device therefor. Namely, in the TIG welding method, the flow rate of a sealed gas to the side of a member having smaller heat capacity is made greater than that on the side of the member having greater heat capacity bordered on the top end of a welding electrode. Since the sealed gas is jetted being localized relative to the welding electrode, arc is restricted in a region of the member having smaller heat capacity and is increased at a region having a larger heat capacity. As a result, the arc is localized, so that the heat input amount to the region having a large heat capacity is increased, and then a plurality of members at the abutting portion are melted uniformly thereby capable of obtaining a uniform molten pool. A bead is formed at the abutting portion thereby capable of obtaining a welded portion with less unevenness and having large strength. (I.S.)

Inductance position sensor for pneumatic cylinder

Science.gov (United States)

Ripka, Pavel; Chirtsov, Andrey; Mirzaei, Mehran; Vyhnanek, Jan

2018-04-01

The position of the piston in pneumatic cylinder with aluminum wall can be measured by external inductance sensor without modifications of the aluminum piston and massive iron piston rod. For frequencies below 20 Hz the inductance is increasing with inserting rod due to the rod permeability. This mode has disadvantage of slow response to piston movement and also high temperature sensitivity. At the frequency of 45 Hz the inductance is position independent, as the permeability effect is compensated by the eddy current effect. At higher frequencies eddy current effects in the rod prevail, the inductance is decreasing with inserting rod. In this mode the sensitivity is smaller but the sensor response is fast and temperature stability is better. We show that FEM simulation of this sensor using measured material properties gives accurate results, which is important for the sensor optimization such as designing the winding geometry for the best linearity.

Standard practice for ultrasonic testing of the Weld Zone of welded pipe and tubing

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This practice describes general ultrasonic testing procedures for the detection of discontinuities in the weld and adjacent heat affected zones of welded pipe and tubing by scanning with relative motion between the search unit and pipe or tube. When contact or unfocused immersion search units are employed, this practice is intended for tubular products having specified outside diameters ≥2 in. (≥50 mm) and specified wall thicknesses of 1/8to 11/16 in. (3 to 27 mm). When properly focused immersion search units are employed, this practice may also be applied to material of smaller diameter and thinner wall. Note 1—When contact or unfocused immersion search units are used, precautions should be exercised when examining pipes or tubes near the lower specified limits. Certain combinations of search unit size, frequency, thin–wall thicknesses, and small diameters could cause generation of unwanted sound waves that may produce erroneous examination results. 1.2 All surfaces of material to be examined in ...

Experimental investigation on the weld pool formation process in plasma keyhole arc welding

Science.gov (United States)

Van Anh, Nguyen; Tashiro, Shinichi; Van Hanh, Bui; Tanaka, Manabu

2018-01-01

This paper seeks to clarify the weld pool formation process in plasma keyhole arc welding (PKAW). We adopted, for the first time, the measurement of the 3D convection inside the weld pool in PKAW by stereo synchronous imaging of tungsten tracer particles using two sets of x-ray transmission systems. The 2D convection on the weld pool surface was also measured using zirconia tracer particles. Through these measurements, the convection in a wide range of weld pools from the vicinity of the keyhole to the rear region was successfully visualized. In order to discuss the heat transport process in a weld pool, the 2D temperature distribution on the weld pool surface was also measured by two-color pyrometry. The results of the comprehensive experimental measurement indicate that the shear force due to plasma flow is found to be the dominant driving force in the weld pool formation process in PKAW. Thus, heat transport in a weld pool is considered to be governed by two large convective patterns near the keyhole: (1) eddy pairs on the surface (perpendicular to the torch axis), and (2) eddy pairs on the bulk of the weld pool (on the plane of the torch). They are formed with an equal velocity of approximately 0.35 m s-1 and are mainly driven by shear force. Furthermore, the flow velocity of the weld pool convection becomes considerably higher than that of other welding processes, such as TIG welding and GMA welding, due to larger plasma flow velocity.

Effect of Manganese on the Mechanical Properties of Welded As-Cast Aluminium Joint

Directory of Open Access Journals (Sweden)

Isiaka Oluwole OLADELE

2013-11-01

Full Text Available The effects of manganese on the mechanical properties of welded and un-weld as-cast 6063 aluminium alloy has been studied. Alloys of varying percentage of manganese from 0.019 to 0.24 were sand cast. A wooden pattern of dimensions 200×100×100mm was used, the aluminium (500g was charged into an induction furnace and heated to 750°C for 15 minutes, this was followed by the addition of weighed powdered manganese, stirred and heated at the same temperature for another 5 minutes and thereafter poured into the already prepared sand mould at a temperature of 690°C. The as-cast aluminium samples, were sectioned into two equal parts of 45mm each using power hack saw; a weld groove was created between the sides of the samples using an electric hand grinding machine, the groove served as the path along which the filler metal was deposited on the aluminium, a single v butt joint was produced from each sample and Metal Inert Gas Welding process was carried out to produce the required joint design. The different cast samples were machined to the different test pieces after which they were assessed to determine their mechanical properties (impact, hardness (welded joint and heat affected zone and tensile tests. The microstructures of the welded samples were also studied. From the results, it was observed that Sample F, which has 0.172% Mn, has the best hardness and impact strength while sample C with 0.160% Mn has the highest ultimate tensile strength.

Induction accelerator test module for HIF

International Nuclear Information System (INIS)

Faltens, A.

1991-04-01

An induction linac test module suitable for investigating the drive requirements and the longitudinal coupling impedance of a high-power ion induction linac has been constructed by the Heavy Ion Fusion (HIF) group at LBL. The induction linac heavy ion driver for inertial confinement fusion (ICF) as presently envisioned uses multiple parallel beams which are transported in separate focusing channels but accelerated together in the induction modules. The resulting induction modules consequently have large beam apertures-1--2 meters in diameter- and correspondingly large outside diameters. The module geometry is related to a low-frequency ''gap capacity'' and high-frequency structural resonances, which are affected by the magnetic core loading and the module pulser impedance. A description of the test module and preliminary results are presented. 3 figs

Automatization of welding

International Nuclear Information System (INIS)

Iwabuchi, Masashi; Tomita, Jinji; Nishihara, Katsunori.

1978-01-01

Automatization of welding is one of the effective measures for securing high degree of quality of nuclear power equipment, as well as for correspondence to the environment at the site of plant. As the latest ones of the automatic welders practically used for welding of nuclear power apparatuses in factories of Toshiba and IHI, those for pipes and lining tanks are described here. The pipe welder performs the battering welding on the inside of pipe end as the so-called IGSCC countermeasure and the succeeding butt welding through the same controller. The lining tank welder is able to perform simultaneous welding of two parallel weld lines on a large thin plate lining tank. Both types of the welders are demonstrating excellent performance at the shops as well as at the plant site. (author)

Electric arc welding gun

Science.gov (United States)

Luttrell, Edward; Turner, Paul W.

1978-01-01

This invention relates to improved apparatus for arc welding an interior joint formed by intersecting tubular members. As an example, the invention is well suited for applications where many similar small-diameter vertical lines are to be welded to a long horizontal header. The improved apparatus includes an arc welding gun having a specially designed welding head which is not only very compact but also produces welds that are essentially free from rolled-over solidified metal. The welding head consists of the upper end of the barrel and a reversely extending electrode holder, or tip, which defines an acute angle with the barrel. As used in the above-mentioned example, the gun is positioned to extend upwardly through the vertical member and the joint to be welded, with its welding head disposed within the horizontal header. Depending on the design of the welding head, the barrel then is either rotated or revolved about the axis of the vertical member to cause the electrode to track the joint.

A novel weld seam detection method for space weld seam of narrow butt joint in laser welding

Science.gov (United States)

Shao, Wen Jun; Huang, Yu; Zhang, Yong

2018-02-01

Structured light measurement is widely used for weld seam detection owing to its high measurement precision and robust. However, there is nearly no geometrical deformation of the stripe projected onto weld face, whose seam width is less than 0.1 mm and without misalignment. So, it's very difficult to ensure an exact retrieval of the seam feature. This issue is raised as laser welding for butt joint of thin metal plate is widely applied. Moreover, measurement for the seam width, seam center and the normal vector of the weld face at the same time during welding process is of great importance to the welding quality but rarely reported. Consequently, a seam measurement method based on vision sensor for space weld seam of narrow butt joint is proposed in this article. Three laser stripes with different wave length are project on the weldment, in which two red laser stripes are designed and used to measure the three dimensional profile of the weld face by the principle of optical triangulation, and the third green laser stripe is used as light source to measure the edge and the centerline of the seam by the principle of passive vision sensor. The corresponding image process algorithm is proposed to extract the centerline of the red laser stripes as well as the seam feature. All these three laser stripes are captured and processed in a single image so that the three dimensional position of the space weld seam can be obtained simultaneously. Finally, the result of experiment reveals that the proposed method can meet the precision demand of space narrow butt joint.

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.

Investigation into Variations of Welding Residual Stresses and Redistribution Behaviors for Different Repair Welding Widths

International Nuclear Information System (INIS)

Park, Chiyong; Lee, Hweesueng; Huh, Namsu

2014-01-01

In this study, we investigated the variations in welding residual stresses in dissimilar metal butt weld due to width of repair welding and re-distribution behaviors resulting from similar metal welding (SMW) and mechanical loading. To this end, detailed two-dimensional axi-symmetric finite element (FE) analyses were performed considering five different repair welding widths. Based on the FE results, we first evaluated the welding residual stress distributions in repair welding. We then investigated the re-distribution behaviors of the residual stresses due to SMW and mechanical loads. It is revealed that large tensile welding residual stresses take place in the inner surface and that its distribution is affected, provided repair welding width is larger than certain value. The welding residual stresses resulting from repair welding are remarkably reduced due to SMW and mechanical loading, regardless of the width of the repair welding

Certification of a weld produced by friction stir welding

Science.gov (United States)

Obaditch, Chris; Grant, Glenn J

2013-10-01

Methods, devices, and systems for providing certification of friction stir welds are disclosed. A sensor is used to collect information related to a friction stir weld. Data from the sensor is compared to threshold values provided by an extrinsic standard setting organizations using a certification engine. The certification engine subsequently produces a report on the certification status of the weld.

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

Process for quality assurance of welded joints for electrical resistance point welding

International Nuclear Information System (INIS)

Schaefer, R.; Singh, S.

1977-01-01

In order to guarantee the reproducibility of welded joints of even quality (above all in the metal working industry), it is proposed that before starting resistance point welding, a preheating current should be allowed to flow at the site of the weld. A given reduction of the total resistance at the site of the weld should effect the time when the preheating current is switched over to welding current. This value is always predetermined empirically. Further possibilities of controlling the welding process are described, where the measurement of thermal expansion of the parts is used. A standard welding time is given. The rated course of electrode movement during the process can be predicted and a running comparison of nominal and actual values can be carried out. (RW) [de

Weld nugget formation in resistance spot welding of new lightweight sandwich material

DEFF Research Database (Denmark)

Sagüés Tanco, J.; Nielsen, Chris Valentin; Chergui, Azeddine

2015-01-01

Weldability of a new lightweight sandwich material, LITECOR®, by resistance spot welding is analyzed by experiments and numerical simulations. The spot welding process is accommodated by a first pulse squeezing out the non-conductive polymer core of the sandwich material locally to allow metal......–metal contact. This is facilitated by the use of a shunt tool and is followed by a second pulse for the actual spot welding and nugget formation. A weldability lobe in the time-current space of the second pulse reveals a process window of acceptable size for automotive assembly lines. Weld growth curves...... with experimental results in the range of welding parameters leading to acceptable weld nugget sizes. The validated accuracy of the commercially available software proves the tool useful for assisting the choice of welding parameters....

Socket weld integrity in nuclear piping under fatigue loading condition

International Nuclear Information System (INIS)

Choi, Young Hwan; Choi, Sun Yeong

2007-01-01

The purpose of this paper is to evaluate the integrity of socket weld in nuclear piping under the fatigue loading. The integrity of socket weld is regarded as a safety concern in nuclear power plants because many failures have been world-widely reported in the socket weld. Recently, socket weld failures in the chemical and volume control system (CVCS) and the primary sampling system (PSS) were reported in Korean nuclear power plants. The root causes of the socket weld failures were known as the fatigue due to the pressure and/or temperature loading transients and the vibration during the plant operation. The ASME boiler and pressure vessel (B and PV) Code Sec. III requires 1/16 in. gap between the pipe and fitting in the socket weld with the weld leg size of 1.09 x t 1 , where t 1 is the pipe wall thickness. Many failure cases, however, showed that the gap requirement was not satisfied. In addition, industry has demanded the reduction of weld leg size from 1.09 x t 1 to 0.75 x t 1 . In this paper, the socket weld integrity under the fatigue loading was evaluated using three-dimensional finite element analysis considering the requirements in the ASME Code. Three types of loading conditions such as the deflection due to vibration, the pressure transient ranging from P = 0 to 15.51 MPa, and the thermal transient ranging from T = 25 to 288 deg. C were considered. The results are as follows; (1) the socket weld is susceptible to the vibration where the vibration levels exceed the requirement in the ASME operation and maintenance (OM) code. (2) The effect of pressure or temperature transient load on socket weld in CVCS and PSS is not significant owing to the low frequency of transient during plant operation. (3) 'No gap' is very risky to the socket weld integrity for the systems having the vibration condition to exceed the requirement specified in the ASME OM Code and/or the transient loading condition from P = 0 and T = 25 deg. C to P = 15.51 MPa and T = 288 deg. C. (4

Residual stress by repair welds

International Nuclear Information System (INIS)

Mochizuki, Masahito; Toyoda, Masao

2003-01-01

Residual stress by repair welds is computed using the thermal elastic-plastic analysis with phase-transformation effect. Coupling phenomena of temperature, microstructure, and stress-strain fields are simulated in the finite-element analysis. Weld bond of a plate butt-welded joint is gouged and then deposited by weld metal in repair process. Heat source is synchronously moved with the deposition of the finite-element as the weld deposition. Microstructure is considered by using CCT diagram and the transformation behavior in the repair weld is also simulated. The effects of initial stress, heat input, and weld length on residual stress distribution are studied from the organic results of numerical analysis. Initial residual stress before repair weld has no influence on the residual stress after repair treatment near weld metal, because the initial stress near weld metal releases due to high temperature of repair weld and then stress by repair weld regenerates. Heat input has an effect for residual stress distribution, for not its magnitude but distribution zone. Weld length should be considered reducing the magnitude of residual stress in the edge of weld bead; short bead induces high tensile residual stress. (author)

Corrosion Resistant Cladding by YAG Laser Welding in Underwater Environment

International Nuclear Information System (INIS)

Tsutomi Kochi; Toshio Kojima; Suemi Hirata; Ichiro Morita; Katsura Ohwaki

2002-01-01

It is known that stress-corrosion cracking (SCC) will occur in nickel-base alloys used in Reactor Pressure Vessel (RPV) and Internals of nuclear power plants. A SCC sensitivity has been evaluated by IHI in each part of RPV and Internals. There are several water level instrumentation nozzles installed in domestic BWR RPV. In water level instrumentation nozzles, 182 type nickel-base alloys were used for the welding joint to RPV. It is estimated the SCC potential is high in this joint because of a higher residual stress than the yield strength (about 400 MPa). This report will describe a preventive maintenance method to these nozzles Heat Affected Zone (HAZ) and welds by a corrosion resistant cladding (CRC) by YAG Laser in underwater environment (without draining a reactor water). There are many kinds of countermeasures for SCC, for example, Induction Heating Stress Improvement (IHSI), Mechanical Stress Improvement Process (MSIP) and so on. A YAG laser CRC is one of them. In this technology a laser beam is used for heat source and irradiated through an optical fiber to a base metal and SCC resistant material is used for welding wires. After cladding the HAZ and welds are coated by the corrosion resistant materials so their surfaces are improved. A CRC by gas tungsten arc welding (GTAW) in an air environment had been developed and already applied to a couple of operating plants (16 Nozzles). This method was of course good but it spent much time to perform because of an installation of some water-proof working boxes to make a TIG-weldability environment. CRC by YAG laser welding in underwater environment has superior features comparing to this conventional TIG method as follows. At the viewpoint of underwater environment, (1) an outage term reduction (no drainage water). (2) a radioactive exposure dose reduction for personnel. At that of YAG laser welding, (1) A narrower HAZ. (2) A smaller distortion. (3) A few cladding layers. A YAG laser CRC test in underwater

Handbook of Plastic Welding

DEFF Research Database (Denmark)

Islam, Aminul

The purpose of this document is to summarize the information about the laser welding of plastic. Laser welding is a matured process nevertheless laser welding of micro dimensional plastic parts is still a big challenge. This report collects the latest information about the laser welding of plastic...... materials and provides an extensive knowhow on the industrial plastic welding process. The objectives of the report include: - Provide the general knowhow of laser welding for the beginners - Summarize the state-of-the-art information on the laser welding of plastics - Find the technological limits in terms...... of design, materials and process - Find the best technology, process and machines adaptive to Sonion’s components - Provide the skills to Sonion’s Design Engineers for successful design of the of the plastic components suitable for the laser welding The ultimate goal of this report is to serve...

Boosting Active Contours for Weld Pool Visual Tracking in Automatic Arc Welding

DEFF Research Database (Denmark)

Liu, Jinchao; Fan, Zhun; Olsen, Søren Ingvor

2015-01-01

Detecting the shape of the non-rigid molten metal during welding, so-called weld pool visual sensing, is one of the central tasks for automating arc welding processes. It is challenging due to the strong interference of the high-intensity arc light and spatters as well as the lack of robust...... approaches to detect and represent the shape of the nonrigid weld pool. We propose a solution using active contours including an prior for the weld pool boundary composition. Also, we apply Adaboost to select a small set of features that captures the relevant information. The proposed method is applied...... to weld pool tracking and the presented results verified its feasibility....

Analysis of welding distortion due to narrow-gap welding of upper port plug

International Nuclear Information System (INIS)

Biswas, Pankaj; Mandal, N.R.; Vasu, Parameswaran; Padasalag, Shrishail B.

2010-01-01

Narrow-gap welding is a low distortion welding process. This process allows very thick plates to be joined using fewer weld passes as compared to conventional V-groove or double V-groove welding. In case of narrow-gap arc welding as the heat input and weld volume is low, it reduces thermal stress leading to reduction of both residual stress and distortion. In this present study the effect of narrow-gap welding was studied on fabrication of a scaled down port plug in the form of a trapezoidal box made of 10 mm thick mild steel (MS) plates using gas tungsten arc welding (GTAW). Inherent strain method was used for numerical prediction of resulting distortions. The numerical results compared well with that of the experimentally measured distortion. The validated numerical scheme was used for prediction of weld induced distortion due to narrow-gap welding of full scale upper port plug made of 60 mm thick SS316LN material as is proposed for use in ITER project. It was observed that it is feasible to fabricate the said port plug keeping the distortions minimum within about 7 mm using GTAW for root pass welding followed by SMAW for filler runs.

Welding processes handbook

CERN Document Server

Weman, Klas

2003-01-01

Deals with the main commercially significant and commonly used welding processes. This title takes the student or novice welder through the individual steps involved in each process in an easily understood way. It covers many of the requirements referred to in European Standards including EN719, EN 729, EN 729 and EN 287.$bWelding processes handbook is a concise, explanatory guide to the main commercially significant and commonly-used welding processes. It takes the novice welder or student through the individual steps involved in each process in a clear and easily understood way. It is intended to provide an up-to-date reference to the major applications of welding as they are used in industry. The contents have been arranged so that it can be used as a textbook for European welding courses in accordance with guidelines from the European Welding Federation. Welding processes and equipment necessary for each process are described so that they can be applied to all instruction levels required by the EWF and th...

Pulse induction heating

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, A S; Kachanov, B Y; Kogan, B V

1993-12-31

Induction heating and three types of pulse processes were studied. It was found that in pulse processes the frequency and pulse duration of heat treatments do not remain constant. High frequency pulse heat treatments can be used on sprayed coatings; such treatments will result in stronger surfaces with no cracks. For induction hardening, the rate of specific power was 1 to 1.5 kW/sq.cm, for forging it was 0.2 to 0.3 kW/sq.cm and for melting it was 0.05 to 0.1 kW/sq.cm. The application of pulse heating will result in higher rates of specific power.

The effects of welded joint characteristics on its properties in HDPE thermal fusion welding

Science.gov (United States)

Dai, Hongbin; Peng, Jun

2017-05-01

In this paper, PE100 pipes with the diameter of 200 mm and the thickness of 11.9 mm were used as material. The welded joints were obtained in different welding pressures with the optimal welding temperature of 220∘C. Reheating process on the welded joints with the temperature of 130∘C was carried out. The joints exhibited X-type, and the cause of X-type joints was discussed. The temperature field in the forming process of welded joints was measured, and tensile and bending tests on welded joints were carried out. The fracture surface of welded joints was observed by scanning electron microscopy (SEM), and crystallinity calculation was taken by X-ray diffraction (XRD). The mechanism of X-type weld profile effects on welded joints properties was analyzed. It was concluded that the mechanical properties of welded joints decrease with the reduced X distance between lines.

Application of the pulsed magnetic welding process to nuclear breeder reactor fuel pin end closures

International Nuclear Information System (INIS)

Brown, W.F.

1984-01-01

The pulsed magnetic welding process is a solid state welding process in which metallurgical bonding is effected by impacting metal or alloy parts against each other at high velocity by use of controlled high frequency, high intensity pulsed magnetic fields. This process is similar to the explosive welding process except that magnetic energy is used for impacting the parts together instead of using explosive energy. The pulsed magnetic welding (PMW) process is readily applied to the welding of cylindrical plugs to small diameter tubes. Although breeder reactor fuel pin design may vary in size, the application described here consisted of cladding tubes approximately 6.4 mm in diameter by 244 cm long with a wall thickness of 0.38 mm. After the cladding tubes are filled with fuel pellets and associated metal hardware, tapered end plugs are inserted into the end of the tubes and welded. A typical setup for PMW is described

Inductance position sensor for pneumatic cylinder

Directory of Open Access Journals (Sweden)

Pavel Ripka

2018-04-01

Full Text Available The position of the piston in pneumatic cylinder with aluminum wall can be measured by external inductance sensor without modifications of the aluminum piston and massive iron piston rod. For frequencies below 20 Hz the inductance is increasing with inserting rod due to the rod permeability. This mode has disadvantage of slow response to piston movement and also high temperature sensitivity. At the frequency of 45 Hz the inductance is position independent, as the permeability effect is compensated by the eddy current effect. At higher frequencies eddy current effects in the rod prevail, the inductance is decreasing with inserting rod. In this mode the sensitivity is smaller but the sensor response is fast and temperature stability is better. We show that FEM simulation of this sensor using measured material properties gives accurate results, which is important for the sensor optimization such as designing the winding geometry for the best linearity.

Recent advances in the TIG welding process and the application of the welding of nuclear components

International Nuclear Information System (INIS)

Lucas, W.; Males, B.O.

1982-01-01

Recent advances in the field of precision arc welding techniques and infacilities for production of nuclear power plant components arc presented. Of the precision welding techniques, pulsed TIG welding, pulsed plasma arc welding, hot-wire TIG welding, and pulsed inert-gas metal-arc welding. In the field of weld cladding, GMA plasma welding is cited as an alternative to submerged-arc welding with a strip electrode. Transistors and computer-controlled welding systems get a special mention. Applications of TIG welding in the UK are cited, e.g. welding of components for the AGR nuclear power plant and construction of equipment for repair work in feedwater pipes of the MAGNOX reactor. (orig.) [de

WELDING TORCH

Science.gov (United States)

Correy, T.B.

1961-10-01

A welding torch into which water and inert gas are piped separately for cooling and for providing a suitable gaseous atmosphere is described. A welding electrode is clamped in the torch by a removable collet sleeve and a removable collet head. Replacement of the sleeve and head with larger or smaller sleeve and head permits a larger or smaller welding electrode to be substituted on the torch. (AEC)

Welding procedure specification for arc welding of St 52-3N steel plates with covered electrodes

International Nuclear Information System (INIS)

Cvetkovski, S.; Slavkov, D.; Magdeski, J.

2003-01-01

In this paper the results of approval welding technology for arc welding of plates made of St 52-3N steel are presented. Metal arc welding with covered electrode is used welding process. Test specimens are butt welded in different welding positions P A , P F , P C and P D . Before start welding preliminary welding procedure was prepared. After welding of test specimens non destructive and destructive testing was performed. Obtained results were compared with standard DIN 17100 which concerns to chemical composition and mechanical properties of base material. It was confirmed that in all cases mechanical properties of welded joint are higher than those of base material, so preliminary welding procedure (pWTS) can be accepted as welding procedure specification WPS for metal arc welding of St52-3N steel. (Original)

Variant selection of martensites in steel welded joints with low transformation temperature weld metals

International Nuclear Information System (INIS)

Takahashi, Masaru; Yasuda, Hiroyuki Y.

2013-01-01

Highlights: ► We examined the variant selection of martensites in the weld metals. ► We also measured the residual stress developed in the butt and box welded joints. ► 24 martensite variants were randomly selected in the butt welded joint. ► High tensile residual stress in the box welded joint led to the strong variant selection. ► We discussed the rule of the variant selection focusing on the residual stress. -- Abstract: Martensitic transformation behavior in steel welded joints with low transformation temperature weld (LTTW) metal was examined focusing on the variant selection of martensites. The butt and box welded joints were prepared with LTTW metals and 980 MPa grade high strength steels. The residual stress of the welded joints, which was measured by a neutron diffraction technique, was effectively reduced by the expansion of the LTTW metals by the martensitic transformation during cooling after the welding process. In the LTTW metals, the retained austenite and martensite phases have the Kurdjumov–Sachs (K–S) orientation relationship. The variant selection of the martensites in the LTTW metals depended strongly on the type of welded joints. In the butt welded joint, 24 K–S variants were almost randomly selected while a few variants were preferentially chosen in the box welded joint. This suggests that the high residual stress developed in the box welded joint accelerated the formation of specific variants during the cooling process, in contrast to the butt welded joint with low residual stress

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

The Effect of Weld Reinforcement and Post-Welding Cooling Cycles on Fatigue Strength of Butt-Welded Joints under Cyclic Tensile Loading.

Science.gov (United States)

Araque, Oscar; Arzola, Nelson; Hernández, Edgar

2018-04-12

This research deals with the fatigue behavior of butt-welded joints, by considering the geometry and post-welding cooling cycles, as a result of cooling in quiet air and immersed in water. ASTM A-36 HR structural steel was used as the base metal for the shielded metal arc welding (SMAW) process with welding electrode E6013. The welding reinforcement was 1 mm and 3 mm, respectively; axial fatigue tests were carried out to determine the life and behavior in cracks propagation of the tested welded joints, mechanical characterization tests of properties in welded joints such as microhardness, Charpy impact test and metallographic analysis were carried out. The latter were used as input for the analysis by finite elements which influence the initiation and propagation of cracks and the evaluation of stress intensity factors (SIF). The latter led to obtaining the crack propagation rate and the geometric factor. The tested specimens were analyzed, by taking photographs of the cracks at its beginning in order to make a count of the marks at the origin of the crack. From the results obtained and the marks count, the fatigue crack growth rate and the influence of the cooling media on the life of the welded joint are validated, according to the experimental results. It can be concluded that the welded joints with a higher weld reinforcement have a shorter fatigue life. This is due to the stress concentration that occurs in the vicinity of the weld toe.

Distortion Control during Welding

NARCIS (Netherlands)

Akbari Pazooki, A.M.

2014-01-01

The local material expansion and contraction involved in welding result in permanent deformations or instability i.e., welding distortion. Considerable efforts have been made in controlling welding distortion prior to, during or after welding. Thermal Tensioning (TT) describes a group of in-situ

Arc-weld pool interactions

International Nuclear Information System (INIS)

Glickstein, S.S.

1978-08-01

The mechanisms involved in arc-weld pool interactions are extremely complex and no complete theory is presently available to describe much of the phenomena observed during welding. For the past several years, experimental and analytical studies have been undertaken at the Bettis Atomic Power Laboratory to increase basic understanding of the gas tungsten arc welding process. These studies have included experimental spectral analysis of the arc in order to determine arc temperature and analytical modeling of the arc and weld puddle. The investigations have been directed toward determining the cause and effects of variations in the energy distribution incident upon the weldment. In addition, the effect of weld puddle distortion on weld penetration was investigated, and experimental and analytical studies of weld process variables have been undertaken to determine the effects of the variables upon weld penetration and configuration. A review of the results and analysis of these studies are presented

Welding electrode for peripheral welds of A-1 reactor pressure vessel

International Nuclear Information System (INIS)

Lakatos, L.

1975-01-01

The properties are outlined of the VUZ-AC1-52 welding electrode used in welding the Bohunice A-1 reactor pressure vessel. The mechanical properties of welded joints after the final thermal treatment are summed up. (J.K.)

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.

Nickel-base alloy overlay weld with improved ultrasonic flaw detection by magnetic stirring welding

International Nuclear Information System (INIS)

Takashi, Hirano; Kenji, Hirano; Masayuki, Watando; Takahiro, Arakawa; Minoru, Maeda

2001-01-01

Ultrasonic flaw detection is more difficult in Nickel-base alloy welds containing dendrites owing to the decrease ultrasonic transmissibility they cause. The present paper discusses application of magnetic stirring welding as a means for reducing dendrite growth with consequent improvement in ultrasonic transmissibility. Single pass and multi-pass welding tests were conducted to determine optimal welding conditions. By PT and macro observation subsequent to welding was carried out, optimal operation conditions were clarified. Overlay welding tests and UT clearly indicated ultrasonic beam transmissibility in overlay welds to be improved and detection capacity to be greater through application of magnetic stirring welding. Optimal operation conditions were determined based on examination of temper bead effects in the heat affected zone of low alloy steel by application of magnetic stirring welding to the butt welded joints between low alloy and stainless steel. Hardness in this zone of low alloy steel after the fourth layer was less than 350 HV. (author)

Effect of weld spacing on microstructure and mechanical properties of CLAM electron beam welding joints

Energy Technology Data Exchange (ETDEWEB)

Zhai, Yutao; Huang, Bo, E-mail: aufa0007@163.com; Zhang, Junyu; Zhang, Baoren; Liu, Shaojun; Huang, Qunying

2016-11-15

Highlights: • The welded joints of CLAM steel with different weld spacings have been fabricated with electron beam welding, and a simplified model of CLAM sheet was proposed. • The microstructure and mechanical properties such as microhardness, impact and tensile were investigated at different welding spacing for both conditions of as-welded and post weld heat treatment (PWHT). • The effect of the welding thermal cycle was significantly when the weld spacings were smaller than 4 mm. • When the weld spacing was small enough, the original microstructures would be fragmented with the high heat input. - Abstract: China low activation martensitic (CLAM) steel has been chosen as the primary structural material in the designs of dual function lithium-lead (DFLL) blanket for fusion reactors, China helium cooled ceramic breeder (HCCB) test blanket module (TBM) for ITER and China fusion engineering test reactor (CFETR) blanket. The cooling components of the blankets are designed with high density cooling channels (HDCCs) to remove the high nuclear thermal effectively. Hence, the welding spacing among the channels are small. In this paper, the welded joints of CLAM steel with different weld spacings have been fabricated with electron beam welding (EBW). The weld spacing was designed to be 2 mm, 3 mm, 4 mm, 6 mm and 8 mm. The microstructure and mechanical properties such as microhardness, impact and tensile were investigated at different welding spacing for both conditions of as-welded and post weld heat treatment (PWHT). The PWHT is tempering at 740 °C for 120 min. The results showed that the grain size in the heat affected zone (HAZ) increased with the increasing weld spacing, and the joint with small weld spacing had a better performance after PWHT. This work would give useful guidance to improve the preparation of the cooling components of blanket.

Capabilities of infrared weld monitor

Energy Technology Data Exchange (ETDEWEB)

Sanders, P.G.; Keske, J.S.; Leong, K.H.; Kornecki, G.

1997-11-01

A non-obtrusive pre-aligned, solid-state device has been developed to monitor the primary infrared emissions during laser welding. The weld monitor output is a 100-1000 mV signal that depends on the beam power and weld characteristics. The DC level of this signal is related to weld penetration, while AC portions of the output can be correlated with surface irregularities and part misalignment or contamination. Changes in DC behavior are also noted for both full and deep penetration welds. Full penetration welds are signified by an abrupt reduction in the weld monitor output. Bead on plate welds were made on steel, aluminum, and magnesium with both a CW CO{sub 2} laser and a pulsed Nd:YAG laser to explore the relationships between the weld characteristics and the weld monitor output.

Welding overlay analysis of dissimilar metal weld cracking of feedwater nozzle

International Nuclear Information System (INIS)

Tsai, Y.L.; Wang, Li. H.; Fan, T.W.; Ranganath, Sam; Wang, C.K.; Chou, C.P.

2010-01-01

Inspection of the weld between the feedwater nozzle and the safe end at one Taiwan BWR showed axial indications in the Alloy 182 weld. The indication was sufficiently deep that continued operation could not be justified considering the crack growth for one cycle. A weld overlay was decided to implement for restoring the structural margin. This study reviews the cracking cases of feedwater nozzle welds in other nuclear plants, and reports the lesson learned in the engineering project of this weld overlay repair. The overlay design, the FCG calculation and the stress analysis by FEM are presented to confirm that the Code Case structural margins are met. The evaluations of the effect of weld shrinkage on the attached feedwater piping are also included. A number of challenges encountered in the engineering and analysis period are proposed for future study.

Multi-physics modeling and numerical simulation of weld pool in GTA welding

International Nuclear Information System (INIS)

Nguyen, Minh-Chien

2015-01-01

In this work, we develop a 3D physical and numerical model of the GTA (Gas Tungsten Arc) welding process in order to predict, for given welding parameters, useful quantities for the designer of welded assembly: weld bead shape, fluid flow in the weld pool as well as thermal distribution in the work piece. The model is developed in the Cast3M (http://www-cast3m.cea.fr/) finite element software and takes into account the main physical phenomena acting in the work piece and particularly in the weld pool, subject to source terms modeling the arc part of the welding process. A steady solution of this model is thought for and involves the coupling of the nonlinear thermohydraulics and electromagnetic equations together with the displacement of the deformable free surface of the weld pool. A first step in the development consisted in modeling the electromagnetic phenomena with two different numerical methods, in comparing the numerical results obtained with those of the literature and in quantifying the importance of the Lorentz force and the Joule effect compared to the other mechanical and thermal sources by computing power balances. Then, in order to assess the predictive capability of the model, simulations of various welding configurations are performed: variation in the chemical composition of the material, of the welding speed, of the prescribed arc pressure and of the welding positions, which is a focus of this work, are studied. A good agreement is obtained between the results of our model and other experimental and numerical results of the literature. Eventually, a model accounting for metal filling is proposed and its results are discussed. Thus, our complete model can be seen as a solid foundation towards future totally-coupled 3D welding models including the arc and it will be included in WPROCESS the in-house CEA software dedicated to the numerical simulation of welding. (author) [fr

Detecting flaws in welds

International Nuclear Information System (INIS)

Woodacre, A.; Lawton, H.

1979-01-01

An apparatus and a method for detecting flaws in welds in a workpiece, the portion of the workpiece containing the weld is maintained at a constant temperature and the weld is scanned by an infra red detector. The weld is then scanned again with the workpiece in contact with a cooling probe to produce a steeper temperature gradient across the weld. Comparison of the signals produced by each scan reveals the existence of defects in the welds. The signals may be displayed on an oscilloscope and the display may be observed by a TV camera and recorded on videotape. (UK)

Multipass autogenous electron beam welding

International Nuclear Information System (INIS)

Murphy, J.L.; Mustaleski, T.M. Jr.; Watson, L.C.

1986-01-01

A multipass, autogenous welding procedure was developed for 7.6 mm (0.3 in.) wall thickness Type 304L stainless steel cylinders. The joint geometry has a 1.5 mm (0.06 in.) root-face width and a rectangular stepped groove that is 0.762 mm (0.03 in.) wide at the top of the root face and extends 1.5 mm in height, terminating into a groove width of 1.27 mm which extends to the outside of the 1.27 mm high weld-boss. One weld pass is made on the root, three passes on the 0.762 mm wide groove and three passes to complete the weld. Multipass, autogenous, electron beam welds maintain the characteristic high depth-to-width ratios and low heat input of single-pass, electron beam welds. The increased part distortion (which is still much less than from arc processes) in multipass weldments is corrected by a preweld machined compensation. Mechanical properties of multipass welds compare well with single-pass welds. The yield strength of welds in aluminum alloy 5083 is approximately the same for single-pass or multipass electron beam and gas, metal-arc welds. The incidence and size of porosity is less in multipass electron beam welding of aluminum as compared to gas, metal-arc welds. The multipass, autogenous, electron beam welding method has proven to be a reliable way to make some difficult welds in multilayer parts or in an instance where inside part temperature or weld underbead must be controlled and weld discontinuities must be minimized

Influence of the arc plasma parameters on the weld pool profile in TIG welding

Science.gov (United States)

Toropchin, A.; Frolov, V.; Pipa, A. V.; Kozakov, R.; Uhrlandt, D.

2014-11-01

Magneto-hydrodynamic simulations of the arc and fluid simulations of the weld pool can be beneficial in the analysis and further development of arc welding processes and welding machines. However, the appropriate coupling of arc and weld pool simulations needs further improvement. The tungsten inert gas (TIG) welding process is investigated by simulations including the weld pool. Experiments with optical diagnostics are used for the validation. A coupled computational model of the arc and the weld pool is developed using the software ANSYS CFX. The weld pool model considers the forces acting on the motion of the melt inside and on the surface of the pool, such as Marangoni, drag, electromagnetic forces and buoyancy. The experimental work includes analysis of cross-sections of the workpieces, highspeed video images and spectroscopic measurements. Experiments and calculations have been performed for various currents, distances between electrode and workpiece and nozzle diameters. The studies show the significant impact of material properties like surface tension dependence on temperature as well as of the arc structure on the weld pool behaviour and finally the weld seam depth. The experimental weld pool profiles and plasma temperatures are in good agreement with computational results.

Influence of the arc plasma parameters on the weld pool profile in TIG welding

International Nuclear Information System (INIS)

Toropchin, A; Frolov, V; Pipa, A V; Kozakov, R; Uhrlandt, D

2014-01-01

Magneto-hydrodynamic simulations of the arc and fluid simulations of the weld pool can be beneficial in the analysis and further development of arc welding processes and welding machines. However, the appropriate coupling of arc and weld pool simulations needs further improvement. The tungsten inert gas (TIG) welding process is investigated by simulations including the weld pool. Experiments with optical diagnostics are used for the validation. A coupled computational model of the arc and the weld pool is developed using the software ANSYS CFX. The weld pool model considers the forces acting on the motion of the melt inside and on the surface of the pool, such as Marangoni, drag, electromagnetic forces and buoyancy. The experimental work includes analysis of cross-sections of the workpieces, highspeed video images and spectroscopic measurements. Experiments and calculations have been performed for various currents, distances between electrode and workpiece and nozzle diameters. The studies show the significant impact of material properties like surface tension dependence on temperature as well as of the arc structure on the weld pool behaviour and finally the weld seam depth. The experimental weld pool profiles and plasma temperatures are in good agreement with computational results

Numerical weld modeling - a method for calculating weld-induced residual stresses

International Nuclear Information System (INIS)

Fricke, S.; Keim, E.; Schmidt, J.

2001-01-01

In the past, weld-induced residual stresses caused damage to numerous (power) plant parts, components and systems (Erve, M., Wesseling, U., Kilian, R., Hardt, R., Bruemmer, G., Maier, V., Ilg, U., 1994. Cracking in Stabilized Austenitic Stainless Steel Piping of German Boiling Water Reactors - Characteristic Features and Root Causes. 20. MPA-Seminar 1994, vol. 2, paper 29, pp.29.1-29.21). In the case of BWR nuclear power plants, this damage can be caused by the mechanism of intergranular stress corrosion cracking in austenitic piping or the core shroud in the reactor pressure vessel and is triggered chiefly by weld-induced residual stresses. One solution of this problem that has been used in the past involves experimental measurements of residual stresses in conjunction with weld optimization testing. However, the experimental analysis of all relevant parameters is an extremely tedious process. Numerical simulation using the finite element method (FEM) not only supplements this method but, in view of modern computer capacities, is also an equally valid alternative in its own right. This paper will demonstrate that the technique developed for numerical simulation of the welding process has not only been properly verified and validated on austenitic pipe welds, but that it also permits making selective statements on improvements to the welding process. For instance, numerical simulation can provide information on the starting point of welding for every weld bead, the effect of interpass cooling as far as a possible sensitization of the heat affected zone (HAZ) is concerned, the effect of gap width on the resultant weld residual stresses, or the effect of the 'last pass heat sink welding' (welding of the final passes while simultaneously cooling the inner surface with water) producing compressive stresses in the root area of a circumferential weld in an austenitic pipe. The computer program FERESA (finite element residual stress analysis) was based on a commercially

Modeling of Lossy Inductance in Moving-Coil Loudspeakers

DEFF Research Database (Denmark)

Kong, Xiao-Peng; Agerkvist, Finn T.; Zeng, Xin-Wu

2015-01-01

The electrical impedance of moving-coil loudspeakers is dominated by the lossy inductance in high frequency range. Using the equivalent electrical circuit method, a new model for the lossy inductance based on separate functions for the magnitude and phase of the impedance is presented. The electr......The electrical impedance of moving-coil loudspeakers is dominated by the lossy inductance in high frequency range. Using the equivalent electrical circuit method, a new model for the lossy inductance based on separate functions for the magnitude and phase of the impedance is presented...

Apparatus and process for ultrasonic seam welding stainless steel foils

Science.gov (United States)

Leigh, Richard W.

1992-01-01

An ultrasonic seam welding apparatus having a head which is rotated to form contact, preferably rolling contact, between a metallurgically inert coated surface of the head and an outside foil of a plurality of layered foils or work materials. The head is vibrated at an ultrasonic frequency, preferably along a longitudinal axis of the head. The head is constructed to transmit vibration through a contacting surface of the head into each of the layered foils. The contacting surface of the head is preferably coated with aluminum oxide to prevent the head from becoming welded to layered stainless steel foils.

Automatic welding of fuel elements

International Nuclear Information System (INIS)

Briola, J.

1958-01-01

The welding process depends on the type of fuel element, the can material and the number of cartridges to be welded: - inert-gas welding (used for G2 and the 1. set of EL3), - inert atmosphere arc welding (used for welding uranium and zirconium), - electronic welding (used for the 2. set of EL3 and the tank of Proserpine). (author) [fr

Vision-based weld pool boundary extraction and width measurement during keyhole fiber laser welding

Science.gov (United States)

Luo, Masiyang; Shin, Yung C.

2015-01-01

In keyhole fiber laser welding processes, the weld pool behavior is essential to determining welding quality. To better observe and control the welding process, the accurate extraction of the weld pool boundary as well as the width is required. This work presents a weld pool edge detection technique based on an off axial green illumination laser and a coaxial image capturing system that consists of a CMOS camera and optic filters. According to the difference of image quality, a complete developed edge detection algorithm is proposed based on the local maximum gradient of greyness searching approach and linear interpolation. The extracted weld pool geometry and the width are validated by the actual welding width measurement and predictions by a numerical multi-phase model.

Automatic welding machine for piping

International Nuclear Information System (INIS)

Yoshida, Kazuhiro; Koyama, Takaichi; Iizuka, Tomio; Ito, Yoshitoshi; Takami, Katsumi.

1978-01-01

A remotely controlled automatic special welding machine for piping was developed. This machine is utilized for long distance pipe lines, chemical plants, thermal power generating plants and nuclear power plants effectively from the viewpoint of good quality control, reduction of labor and good controllability. The function of this welding machine is to inspect the shape and dimensions of edge preparation before welding work by the sense of touch, to detect the temperature of melt pool, inspect the bead form by the sense of touch, and check the welding state by ITV during welding work, and to grind the bead surface and inspect the weld metal by ultrasonic test automatically after welding work. The construction of this welding system, the main specification of the apparatus, the welding procedure in detail, the electrical source of this welding machine, the cooling system, the structure and handling of guide ring, the central control system and the operating characteristics are explained. The working procedure and the effect by using this welding machine, and the application to nuclear power plants and the other industrial field are outlined. The HIDIC 08 is used as the controlling computer. This welding machine is useful for welding SUS piping as well as carbon steel piping. (Nakai, Y.)

Quantitative Acoustic Emission Fatigue Crack Characterization in Structural Steel and Weld

Directory of Open Access Journals (Sweden)

Adutwum Marfo

2013-01-01

Full Text Available The fatigue crack growth characteristics of structural steel and weld connections are analyzed using quantitative acoustic emission (AE technique. This was experimentally investigated by three-point bending testing of specimens under low cycle constant amplitude loading using the wavelet packet analysis. The crack growth sequence, that is, initiation, crack propagation, and fracture, is extracted from their corresponding frequency feature bands, respectively. The results obtained proved to be superior to qualitative AE analysis and the traditional linear elastic fracture mechanics for fatigue crack characterization in structural steel and welds.

Laser welding to expand the allowable gap in bore welding for ITER blanket hydraulic connection

Energy Technology Data Exchange (ETDEWEB)

Tanigawa, Hisashi, E-mail: tanigawa.hisashi@jaea.go.jp; Maruyama, Takahito; Noguchi, Yuto; Takeda, Nobukazu; Kakudate, Satoshi

2015-10-15

For application to bore welding of hydraulic connection in the ITER blanket module, laser welding presents the following benefits: low weld heat input is preferred for re-welding of the irradiated material. Its contactless process can intrinsically avoid a failure mode of the tool sticking on the weld. The exact requirements for pipe alignment were assessed in comparison with the assembly tolerance. The groove geometry was modified to expand the allowable initial gap. The groove was machined to be partially thick to obviate the filler wire. First, plates with partially thick grooves were welded to elucidate the preferred groove geometry and welding conditions. With the modified groove, the plates were welded for the initial gap of 1.0 mm. Then the groove geometry and welding conditions were adjusted based on results of pipe welding tests. By application of the additional 0.5-mm-thick and 2.5-mm-wide metal in the groove, pipes with an initial gap of 0.7 mm were welded successfully.

Dynamic analysis of I cross beam section dissimilar plate joined by TIG welding

Science.gov (United States)

Sani, M. S. M.; Nazri, N. A.; Rani, M. N. Abdul; Yunus, M. A.

2018-04-01

In this paper, finite element (FE) joint modelling technique for prediction of dynamic properties of sheet metal jointed by tungsten inert gas (TTG) will be presented. I cross section dissimilar flat plate with different series of aluminium alloy; AA7075 and AA6061 joined by TTG are used. In order to find the most optimum set of TTG welding dissimilar plate, the finite element model with three types of joint modelling were engaged in this study; bar element (CBAR), beam element and spot weld element connector (CWELD). Experimental modal analysis (EMA) was carried out by impact hammer excitation on the dissimilar plates that welding by TTG method. Modal properties of FE model with joints were compared and validated with model testing. CWELD element was chosen to represent weld model for TTG joints due to its accurate prediction of mode shapes and contains an updating parameter for weld modelling compare to other weld modelling. Model updating was performed to improve correlation between EMA and FEA and before proceeds to updating, sensitivity analysis was done to select the most sensitive updating parameter. After perform model updating, average percentage of error of the natural frequencies for CWELD model is improved significantly.

Profiling mild steel welding processes to reduce fume emissions and costs in the workplace.

Science.gov (United States)

Keane, Michael J; Siert, Arlen; Chen, Bean T; Stone, Samuel G

2014-05-01

To provide quantitative information to choose the best welding processes for minimizing workplace emissions, nine gas metal arc welding (GMAW) processes for mild steel were assessed for fume generation rates, normalized fume generation rates (milligram fume per gram of electrode consumed), and normalized generation rates for elemental manganese, nickel, and iron. Shielded metal arc welding (SMAW) and flux-cored arc-welding (FCAW) processes were also profiled. The fumes were collected quantitatively in an American Welding Society-type fume chamber and weighed, recovered, homogenized, and analyzed by inductively coupled atomic emission spectroscopy for total metals. The processes included GMAW with short circuit, globular transfer, axial spray, pulsed spray, Surface Tension Transfer™, Regulated Metal Deposition™, and Cold Metal Transfer™ (CMT) modes. Flux-cored welding was gas shielded, and SMAW was a single rod type. Results indicate a wide range of fume emission factors for the process variations studied. Fume emission rates per gram of electrode consumed were highest for SMAW (~13 mg fume g(-1) electrode) and lowest for GMAW processes such as pulsed spray (~1.5mg g(-1)) and CMT (~1mg g(-1)). Manganese emission rates per gram of electrode consumed ranged from 0.45 mg g(-1) (SMAW) to 0.08 mg g(-1) (CMT). Nickel emission rates were generally low and ranged from ~0.09 (GMAW short circuit) to 0.004 mg g(-1) (CMT). Iron emission rates ranged from 3.7 (spray-mode GMAW) to 0.49 mg g(-1) (CMT). The processes studied have significantly different costs, and cost factors are presented based on a case study to allow comparisons between processes in specific cost categories. Costs per linear meter of weld were $31.07 (SMAW), $12.37 (GMAW short circuit), and $10.89 (FCAW). Although no single process is the best for minimizing fume emissions and costs while satisfying the weld requirements, there are several processes that can minimize emissions. This study provides

A Study on the Residual Stress Improvement of PWSCC(Primary Water Stress Corrosion Cracking) in DMW(Dissimilar Metal Weld)

International Nuclear Information System (INIS)

Kang, Sung Sik; Kim, Seok Hun; Lee, Seung Gun; Park, Heung Bae

2010-01-01

Since 2000s, most of the cracks are found in welds, especially in (DMW) dissimilar metal welds such as pressurizer safety relief nozzle, reactor head penetration, reactor bottom mounted instrumentation (BMI), and reactor nozzles. Even the cracks are revealed as a primary water stress corrosion cracking (PWSCC), it is difficult to find the cracks by current non destructive examination. The PWSCC is occurred by three incident factors, such as susceptible material, environmental corrosive condition, and welding residual stress. If one of the three factors can be erased or decreased, the PWSCC could be prevented. In this study, we performed residual stress analysis for DMW and several residual stress improvement methods. As the preventive methods of PWSCC, we used laser peening(IP) method, inlay weld(IW) method, and induction heating stress improvement(IHSI) method. The effect of residual stress improvement for preventive methods was compared and discussed by finite element modeling and residual stress of repaired DMW

Arc Interference Behavior during Twin Wire Gas Metal Arc Welding Process

Directory of Open Access Journals (Sweden)

Dingjian Ye

2013-01-01

Full Text Available In order to study arc interference behavior during twin wire gas metal arc welding process, the synchronous acquisition system has been established to acquire instantaneous information of arc profile including dynamic arc length variation as well as relative voltage and current signals. The results show that after trailing arc (T-arc is added to the middle arc (M-arc in a stable welding process, the current of M arc remains unchanged while the agitation increases; the voltage of M arc has an obvious increase; the shape of M arc changes, with increasing width, length, and area; the transfer frequency of M arc droplet increases and the droplet itself becomes smaller. The wire extension length of twin arc turns out to be shorter than that of single arc welding.

Determination of welding parameters for execution of weld overlayer on PWR nuclear reactor nozzles

International Nuclear Information System (INIS)

Ribeiro, Gabriela M.; Lima, Luciana I.; Quinan, Marco A.; Schvartzman, Monica M.

2009-01-01

In the PWR reactors, nickel based dissimilar welds have been presented susceptibilities the stress corrosion (S C). For the mitigation the problem a deposition of weld layers on the external surface of the nozzle is an alternative, viewing to provoke the compression of the region subjected to S C. This paper presents a preliminary study on the determination of welding parameters to obtain these welding overlayers. Welding depositions were performed on a test piece welded with nickel 182 alloy, simulating the conditions of a nozzle used in a PWR nuclear power plant. The welding process was the GTAW (Gas Tungsten Arc Welding), and a nickel 52 alloy as addition material. The overlayers were performed on the base metals, carbon steel an stainless steel, changing the welding parameters and verifying the the time of each weld filet. After that, the samples were micro structurally characterized. The macro structures and the microstructures obtained through optical microscopy and Vickers microhardness are presented. The preliminary results make evident the good weld quality. However, a small weld parameters influence used in the base material microstructure (carbon steel and stainless steel). The obtained results in this study will be used as reference in the construction of a mock up which will simulate all the conditions of a pressurizer nozzle of PWR reactor

Grinding Parts For Automatic Welding

Science.gov (United States)

Burley, Richard K.; Hoult, William S.

1989-01-01

Rollers guide grinding tool along prospective welding path. Skatelike fixture holds rotary grinder or file for machining large-diameter rings or ring segments in preparation for welding. Operator grasps handles to push rolling fixture along part. Rollers maintain precise dimensional relationship so grinding wheel cuts precise depth. Fixture-mounted grinder machines surface to quality sufficient for automatic welding; manual welding with attendant variations and distortion not necessary. Developed to enable automatic welding of parts, manual welding of which resulted in weld bead permeated with microscopic fissures.

Welding repair of a dissimilar weld and respective consequences for other German plants

International Nuclear Information System (INIS)

Brummer, G.; Dauwel, W.; Wesseling, U.; Ilg, U.; Lauer, P.; Widera, M.; Wachter, O.

2002-01-01

During a regular refueling outage in a German nuclear power plant in year 2000, additional non-destructive examinations have been performed on request of the Authority, to fulfill some recommendations of the independent experts with regard to the retrospective application of the Basic Safety Concept for the ferritic main coolant piping of this plant. During these inspections, indications were found in a dissimilar weld between one of the fifteen MCL (main coolant lines) nozzles and the ECC (emergency core cooling) system piping. By means of on-site metallography and laboratory investigations on three boat samples taken from this weld, it could be shown that the indications were due to hot cracking in the surface layer of the weld. In the course of these investigations, at three locations at the circumference of the weld, dis-bonding defects were found between the ferritic base metal of the nozzle and the austenitic weld butter, which has been applied to join the nozzle to the austenitic safe-end. According to the results of the extensive investigations, the dis-bonding occurred during the manufacturing process after stress-relief heat-treatment of the buttering during the welding of the austenitic safe-end to the butter material. There was no evidence for any crack growth during operation of the plant. Due to the large size of the boat-samples, a weld repair was mandatory. This repair has been performed using the so-called temper-bead technique as specified in the ASME Code, without subsequent stress relief heat treatment, using an advanced automatic orbital TIG welding process. The welding has been successfully performed without the need of further repair work. For those dissimilar welds, all other plants, except one, had used Inconel welding material for buttering the ferritic nozzle instead of stainless steel welding metal. For metallurgical reasons, dis-bonding along the fusion line for Inconel buttered dissimilar welds is unlikely to occur. Nevertheless all

EFFECTS OF ELECTRODE DEFORMATION OF RESISTANCE SPOT WELDING ON 304 AUSTENITIC STAINLESS STEEL WELD GEOMETRY

Directory of Open Access Journals (Sweden)

Nachimani Charde

2012-12-01

Full Text Available The resistance spot welding process is accomplished by forcing huge amounts of current flow from the upper electrode tip through the base metals to the lower electrode tip, or vice versa or in both directions. A weld joint is established between the metal sheets through fusion, resulting in a strong bond between the sheets without occupying additional space. The growth of the weld nugget (bond between sheets is therefore determined from the welding current density; sufficient time for current delivery; reasonable electrode pressing force; and the area provided for current delivery (electrode tip. The welding current and weld time control the root penetration, while the electrode pressing force and electrode tips successfully accomplish the connection during the welding process. Although the welding current and weld time cause the heat generation at the areas concerned (electrode tip area, the electrode tips’ diameter and electrode pressing forces also directly influence the welding process. In this research truncated-electrode deformation and mushrooming effects are observed, which result in the welded areas being inconsistent due to the expulsion. The copper to chromium ratio is varied from the tip to the end of the electrode whilst the welding process is repeated. The welding heat affects the electrode and the electrode itself influences the shape of the weld geometry.

Research on the Effects of Technical Parameters on the Molding of the Weld by A-TIG Welding

OpenAIRE

Shi, Kai; Pan, Wu

2012-01-01

The effects of welding parameters on the molding of weld by A-TIG welding of a 4mm thickness mild steel plate is studied in the present paper. The results obtained show that: as welding current increases A-TIG welding penetration gets deeper than TIG welding; size and shape of HAZ has remarkable change; A-TIG welding has the narrower weld pool width than TIG welding.

Electron beam welding

International Nuclear Information System (INIS)

Schwartz, M.M.

1974-01-01

Electron-beam equipment is considered along with fixed and mobile electron-beam guns, questions of weld environment, medium and nonvacuum welding, weld-joint designs, tooling, the economics of electron-beam job shops, aspects of safety, quality assurance, and repair. The application of the process in the case of individual materials is discussed, giving attention to aluminum, beryllium, copper, niobium, magnesium, molybdenum, tantalum, titanium, metal alloys, superalloys, and various types of steel. Mechanical-property test results are examined along with the areas of application of electron-beam welding

Predictions of ion energy distributions and radical fluxes in radio frequency biased inductively coupled plasma etching reactors

Science.gov (United States)

Hoekstra, Robert J.; Kushner, Mark J.

1996-03-01

Inductively coupled plasma (ICP) reactors are being developed for low gas pressure (radio frequency (rf) bias is applied to the substrate. One of the goals of these systems is to independently control the magnitude of the ion flux by the inductively coupled power deposition, and the acceleration of ions into the substrate by the rf bias. In high plasma density reactors the width of the sheath above the wafer may be sufficiently thin that ions are able to traverse it in approximately 1 rf cycle, even at 13.56 MHz. As a consequence, the ion energy distribution (IED) may have a shape typically associated with lower frequency operation in conventional reactive ion etching tools. In this paper, we present results from a computer model for the IED incident on the wafer in ICP etching reactors. We find that in the parameter space of interest, the shape of the IED depends both on the amplitude of the rf bias and on the ICP power. The former quantity determines the average energy of the IED. The latter quantity controls the width of the sheath, the transit time of ions across the sheath and hence the width of the IED. In general, high ICP powers (thinner sheaths) produce wider IEDs.

Recent developments in pipeline welding practice

Energy Technology Data Exchange (ETDEWEB)

1979-01-01

Fourteen chapters are included: overview of pipeline welding systems and quality assurance, CRC automatic welding system, H.C. Price Co. automatic welding system, semi-automatic MIG-welding process, partial penetration welding of steel pipes for gas distribution, construction procedures and quality control in offshore pipeline construction, welding in repair and maintenance of gas transmission pipelines, British Gas studies of welding on pressurized gas transmission pipelines, hot tapping pipelines, underwater welding for offshore pipelines and associated equipment, radial friction welding, material composition vs weld properties, review of NDT of pipeline welds, and safety assurance in pipeline construction. A bibliography of approximately 150 references is included, arranged according to subject and year.

X-ray radiography of Ti6Al4V welded by plasma tungsten arc (PTA) welding

Energy Technology Data Exchange (ETDEWEB)

Dikbas, Halil; Caligulu, Ugur; Taskin, Mustafa; Turkmen, Mustafa [Firat Univ., Elazig (Turkey). Metallurgy Dept.

2013-03-01

In this study, X-ray radiographic tests of Ti6Al4V alloys welded by plasma tungsten arc welding (PTA) were investigated. PTA welding experiments were carried out under argon shielding gas atmosphere, at 1400-1600 W and 1800 W welding powers as well as 1 m/min, 0.75 m/min, and 0.50 m/min welding speeds. After this process, radiography of the welded joints was performed by X-ray diffraction. The result of the radiographic tests indicated that by increasing welding power the widths of deep penetration increased in all specimens. On the contrary, increasing welding speeds decreases the widths deep penetration. The best properties of Ti6Al4V joints were observed for specimens welded at 1800 W welding power and at 0.50 m/min welding speed. (orig.)

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.

Welding problems in nuclear power engineering

International Nuclear Information System (INIS)

Zubchenko, A.S.

1986-01-01

The problems of welding industry in nuclear power plant engineering, mainly related to the improvement of molten bath protection, are considered. Development of new materials for welding electrodes, for cladding and welding fluxes, is pointed out. Production of the following equipment is brought to a commercial level: welding heads and welding machines for branch pipe welding, anticorrosion cladding, zonal thermal treatment, electron beam welding facilities for the welding and maintenance of turbineblades, equipment for nondestructive testing of welded joints

Laser weld process monitoring and control using chromatic filtering of thermal radiation from a weld pool

International Nuclear Information System (INIS)

Kim, Cheol Jung; Kim, Min Suk; Baik, Sung Hoon; Chung, Chin Man

2000-06-01

The application of high power Nd: YAG lasers for precision welding in industry has been growing quite fast these days in diverse areas such as the automobile, the electronics and the aerospace industries. These diverse applications also require the new developments for the precise control and the reliable process monitoring. Due to the hostile environment in laser welding, a remote monitoring is required. The present development relates in general to weld process monitoring techniques, and more particularly to improved methods and apparatus for real-time monitoring of thermal radiation of a weld pool to monitor a size variation and a focus shift of the weld pool for weld process control, utilizing the chromatic aberration of focusing lens or lenses. The monitoring technique of the size variation and the focus shift of a weld pool is developed by using the chromatic filtering of the thermal radiation from a weld pool. The monitoring of weld pool size variation can also be used to monitor the weld depth in a laser welding. Furthermore, the monitoring of the size variation of a weld pool is independent of the focus shift of a weld pool and the monitoring of the focus shift of a weld pool is independent of the size variation of a weld pool

Laser weld process monitoring and control using chromatic filtering of thermal radiation from a weld pool

Energy Technology Data Exchange (ETDEWEB)

Kim, Cheol Jung; Kim, Min Suk; Baik, Sung Hoon; Chung, Chin Man

2000-06-01

The application of high power Nd: YAG lasers for precision welding in industry has been growing quite fast these days in diverse areas such as the automobile, the electronics and the aerospace industries. These diverse applications also require the new developments for the precise control and the reliable process monitoring. Due to the hostile environment in laser welding, a remote monitoring is required. The present development relates in general to weld process monitoring techniques, and more particularly to improved methods and apparatus for real-time monitoring of thermal radiation of a weld pool to monitor a size variation and a focus shift of the weld pool for weld process control, utilizing the chromatic aberration of focusing lens or lenses. The monitoring technique of the size variation and the focus shift of a weld pool is developed by using the chromatic filtering of the thermal radiation from a weld pool. The monitoring of weld pool size variation can also be used to monitor the weld depth in a laser welding. Furthermore, the monitoring of the size variation of a weld pool is independent of the focus shift of a weld pool and the monitoring of the focus shift of a weld pool is independent of the size variation of a weld pool.

Experimental Analysis of Linear Induction Motor under Variable Voltage Variable Frequency (VVVF Power Supply

Directory of Open Access Journals (Sweden)

Prasenjit D. Wakode

2016-07-01

Full Text Available This paper presents the complete analysis of Linear Induction Motor (LIM under VVVF. The complete variation of LIM air gap flux under ‘blocked Linor’ condition and starting force is analyzed and presented when LIM is given VVVF supply. The analysis of this data is important in further understanding of the equivalent circuit parameters of LIM and to study the magnetic circuit of LIM. The variation of these parameters is important to know the LIM response at different frequencies. The simulation and application of different control strategies such as vector control thus becomes quite easy to apply and understand motor’s response under such strategy of control.

Analysis of weld-cracking and improvement of the weld-repair process of superplastic forming tools

International Nuclear Information System (INIS)

Duchosal, A.; Deschaux-Beaume, F.; Lours, P.; Haro, S.; Fras, G.

2013-01-01

Highlights: ► Characterisation of the microstructure of a heat-resistant austenitic cast steel. ► Failure analysis using in situ tensile tests and isothermal fatigue tests. ► Analyses of weld cracking mechanism during shielded metal arc welding process. ► Improvement of weld-repair method by re-melting of the base material surface with GTAW process. - Abstract: Superplastic forming (SPF) dies are generally made of using heat resistant cast steels, which are very sensitive to weld cracking. In order to improve the weld-repair process of such dies to prevent weld-cracking, the microstructure and the mechanical behaviour of a typical heat-resistant cast steel was first studied, using isothermal low-cycle fatigue tests and in situ tensile tests. The welding behaviour of such steel was also investigated, using a shielded metal arc welding (SMAW) process and welding conditions similar to those employed for weld repair industrial dies. The comparison of the aspect of weld-cracking with the fracture mechanisms observed at room temperature or during isothermal low-cycle fatigue tests suggests a similar brittle failure mechanism, due to the presence of large interdendritic carbides in the cast steel. The melting of the cast steel surface using a gas tungsten arc welding (GTAW) process allowed to refine the primary carbides, and then to reduce the weld-cracking sensitivity. The refining method with GTAW before welding has been successfully tested to weld-repair a sample representative of SPF dies, and is recommended for subsequent repairs of such dies

Real weld geometry determining mechanical properties of high power laser welded medium plates

Science.gov (United States)

Liu, Sang; Mi, Gaoyang; Yan, Fei; Wang, Chunming; Li, Peigen

2018-06-01

Weld width is commonly used as one of main factors to assess joint performances in laser welding. However, it changes significantly through the thickness direction in conditions of medium or thick plates. In this study, high-power autogenous laser welding was conducted on 7 mm thickness 201 stainless steel to elucidate the factor of whole weld transverse shape critically affecting the mechanical properties with the aim of predicting the performance visually through the weld appearance. The results show that single variation of welding parameters could result in great changes of weld pool figures and subsequently weld transverse shapes. All the obtained welds are composed of austenite containing small amount of cellular dendritic δ-Ferrite. The 0.2% proof stresses of Nail- and Peanut-shaped joint reach 458 MPa and 454 MPa, 88.2% and 87.5% of the base material respectively, while that of Wedge-shaped joint only comes to 371 MPa, 71.5% of the base material. The deterioration effect is believed to be caused by the axial grain zone in the weld center. The fatigue strength of joint P is a bit lower than N, but much better than W. Significant deformation incompatibility through the whole thickness and microstructure resistance to crack initiation should be responsible for the poor performance of W-shaped joints.

Tailoring weld geometry during keyhole mode laser welding using a genetic algorithm and a heat transfer model

International Nuclear Information System (INIS)

Rai, R; DebRoy, T

2006-01-01

Tailoring of weld attributes based on scientific principles remains an important goal in welding research. The current generation of unidirectional laser keyhole models cannot determine sets of welding variables that can lead to a particular weld attribute such as specific weld geometry. Here we show how a computational heat transfer model of keyhole mode laser welding can be restructured for systematic tailoring of weld attributes based on scientific principles. Furthermore, the model presented here can calculate multiple sets of laser welding variables, i.e. laser power, welding speed and beam defocus, with each set leading to the same weld pool geometry. Many sets of welding variables were obtained via a global search using a real number-based genetic algorithm, which was combined with a numerical heat transfer model of keyhole laser welding. The reliability of the numerical heat transfer calculations was significantly improved by optimizing values of the uncertain input parameters from a limited volume of experimental data. The computational procedure was applied to the keyhole mode laser welding of the 5182 Al-Mg alloy to calculate various sets of welding variables to achieve a specified weld geometry. The calculated welding parameter sets showed wide variations of the values of welding parameters, but each set resulted in a similar fusion zone geometry. The effectiveness of the computational procedure was examined by comparing the computed weld geometry for each set of welding parameters with the corresponding experimental geometry. The results provide hope that systematic tailoring of weld attributes via multiple pathways, each representing alternative welding parameter sets, is attainable based on scientific principles

Molecular dynamics modeling of bonding two materials by atomic scale friction stir welding

Science.gov (United States)

Konovalenko S., Iv.; Konovalenko, Ig. S.; Psakhie, S. G.

2017-12-01

Molecular dynamics model of atomic scale friction stir welding has been developed. Formation of a butt joint between two crystallites was modeled by means of rotating rigid conical tool traveling along the butt joint line. The formed joint had an intermixed atomic structure composed of atoms initially belonged to the opposite mated piece of metal. Heat removal was modeled by adding the extra viscous force to peripheral atomic layers. This technique provides the temperature control in the tool-affected zone during welding. Auxiliary vibration action was added to the rotating tool. The model provides the variation of the tool's angular velocity, amplitude, frequency and direction of the auxiliary vibration action to provide modeling different welding modes.

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.

Inspection of welded zone and flat plate using flexible ECA probe

Energy Technology Data Exchange (ETDEWEB)

Lee, Chang Jun; Lee, Kyu Sung; Shin, Chung Ho; Lee, Kyoung Jun; Jang, Yoon Young [ANSCO Inc., Daejeon (Korea, Republic of)

2016-08-15

This paper aims to compare the ability to detect notch defects existing in the plate and welded area using a flexible ECA (eddy current array) probe with OmniScan MX and MS-5800E. The characteristics of signals with various frequencies and lift-offs were also compared. As a result, when signals of frequencies 500, 1000, and 1500 kHz were used, the amplitude of the signal increased, as the depth of the notch increased, but reduced linearly in accordance with the lift-off variation. In addition, the detection sensitivity of the weld defect was found to be closely related to the contact surface of the probe and specimen. In this paper, it was demonstrated that the detection sensitivity was excellent when the contact surface of the probe and the specimen was sufficient, but it was poor when the contact surface was insufficient.

Residual stresses and their mechanisms of production at circumferential weld by heat-sink welding

International Nuclear Information System (INIS)

Ueda, Yukio; Nakacho, Keiji; Ohkubo, Katsumi; Shimizu, Tsubasa.

1983-01-01

In the previous report, the authors showed effectiveness of the heat-sink welding (water cooling) to accomplish this end by conducting theoretical analysis and an experiment on residual stresses in the 4B pipe of SUS 304 by the conventional welding and the heat-sink welding at a certain standard heat-input condition. In this research, different pipe sizes and varied heat-input are applied. The welding residual stresses by the conventional welding and the heat-sink welding are obtained by the theoretical analysis and their production mechanisms are clarified. Hence the influence of the above changes of conditions on effectiveness of the heat-sink welding is investigated. The main results are summarized as follow. (1) In case of this pipes such as 2B and 4B pipes, it is important to minimize heat-input per one pass (especially for latter half passes) in order to improve the effectiveness of the heat-sink welding. The effectiveness can be predicted either by theoretical analysis of the temperature distribution history with consideration of the characteristic of heat transfer under spray-watering or by experimental measurement. (2) In case of 24B pipes, thick pipes, it is desirable to minimize heat-input for the first half passes, by which the heat-sink welding becomes more effective. In addition, no matter whether the conventional welding or the heat-sink welding, it is important to prevent angular distorsion which produces tensile axial stresses on the inner surface of the pipe in the weld zone. Possible measures to meet these requirements are to apply restraining jigs, to minimize the section area of the groove (ex. application of the narrow gap arc welding), and to change continuous welding to skip one. (J.P.N.)

Instructional Guidelines. Welding.

Science.gov (United States)

Fordyce, H. L.; Doshier, Dale

Using the standards of the American Welding Society and the American Society of Mechanical Engineers, this welding instructional guidelines manual presents a course of study in accordance with the current practices in industry. Intended for use in welding programs now practiced within the Federal Prison System, the phases of the program are…

Welding process

International Nuclear Information System (INIS)

Abdul Nassir Ibrahim; Azali Muhammad; Ab. Razak Hamzah; Abd. Aziz Mohamed; Mohamad Pauzi Ismail

2008-01-01

For the final chapter of this book, there is basic introduction on welding process. The good radiography must know somehow on welding process so that they can know what kind of welding that must rejected or not. All of the exposure technique that mention in earlier chapter almost applicable in this field because welding process is critical problem if there is no inspection will be done. So, for this chapter, all the discontinuity that usually appeared will be discussed and there is another discontinuity maybe not to important and do not give big impact if found it, do not described here. On top of that, the decision to accept or reject based on code, standard and specification that agreed by both to make sure that decision that agreed is corrected and more meaningful.

Influence of weld discontinuities on strain controlled fatigue behavior of 308 stainless steel weld metal

International Nuclear Information System (INIS)

Bhanu Sankara Rao, K.; Valsan, M.; Sandhya, R.; Mannan, S.L.; Rodriguez, P.

1994-01-01

Detailed investigations have been performed for assessing the importance of weld discontinuities in strain controlled low cycle fatigue (LCF) behavior of 308 stainless steel (SS) welds. The LCF behavior of 308 SS welds containing defects was compared with that of type 304 SS base material and 308 SS sound weld metal. Weld pads were prepared by shielded metal arc welding process. Porosity and slag inclusions were introduced deliberately into the weld metal by grossly exaggerating the conditions normally causing such defects. Total axial strain controlled LCF tests have been conducted in air at 823 K on type 304 SS base and 308 SS sound weld metal employing strain amplitudes in the range from ±0.25 to ±0.8 percent. A single strain amplitude of ±0.25 percent was used for all the tests conducted on weld samples containing defects. The results indicated that the base material undergoes cyclic hardening whereas sound and defective welds experience cyclic softening. Base metal showed higher fatigue life than sound weld metal at all strain amplitudes. The presence of porosity and slag inclusions in the weld metal led to significant reduction in life. Porosity on the specimen surface has been found to be particularly harmful and caused a reduction in life by a factor of seven relative to sound weld metal

Development of resistance welding process. 6. Evaluation test of welding properties of martensitic ODS steel)

International Nuclear Information System (INIS)

Kono, Shusaku; Seki, Masayuki; Ishibashi, Fujio

2003-05-01

The welding condition and the heat-treatment condition were optimized to evaluate welding properties of the martensitic ODS steel cladding tube. The test pieces for evaluation of strength properties of the welded zone were produced by the optimized welding condition. In order to evaluate the strength of the welded zone, the internal creep rapture test, the single axis creep rapture test, the burst test and the tensile test were conducted. Following results were obtained in these tests. (1) Weld ability: An excellent welding characteristic was observed. The micro cracks, etc. were not served at the joint starting point. The joint starting points were connected uniformly with errors less than 0.05 mm. It is considered that an excellent welding characteristic was result of homogeneous micro structure of cladding material. (2) End plug material: In case of the material of end plug was martensitic ODS steel as same as that of cladding tube, the micro structure and the precipitation state carbide near the welded zone were found to be almost same as that of cladding tube. (3) Optimization of heat-treatment condition: The heat treatments of normalizing (1050degC) and tempering (780degC) were performed after welding and the micro structure near the welded zone was the isometric structure with low dislocation density, the precipitation state of carbide was uniform as same as that of cladding tube. These heat treatments can relax the residual stress accumulated when welding; it is considered that these heat treatments after welding are indispensable. (4) Strength of welded zone: The strength of the welded zone was found to be equal to that of cladding tube in all the strength tests. Therefore, it is concluded that the welding technology for the martensitic ODS steel is completed. (author)

Welding method by remote handling

International Nuclear Information System (INIS)

Hashinokuchi, Minoru.

1994-01-01

Water is charged into a pit (or a water reservoir) and an article to be welded is placed on a support in the pit by remote handling. A steel plate is disposed so as to cover the article to be welded by remote handling. The welding device is positioned to the portion to be welded and fixed in a state where the article to be welded is shielded from radiation by water and the steel plate. Water in the pit is drained till the portion to be welded is exposed to the atmosphere. Then, welding is conducted. After completion of the welding, water is charged again to the pit and the welding device and fixing jigs are decomposed in a state where the article to be welded is shielded again from radiation by water and the steel plate. Subsequently, the steel plate is removed by remote handling. Then, the article to be welded is returned from the pit to a temporary placing pool by remote handling. This can reduce operator's exposure. Further, since the amount of the shielding materials can be minimized, the amount of radioactive wastes can be decreased. (I.N.)

Weld pool boundary and weld bead shape reconstruction based on passive vision in P-GMAW

Institute of Scientific and Technical Information of China (English)

Yan Zhihong; Zhang Guangjun; Gao Hongming; Wu Lin

2006-01-01

A passive visual sensing system is established in this research, and clear weld pool images in pulsed gas metal arc welding ( P-GMA W) can be captured with this system. The three-dimensional weld pool geometry, especially the weld height,is not only a crucial factor in determining workpiece mechanical properties, but also an important parameter for reflecting the penetration. A new three-dimensional (3D) model is established to describe the weld pool geometry in P-GMAW. Then, a series of algorithms are developed to extract the model geometrical parameters from the weld pool images. Furthermore, the method to reconstruct the 3D shape of weld pool boundary and weld bead from the two-dimensional images is investigated.

Computational modeling and experimental studies of the dynamic performance of ultrasonic horn profiles used in plastic welding.

Science.gov (United States)

Roopa Rani, M; Rudramoorthy, R

2013-03-01

Ultrasonic horns are tuned components designed to vibrate in a longitudinal mode at ultrasonic frequencies. Reliable performance of such horns is normally decided by the uniformity of vibration amplitude at the working surface and the stress developed during loading condition. The horn design engineer must pay particular attention to designing a tool that will produce the desired amplitude without fracturing. The present work discusses horn configurations which satisfy these criteria and investigates the design requirements of horns in ultrasonic system. Different horn profiles for ultrasonic welding of thermoplastics have been characterized in terms of displacement amplitude and von-Mises stresses using modal and harmonic analysis. To validate the simulated results, five different horns are fabricated from Aluminum, tested and tuned to the operating frequency. Standard ABS plastic parts are welded using these horns. Temperature developed during the welding of ABS test parts using different horns is recorded using sensors and National Instruments (NIs) data acquisition system. The recorded values are compared with the predicted values. Experimental results show that welding using a Bezier horn has a high interface temperature and the welded joints had higher strength as compared to the other horn profiles. Copyright © 2012 Elsevier B.V. All rights reserved.

Welding Course Curriculum.

Science.gov (United States)

Genits, Joseph C.

This guide is intended for use in helping students gain a fundamental background on the major aspects of the welding trade. The course emphasis is on mastery of the manipulative skills necessary to develop successful welding techniques and on acquisition of an understanding of the specialized tools and equipment used in welding. The first part…

On post-weld heat treatment cracking in tig welded superalloy ATI 718Plus

Science.gov (United States)

Asala, G.; Ojo, O. A.

The susceptibility of heat affected zone (HAZ) to cracking in Tungsten Inert Gas (TIG) welded Allvac 718Plus superalloy during post-weld heat treatment (PWHT) was studied. Contrary to the previously reported case of low heat input electron beam welded Allvac 718Plus, where HAZ cracking occurred during PWHT, the TIG welded alloy is crack-free after PWHT, notwithstanding the presence of similar micro-constituents that caused cracking in the low input weld. Accordingly, the formation of brittle HAZ intergranular micro-constituents may not be a sufficient factor to determine cracking propensity, the extent of heat input during welding may be another major factor that influences HAZ cracking during PWHT of the aerospace superalloy Allvac 718Plus.

Welding for the CRBRP steam generators

International Nuclear Information System (INIS)

Spalaris, C.N.; Ring, P.J.; Durand, R.E.; Wright, E.A.

1979-01-01

The rationale for selecting weld design, welding procedures and inspection methods was based upon the desire to obtain the highest reliability welds for the CRBRP steam generators. To assure the highest weld reliability, heavy emphasis was placed on the control of material cleanliness and composition substantially exceeding the requirements of the ASME Code for 2-1/4Cr--1Mo. The high tube/tubesheet weld quality was achieved through close material control, an extensive weld development program and the selection of high reliability welding equipment. Shell and nozzle weld fabrication using TIG, MIG, and submerged arc procedures are also being controlled through precise specifications, including preheat and postheat programs, together with radiography and ultrasonic inspection to ascertain the weld quality desired. Details of the tube/tubesheet welding and shell welding are described and results from the weld testing program are discussed

Performance of mesh seam welds in tailor welded blanks; Terado blank yo mash seam yosetsubu no tokusei

Energy Technology Data Exchange (ETDEWEB)

Uchihara, M; Takahashi, M; Kurita, M; Hirose, Y; Fukui, K [Sumitomo Metal Industries, Ltd., Osaka (Japan)

1997-10-01

Formability, fatigue properties and corrosion behavior of mash seam welded steel sheets were investigated and the results were compared with laser weld. The stretch formability of mash seam weld and laser weld were same level. Mash seam weld however, showed slightly smaller formability in hole expansion test. The fatigue strength of mash seam welds was lower than that of laser welds in case of differential thickness joints. Corrosion was apt to initiate at weld in both mash seam and laser weld with E-coat. The corrosion resistance of welds was improved by using zinc coated steel. 3 refs., 14 figs., 2 tabs.

Resistance Spot Welding of dissimilar Steels

Directory of Open Access Journals (Sweden)

Ladislav Kolařík

2012-01-01

Full Text Available This paper presents an analysis of the properties of resistance spot welds between low carbon steel and austenitic CrNi stainless steel. The thickness of the welded dissimilar materials was 2 mm. A DeltaSpot welding gun with a process tape was used for welding the dissimilar steels. Resistance spot welds were produced with various welding parameters (welding currents ranging from 7 to 8 kA. Light microscopy, microhardness measurements across the welded joints, and EDX analysis were used to evaluate the quality of the resistance spot welds. The results confirm the applicability of DeltaSpot welding for this combination of materials.

Inverter-Current-Feedback Resonance-Suppression Method for LCL-Type DG System to Reduce Resonance-Frequency Offset and Grid-Inductance Effect

DEFF Research Database (Denmark)

Zhou, Leming; Zhou, Xiaoping; Chen, Yandong

2018-01-01

For the LCL-type grid-connected distributed generation system, the grid-current-feedback active damping (GCFAD) methods have a conflict between the resonance-suppression ability and harmonic-currents amplification. For this, an inverter-current-feedback reso-nance-suppression (ICFRS) method without...... additional sensors is proposed to reduce resonance-frequency offset and grid-inductance effect due to its unattenuated damping characteristic under high-frequency bandwidth. By analyzing two types of equivalent impedance models of ICFRS and GCFAD with a high-pass filter (HPF), GCFAD can suppress...

Using Taguchi method to optimize welding pool of dissimilar laser welded components

OpenAIRE

Anawa, E.; Olabi, Abdul-Ghani

2008-01-01

In the present work CO2 continuous laser welding process was successfully applied and optimized for joining a dissimilar AISI 316 stainless steel and AISI 1009 low carbon steel plates. Laser power, welding speed, and defocusing distance combinations were carefully selected with the objective of producing welded joint with complete penetration, minimum fusion zone size and acceptable welding profile. Fusion zone area and shape of dissimilar austenitic stainless steel with ferritic low carbon s...

Welding, Bonding and Fastening, 1984

Science.gov (United States)

Buckley, J. D. (Editor); Stein, B. A. (Editor)

1985-01-01

A compilation of papers presented in a joint NASA, American Society for Metals, The George Washington University, American Welding Soceity, and Society of Manufacturing Engineers conference on Welding, Bonding, and Fastening at Langley Research Center, Hampton, VA, on October 23 to 25, 1984 is given. Papers were presented on technology developed in current research programs relevant to welding, bonding, and fastening of structural materials required in fabricating structures and mechanical systems used in the aerospace, hydrospace, and automotive industries. Topics covered in the conference included equipment, hardware and materials used when welding, brazing, and soldering, mechanical fastening, explosive welding, use of unique selected joining techniques, adhesives bonding, and nondestructive evaluation. A concept of the factory of the future was presented, followed by advanced welding techniques, automated equipment for welding, welding in a cryogenic atmosphere, blind fastening, stress corrosion resistant fasteners, fastening equipment, explosive welding of different configurations and materials, solid-state bonding, electron beam welding, new adhesives, effects of cryogenics on adhesives, and new techniques and equipment for adhesive bonding.

Induction of somatic embryogenesis and plant regeneration in the ...

African Journals Online (AJOL)

A high frequency of callus induction was observed at relatively low concentrations (0.5 and 1 mg L-1) of both 2,4-D or 4-FA. However, high concentrations (3, 4 and 5 mg L-1) of either auxin suppressed callus induction. When applied for the first time, 1.0 mg L-1 4-FA markedly improved the frequency of callus induction (up ...

Selected Welding Techniques, Part 2

National Research Council Canada - National Science Library

1964-01-01

Partial contents: CONVENTIONAL WELD JOINTS VERSUS BUTT JOINTS IN 1-INCH ALUMINUM PLATE, SPECIAL WELD JOINT PREPARATION, UPSET METAL EDGES FOR INCREASED WELD JOINT STRENGTH, OUT-OF-POSITION WELDING OF HEAVY GAGE...

Nondestructive Online Detection of Welding Defects in Track Crane Boom Using Acoustic Emission Technique

Directory of Open Access Journals (Sweden)

Yong Tao

2014-04-01

Full Text Available Nondestructive detection of structural component of track crane is a difficult and costly problem. In the present study, acoustic emission (AE was used to detect two kinds of typical welding defects, that is, welding porosity and incomplete penetration, in the truck crane boom. Firstly, a subsidiary test specimen with special preset welding defect was designed and added on the boom surface with the aid of steel plates to get the synchronous deformation of the main boom. Then, the AE feature information of the welding defect could be got without influencing normal operation of equipment. As a result, the rudimentary location analysis can be attained using the linear location method and the two kinds of welding defects can be distinguished clearly using AE characteristic parameters such as amplitude and centroid frequency. Also, through the comparison of two loading processes, we concluded that the signal produced during the first loading process was mainly caused by plastic deformation damage and during the second loading process the stress release and structure friction between sections in welding area are the main acoustic emission sources. Thus, the AE is an available tool for nondestructive online detection of latent welding defects of structural component of track crane.

Homogeneous weldings of copper

International Nuclear Information System (INIS)

Campurri, C.; Lopez, M.; Fernandez, R.; Osorio, V.

1995-01-01

This research explored the metallurgical and mechanical properties of arc welding of copper related with influence of Argon, Helium and mixtures of them. Copper plates of 6 mm thickness were welded with different mixtures of the mentioned gases. The radiography of welded specimens with 100% He and 100% Ar does not show show any porosity. On the other hand, the copper plates welded different gas mixtures presented uniform porosity in the welded zone. The metallographies show recrystallized grain in the heat affected zone, while the welding zone showed a dendritic structure. The results of the tensile strength vary between a maximum of 227 MPa for 100% He and a minimum of 174 MOa for the mixture of 60% He and 40% Ar. For the elongation after fracture the best values, about 36%, were obtained for pure gases. As a main conclusion, we can say that arc welding of copper is possible without loosing the mechanical and metallurgical properties of base metal. 6 refs

Optimization of process parameters in welding of dissimilar steels using robot TIG welding

Science.gov (United States)

Navaneeswar Reddy, G.; VenkataRamana, M.

2018-03-01

Robot TIG welding is a modern technique used for joining two work pieces with high precision. Design of Experiments is used to conduct experiments by varying weld parameters like current, wire feed and travelling speed. The welding parameters play important role in joining of dissimilar stainless steel SS 304L and SS430. In this work, influences of welding parameter on Robot TIG Welded specimens are investigated using Response Surface Methodology. The Micro Vickers hardness tests of the weldments are measured. The process parameters are optimized to maximize the hardness of the weldments.

Welding technologies for nuclear machinery and equipment

International Nuclear Information System (INIS)

Kobayashi, Masahiro; Yokono, Tomomi.

1991-01-01

The main welding methods applied to nuclear machinery and equipment are shielded metal arc welding, submerged arc welding, MAG welding and TIG welding. But in the last 10 years, in order to improve the reliability required for the welding of nuclear machinery and equipment, the welding technologies aiming at the reduction of heat input, the decrease of the number of welding pass and the automatic control of welding factors have been applied for the main purpose of bettering the quality and excluding human errors. The merits and the technology of narrow gap, pulsed MAG welding and melt-through welding are explained. As the automation of TIG welding, image processing type narrow gap, hot wire TIG welding and remote control type automatic TIG welding are described. For the longitudinal welding of active metal sheet products, plasma key-hole welding is applied. Since the concentration of its arc is good, high speed welding with low heat input can be done. For the stainless steel cladding by welding, electroslag welding has become to be employed in place of conventional submerged arc welding. Arc is not generated in the electroslag welding, and the penetration into base metal is small. (K.I.)

Ultrasonic inspection of austenitic welds

International Nuclear Information System (INIS)

Baikie, B.L.; Wagg, A.R.; Whittle, M.J.; Yapp, D.

1976-01-01

The ultrasonic examination of austenitic stainless steel weld metal has always been regarded as a difficult proposition because of the large and variable ultrasonic attenuations and back scattering obtained from apparently similar weld deposits. The work to be described shows how the existence of a fibre texture within each weld deposit (as a result of epitaxial growth through successive weld beads) produces a systematic variation in the ultrasonic attenuation coefficient and the velocity of sound, depending upon the angle between the ultrasonic beam and the fibre axis. Development work has shown that it is possible to adjust the welding parameters to ensure that the crystallographic texture within each weld is compatible with improved ultrasonic transmission. The application of the results to the inspection of a specific weld in type 316 weld metal is described

Electron beam welding of aluminium components

International Nuclear Information System (INIS)

Maajid, Ali; Vadali, S.K.; Maury, D.K.

2015-01-01

Aluminium is one of the most widely used materials in industries like transportation, shipbuilding, manufacturing, aerospace, nuclear, etc. The challenges in joining of aluminium are distortion, cleanliness and quality. Main difficulties faced during fusion welding of aluminium components are removal of surface oxide layer, weld porosity, high heat input requirement, distortion, hot cracking, etc. Physical properties of aluminium such as its high thermal conductivity, high coefficient of thermal expansion, no change in colour at high temperature, large difference in the melting points of the metal and its oxide (∼ 1400 °C) compound the difficulties faced during welding. Gas Tungsten Arc Welding (GTAW), Gas Metal Arc Welding (GMAW), Plasma Arc Welding (PAW), etc are generally used in industries for fusion welding of aluminium alloys. However in case of thicker jobs the above processes are not suitable due to requirements of elaborate edge preparation, preheating of jobs, fixturing to prevent distortion, etc. Moreover, precise control over the heat input during welding and weld bead penetration is not possible with above processes. Further, if heat sensitive parts are located near the weld joint then high energy density beam welding process like Electron Beam Welding (EBW) is the best possible choice for aluminium welding.This paper discusses EB welding of aluminium components, typical geometry of components, selection/optimization of welding parameters, problems faced during standardization of welding and process parameters and their remedies etc.

Investigation of Global Lightning using Schumann Resonances measured by High Frequency Induction Coil Magnetometers in the UK

Science.gov (United States)

Beggan, C.; Gabillard, T.; Swan, A.; Flower, S. M.; Thomson, A. W.

2012-12-01

In June 2012, the British Geological Survey Geomagnetism team installed two high frequency (100 Hz) induction coil magnetometers at the Eskdalemuir Observatory, in the Scottish Borders of the United Kingdom. The induction coils permit us to measure the very rapid changes of the magnetic field. The Eskdalemuir Observatory is one of the longest running geophysical sites in the UK (beginning operation in 1904) and is located in a rural valley with a quiet magnetic environment. The data output from the induction coils are digitized and logged onsite before being collected once per hour and sent to the Edinburgh office via the Internet. We intend to run the coils as a long term experiment. We present initial results from first five months of data. Analysis of spectrograms and power spectral density plots in the frequency band of 3-40 Hz from the coils show diffuse bands of peak power around 7.8 Hz, 14.3 Hz, 20.8 Hz, 27 Hz, 34 Hz and 39Hz related to the global Schumann resonances. We also detect a strong narrow peak at 25 Hz, which is a harmonic of the UK electrical power system. There are a number of features in the data that we wish to investigate, including the diurnal and seasonal variation of the Schumann resonances. For example, it has been suggested that lightning activity is related to climate variability in the tropics and that perhaps Madden-Julian Oscillations (MJO) or El Niño Southern Oscillation (ENSO)-like correlations are detectable within the data. On longer timescales, we will look for solar cycle and climate variations. We also wish to note that the data is freely available on request to the community.

Waste canister closure welding using the inertia friction welding process

International Nuclear Information System (INIS)

Klein, R.F.; Siemens, D.H.; Kuruzar, D.L.

1986-02-01

Liquid radioactive waste presently stored in underground tanks is to undergo a vitrifying process which will immobilize it in a solid form. This solid waste will be contained in a stainless steel canister. The canister opening requires a positive seal weld, the properties and thickness of which are at least equal to those of the canister material. This paper describes the inertia friction welding process and a proposed equipment design concept that will provide a positive, reliable, inspectable, and full thickness seal weld while providing easily maintainable equipment, even though the weld is made in a highly contaminated hot cell. All studies and tests performed have shown the concept to be highly feasible. 2 refs., 6 figs

Environmental Degradation of Dissimilar Austenitic 316L and Duplex 2205 Stainless Steels Welded Joints

Directory of Open Access Journals (Sweden)

Topolska S.

2017-12-01

Full Text Available The paper describes structure and properties of dissimilar stainless steels welded joints between duplex 2205 and austenitic 316L steels. Investigations were focused on environmentally assisted cracking of welded joints. The susceptibility to stress corrosion cracking (SCC and hydrogen embrittlement was determined in slow strain rate tests (SSRT with the strain rate of 2.2 × 10−6 s−1. Chloride-inducted SCC was determined in the 35% boiling water solution of MgCl2 environment at 125°C. Hydrogen assisted SCC tests were performed in synthetic sea water under cathodic polarization condition. It was shown that place of the lowest resistance to chloride stress corrosion cracking is heat affected zone at duplex steel side of dissimilar joins. That phenomenon was connected with undesirable structure of HAZ comprising of large fractions of ferrite grains with acicular austenite phase. Hydrogen assisted SCC tests showed significant reduction in ductility of duplex 2205 steel while austenitic 316L steel remains almost immune to degradation processes. SSR tests of dissimilar welded joints revealed a fracture in the area of austenitic steel.

Spot weld arrangement effects on the fatigue behavior of multi-spot welded joints

International Nuclear Information System (INIS)

Hassanifard, Soran; Zehsaz, Mohammad; Esmaeili, Firooz

2011-01-01

In the present study, the effects of spot weld arrangements in multi-spot welded joints on the fatigue behavior of the joints are studied. Three different four-spot welded joints are considered: one-row four-spot parallel to the loading direction, one-row four-spot perpendicular to the loading direction and two-row four-spot weld specimens. The experimental fatigue test results reveal that the differences between the fatigue lives of three spot welded types in the low cycle regime are more considerable than those in the high cycle regime. However, all kinds of spot weld specimens have similar fatigue strength when approaching a million cycles. A non-linear finite element analysis is performed to obtain the relative stress gradients, effective distances and notch strength reduction factors based on the volumetric approach. The work here shows that the volumetric approach does a very good job in predicting the fatigue life of the multi-spot welded joints

Investigate The Effect Of Welding Parameters On Mechanical Properties During The Welding Of Al-6061 Alloy

Directory of Open Access Journals (Sweden)

Rajendra Prasad

2017-10-01

Full Text Available Friction welding is a solid state welding technique which is being used in recent times to weld similar as well as dissimilar metals for getting defect free weld. Many combinations like low carbon to stainless steel austenitic to ferrite stainless steel aluminium to copper and titanium to aluminium or steel have been tried out by various solid state welding processes with quite good results. In the present work the 3 level full factorial design has been employed to investigate the effect of welding parameters on tensile strength toughness and heat generation during the welding of Al-6061 alloy. Mathematical relationships between friction welding parameters and mechanical properties like heat generation tensile strength and toughness have also been developed. An attempt has also been made to examine the fracture surfaces of test specimens using SEM. It has been found that welding speed is the most significant parameter thats affect the heat generation tensile strength and toughness. it has been found that tensile strength and toughness during welding increases with increased in welding speed while tensile strength and toughness initially increased as the welding time increases after that it decreased with increase in welding time. The difference in weight of alloying elements can be clearly seen by analyzing spectrum of elements.

Mechanical and electrochemical characteristics with welding materials in robotic MIG welding of dissimilar Al alloys

Energy Technology Data Exchange (ETDEWEB)

Kim, Seong Jong; Han, Min Su; Woo, Yong Bin [Mokpo Maritime Univ., Mokpo (Korea, Republic of)

2013-05-15

In this study, mechanical and electrochemical characteristics with welding material in MIG welded with ROBOT for dissimilar Al alloys were investigated using various experiment methods. The MIG welding by ROBOT with ER5183 and ER5556 for the 5456-H116 and 6061-T6 Al alloy were carried out. The hardness of welding zone was lower than that of base metal. In electrochemical experiment, ER5183 welding material presented excellent characteristics. The yield strength and maximum tensile strength in welding with welding material of ER5183 presented lower value than those of ER5556. The elongation and time-to-fracture showed the opposite results.

Microstructure and toughness of ferritic weld metal of hyperbaric welded joints

International Nuclear Information System (INIS)

Mueller, L.

1988-01-01

In the present work ferritic weld metals of hyperbaric MIG/MAG welds with pressures up to 100 bar were examined. As a result of the pressure, interactions with the shielding gas, the filler metal as well as with the welding parameters had to be expected and were consequently included in the analysis. Investigation was focused on the influence of these parameters on the chemical composition of the weld metals, the microstructure and toughness behaviour, including fracture mechanics test. Using quantitative microstructural analysis as well as fractography a correlation between microstructure and toughness has been shown. (orig.) [de

Study on factors affecting the droplet temperature in plasma MIG welding process

Science.gov (United States)

Mamat, Sarizam Bin; Tashiro, Shinichi; Tanaka, Manabu; Yusoff, Mahani

2018-04-01

In the present study, the mechanism to control droplet temperature in the plasma MIG welding was discussed based on the measurements of the droplet temperature for a wide range of MIG currents with different plasma electrode diameters. The measurements of the droplet temperatures were conducted using a two color temperature measurement method. The droplet temperatures in the plasma MIG welding were then compared with those in the conventional MIG welding. As a result, the droplet temperature in the plasma MIG welding was found to be reduced in comparison with the conventional MIG welding under the same MIG current. Especially when the small plasma electrode diameter was used, the decrease in the droplet temperature reached maximally 500 K. Also, for a particular WFS, the droplet temperatures in the plasma MIG welding were lower than those in the conventional MIG welding. It is suggested that the use of plasma contributes to reducing the local heat input into the base metal by the droplet. The presence of the plasma surrounding the wire is considered to increase the electron density in its vicinity, resulting in the arc attachment expanding upwards along the wire surface to disperse the MIG current. This dispersion of MIG current causes a decrease in current density on the droplet surface, lowering the droplet temperature. Furthermore, dispersed MIG current also weakens the electromagnetic pinch force acting on the neck of the wire above the droplet. This leads to a larger droplet diameter with increased surface area through lower frequency of droplet detachment to decrease the MIG current density on the droplet surface, as compared to the conventional MIG welding at the same MIG current. Thus, the lower droplet temperature is caused by the reduction of heat flux into the droplet. Consequently, the mechanism to control droplet temperature in the plasma MIG welding was clarified.

Structural integrity and fatigue crack propagation life assessment of welded and weld-repaired structures

Science.gov (United States)

Alam, Mohammad Shah

2005-11-01

Structural integrity is the science and technology of the margin between safety and disaster. Proper evaluation of the structural integrity and fatigue life of any structure (aircraft, ship, railways, bridges, gas and oil transmission pipelines, etc.) is important to ensure the public safety, environmental protection, and economical consideration. Catastrophic failure of any structure can be avoided if structural integrity is assessed and necessary precaution is taken appropriately. Structural integrity includes tasks in many areas, such as structural analysis, failure analysis, nondestructive testing, corrosion, fatigue and creep analysis, metallurgy and materials, fracture mechanics, fatigue life assessment, welding metallurgy, development of repairing technologies, structural monitoring and instrumentation etc. In this research fatigue life assessment of welded and weld-repaired joints is studied both in numerically and experimentally. A new approach for the simulation of fatigue crack growth in two elastic materials has been developed and specifically, the concept has been applied to butt-welded joint in a straight plate and in tubular joints. In the proposed method, the formation of new surface is represented by an interface element based on the interface potential energy. This method overcomes the limitation of crack growth at an artificial rate of one element length per cycle. In this method the crack propagates only when the applied load reaches the critical bonding strength. The predicted results compares well with experimental results. The Gas Metal Arc welding processes has been simulated to predict post-weld distortion, residual stresses and development of restraining forces in a butt-welded joint. The effect of welding defects and bi-axial interaction of a circular porosity and a solidification crack on fatigue crack propagation life of butt-welded joints has also been investigated. After a weld has been repaired, the specimen was tested in a universal

Analysis of the Corrosion Behavior of an A-TIG Welded SS 409 Weld Fusion Zone

Science.gov (United States)

Vidyarthy, R. S.; Dwivedi, D. K.

2017-11-01

AISI 409 (SS 409) ferritic stainless steel is generally used as the thick gauge section in freight train wagons, in ocean containers, and in sugar refinery equipment. Activating the flux tungsten inert gas (A-TIG) welding process can reduce the welding cost during fabrication of thick sections. However, corrosion behavior of the A-TIG weld fusion zone is a prime concern for this type of steel. In the present work, the effect of the A-TIG welding process parameters on the corrosion behavior of a weld fusion zone made of 8-mm-thick AISI 409 ferritic stainless-steel plate has been analyzed. Potentiodynamic polarization tests were performed to evaluate the corrosion behavior. The maximum corrosion potential ( E corr) was shown by the weld made using a welding current of 215 A, a welding speed of 95 mm/min, and a flux coating density of 0.81 mg/cm2. The minimum E corr was observed in the weld made using a welding current of 190 A, a welding speed of 120 mm/min, and a flux coating density of 1.40 mg/cm2. The current study also presents the inclusive microstructure-corrosion property relationships using the collective techniques of scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray diffraction.

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.

Properties of welded joints in laser welding of aeronautic aluminum-lithium alloys

Science.gov (United States)

Malikov, A. G.; Orishich, A. M.

2017-01-01

The work presents the experimental investigation of the laser welding of the aluminum-lithium alloys (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of the nano-structuring of the surface layer welded joint by the cold plastic deformation method on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys.

Tailor-welded blanks and their production

Science.gov (United States)

Yan, Qi

2005-01-01

Tailor welded blanks had been widely used in the automobile industry. A tailor welded blank consists of several flat sheets that were laser welded together before stamping. A combination of different materials, thickness, and coatings could be welded together to form a blank for stamping car body panels. As for the material for automobile industry, this technology was one of the development trend for automobile industry because of its weight reduction, safety improvement and economical use of materials. In this paper, the characters and production of tailor welded blanks in the market were discussed in detail. There had two major methods to produce tailor welded blanks. Laser welding would replace mesh seam welding for the production of tailor welded blanks in the future. The requirements on the edge preparation of unwelded blanks for tailor welded blanks were higher than the other steel processing technology. In order to produce the laser welded blank, there had the other process before the laser welding in the factory. In the world, there had three kinds of patterns for the large volume production of tailor welded blanks. In China, steel factory played the important role in the promotion of the application of tailor welded blanks. The competition for the supply of tailor welded blanks to the automobile industry would become fierce in the near future. As a result, the demand for the quality control on the production of tailor welded blanks would be the first priority concern for the factory.

Inductance and resistance measurement method for vessel detection and coil powering in all-surface inductive heating systems composed of outer squircle coils

Science.gov (United States)

Kilic, Veli Tayfun; Unal, Emre; Demir, Hilmi Volkan

2017-05-01

In this work, we investigate a method proposed for vessel detection and coil powering in an all-surface inductive heating system composed of outer squircle coils. Besides conventional circular coils, coils with different shapes such as outer squircle coils are used for and enable efficient all-surface inductive heating. Validity of the method, which relies on measuring inductance and resistance values of a loaded coil at different frequencies, is experimentally demonstrated for a coil with shape different from conventional circular coil. Simple setup was constructed with a small coil to model an all-surface inductive heating system. Inductance and resistance maps were generated by measuring coil's inductance and resistance values at different frequencies loaded by a plate made of different materials and located at various positions. Results show that in an induction hob for various coil geometries it is possible to detect a vessel's presence, to identify its material type and to specify its position on the hob surface by considering inductance and resistance of the coil measured on at least two different frequencies. The studied method is important in terms of enabling safe, efficient and user flexible heating in an all-surface inductive heating system by automatically detecting the vessel's presence and powering on only the coils that are loaded by the vessel with predetermined current levels.

Optimization study on inductive-resistive circuit for broadband piezoelectric energy harvesters

Directory of Open Access Journals (Sweden)

Ting Tan

2017-03-01

Full Text Available The performance of cantilever-beam piezoelectric energy harvester is usually analyzed with pure resistive circuit. The optimal performance of such a vibration-based energy harvesting system is limited by narrow bandwidth around its modified natural frequency. For broadband piezoelectric energy harvesting, series and parallel inductive-resistive circuits are introduced. The electromechanical coupled distributed parameter models for such systems under harmonic base excitations are decoupled with modified natural frequency and electrical damping to consider the coupling effect. Analytical solutions of the harvested power and tip displacement for the electromechanical decoupled model are confirmed with numerical solutions for the coupled model. The optimal performance of piezoelectric energy harvesting with inductive-resistive circuits is revealed theoretically as constant maximal power at any excitation frequency. This is achieved by the scenarios of matching the modified natural frequency with the excitation frequency and equating the electrical damping to the mechanical damping. The inductance and load resistance should be simultaneously tuned to their optimal values, which may not be applicable for very high electromechanical coupling systems when the excitation frequency is higher than their natural frequencies. With identical optimal performance, the series inductive-resistive circuit is recommended for relatively small load resistance, while the parallel inductive-resistive circuit is suggested for relatively large load resistance. This study provides a simplified optimization method for broadband piezoelectric energy harvesters with inductive-resistive circuits.

Optimization study on inductive-resistive circuit for broadband piezoelectric energy harvesters

Science.gov (United States)

Tan, Ting; Yan, Zhimiao

2017-03-01

The performance of cantilever-beam piezoelectric energy harvester is usually analyzed with pure resistive circuit. The optimal performance of such a vibration-based energy harvesting system is limited by narrow bandwidth around its modified natural frequency. For broadband piezoelectric energy harvesting, series and parallel inductive-resistive circuits are introduced. The electromechanical coupled distributed parameter models for such systems under harmonic base excitations are decoupled with modified natural frequency and electrical damping to consider the coupling effect. Analytical solutions of the harvested power and tip displacement for the electromechanical decoupled model are confirmed with numerical solutions for the coupled model. The optimal performance of piezoelectric energy harvesting with inductive-resistive circuits is revealed theoretically as constant maximal power at any excitation frequency. This is achieved by the scenarios of matching the modified natural frequency with the excitation frequency and equating the electrical damping to the mechanical damping. The inductance and load resistance should be simultaneously tuned to their optimal values, which may not be applicable for very high electromechanical coupling systems when the excitation frequency is higher than their natural frequencies. With identical optimal performance, the series inductive-resistive circuit is recommended for relatively small load resistance, while the parallel inductive-resistive circuit is suggested for relatively large load resistance. This study provides a simplified optimization method for broadband piezoelectric energy harvesters with inductive-resistive circuits.

The Effect of Welding Energy on the Microstructural and Mechanical Properties of Ultrasonic-Welded Copper Joints

Science.gov (United States)

Yang, Jingwei; Cao, Biao; Lu, Qinghua

2017-01-01

The effects of welding energy on the mechanical and microstructural characteristics of ultrasonic-welded pure copper plates were investigated. Complex dynamic recrystallization and grain growth occurred inside the weld zone during ultrasonic welding. At a low welding energy, a thin band of straight weld interfaces was observed and had an ultra-fine grain structure. With an increase in welding energy, the weld interface progressively changed from flat to sinusoidal, and eventually turned into a convoluted wavy pattern, bearing similarities to shear instabilities, as observed in fluid dynamics. The lap shear load of the joints initially increased and then remained stable as the welding energy increased. The tensile characteristics of the joints significantly depended on the development of plastic deformation at the interface. The influence of the microstructure on the hardness was also discussed. PMID:28772553

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.

Plasma Processes of Cutting and Welding

Science.gov (United States)

1976-02-01

TIG process. 2.2.2 Keyhole Welding In plasma arc welding , the term...Cutting 3 3 4 4 4 2.2 Plasma Arc Welding 5 2.2.1 Needle Arc Welding 2.2.2 Keyhole Welding 5 6 3. Applications 8 93.1 Economics 4. Environmental Aspects of...Arc Lengths III. Needle Arc Welding Conditions IV. Keyhole Welding Conditions v. Chemical Analyses of Plates Used - vii - 1. 2. 3. 4. 5. 6. 7. 8.

10,170 flawless welds

CERN Multimedia

Antonella Del Rosso

2014-01-01

The welding of tubes containing the principal current-carrying busbars in the LHC magnets was one of the main activities of the SMACC project. After a year of preparation and another of intense activity in the tunnel, the last weld was completed on Wednesday 14 May. Over 10,170 welds have been inspected and not a single fault has been found.    The welder (above) creates the weld using an orbital welding machine (below) specifically designed for CERN. Each of the eight sectors of the LHC contains around 210 interconnects between the superconducting magnets. Consolidating these interconnections was the SMACC project’s primary objective. One of the last jobs before closing the interconnects is the welding of the M lines: each has a 104 mm diameter and a radial clearance of just 45 mm. In total: 10,170 welds carried out in a single year of activities. A true challenge, which was carried out by a team of 30 highly specialised welders, working under the supervision o...

Effects of Flux Precoating and Process Parameter on Welding Performance of Inconel 718 Alloy TIG Welds

Science.gov (United States)

Lin, Hsuan-Liang; Wu, Tong-Min; Cheng, Ching-Min

2014-01-01

The purpose of this study is to investigate the effect of activating flux on the depth-to-width ratio (DWR) and hot cracking susceptibility of Inconel 718 alloy tungsten inert gas (TIG) welds. The Taguchi method is employed to investigate the welding parameters that affect the DWR of weld bead and to achieve optimal conditions in the TIG welds that are coated with activating flux in TIG (A-TIG) process. There are eight single-component fluxes used in the initial experiment to evaluate the penetration capability of A-TIG welds. The experimental results show that the Inconel 718 alloy welds precoated with 50% SiO2 and 50% MoO3 flux were provided with better welding performance such as DWR and hot cracking susceptibility. The experimental procedure of TIG welding process using mixed-component flux and optimal conditions not only produces a significant increase in DWR of weld bead, but also decreases the hot cracking susceptibility of Inconel 718 alloy welds.

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.

New process for weld metal reliability