WorldWideScience

Sample records for welded structural components

  1. Experimental study on hollow structural component by explosive welding

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Mianjun, E-mail: dmjwl@163.com [PLA University of Science and Technology, Nanjing 210007 (China); Wei, Ling, E-mail: 386006087@qq.com [Tongda College, Nanjing University of Posts and Telecommunication, Nanjing 210007 (China); Hong, Jin [PLA University of Science and Technology, Nanjing 210007 (China); Ran, Hong [Southwestern Institute of Physics, Chengdu 610041 (China); Ma, Rui; Wang, Yaohua [PLA University of Science and Technology, Nanjing 210007 (China)

    2014-12-15

    Highlights: • This paper relates to a study on a thin double-layers hollow structural component by using an explosive welding technology. • This thin double-layer hollow structural component is an indispensable component required for certain core equipment of thermonuclear experimental reactor. • An adjusted explosive welding technology for manufacturing an inconel625 hollow structural component was developed which cannot be made by common technology. • The result shows that a metallurgical bonding was realized by the ribs and slabs of the hollow sheet. • The shearing strength of bonding interface exceeds that of the parent metal. - Abstract: A large thin-walled hollow structural component with sealed channels is required for the vacuum chamber of a thermonuclear experimental reactor, with inconel625 as its fabrication material. This hollow structural component is rarely manufactured by normal machining method, and its manufacture is also problematic in the field of explosive welding. With this in mind, we developed an adjusted explosive welding technology which involves a two-step design, setting and annealing technology. The joints were evaluated using optical microscope and scanning electron microscope, and a mechanical experiment was conducted, involving micro-hardness test, cold helium leak test and hydraulic pressure test. The results showed that a metallurgical bonding was realized by the ribs and slabs, and the shearing strength of the bonding interface exceeded that of the parent metal. Hence, the hollow structural component has a good comprehensive mechanical performance and sealing property.

  2. Work in Progress in the Nordic Countries Related to Fatigue of Welded Components and Structures

    DEFF Research Database (Denmark)

    Samuelsson, Jack; Haagensen, Per; Agerskov, Henning;

    2008-01-01

    surveyed research work in progress in their respective countries. This report is by no means exhaustive of all the work of fatigue of welded structures progressing in this region, but is does provide a cross-section of those activities that has been brought to the attention of the national societies....

  3. Improvement of Fatigue Life of Welded Structural Components of a Large Two-Stroke Diesel Engine by Grinding

    DEFF Research Database (Denmark)

    Agerskov, Henning; Hansen, Anders V.; Bjørnbak-Hansen, Jørgen

    2004-01-01

    The crankshaft housings of large two-stroke diesel engines are welded structures subjected to constant amplitude loading and designed for infinite life at full design load. A new design of the so-called frame box has been introduced in the engine using butt weld joints of thick plates, welded from...

  4. Monitoring of surface-fatigue crack propagation in a welded steel angle structure using guided waves and principal component analysis

    Science.gov (United States)

    Lu, Mingyu; Qu, Yongwei; Lu, Ye; Ye, Lin; Zhou, Limin; Su, Zhongqing

    2012-04-01

    An experimental study is reported in this paper demonstrating monitoring of surface-fatigue crack propagation in a welded steel angle structure using Lamb waves generated by an active piezoceramic transducer (PZT) network which was freely surface-mounted for each PZT transducer to serve as either actuator or sensor. The fatigue crack was initiated and propagated in welding zone of a steel angle structure by three-point bending fatigue tests. Instead of directly comparing changes between a series of specific signal segments such as S0 and A0 wave modes scattered from fatigue crack tips, a variety of signal statistical parameters representing five different structural status obtained from marginal spectrum in Hilbert-huang transform (HHT), indicating energy progressive distribution along time period in the frequency domain including all wave modes of one wave signal were employed to classify and distinguish different structural conditions due to fatigue crack initiation and propagation with the combination of using principal component analysis (PCA). Results show that PCA based on marginal spectrum is effective and sensitive for monitoring the growth of fatigue crack although the received signals are extremely complicated due to wave scattered from weld, multi-boundaries, notch and fatigue crack. More importantly, this method indicates good potential for identification of integrity status of complicated structures which cause uncertain wave patterns and ambiguous sensor network arrangement.

  5. Picosecond laser welding of optical to metal components

    Science.gov (United States)

    Carter, Richard M.; Troughton, Michael; Chen, Jinanyong; Elder, Ian; Thomson, Robert R.; Lamb, Robert A.; Esser, M. J. Daniel; Hand, Duncan P.

    2016-03-01

    We report on practical, industrially relevant, welding of optical components to themselves and aluminum alloy components. Weld formation is achieved through the tight focusing of a 5.9ps, 400kHz Trumpf laser operating at 1030nm. By selecting suitable surface preparation, clamping and laser parameters, the plasma can be confined, even with comparatively rough surfaces, by exploiting the melt properties of the glass. The short interaction time allows for a permanent weld to form between the two materials with heating limited to a region ~300 µm across. Practical application of these weld structures is typically limited due to the induced stress within the glass and, critically, the issues surrounding post-weld thermal expansion. We report on the measured strength of the weld, with a particular emphasis on laser parameters and surface preparation.

  6. Low distortion laser welding of cylindrical components

    Science.gov (United States)

    Kittel, Sonja

    2011-02-01

    Automotive components are for the most part cylindrical and thus the weld seams are of radial shape. Radial weld seams are usually produced by starting at a point on the component's surface rotating the component resulting in an overlap zone at the start/end of the weld. In this research, it is shown that the component's distortion strongly depends on the overlap of weld start and end. A correlation between overlap zone and distortion is verified by an experimental study. In order to reduce distortion generated by the overlap zone a special optics is used which allows shaping the laser beam into a ring shape which is then focused on the cylindrical surface and produces a radial ring weld seam simultaneously by one laser pulse. In doing this, the overlap zone is eliminated and distortion can be reduced. Radial weld seams are applied on precision samples and distortion is measured after welding. The distortion of the precision samples is measured by a tactile measuring method and a comparison of the results of welding with the ring optics to reference welds is done.

  7. Spot Welding of Honeycomb Structures

    Science.gov (United States)

    Cohal, V.

    2017-08-01

    Honeycomb structures are used to prepare meals water jet cutting machines for textile. These honeycomb structures are made of stainless steel sheet thickness of 0.1-0.2 mm. Corrugated sheet metal strips are between two gears with special tooth profile. Hexagonal cells for obtaining these strips are welded points between them. Spot welding device is three electrodes in the upper part, which carries three welding points across the width of the strip of corrugated sheet metal. Spot welding device filled with press and advance mechanisms. The paper presents the values of the regime for spot welding.

  8. Repair welding of fusion reactor components. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Chin, B.A.; Wang, C.A.

    1997-09-30

    The exposure of metallic materials, such as structural components of the first wall and blanket of a fusion reactor, to neutron irradiation will induce changes in both the material composition and microstructure. Along with these changes can come a corresponding deterioration in mechanical properties resulting in premature failure. It is, therefore, essential to expect that the repair and replacement of the degraded components will be necessary. Such repairs may require the joining of irradiated materials through the use of fusion welding processes. The present ITER (International Thermonuclear Experimental Reactor) conceptual design is anticipated to have about 5 km of longitudinal welds and ten thousand pipe butt welds in the blanket structure. A recent study by Buende et al. predict that a failure is most likely to occur in a weld. The study is based on data from other large structures, particularly nuclear reactors. The data used also appear to be consistent with the operating experience of the Fast Flux Test Facility (FFTF). This reactor has a fuel pin area comparable with the area of the ITER first wall and has experienced one unanticipated fuel pin failure after two years of operation. The repair of irradiated structures using fusion welding will be difficult due to the entrapped helium. Due to its extremely low solubility in metals, helium will diffuse and agglomerate to form helium bubbles after being trapped at point defects, dislocations, and grain boundaries. Welding of neutron-irradiated type 304 stainless steels has been reported with varying degree of heat-affected zone cracking (HAZ). The objectives of this study were to determine the threshold helium concentrations required to cause HAZ cracking and to investigate techniques that might be used to eliminate the HAZ cracking in welding of helium-containing materials.

  9. 49 CFR 192.153 - Components fabricated by welding.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Components fabricated by welding. 192.153 Section....153 Components fabricated by welding. (a) Except for branch connections and assemblies of standard... welding, whose strength cannot be determined, must be established in accordance with paragraph UG-101...

  10. Ultrasonic Phased Array Inspection Simulations of Welded Components at NASA

    Science.gov (United States)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.; Schumacher, E. J.

    2009-01-01

    Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increased role in the future for nondestructive evaluation in order to better understand the physics of the inspection process and help explain the experimental results. It will also help to prove or disprove the feasibility for an inspection method or inspection scenario, help optimize inspections, and allow to a first approximation limits of detectability. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles.

  11. Ultrasonic Phased Array Simulations of Welded Components at NASA

    Science.gov (United States)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.

    2009-01-01

    Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increasing role in the future for nondestructive evaluation in order to better understand the physics of the inspection process, to prove or disprove the feasibility for an inspection method or inspection scenario, for inspection optimization, for better understanding of experimental results, and for assessment of probability of detection. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles. Keywords: nondestructive evaluation, computational simulation, ultrasonics, weld, modeling, phased array

  12. Prediction of Large Structure Welding Residual Stress by Similitude Principles

    Institute of Scientific and Technical Information of China (English)

    Shude Ji; Liguo Zhang; Xuesong Liu; Jianguo Yang

    2009-01-01

    On basis of the similitude principles, the conception of virtual simulative component and the auxiliary value of welding residual stress, which is deduced by the welding conduction theory, the relation of the welding residual stress between the simulative component and the practical component was attained. In order to verify the correctness of the relation, the investigation was done from the view of the welding experiment and the numerical simulation about the simulative component and the practical component. The results show that the distribution of welding residual stress of the simulative component is the same as that of the practical component. The ratio of welding residual stress attained by the experiment or the simulation method between the practical runner and the simulative component was compared with the ratio obtained by the similitude principles. Moreover, the error is less than 10%. This provides a new idea to predict the welding stress distribution of large practical structure by the contractible physical model, which is important for the welding experiment and the numerical simulation.

  13. Integrity analysis of cracked welded components; Analyse de l`integrite des composants soudes fissures

    Energy Technology Data Exchange (ETDEWEB)

    Hornet, P.; Eripret, C.; Gilles, P.; Franco, C.; Ignaccolo, S. [Service Reacteurs Nucleaire et Echangeurs, Departement Mecanique et Technologies des Composants, Direction des Etudes et Recherches, Electricite de France (EDF), 92 - Clamart (France)

    1998-04-01

    In the frame of the integrity analysis of pressure vessel and piping, welded joints can be very sensitive regions since the neighbouring zones of welded joints can be subjected to crack problems. Moreover, the mechanical analysis of a cracked welded component can be difficult because of the presence around the crack of at least three regions (base metal, weld metal and heat affected zone) having very different mechanical properties and metallurgical structures. In fact, common defect assessment procedures have been developed for homogeneous structures and there have to be modified to take into account the heterogeneity. In order to solve this problem a large research program has been conducted since 1992 in the frame of a collaboration between CEA, Framatome and EDF as well as other laboratories in France or around the world. This paper puts forward the work done during the last years and presents the important advantage for the integrity analysis of cracked welded structures. It is a kind of synthesis of the knowledge acquired during this project. Four aspects are pointed out: 1. the important parameters which govern the mechanical behaviour of welded component and more precisely the plasticity development in such structures; 2. some recommendations for the experimental determination of fracture hardness of weld; 3. a defect assessment procedure for cracked welded components, developed in collaboration with Framatome; 4. the ability of finite element codes of modelling the mechanical behaviour of cracked welded structures 15 refs., 9 figs.

  14. Recommendations for fatigue design of welded joints and components

    CERN Document Server

    Hobbacher, A F

    2016-01-01

    This book provides a basis for the design and analysis of welded components that are subjected to fluctuating forces, to avoid failure by fatigue. It is also a valuable resource for those on boards or commissions who are establishing fatigue design codes. For maximum benefit, readers should already have a working knowledge of the basics of fatigue and fracture mechanics. The purpose of designing a structure taking into consideration the limit state for fatigue damage is to ensure that the performance is satisfactory during the design life and that the survival probability is acceptable. The latter is achieved by the use of appropriate partial safety factors. This document has been prepared as the result of an initiative by Commissions XIII and XV of the International Institute of Welding (IIW).

  15. 75 FR 60480 - In the Matter of Certain Bulk Welding Wire Containers and Components Thereof and Welding Wire...

    Science.gov (United States)

    2010-09-30

    ... COMMISSION In the Matter of Certain Bulk Welding Wire Containers and Components Thereof and Welding Wire... importation, or the sale within the United States after importation of certain bulk welding wire containers, components thereof, and welding wire by reason of infringement of certain claims of United States Patent...

  16. 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.

  17. 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

    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...... are hybrid laser-arc welding (HLAW) and submerged arc welding (SAW). Both welding methods are applied for a full penetration butt-weld of 10 mm thick plates made of thermomechanically hot-rolled, low-carbon, fine-grain S355ML grade steel used in offshore steel structures. The welding residual stress state...

  18. Resistance Welding of Advanced Materials and Micro Components

    DEFF Research Database (Denmark)

    Friis, Kasper Storgaard

    presented problems. Simulation of two- and three sheet spot welding of advanced high strength steels DP600 and TRIP700 did generally agree well with experimental observations. Microstructure characterisation revealed that martensite was the main constituent in the final weld. By using empirical formulae......, thermal, electrical and metallurgical effects all signifcantly in uencing the process. Modelling is further complicated when down-scaling the process for welding micro components or when welding new advanced high strength steels in the automotive industry. The current project deals with three main themes...... resistance is addressed both theoretically and experimentally. Secondly the consequences of downscaling the process is investigated experimentally and discussed in relation to simulation of the process. Finally resistance welding of advanced high strength steels is addressed aimed at improving the simulation...

  19. Micromechanical Simulation of Deformation of Friction Stir Welded Components

    Science.gov (United States)

    Sidle, B. C.; Dawson, P. R.; Boyce, D. E.

    2004-06-01

    A microstructure-based finite element formulation for the mechanical response of friction stir welded AL-6XN stainless steel is presented. The welding process generates regions of substantial variations in material state and properties that contribute to strong heterogeneities in the mechanical behavior of welded components We modeled the system with a multiscale elastoplastic formulation in which polycrystalline behavior is computed as the integrated responses of constituent crystals. Model validation is made through comparisons to post-test measurements of shape and hardness and to lattice strain measurements from in situ neutron diffraction experiments.

  20. Effect of Welding Methods on the Structure and Mechanical Properties of Welded Joints of Screw Piles

    Science.gov (United States)

    Golikov, N. I.; Sidorov, M. M.; Stepanova, K. V.

    2016-11-01

    Mechanical properties and characteristics of the structure of welded joints of screw piles are studied. It is shown that cast tips from steel 25L do not meet the performance specifications for operation in the Northern climatic zone. Quality welded joints of screw piles can be obtained by semiautomatic welding in an environment of CO2 with Sv-08G2S welding wire.

  1. Investigations of Spot Weld Material Characterization for Hat Beam Component Impact Analysis

    Directory of Open Access Journals (Sweden)

    Sachin Patil

    2016-07-01

    Full Text Available With a greater emphasis placed on weight reduction the ground vehicle industry has increased the use of higher strength, thinner gage steels, particularly cold rolled high strength steels (HSS. Choice of a particular HSS will depend upon such factors as cost, formability, fatigue resistance and weldability, in particular spot weldability. Vehicle collision characteristics significantly influenced by spot welded joints in vehicle steel body components.In engineering practice, spot welds are normally not modeled in detail, but as connection elements which transfer forces and moments. Therefore a proper methodology for the development detailed weld model to study structural response of the weld when the applied load range is beyond the yield strength discussed in this paper. Three-dimensional finite element (FE models of spot welded joints are developed using LS-Dyna. Simple spot weld models are developed based on the detailed model behavior developed earlier. In order to generate testing data, virtual tensile testing simulations are carried out with mesh sensitivity in the necking zone. This high mesh resolution around necking zone is required to capture the steep gradients in the pressure and stress tri-axility, etc. Once the stress strain curve are generated in the simulations examined damage function and evolution to represent failure. Various EHSS steels grades used in this study. The results from this study shows reasonable agreement between the simulations and the test results. Hence, spot weld model obtained should be considered for crash analysis applications to understand behaviors of structural parts.

  2. Fundamentals of evaluation and diagnostics of welded structures

    CERN Document Server

    Nedoseka, Anatoliy Yakovlevich

    2012-01-01

    Provides an essential guide to the key principles and problems involved in the analysis of welded structures. This title discusses design issues, key equations and calculations, and the effects of varied heat sources in relation to the temperature field in welding. It goes on to explore welding stresses and strains.$bFundamentals of evaluation and diagnostics of welded structures provides an essential guide to the key principles and problems involved in the analysis of welded structures. Chapter one discusses design issues, key equations and calculations, and the effects of varied heat sources in relation to the temperature field in welding. Chapter two goes on to explore welding stresses and strains. Fracture mechanics and the load-carrying capacity of welded structures are the focus of chapter three. Chapter four considers diagnostics and prediction of the residual life of welded structures, whilst acoustic emission techniques for the analysis of welded structures are reviewed in Chapter five. Finally, chap...

  3. 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.

  4. Local equivalent welding element to predict the welding deformations of plate-type structures

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Considering the Heat Affected Zone (HAZ) of welding joint, the residual strain be-haviors of material under constraint and temperature circulation, as well as the activating mechanism of welding process, this paper addresses a new type welding element for numerical simulation of welding deformation, which is called the LEWE (the local equivalent welding element). This element can describe the basic char-acteristics of welded seam: the local position points of inherent strain, the equiva-lent size, the bending radius (or bending angle) from inherent strain, etc. It could be used to predict the welding deformation of plate-type structure. The comparisons between the computed deflection of welded plate and its experiment measurement are present. The results showed that the LEWE possesses a potential to simulate the deformation of welding process high-efficiently and precisely.

  5. Investigation of flux-powder wire’s components-stabilizers on welding and technological properties in underwater welding

    Directory of Open Access Journals (Sweden)

    М. Ю. Каховський

    2015-03-01

    Full Text Available Based on long-term experience of welding by mechanized flux-cored wires, the E.O. Paton Electric Welding Institute investigated a self-protecting flux-cored wire for wet underwater welding of stainless steels type 18-10. It allows to perform welding of butt, fillet and overlapped joints in flat and vertical positions of high-alloy corrosion-resistant steels type of 18-10 (AISI 304L, 308L, 347 and 321. The article presents results of development of welding-repair technology using self-shielded flux-cored wire for wet underwater welding of high-alloy stainless steels type 18-10. Also, the article describes a method of increasing the process stability of the arc in wet underwater welding high corrosion resistant steels type 18-10 by self-shielded flux cored wire. Studied welding characteristics of the weld metal with the introduction of the charge wire components stabilizers. The application of this technology allows partially or completely reducing the human participation in welding process under the extreme conditions: at large depth, in radioactive environments (in case of NPS and also gaining a significant economic effect due to greater efficiency (productivity of welding-repair works. The practical value of this technology consists in possibility of welding-repair works directly under water without any additional assembly works. As to its properties the developed self-shielding wire for underwater welding of high-alloy corrosion resistant steel meets completely the requirements of class (B of the International standard ANSI/AWS D3.6 on underwater welding

  6. 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.

  7. Welding sequence effects on residual stress distribution in offshore wind monopile structures

    Directory of Open Access Journals (Sweden)

    Ali Mehmanparast

    2016-01-01

    Full Text Available Residual stresses are often inevitably introduced into the material during the fabrication processes, such as welding, and are known to have significant effects on the subsequent fatigue crack growth behavior of welded structures. In this paper, the importance of welding sequence on residual stress distribution in engineering components has been reviewed. In addition, the findings available in the literature have been used to provide an accurate interpretation of the fatigue crack growth data on specimens extracted from the welded plates employed in offshore wind monopile structures. The results have been discussed in terms of the role of welding sequence in damage inspection and structural integrity assessment of offshore renewable energy structures.

  8. Feature-based Design of Welded Structure for Robotic Arc Welding Off-line Programming

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Feature modeler of welded structure provides both 3D-geographical and non-geographical features for the off-line programming of arc welded robot. Welded structure is regarded as an assembly, the design of welded structure consists of three aspects: plane, joint, and groove design. Each aspect corresponds to a category of features. The plane features are defined by interactive feature definition. A method analogous to the “mating feature” is introduced to represent the joint features. Based on AutoCAD 2000, a B-rep solid modeler, a prototype system is implemented.

  9. Welding metallurgy of nickel alloys in gas turbine components

    Energy Technology Data Exchange (ETDEWEB)

    Lingenfelter, A. C., LLNL

    1997-05-21

    Materials for gas turbine engines are required to meet a wide range of temperature and stress application requirements. These alloys exhibit a combination of creep resistance, creep rupture strength, yield and tensile strength over a wide temperature range, resistance to environmental attack (including oxidation, nitridation, sulphidation and carburization), fatigue and thermal fatigue resistance, metallurgical stability and useful thermal expansion characteristics. These properties are exhibited by a series of solid-solution-strengthened and precipitation-hardened nickel, iron and cobalt alloys. The properties needed to meet the turbine engine requirements have been achieved by specific alloy additions, by heat treatment and by thermal mechanical processing. A thorough understanding of the metallurgy and metallurgical processing of these materials is imperative in order to successfully fusion weld them. This same basic understanding is required for repair of a component with the added dimension of the potential effects of thermal cycling and environmental exposure the component will have endured in service. This article will explore the potential problems in joining and repair welding these materials.

  10. Laser Welding of Large Scale Stainless Steel Aircraft Structures

    Science.gov (United States)

    Reitemeyer, D.; Schultz, V.; Syassen, F.; Seefeld, T.; Vollertsen, F.

    In this paper a welding process for large scale stainless steel structures is presented. The process was developed according to the requirements of an aircraft application. Therefore, stringers are welded on a skin sheet in a t-joint configuration. The 0.6 mm thickness parts are welded with a thin disc laser, seam length up to 1920 mm are demonstrated. The welding process causes angular distortions of the skin sheet which are compensated by a subsequent laser straightening process. Based on a model straightening process parameters matching the induced welding distortion are predicted. The process combination is successfully applied to stringer stiffened specimens.

  11. Three Dimensional Numerical Simulation and Characterization of Crack Growth in the Weld Region of a Friction Stir Welded Structure

    Science.gov (United States)

    Seshadri, Banavara R.; Smith, Stephen W.; Newman, John A.

    2013-01-01

    Friction stir welding (FSW) fabrication technology is being adopted in aerospace applications. The use of this technology can reduce production cost, lead-times, reduce structural weight and need for fasteners and lap joints, which are typically the primary locations of crack initiation and multi-site fatigue damage in aerospace structures. FSW is a solid state welding process that is well-suited for joining aluminum alloy components; however, the process introduces residual stresses (both tensile and compressive) in joined components. The propagation of fatigue cracks in a residual stress field and the resulting redistribution of the residual stress field and its effect on crack closure have to be estimated. To insure the safe insertion of complex integral structures, an accurate understanding of the fatigue crack growth behavior and the complex crack path process must be understood. A life prediction methodology for fatigue crack growth through the weld under the influence of residual stresses in aluminum alloy structures fabricated using FSW will be detailed. The effects and significance of the magnitude of residual stress at a crack tip on the estimated crack tip driving force are highlighted. The location of the crack tip relative to the FSW and the effect of microstructure on fatigue crack growth are considered. A damage tolerant life prediction methodology accounting for microstructural variation in the weld zone and residual stress field will lead to the design of lighter and more reliable aerospace structures

  12. Fatigue performance of welded aluminum deck structures

    Energy Technology Data Exchange (ETDEWEB)

    Haagensen, P.J.; Ranes, M.; Kluken, A.O.; Kvale, I.

    1996-12-01

    Aluminum alloys are used increasingly in load carrying structures where low weight and low maintenance costs are at a premium. Helicopter decks, structures for living quarters and personnel transfer bridges between platforms are examples of offshore applications. While these structures are not usually subjected to high fatigue loads, the increasing use of aluminum in high speed ships, and more recently in highway bridge structures, makes the question of fatigue performance more important. In this paper the fatigue properties of small scale weldments in an AA6005 alloy are compared with the results of fatigue tests on full scale sections of welded extrusions in the same material, which were used in an aluminum bridge deck structure. The fatigue performance is also compared with the fatigue clauses in the new British design code BS8118 for aluminium structures and the proposed Eurocode 9. The prospects of using a new joining technique, friction stir welding (FSW), in the production of large scale panels for deck and ship hull structures is discussed. The FSW process is described briefly, and some fatigue test data are presented.

  13. Mechanical and Microstructural Evaluation of DMAG Welding of Structural Steel

    Directory of Open Access Journals (Sweden)

    Tolga Mert

    2015-01-01

    Full Text Available Double channel torch, which allows concentric flow of two different shielding gases, was designed and manufactured in order to pursue double channel torch gas metal arc welding of unalloyed structural steel S235JR (EN 10025-2 with fourteen passes. Tensile and Charpy V-notch tests were realized and the results were compared with those of conventional gas metal arc welding. In order to evaluate mechanical testing results, microstructural analyses were conducted. It was found that the increase with double channel gas metal arc welding process in yield and tensile strengths as well as in toughness tests, especially in subzero temperatures, compared with conventional gas metal arc welding was due to longer columnar grains and finer tempered zone grain structure between passes and due to solidification and less dendritic structure formation in all-weld metal in double channel gas metal arc welding.

  14. Welding distortion of aluminium structural members

    Energy Technology Data Exchange (ETDEWEB)

    Goglio, L. [Politecnico di Torino (Italy). Dept. of Mech.; Gugliotta, A. [Politecnico di Torino (Italy). Dept. of Mech.; Pasquino, D. [Politecnico di Torino (Italy). Dept. of Mech.

    1996-12-31

    The paper deals with the angular distortion induced in aluminium tubular beams during welding to prepare T junctions. The research, based on experimental measurements, makes use of statistical methods to identify the parameters (beam section, weld length, welding direction, etc.) that influence the angular change. The results are discussed also considering a model known from the literature. It is found that the distortion is generally low and can be minimized by a proper welding process. (orig.)

  15. Structure of the welding zone between titanium and orthorhombic titanium aluminide for explosion welding: I. Interface

    Science.gov (United States)

    Rybin, V. V.; Grinberg, B. A.; Ivanov, M. A.; Kuz'min, S. V.; Lysak, V. I.; Elkina, O. A.; Patselov, A. M.; Inozemtsev, A. V.; Antonova, O. V.; Kozhevnikov, V. E.

    2011-10-01

    The structures of the interfaces and transition zones of bimetallic metal-intermetallide joints produced by explosion welding under various conditions have been studied. The welded materials were commercial-purity titanium and orthorhombic titanium aluminide of two alloying schemes. The specific features of the structure and substructure of the zones under study are discussed. Wave formation and formation of isolated vortex zones, as well as tracks of particles related to the transfer of particles of one metal into the other one, were observed. A possible scenario of formation of interfaces, depending on the composition of titanium aluminide and welding conditions, is proposed.

  16. Low temperature impact testing of welded structural wrought iron

    Science.gov (United States)

    Rogers, Zachary

    During the second half of the 19th century, structural wrought iron was commonly used in construction of bridges and other structures. Today, these remaining structures are still actively in use and may fall under the protection of historic preservation agencies. Continued use and protection leads to the need for inspection, maintenance, and repair of the wrought iron within these structures. Welding can be useful to achieve the appropriate repair, rehabilitation, or replacement of wrought iron members. There is currently very little published on modern welding techniques for historic wrought iron. There is also no pre-qualified method for this welding. The demand for welding in the repair of historic structural wrought iron has led to a line of research investigating shielded metal arc welding (SMAW) of historic wrought iron at the University of Colorado Denver. This prior research selected the weld type and other weld specifications to try and achieve a recognized specific welding procedure using modern SMAW technology and techniques. This thesis continues investigating SMAW of historic wrought iron. Specifically, this thesis addresses the toughness of these welds from analysis of the data collected from performing Charpy V-Notch (CVN) Impact Tests. Temperature was varied to observe the material response of the welds at low temperature. The wrought iron used in testing was from a historic vehicle bridge in Minnesota, USA. This area, and many other areas with wrought iron structures, can experience sustained or fluctuating temperatures far below freezing. Investigating the toughness of welds in historic wrought iron at these temperatures is necessary to fully understand material responses of the existing structures in need of maintenance and repair. It was shown that welded wrought iron is tougher and more ductile than non-welded wrought iron. In regards to toughness, welding is an acceptable repair method. Information on wrought iron, low temperature failure

  17. Influence of deformation on structural-phase state of weld material in St3 steel

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, Alexander, E-mail: galvas.kem@gmail.ru; Ababkov, Nicolay, E-mail: n.ababkov@rambler.ru; Ozhiganov, Yevgeniy, E-mail: zhigan84@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); LLC “Kuzbass Center of Welding and Control”, 33/2, Lenin Str., 650055, Kemerovo (Russian Federation); Kozlov, Eduard, E-mail: kozlov@tsuab.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Popova, Natalya, E-mail: natalya-popova-44@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk (Russian Federation); Nikonenko, Elena, E-mail: vilatomsk@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Str., 634050, Tomsk (Russian Federation); Zboykova, Nadezhda, E-mail: tezaurusn@gmail.com; Koneva, Nina, E-mail: koneva@tsuab.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation)

    2016-01-15

    The structural-phase condition of the weld material subjected to the plastic deformation was investigated using the translucent diffraction electron microscopy method. The investigations were carried out near the joint of the weld and the base metal. The seam was done by the method of manual arc welding without artificial defects. The St3 steel was taken as the welded material. Influence of the plastic deformation on morphology, phase composition, defect structure and its parameters of weld metal was revealed. All investigations were done at the distance of 0.5 mm from the joint of the weld and the base metal at the deformation degrees from 0 to 5% and after destruction of a sample. It was established that deformation of the sample did not lead to qualitative changes in the structure (the structure is still presented by ferrite-pearlite mixture) but changed the quantitative parameters of the structure, namely, with the increase of plastic deformation a part of the pearlite component becomes more and more imperfect. In the beginning it turns into the destroyed pearlite then into ferrite, the volume fraction of pearlite is decreased. The polarization of dislocation structure takes place but it doesn’t lead to the internal stresses that can destroy the sample.

  18. New development in welding thin-shell aluminum alloy structures with high strength

    Institute of Scientific and Technical Information of China (English)

    徐文立; 范成磊; 方洪渊; 田锡唐

    2004-01-01

    From the viewpoint of welding mechanics, two new welding methods-welding with trailing peening and welding with trailing impactive rolling were introduced. For aluminum alloy thin-shell structures with high strength, welding will lead to hot cracking, poor joint and distortion. In order to solve them, trailing impactive device was used behind welding torch to impact the different positions of welded joints, thus realizing the welding with free-hot cracking, low distortion and joint strengthening. By use of impactive rolling wheels instead of peening heads, the outlook of welded specimen can be improved and stress concentration at weld toes can be reduced. Equipment of this technology is simple and portable. It can used to weld sheets, longitudinal and ring-like beams of tube-like structures, as well as the thin-shell structures with closed welds such as flanges and hatches. So the technology has the wide application foreground in the fields of aviation and aerospace.

  19. Structural integrity analyses for preemptive weld overlay on the dissimilar metal weld of a pressurizer nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chin-Cheng, E-mail: cchuang@iner.gov.tw [Institute of Nuclear Energy Research, Taiwan (China); Liu, Ru-Feng [Institute of Nuclear Energy Research, Taiwan (China)

    2012-02-15

    This paper presents structural integrity analyses for preemptive weld overlay on the dissimilar metal weld (DMW) of a pressurizer nozzle in a pressurized water reactor (PWR). Based on MRP-169 and ASME Code Case N-504-2, weld overlay sizing calculation, residual stress improvement, shrinkage evaluation, fatigue crack growth and fatigue usage analysis are performed. The weld overlay procedure has to be confirmed to improve the residual stresses around the inside surface of DMW. The residual compressive stress distribution is thus addressed to be resistant to subsequent primary water stress corrosion cracking (PWSCC) initiation and further crack growth. To ensure the structural integrity of the original attached piping system, the measured displacement is transformed to temperature gradient to simulate the shrinkage after overlay and is used to determine the post weld distortion and stress situation. Further, the conservative postulated surface cracks are assumed in the DMW for fatigue crack growth analysis with system design cycles. The stress limits and cumulative fatigue usages of the pressurizer nozzle with overlay are also evaluated to meet ASME Code, Section III. Based on the present results, the structural integrity of the pressurizer nozzle with preemptive weld overlay is shown.

  20. Modelling the grain orientation of austenitic stainless steel multipass welds to improve ultrasonic assessment of structural integrity

    Energy Technology Data Exchange (ETDEWEB)

    Moysan, J.; Apfel, A.; Corneloup, G.; Chassignole, B

    2003-02-01

    Knowledge of the grain orientation quantifies the material anisotropy which helps to ensure the good ultrasonic testing of welded assemblies and the assessment of their mechanical integrity. The model described here concerns the weld solidification of 316L stainless steel. The solidification of multipass welds made with a shielded electrode raises many unsolved modelling questions as it involves heat and fluid flow modelling in addition to solute redistribution models. To overcome these difficulties we have developed the MINA model to predict the resulting grain orientations without using a complete solidification model. This model relies upon a phenomenological description of grain orientations from macrograph analysis. One important advance of this model is to include data reporting in the welding notebook that ensures the generality of the model. This model allows us to accurately simulate the ultrasonic testing of welded components and to propose a new tool to associate welding design with the ultrasonic assessment of structural integrity.

  1. The reliability of the repair weld joints of aged high temperature components in fossil power boilers

    Energy Technology Data Exchange (ETDEWEB)

    Okamura, Hiroyuki [Science Univ. of Tokyo (Japan); Ohtani, Ryuichi [Kyoto Univ. (Japan); Fujii, Kazuya [Japan Power Engineering and Inspection Corp., Tokyo (Japan); Yokoyama, Tomomitsu; Nishimura, Nobuhiko [Mitsubishi Heavy Industries Ltd., Tokyo (Japan); Suzuki, Komei [Japan Steel Works Ltd., Tokyo (Japan)

    1998-11-01

    It is of fundamental engineering importance to be able to give reliable assessments of the effective service life of the critical components used within fossil power plants, particularly for those operating for prolonged periods. It is common practice for such assessments to have been estimated using destructive tests, typically the stress rupture test, this having been recognized as one of the most reliable evaluation methods available. Its only drawback is that it often does not permit the component to be in use following the sampling of the test specimen without repairing. The current piece of work focuses on the reliability of the repair welds of components for specimens taken from fossil power plants, having been in service for prolonged periods. Several such repairs to welds have been made to an old power boiler, in particular to a superheater header which is fabricated from 2.25Cr-1Mo steel. Under close examination the repairs to the girth weldment showed susceptibilities of weld cracking, similar to that observed in as-manufactured material. Within the repaired region of the welded joint the microstructure, tensile properties and toughness seemed to be unaffected. The hardness attained its minimum value within the heat affected zone, HAZ of the repair weld, overlapping that of original girth weld HAZ. Furthermore, the stress rupture strength achieved its minimum value at the same position taking on the same value as the strength associated with the aged girth welded joint. (orig.)

  2. Validation and implementation of sandwich structure bottom plate to rib weld joint in the base section of ITER Cryostat

    Energy Technology Data Exchange (ETDEWEB)

    Prajapati, Rajnikant, E-mail: rajnikant@iter-india.org [ITER-India, Institute For Plasma Research, A-29, GIDC Electronics Estate, Sector-25, Gandhinagar 382016 (India); Bhardwaj, Anil K.; Gupta, Girish; Joshi, Vaibhav; Patel, Mitul; Bhavsar, Jagrut; More, Vipul; Jindal, Mukesh; Bhattacharya, Avik; Jogi, Gaurav; Palaliya, Amit; Jha, Saroj; Pandey, Manish [ITER-India, Institute For Plasma Research, A-29, GIDC Electronics Estate, Sector-25, Gandhinagar 382016 (India); Jadhav, Pandurang; Desai, Hemal [Larsen & Toubro Limited, Heavy Engineering, Hazira Manufacturing Complex, Gujarat (India)

    2016-11-01

    Highlights: • ITER Cryostat base section sandwich structure bottom plate to rib weld joint is qualified through mock-up. • Established welding sequence was successfully implemented on all six sectors of cryostat base section. • Each layer liquid penetrant examination has been carried out for these weld joints and found satisfactory. - Abstract: Cryostat is a large stainless steel vacuum vessel providing vacuum environment to ITER machine components. The cryostat is ∼30 m in diameter and ∼30 m in height having variable thickness from 25 mm to 180 mm. Sandwich structure of cryostat base section withstands vacuum loading and limits the deformation under service conditions. Sandwich structure consists of top and bottom plates internally strengthened with radial and circular ribs. In current work, sandwich structure bottom plate to rib weld joint has been designed with full penetration joint as per ITER Vacuum Handbook requirement considering nondestructive examinations and welding feasibility. Since this joint was outside the scope of ASME Section VIII Div. 2, it was decided to validate through mock-up of bottom plate to rib joint. Welding sequence was established to control the distortion. Tensile test, macro-structural examination and layer by layer LPE were carried out for validation of this weld joint. However possibility of ultrasonic examination method was also investigated. The test results from the welded joint mock-up were found to confirm all code and specification requirements. The same was implemented in first sector (0–60°) of base section sandwich structure.

  3. The Investigation of Structure Heterogeneous Joint Welds in Pipelines

    Directory of Open Access Journals (Sweden)

    Lyubimova Lyudmila

    2016-01-01

    Full Text Available Welding joints of dissimilar steels don’t withstand design life. One of the important causes of premature destructions can be the acceleration of steel structural degradation due to cyclic mechanical and thermal gradients. Two zones of tube from steel 12H18N9T, exhibiting the structural instability at early stages of the decomposition of a supersaturated solid austenite solution, were subjected to investigation. Methods of x-ray spectral and structure analysis, micro hardnessmetry were applied for the research. Made the following conclusions, inside and outside tube wall surfaces of hazardous zones in welding joint have different technological and resource characteristics. The microhardness very sensitive to changes of metal structure and can be regarded as integral characteristic of strength and ductility. The welding processes are responsible for the further fibering of tube wall structure, they impact to the characteristics of hot-resistance and long-term strength due to development of ring cracks in the welding joint of pipeline. The monitoring of microhardness and structural phase conversions can be used for control by changes of mechanical properties in result of post welding and reductive heat treatment of welding joints.

  4. Combined Cycle Fatigue Testing with Ultrasonic Frequency Component of S350 Steel Welded Joint

    Institute of Scientific and Technical Information of China (English)

    柳阳; 王东坡; 邓彩艳; 吴良晨; 尹丹青; 龚宝明

    2014-01-01

    A combined cycle fatigue (CCF) testing system with ultrasonic frequency component was developed to evaluate the CCF properties of S350 steel welded joints in this study. The fatigue testing results indicated that the S-N curves of CCF did not have fatigue limit, which agreed with those of pure high frequency fatigue of welded joints. The S-N curves showed that the CCF strength of welded joints dropped greatly with the increasing interaction between high and low frequency fatigue loading. An approximation design method of CCF was presented using amplitude envelope as the stress range.

  5. Investigations of Spot Weld Material Characterization for Hat Beam Component Impact Analysis

    OpenAIRE

    Sachin Patil; Hamid Lankarani

    2016-01-01

    With a greater emphasis placed on weight reduction the ground vehicle industry has increased the use of higher strength, thinner gage steels, particularly cold rolled high strength steels (HSS). Choice of a particular HSS will depend upon such factors as cost, formability, fatigue resistance and weldability, in particular spot weldability. Vehicle collision characteristics significantly influenced by spot welded joints in vehicle steel body components.In engineering practice, spot welds are n...

  6. A Concurrent Product-Development Approach for Friction-Stir Welded Vehicle-Underbody Structures

    Science.gov (United States)

    Grujicic, M.; Arakere, G.; Hariharan, A.; Pandurangan, B.

    2012-04-01

    High-strength aluminum and titanium alloys with superior blast/ballistic resistance against armor piercing (AP) threats and with high vehicle light-weighing potential are being increasingly used as military-vehicle armor. Due to the complex structure of these vehicles, they are commonly constructed through joining (mainly welding) of the individual components. Unfortunately, these alloys are not very amenable to conventional fusion-based welding technologies [e.g., gas metal arc welding (GMAW)] and to obtain high-quality welds, solid-state joining technologies such as friction-stir welding (FSW) have to be employed. However, since FSW is a relatively new and fairly complex joining technology, its introduction into advanced military-vehicle-underbody structures is not straight forward and entails a comprehensive multi-prong approach which addresses concurrently and interactively all the aspects associated with the components/vehicle-underbody design, fabrication, and testing. One such approach is developed and applied in this study. The approach consists of a number of well-defined steps taking place concurrently and relies on two-way interactions between various steps. The approach is critically assessed using a strengths, weaknesses, opportunities, and threats (SWOT) analysis.

  7. Improving Stiffness-to-weight Ratio of Spot-welded Structures based upon Nonlinear Finite Element Modelling

    Science.gov (United States)

    Zhang, Shengyong

    2017-07-01

    Spot welding has been widely used for vehicle body construction due to its advantages of high speed and adaptability for automation. An effort to increase the stiffness-to-weight ratio of spot-welded structures is investigated based upon nonlinear finite element analysis. Topology optimization is conducted for reducing weight in the overlapping regions by choosing an appropriate topology. Three spot-welded models (lap, doubt-hat and T-shape) that approximate “typical” vehicle body components are studied for validating and illustrating the proposed method. It is concluded that removing underutilized material from overlapping regions can result in a significant increase in structural stiffness-to-weight ratio.

  8. Structural and mechanical properties of welded joints of reduced activation martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Filacchioni, G. E-mail: gianni.filacchioni@casaccia.enea.it; Montanari, R.; Tata, M.E.; Pilloni, L

    2002-12-01

    Gas tungsten arc welding and electron beam welding methods were used to realise welding pools on plates of reduced activation martensitic steels. Structural and mechanical features of these simulated joints have been investigated in as-welded and post-welding heat-treated conditions. The research allowed to assess how each welding technique affects the original mechanical properties of materials and to find suitable post-welding heat treatments. This paper reports results from experimental activities on BATMAN II and F82H mod. steels carried out in the frame of the European Blanket Project - Structural Materials Program.

  9. ELECTRIC WELDING EQUIPMENT AND AUTOMATION OF WELDING IN CONSTRUCTION,

    Science.gov (United States)

    WELDING , *ARC WELDING , AUTOMATION, CONSTRUCTION, INDUSTRIES, POWER EQUIPMENT, GENERATORS, POWER TRANSFORMERS, RESISTANCE WELDING , SPOT WELDING , MACHINES, AUTOMATIC, STRUCTURES, WIRING DIAGRAMS, USSR.

  10. Narrow gap HST welding process and its application to candidate pipe material for 700 C USC boiler component

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Gang; Sato, Takashi; Fukuda, Yuji [Babcock-Hitachi K.K., Hiroshima (Japan). Kure Research Lab.; Mitsuhata, Koichi [Babcock-Hitachi K.K., Hiroshima (Japan). Kure Div.

    2008-07-01

    Increasing steam temperature and pressure conditions of 700 C USC (Ultra Super Critical) power plants under consideration require the adoption of Ni-based alloys. One of the most crucial issues for the application of 700 C USC power plants is the establishment of welding technology for the thick-walled components. This paper reports the research results on the practicability of candidate material for the thickwalled components. The weld test was conducted on Ni-based Alloy617 (52Ni-22Cr- 13Co-9Mo-Ti-Al) by using the narrow gap HST (Hot wire Switching TIG) welding process developed by Babcock-Hitachi K.K with the matching filler wire of Alloy617. The weldability and strength properties of weld joint were examined. The sound weld joint was achieved. The advantages of narrow gap HST welding process for the thick-walled components of Ni-based alloy were discussed from the viewpoints of weld metal chemical composition and creep rupture strength. Due to the good shielding effect, the melting loss of alloy elements in the weld consumable during the narrow gap HST welding procedure was suppressed successfully. The narrow gap HST weld joint showed comparable strength with the parent metal. (orig.)

  11. Laser ultrasound: a flexible tool for the inspection of complex CFK components and welded seams

    Science.gov (United States)

    von Kopylow, Christoph; Focke, Oliver; Kalms, Michael

    2007-06-01

    Modern production processes use more and more components made of new materials like carbon fiber reinforced plastics (CFRP). These components have different sizes, functionalities, high assembly complexity and high security requirements. In addition optimized joining processes, especially during welding are implemented in manufacturing processes. The increasing requirements during the manufacturing of complex products like cars and aircrafts demand new solutions for the quality assurance. The main focus is to find a measurement strategy that is cost effective, flexible and adaptive. The extension of the conventional ultrasound technique for non destructive testing with the laser ultrasound method brings new possibilities into the production processes for example for the inspection of small complex CFRP-parts like clips and the online observation during seam welding. In this paper we describe the principle of laser ultrasound, especially the adaptation of a laser ultrasound system to the requirements of non destructive testing of CFRP-components. An important point is the generation of the ultrasound wave in the surface of the component under investigation. We will show experimental results of different components with complex shape and different defects under the surface. In addition we will present our results for the detection of defects in metals. Because the online inspection of welded seams is of high interest experiments for the investigation of welded seams are demonstrated.

  12. Nano-structural and Nano-chemical analysis of dissimilar metal weld interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung Joon; Shin, Shang Hoon; Kim, Jong Jin; Jung, Ju Ang; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2011-10-15

    Dissimilar metal weld is generally applied to nuclear power plant for manufacturing and machining in structural components such as RPV and Pressurizer nozzles. Alloy 152 is used frequently as filler metal in the manufacture of dissimilar metal welds (DMWs) in light water reactors (LWR) to join the low alloy steel (LAS) pressure vessel nozzles and steam generator nozzles to nickel-based wrought alloy or austenitic stainless steel components. The thermal expansion coefficient of the alloy lies between those of ferrite steel and austenitic stainless steel, and it also significantly retards the carbon diffusion from the ferrite base metal to the weld metal. However, in recent years cracking phenomena have been observed in the welded joints. A concern has been raised about the integrity and reliability in the joint transition zone due to the high susceptibility of heat affected zone (HAZ) and fusion zone (FZ) to stress corrosion cracking (SCC). The dissimilar metal joints which were welded between Inconel 690, Ni-based alloy and A533B, low alloy steel with Inconel 152, filler metal were investigated. This study shows microstructural and chemical analysis between Inconel 152 and A533B by using optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), secondary ion mass spectrometry (SIMS) and 3 dimension atom probe (3D AP). In the root region, OM and SEM analysis show the microstructure which contains the interface of Inconel 152 and A533B near the rooter region. And it shows unidentified band structure which is formed along weld interface. AP and TEM/EDS analyses show the chemical gradient containing higher Fe but lower Mn, Ni and Cr than Inconel 152 and the unidentified band

  13. Measurement of the stressed state of welded joints in the NPP process components and circulation pipelines based on acoustoelasticity theory

    Directory of Open Access Journals (Sweden)

    A.I. Trofimov

    2016-09-01

    Full Text Available The paper presents the results of a theoretical justification and an experimental research for a method to measure the stressed state of welded joints in the nuclear power plant (NPP process components and circulation pipelines based on acoustoelasticity theory, as well as for ways to implement them technically. Devices for measuring the stressed state of welded joints in the NPP process components and circulation pipelines based on acoustoelasticity theory allow online measurement of residual stresses along the weld height and detection of crack formation points. The use of such devices will enable early crack detection in welded joints for an increased safety of the NPP operation.

  14. Development of explosive welding procedures to fabricate channeled nozzle structures

    Science.gov (United States)

    Pattee, H. E.; Linse, V. D.

    1976-01-01

    Research was conducted to demonstrate the feasibility of fabricating a large contoured structure with complex internal channeling by explosive welding procedures. Structures or nozzles of this nature for wind tunnel applications were designed. Such nozzles vary widely in their complexity. However, in their simplest form, they consist of a grooved base section to which a cover sheet is attached to form a series of internal cooling passages. The cover sheet attachment can be accomplished in various ways: fusion welding, brazing, and diffusion welding. The cover sheet has also been electroformed in place. Of these fabrication methods, brazing has proved most successful in producing nozzles with complex contoured surfaces and a multiplicity of internal channels.

  15. Characterization of the mechanical properties and structural integrity of T-welded connections repaired by grinding and wet welding

    Energy Technology Data Exchange (ETDEWEB)

    Terán, G., E-mail: gteran@imp.mx [Instituto Mexicano del Petróleo, Eje central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, México D.F. CP 07730, México (Mexico); Cuamatzi-Meléndez, R., E-mail: rcuamatzi@imp.mx [Instituto Mexicano del Petróleo, Eje central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, México D.F. CP 07730, México (Mexico); Albiter, A., E-mail: aalbiter@imp.mx [Instituto Mexicano del Petróleo, Eje central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, México D.F. CP 07730, México (Mexico); Maldonado, C., E-mail: cmzepeda@umich.mx [Instituto de Investigaciones Metalúrgicas, UMSNH, PO Box 52-B, 58000, México (Mexico); Bracarense, A.Q., E-mail: bracarense@ufmg.br [UFMG Departamento de Engeharia Mecánica Belo Horizonte, MG (Brazil)

    2014-04-01

    This paper presents an experimental methodology to characterize the structural integrity and mechanical properties of repaired T-welded connections using in fixed offshore structures. Grinding is employed to remove localized damage like cracking and corrosion and subsequent wet welding can be used to fill the grinded material. But it is important to define the grinding depth and profile in order to maintain structural integrity during the repair. Therefore, in this work different grinding depths were performed, for damage material removal, at the weld toe of the T-welded connections. The grinding was filled by wet welding in a hyperbaric chamber, simulating three different water depths: 50 m, 70 m and 100 m. The electrodes were coated with vinilic varnish, which is cheap and easy to apply. The characterization of the mechanical properties of the T-welded connections was done with standard tensile, hardness and Charpy tests; microstructure and porosity analysis were also performed. The samples were obtained from the welded connections in regions of the wet weld beads. The test results were compared with the mechanical properties of the T-welded connections welded in air conditions performed by other authors. The results showed that the wet welding technique performed in this work produced good mechanical properties of the repaired T-welded connection. The mechanical properties, measured in wet conditions, for 6 mm grinding depth, were similar for the 3 different water depths measured in air conditions. But for 10 mm grinding depth, the values of the mechanical properties measured in wet conditions were quite lower than that for air conditions for the 3 water depths. However a porosity analysis, performed with a Scanning Electronic Microscopy (SEM), showed that the level of porosity in the resulted wet weld beads is in the range of that published in the literature and some samples revealed lower level of porosity. The main resulting microstructure was polygonal

  16. Stress Engineering of Multi-pass Welds of Structural Steel to Enhance Structural Integrity

    Science.gov (United States)

    Ganguly, Supriyo; Sule, Jibrin; Yakubu, Mustapha Y.

    2016-08-01

    In multi-pass welding, the weld metal and the associated heat-affected zone are subjected to repeated thermal cycling from successive deposition of filler metals. The thermal straining results into multi-mode deformation of the weld metal which causes a variably distributed residual stress field through the thickness and across the weld of a multi-pass weldment. In addition to this, the as-welded fusion zone microstructure shows dendritic formation of grains and segregation of alloying element. This may result in formation of micro-corrosion cells and the problem would aggravate in case of highly alloyed materials. Local mechanical tensioning is an effective way of elimination of the weld tensile residual stress. It has been shown that application of cold rolling is capable not only of removing the residual stress, but depending on its magnitude it may also form beneficial compressive stress state. Multi-pass structural steel welds used as structural alloy in general engineering and structural applications. Such alloys are subjected to severe in-service degradation mechanisms e.g., corrosion and stress corrosion cracking. Welds and the locked-in residual stress in the welded area often initiate the defect which finally results in failure. In the present study, a multi-pass structural steel weld metal was first subjected to post-weld cold rolling which was followed by controlled heating by a fiber laser. Cold straining resulted in redistribution of the internal stress through the thickness and controlled laser processing helps in reforming of the grain structure. However, even with controlled laser, processing the residual stress is reinstated. Therefore, a strategy has been adopted to roll the metal post-laser processing so as to obtain a complete stress-free and recrystallized microstructure.

  17. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    Energy Technology Data Exchange (ETDEWEB)

    Klimenov, V. A., E-mail: klimenov@tpu.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation); Kurgan, K. A., E-mail: kirill-k2.777@mail.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); Chumaevskii, A. V., E-mail: tch7av@gmail.com [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, 2/4 Akademicheskii pr., Tomsk, 634021 (Russian Federation); Klopotov, A. A., E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Gnyusov, S. F., E-mail: gnusov@rambler.ru [National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  18. Welding.

    Science.gov (United States)

    Cowan, Earl; And Others

    The curriculum guide for welding instruction contains 16 units presented in six sections. Each unit is divided into the following areas, each of which is color coded: terminal objectives, specific objectives, suggested activities, and instructional materials; information sheet; transparency masters; assignment sheet; test; and test answers. The…

  19. Mechanical Behaviour of Inconel 718 Thin-Walled Laser Welded Components for Aircraft Engines

    Directory of Open Access Journals (Sweden)

    Enrico Lertora

    2014-01-01

    Full Text Available Nickel alloys are very important in many aerospace applications, especially to manufacture gas turbines and aero engine components, where high strength and temperature resistance are necessary. These kinds of alloys have to be welded with high energy density processes, in order to preserve their high mechanical properties. In this work, CO2 laser overlap joints between Inconel 718 sheets of limited thickness in the absence of postweld heat treatment were made. The main application of this kind of joint is the manufacturing of a helicopter engine component. In particular the aim was to obtain a specific cross section geometry, necessary to overcome the mechanical stresses found in these working conditions without failure. Static and dynamic tests were performed to assess the welds and the parent material fatigue life behaviour. Furthermore, the life trend was identified. This research pointed out that a full joint shape control is possible by choosing proper welding parameters and that the laser beam process allows the maintenance of high tensile strength and ductility of Inconel 718 but caused many liquation microcracks in the heat affected zone (HAZ. In spite of these microcracks, the fatigue behaviour of the overlap welds complies with the technical specifications required by the application.

  20. Structure and properties of joints produced by ultrasound-assisted explosive welding

    Science.gov (United States)

    Peev, A. P.; Kuz'min, S. V.; Lysak, V. I.; Kuz'min, E. V.; Dorodnikov, A. N.

    2015-08-01

    This paper presents the results of the effect of ultrasound on explosion welded materials. It has been established that simultaneous treatment with ultrasonic vibrations and explosion welding of the materials to be welded has a significant effect on the structure and properties of the heat-affected zone of formed joints.

  1. 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.)

  2. Effect of secondary weld thermal cycle on structure and properties

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper deals with structure and impact energy of weld HAZ of 10CrNi3MoV steel after secondary weld thermal cycle (t8/5=8(¨)s~120(¨)s; peak temperature Tm=750℃~1(¨)300℃). It is demonstrated that the coarse grain and structure produced by first thermal cycle keep unchanged after secondary thermal cycle above Ac1 critical temperature but below 1(¨)050(¨)℃. At the same time the low temperature impact energy decreases obviously with increasing t8/5. By metallurgical microscope and transmission electron microscope(TEM) , it is revealed that the effect of coarse grain and structure caused by secondary thermal cycle on low temperature impact energy.

  3. Regularized Generalized Structured Component Analysis

    Science.gov (United States)

    Hwang, Heungsun

    2009-01-01

    Generalized structured component analysis (GSCA) has been proposed as a component-based approach to structural equation modeling. In practice, GSCA may suffer from multi-collinearity, i.e., high correlations among exogenous variables. GSCA has yet no remedy for this problem. Thus, a regularized extension of GSCA is proposed that integrates a ridge…

  4. Temperature Histories of Structural Steel Laser and Hybrid Laser-GMA Welds Calculated Using Multiple Constraints

    Science.gov (United States)

    2015-12-10

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6390--15-9665 Temperature Histories of Structural Steel Laser and Hybrid Laser-GMA Welds...NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Temperature Histories of Structural Steel Laser and Hybrid Laser-GMA Welds Calculated Using Multiple...202) 767-2601 Inverse thermal analyses of structural steel deep-penetration welds are presented. These analyses employ a methodology that is in terms of

  5. Friction Stir Welding of Metal Matrix Composites for use in aerospace structures

    Science.gov (United States)

    Prater, Tracie

    2014-01-01

    Friction Stir Welding (FSW) is a relatively nascent solid state joining technique developed at The Welding Institute (TWI) in 1991. The process was first used at NASA to weld the super lightweight external tank for the Space Shuttle. Today FSW is used to join structural components of the Delta IV, Atlas V, and Falcon IX rockets as well as the Orion Crew Exploration Vehicle. A current focus of FSW research is to extend the process to new materials which are difficult to weld using conventional fusion techniques. Metal Matrix Composites (MMCs) consist of a metal alloy reinforced with ceramics and have a very high strength to weight ratio, a property which makes them attractive for use in aerospace and defense applications. MMCs have found use in the space shuttle orbiter's structural tubing, the Hubble Space Telescope's antenna mast, control surfaces and propulsion systems for aircraft, and tank armors. The size of MMC components is severely limited by difficulties encountered in joining these materials using fusion welding. Melting of the material results in formation of an undesirable phase (formed when molten Aluminum reacts with the reinforcement) which leaves a strength depleted region along the joint line. Since FSW occurs below the melting point of the workpiece material, this deleterious phase is absent in FSW-ed MMC joints. FSW of MMCs is, however, plagued by rapid wear of the welding tool, a consequence of the large discrepancy in hardness between the steel tool and the reinforcement material. This work characterizes the effect of process parameters (spindle speed, traverse rate, and length of joint) on the wear process. Based on the results of these experiments, a phenomenological model of the wear process was constructed based on the rotating plug model for FSW. The effectiveness of harder tool materials (such as Tungsten Carbide, high speed steel, and tools with diamond coatings) to combat abrasive wear is explored. In-process force, torque, and

  6. Robot based three-dimensional welding for jet engine blade repair and rapid prototyping of small components

    Science.gov (United States)

    Thukaram, Santosh Kumar

    Aero engines are made up of a large number of blades which are subject to wear and damage. They are expensive and must be repaired wherever possible. Engines also have small components which are required in small numbers that need to be developed rapidly. The first part of this research work focuses on developing a robust automated blade repair method using robotic welding. Optimal weld parameters were developed for build-up of edges having different thicknesses. Samples with varying Current and varying travel speed were produced and their micro hardness values were compared. Blade profiles were welded upon. The second part involves a methodology for producing small components using rapid prototyping (RP) techniques. This part involves use of 3D robotic welding for layered manufacturing. Tensile samples produced using the metal RP method were tested and results were found to be well above the minimum cast specifications for the given material.

  7. Development of Temper Bead Welding Process for Weld Overlay of Dissimilar Welds

    Energy Technology Data Exchange (ETDEWEB)

    Byeon, J. G.; Park, K. S.; Kim, Y. J. [Doosan Heavy Industries and Construction Co., Ltd., Seoul (Korea, Republic of)

    2008-10-15

    In recent years, the dissimilar weld metal used to connect stainless steel piping and low alloy steel or carbon steel components have experienced cracking in nuclear reactor piping systems. The cracking has been observed in several Pressurized Water Reactors in overseas. In Several cases, the cracking was repaired using structural weld overlays, a repair technique that has been in use in the U.S. in Boiling Water Reactors for over twenty years. Although weld overlays have been used primarily as a repair for flawed piping, they can also be applied at locations that have not yet exhibited any cracking, but are considered susceptible to cracking. The purpose of this research is to develop the temper bead weld process for the weld overlay of the dissimilar weld pipe. We developed equipment for the overlay system, applied Procedure Qualification(PQ) for the temper bead welding process.

  8. Prediction of welding distortion during assembly process of thin plate structures

    Institute of Scientific and Technical Information of China (English)

    Luo Yu; Deng De'an; Jiang Xiaoling

    2005-01-01

    Ships and automobiles are fabricated from thin plates. To assemble parts, welding is commonly employed.However, welding distortion in large thin-plate panel structure is usually cased by buckling due to the residual stress. In this study, an elastic finite element method for predicting the welding distortion of three-dimensional thin-plate structures with considering welding sequence was proposed. In this method, the inherent strain was employed to model the local shrinkage due to welding itself, and the interface element was introduced to simulate the assembly process. The proposed method was applied to study the influence of welding sequence on the buckling distortion of the large thin-plate panel structure during assembly.

  9. Fluid-structure-interaction analysis for welded pipes with flow-accelerated corrosion wall thinning

    Energy Technology Data Exchange (ETDEWEB)

    Sun, L.; Ding, Y., E-mail: lan.sun@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2016-06-15

    The flow-accelerated corrosion (FAC) entrance effect results in enhanced wall thinning immediately downstream of a weld if the weld connects an upstream FAC-resistant material with a downstream less resistant material. The weld regions, especially those with local repairs, are susceptible to cracking due to the high residual stresses induced by fabrication. The combined effects of the FAC entrance effect and high stresses at a weld might compromise the structural integrity of the piping and lead to a failure. Weld degradation by FAC entrance effect has been observed at nuclear and fossil power plants. This paper describes an application using fluid-structure-interaction (FSI) modelling to study the combined effects of FAC wall thinning, weld residual stresses, and in-service loads on welded structures. Simplified cases analyzed were based on CANDU outlet feeder conditions. The analysis includes the flow and mass transfer modelling of the FAC entrance effect using computational fluid dynamics (CFD) and nonlinear structural analyses of the welded structures with wall thinning and an assumed weld residual stress and strain distribution. The FSI analyses were performed using ANSYS Workbench, an integrated platform that enables the coupling of CFD and structural analysis solutions. The obtained results show that the combination of FAC, weld residual stresses, in-service loads (including the internal pressure) and (or) extreme loads could cause high stresses and affect the integrity of the welded pipes. The present work demonstrated that the FSI modelling can be used as an effective approach to assess the integrity of welded structures. (author)

  10. Detection of damage in welded structure using experimental modal data

    Science.gov (United States)

    Abu Husain, N.; Ouyang, H.

    2011-07-01

    A typical automotive structure could contain thousands of spot weld joints that contribute significantly to the vehicle's structural stiffness and dynamic characteristics. However, some of these joints may be imperfect or even absent during the manufacturing process and they are also highly susceptible to damage due to operational and environmental conditions during the vehicle lifetime. Therefore, early detection and estimation of damage are important so necessary actions can be taken to avoid further problems. Changes in physical parameters due to existence of damage in a structure often leads to alteration of vibration modes; thus demonstrating the dependency between the vibration characteristics and the physical properties of structures. A sensitivity-based model updating method, performed using a combination of MATLAB and NASTRAN, has been selected for the purpose of this work. The updating procedure is regarded as parameter identification which aims to bring the numerical prediction to be as closely as possible to the measured natural frequencies and mode shapes data of the damaged structure in order to identify the damage parameters (characterised by the reductions in the Young's modulus of the weld patches to indicate the loss of material/stiffness at the damage region).

  11. A theoretical study of the influence of technological friction stir welding parameters on weld structures

    Science.gov (United States)

    Astafurov, Sergey; Shilko, Evgeny; Kolubaev, Evgeny; Psakhie, Sergey

    2015-10-01

    Computer simulation by the movable cellular automaton method was performed to study the dynamics of friction stir welding of duralumin plates. It was shown that the ratio of the rotation rate to the translational velocity of the rotating tool has a great influence on the quality of the welded joint. A suitably chosen ratio of these parameters combined with an additional ultrasonic impact reduces considerably the porosity and the amount of microcracks in the weld.

  12. Evaluation of weld indications detected in inservice inspections for Class 1 ferritic steel components

    Energy Technology Data Exchange (ETDEWEB)

    Idvorian, N.; Cao, J. [Babcock and Wilcox Canada, Nuclear Engineering, Cambridge, Ontario (Canada)

    2007-07-01

    For different class 1 ferritic steel components, acceptance standards for flaws detected in inservice inspections are stipulated in the ASME Code, Section XI, Subsection IWB. For flaws exceeding ASME Code acceptance standards, analytical evaluation can be used to justify if the flaws are acceptable. The end-of-service size of a flaw is used to determine if the flaw is acceptable for service without repair. Growth of the flaw can be calculated based on the stress conditions at the flaw location and environment. A case of a heater nozzle/head weld of a pressurizer with indications is evaluated to demonstrate the analysis procedure. (author)

  13. Strength of gusset plates in welded steel structures

    DEFF Research Database (Denmark)

    Jensen, Aage

    2004-01-01

    The design of gusset plates is normally carried out on the bases of the technical beam theory or other assumptions proved safe by experience. This design procedure has proved its usefulness by the length of life and use of existing structures, and is to some extend justified in simple loading cases....... A different approach is taken in the paper where upper and lower bounds are derived for the yield load assuming a perfect plastic material and Tresca's yield condition. Ther theoretical results are supported by a few numbers of tests. The paper deals mainly with the case of a single member welded into a cut...

  14. Structural State of a Weld Formed in Aluminum Alloy by Friction Stir Welding and Treated by Ultrasound

    Science.gov (United States)

    Klimenov, V. A.; Abzaev, Yu. A.; Potekaev, A. I.; Vlasov, V. A.; Klopotov, A. A.; Zaitsev, K. V.; Chumaevskii, A. V.; Porobova, S. A.; Grinkevich, L. S.; Tazin, I. D.; Tazin, D. I.

    2016-11-01

    The experimental data on structural state of an aluminum alloy, AlMg6, in the weld zone formed by friction stir welding are analyzed in order to evaluate the effect of its subsequent ultrasonic treatment. It is found that the crystal lattice transits into a low-stability state as a result of combined heat-induced and severe shear deformation. This transition is accompanied by considerable structural-phase changes that are manifested as an increased lattice parameter of the solid solution. This increase is caused by both high values of internal stresses and increased concentration of Mg atoms in the solid solution due to essential dissolution of the β-Al2Mg3 particles with the content of manganese higher than that in the matrix. This is accompanied by high-intensity diffusion and relaxation processes due to the low-stability state of crystal lattice (inhomogeneous stresses) in the weld zone.

  15. Structural Changes of Surface Layers of Steel Plates in the Process of Explosive Welding

    Science.gov (United States)

    Bataev, I. A.; Bataev, A. A.; Mali, V. I.; Bataev, V. A.; Balaganskii, I. A.

    2014-01-01

    Structural changes developing in surface layers of plates from steel 20 in the process of explosive welding are studied with the help of light metallography and scanning and transmission electron microscopy. Mathematical simulation is used to compute the depth of the action of severe plastic deformation due to explosive welding of steel plates on the structure of their surface layers.

  16. Laser Welding Characterization of Kovar and Stainless Steel Alloys as Suitable Materials for Components of Photonic Devices Packaging

    Science.gov (United States)

    Fadhali, M. M. A.; Zainal, Saktioto J.; Munajat, Y.; Jalil, A.; Rahman, R.

    2010-03-01

    The weldability of Kovar and stainless steel alloys by Nd:YAG laser beam is studied through changing of some laser beam parameters. It has been found that there is a suitable interaction of the pulsed laser beam of low power laser pulse with both the two alloys. The change of thermophysical properties with absorbed energy from the laser pulse is discussed in this paper which reports the suitability of both Kovar and stainless steel 304 as the base materials for photonic devices packaging. We used laser weld system (LW4000S from Newport) which employs Nd:YAG laser system with two simultaneous beams output for packaging 980 nm high power laser module. Results of changing both laser spot weld width and penetration depth with changing both the pulse peak power density, pulse energy and pulse duration show that there are good linear relationships between laser pulse energy or peak power density and pulse duration with laser spot weld dimensions( both laser spot weld width and penetration depth). Therefore we concluded that there should be an optimization for both the pulse peak power and pulse duration to give a suitable aspect ratio (laser spot width to penetration depth) for achieving the desired welds with suitable penetration depth and small spot width. This is to reduce the heat affected zone (HAZ) which affects the sensitive optical components. An optimum value of the power density in the order of 105 w/cm2 found to be suitable to induce melting in the welded joints without vaporization. The desired ratio can also be optimized by changing the focus position on the target material as illustrated from our measurements. A theoretical model is developed to simulate the temperature distribution during the laser pulse heating and predict the penetration depth inside the material. Samples have been investigated using SEM with EDS. The metallographic measurements on the weld spot show a suitable weld yield with reasonable weld width to depth ratio.

  17. Monitoring changes of proteins and lipids in laser welded aorta tissue using Raman spectroscopy and basis biochemical component analyses

    Science.gov (United States)

    Liu, C. H.; Wang, W. B.; Alimova, A.; Sriramoju, V.; Kartazayev, V.; Alfano, R. R.

    2009-02-01

    The changes of Raman spectra from ex-vivo porcine aorta tissues were studied before and after laser tissue welding (LTW). Raman spectra were measured and compared for normal and welded tissues in both tunica adventitial and intimal sides. The vibrational modes at the peak of 1301 cm-1 and the weak shoulder peak of 1264 cm-1 of amide III for the normal tissue changed to a peak at 1322cm-1 and a relative intense peak at 1264cm-1, respectively, for the welded tissue. The Raman spectra were analyzed using a linear regression fitting method and compared with characteristic Raman spectra from proteins and lipids compounds. The relative biochemical molecular composition changes of proteins (Collagen types I, III, V and Elastin) and lipids for the laser welded tissue were modeled by basis biochemical component analyses (BBCA) and compared with the normal tissue.

  18. Effect of weld microstructure on weld properties in A-TIG welding of titanium alloy

    Institute of Scientific and Technical Information of China (English)

    刘凤尧; 杨春利; 林三宝; 吴林; 苏生

    2003-01-01

    Conventional TIG welding is known as its low productivity and limited weld depth in a single pass. Activating TIG welding (A-TIG) can greatly improve the penetration when compared with the conventional TIG welding. The effects of five kinds of activating fluxes with single component (NaF, CaF2, AlF3, NaCl or CaCl2) on penetration, microstructure and weld mechanical properties during the TIG welding of titanium alloy Ti-6Al-4V were studied. Compared with the conventional TIG welding, the experimental results show that the fluxes can greatly improve the penetration at the same welding specifications. This is because of the constriction of anode spots and the change of surface tension grads. Among them the effect of flux NaF is the best in the weld tensile strength, and the effect of flux CaF2 on the weld bend intension is the best. The appearance of inferior crystal grains and the structure of trident crystal grains are the main reasons that the performance of weld with fluoride is improved. These experimental results can be used as an aid for selecting suitable activating flux for titanium alloy.

  19. Effect of adhesive on molten pool structure and penetration in laser weld bonding of magnesium alloy

    Science.gov (United States)

    Liu, L. M.; Ren, D. X.

    2010-09-01

    Laser weld bonding (LWB) is a new hybrid technique that combines adhesive bonding with laser seam welding together, and can achieve higher joint strength than adhesive bonding or laser welding individually. Some new physical phenomena have been observed in this welding method, and the phenomena are different from the normal laser welding process, such as a remarkable deeper penetration in LWB than that in laser welding direct (LWD). The adhesive-induced gas can influence the molten pool structure in front of the keyhole, so that less energy is required for laser keyhole through the upper sheet; thus, higher laser power density can interact with the lower sheet, leading to deeper penetration. Simulation comparison experiments are set to indirectly verify these conclusions above.

  20. Contribution to the determination of priority constructive influences on the hot crack initiation of welded components; Beitrag zur Ermittlung vorrangig konstruktiver Einflussgroessen auf die Heissrissinitiierung an geschweissten Bauteilen

    Energy Technology Data Exchange (ETDEWEB)

    Gollnow, Christian

    2015-07-01

    The previous research results do not allow a general hot crack characterisation although a variety of experimental and numerical knowledge is available. The reason for this is mainly the large number of influencing factors that complicate a complete description of the hot cracking phenomenon and especially solidification cracking. The hot crack formation and thus the solidification crack initiation can be described by the interaction of process, metallurgy and design. However, the literature examination shows that in the solidifaction crack characterisation the influence of the design aspect is often underestimated. The pre-stresses of the structural components is up to now not considered as an essential cause for the formation of solidification cracks. The evaluation of the influence of the various parameters is presented partly inconsistent. In addition, the targeted presentation of the design influence with respect to the solidification cracks in the weld is because the limited transferability of the various component-specific stresses on a laboratory scale and thus to the respective hot cracking tests restricted. Hence, the difficulty to transfer the results between laboratory specimen and component as well as the general hot crack characterisation is given. In this work the different types of stresses from the component welding in the laboratory and to quantify experimentally the solidification crack critical values, displacements and displacement rates were detected. In this regard external loaded hot cracking tests were carried out by using the advantages of contactless measurement techniques close to the weld and to analyse the welding process with respect to various local and global design-specific factors influencing the formation of solidification cracks in high alloyed steel. These investigations were performed on austenitic (1.4828) and ferritic (1.4509) materials with different mechanical and technological properties. To reflect the praxis relevant

  1. Nano-structural and Nano-chemical analysis of dissimilar metal weld interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung Joon; Shin, Sang Hoon; Kim, Jong Jin; Jung, Ju Ang; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2012-05-15

    Dissimilar Metal Welds (DMWs) is generally applied to nuclear power plants for manufacturing and machining in structural components such as reactor pressure vessels and pressurizer nozzles. Alloy 152 is used frequently as filler metal in the manufacture of the DMW in light water reactors to join the low alloy steel pressure vessel nozzles and steam generator nozzles to nickel-based wrought alloy or austenitic stainless steel components. However, in recent years cracking phenomena has been observed in the welded joints. Concerns have been raised to the integrity and reliability in the joint transition zone due to the high susceptibility of the heat affected zone (HAZ) and the fusion boundary (FB) to stress corrosion cracking in combination with thermal aging. Since the material microstructure and chemical composition are key parameters affecting the stress corrosion cracking, improving the understanding of stress corrosion cracking at the FB region requires fundamental understanding of the unique microstructure of the FB region in DMW. Despite the potential degradation and consequent risk in the DMW, there is still a lack of the fundamental understanding of microstructure in the FB region, in particular the region containing unidentified band structures near the FB. The scale of the microstructure in modern metallic materials is becoming increasingly smaller. The 3-dimensional atom probe tomography (3D APT) has a truly quantitative analytical capability to characterize nanometer scale particles in metallic materials, thus its application to the microstructural analysis in multi-component metallic materials provides critical information on the mechanism of nanoscale microstructural evolution. The 3D APT is a microscope that allows the reconstruction of 3D 'atom maps'. These reconstructions can be interrogated and interpreted to determine the nanoscale chemistry of the material. Therefore, the current study is aiming at the establishment of detail procedure

  2. Enhancing a service life of torch components for MIG/MAG welding

    Science.gov (United States)

    Filonov, A. V.; Kryukov, A. V.; Galimov, M. I.

    2016-08-01

    The paper analyzes the main vulnerable elements of torches used in mechanized gas-shielded welding. Particular attention is given to the gas nozzle designs, materials they are made of, and other welding torch elements exposed to increased electrical and thermal stresses during the welding process.

  3. Structural changes in VT1-0 titanium induced by deformation during explosion welding

    Science.gov (United States)

    Makarova, E. B.; Esikov, M. A.; Gontarenko, A. S.; Sameishcheva, T. S.

    2012-09-01

    The hardening of VT1-0 titanium is studied during the formation of a multilayer material by explosion welding. The structural transformations in titanium plates are analyzed by metallographic and electron-microscopic methods. The mechanical properties of the welded multilayer titanium stacks are estimated using static and dynamic mechanical tests.

  4. Ultrasound influence on materials structure in parts reconditioned by welding with ultrasonic field

    Directory of Open Access Journals (Sweden)

    D. Dobrotă

    2013-01-01

    Full Text Available Research presented in the paper refers to the structural analysis of materials that are thermally influenced for loading by welding of pieces in the classical variant of manual coated electric arc welding and the version that in which the welding bath is activated by ultrasounds. The structural analysis made refer to: the size of the grains of the structure obtained under certain loading conditions through welding, grain size variation on the submission of a single layer in the ultrasonic field, the mode of solidification and fragmentation of grains when loaded in welding in a ultrasonic field, acceleration of the diffusion process for ultrasonic activation, the appearance of hard carbides between grains.

  5. A novel ultrasonic NDE for shrink fit welded structures using interface waves.

    Science.gov (United States)

    Lee, Jaesun; Park, Junpil; Cho, Younho

    2016-05-01

    Reactor vessel inspection is a critical part of safety maintenance in a nuclear power plant. The inspection of shrink fit welded structures in a reactor nozzle can be a challenging task due to the complicated geometry. Nozzle inspection using pseudo interface waves allows us to inspect the nozzle from outside of the nuclear reactor. In this study, layered concentric pipes were manufactured with perfect shrink fit conditions using stainless steel 316. The displacement distributions were calculated with boundary conditions for a shrink fit welded structure. A multi-transducer guided wave phased array system was employed to monitor the welding quality of the nozzle end at a distance from a fixed position. The complicated geometry of a shrink fit welded structure can be overcome by using the pseudo interface waves in identifying the location and size of defects. The experimental results demonstrate the feasibility of detecting weld delamination and defects.

  6. Predictive analysis of buckling distortion of thin-plate welded structures

    Institute of Scientific and Technical Information of China (English)

    杨新岐; 霍立兴; 张玉凤; 阎俊霞

    2002-01-01

    The welding buckling distortions of thin-plated structures were investigated based on finite element methods. An engineering treatment method for predicating the buckling distortion was proposed. The equivalent applied thermal-load was used to simulate the welding residual stress, thus the calculation of complex welding distortion can be transformed into 3D elastic structural applied-load analyses, which can reduce the quantities of calculating work effectively. The validation of the method was verified by comparison of the numerical calculation with experimental results. The prediction of buckling distortion for side-walled structures of passenger train was performed and the calculation was in agreement with measuring results in general. It is shown that the main factors for producing the buckling are the intermittent fillet and plug weld during welding the stiffened beams and columns to the panel.

  7. Welding Distortion Prediction in 5A06 Aluminum Alloy Complex Structure via Inherent Strain Method

    Directory of Open Access Journals (Sweden)

    Zhi Zeng

    2016-09-01

    Full Text Available Finite element (FE simulation with inherent deformation is an ideal and practical computational approach for predicting welding stress and distortion in the production of complex aluminum alloy structures. In this study, based on the thermal elasto-plastic analysis, FE models of multi-pass butt welds and T-type fillet welds were investigated to obtain the inherent strain distribution in a 5A06 aluminum alloy cylindrical structure. The angular distortion of the T-type joint was used to investigate the corresponding inherent strain mechanism. Moreover, a custom-designed experimental system was applied to clarify the magnitude of inherent deformation. With the mechanism investigation of welding-induced buckling by FE analysis using inherent deformation, an application for predicting and mitigating the welding buckling in fabrication of complex aluminum alloy structure was developed.

  8. Feasibility study of the cut and weld operations by RH on the cooling pipes of ITER NB components

    Energy Technology Data Exchange (ETDEWEB)

    Pineiro, Oscar; Fernandez, Carlos [TECNATOM Avda. Montes de Oca 28700 S Sebastian de los Reyes, Madrid (Spain); Medrano, Mercedes [EURATOM-CIEMAT Association for Fusion. Avda. Complutense, 22. 28040 Madrid (Spain)], E-mail: mercedes.medrano@ciemat.es; Liniers, Macarena; Botija, Jose; Alonso, Javier; Sarasola, Xabier [EURATOM-CIEMAT Association for Fusion. Avda. Complutense, 22. 28040 Madrid (Spain); Damiani, Carlo [EFDA-Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain)

    2009-06-15

    The maintenance operations of ITER NB components inside the vessel - Beam Line Components (BLC's) involve the removal of the faulty component, its transport to the hot cell as well as the reverse operations of transport of the repaired/new component and its reinstallation inside the vessel. Prior to the removal of the BLC's the cooling pipes must be detached from the component following a procedure that applies to the cutting of the pipes and subsequent welding when the component is re-installed. The purpose of this study, conducted in the framework of EFDA, is to demonstrate the feasibility of the cut and weld operations on the water pipes of the BLC's using fully remote handling techniques. Viable technologies for the cut and weld operations have been identified within the study; in particular the following aspects will be presented in the paper: - Different strategies can be pursued in the detachment of the components depending on the number of cut and weld operations to be performed on the pipes. The selected strategy will impact on the procedure to be followed likewise on important aspects as the requirements of the flexible joints assembled on the pipes. - The existing cutting techniques have been examined in the light of the remotely performed pipe cutting at the NB cell. Modifications of commercial tools have been proposed in order to adapt them to the BLC's pipes requirements. The debris produced during the cutting process must be controlled and collected, therefore a cleaning system has been integrated in the adapted cutting tool referred above. - The existing welding techniques have been also examined and compared based on different criteria such as complexity, reliability, alignment tolerances, etc. TIG welding is the preferred technique as it stands out for its superior performance. The commercial tools identified need to be adapted to the NB environment. - The alignment of the pipes is a critical issue concerning the remote welding

  9. Nanostructured Polyphase Catalysts Based on the Solid Component of Welding Aerosol for Ozone Decomposition

    Science.gov (United States)

    Rakitskaya, Tatyana; Truba, Alla; Ennan, Alim; Volkova, Vitaliya

    2015-12-01

    Samples of the solid component of welding aerosols (SCWAs) were obtained as a result of steel welding by ANO-4, TsL-11, and UONI13/55 electrodes of Ukrainian manufacture. The phase compositions of the samples, both freshly prepared (FP) and modified (M) by water treatment at 60 °C, were studied by X-ray phase analysis and IR spectroscopy. All samples contain magnetite demonstrating its reflex at 2 θ ~ 35° characteristic of cubic spinel as well as manganochromite and iron oxides. FP SCWA-TsL and FP SCWA-UONI contain such phases as CaF2, water-soluble fluorides, chromates, and carbonates of alkali metals. After modification of the SCWA samples, water-soluble phases in their composition are undetectable. The size of magnetite nanoparticles varies from 15 to 68 nm depending on the chemical composition of electrodes under study. IR spectral investigations confirm the polyphase composition of the SCWAs. As to IR spectra, the biggest differences are apparent in the regions of deformation vibrations of M-O-H bonds and stretching vibrations of M-O bonds (M-Fe, Cr). The catalytic activity of the SCWAs in the reaction of ozone decomposition decreases in the order SCWA-ANO > SCWA-UONI > SCWA-TsL corresponding to the decrease in the content of catalytically active phases in their compositions.

  10. Experimental and Theoretical Investigation of Three Alloy 690 Mockup Components: Base Metal and Welding Induced Changes

    Directory of Open Access Journals (Sweden)

    Rickard R. Shen

    2014-01-01

    Full Text Available The stress corrosion cracking (SCC resistance of cold deformed thermally treated (TT Alloy 690 has been questioned in recent years. As a step towards understanding its relevancy for weld deformed Alloy 690 in operating plants, Alloy 690 base metal and heat affected zone (HAZ microstructures of three mockup components have been studied. All mockups were manufactured using commercial heats and welding procedures in order to attain results relevant to the materials in the field. Thermodynamic calculations were performed to add confidence in phase identification as well as understanding of the evolution of the microstructure with temperature. Ti(C,N banding was found in all materials. Bands with few large Ti(C,N precipitates had negligible effect on the microstructure, whereas bands consisting of numerous small precipitates were associated with locally finer grains and coarser M23C6 grain boundary carbides. The Ti(C,N remained unaffected in the HAZ while the M23C6 carbides were fully dissolved close to the fusion line. Cold deformed solution annealed Alloy 690 is believed to be a better representation of this region than cold deformed TT Alloy 690.

  11. The ways of reliability enhancement of welded metal structures for critical applications in the conditions of low climatic temperatures

    Science.gov (United States)

    Saraev, Yu. N.; Bezborodov, V. P.; Gladkovsky, S. V.; Golikov, N. I.

    2016-11-01

    The paper studies how the energy parameters of an effective welding technology based on adaptive pulse-arc welding method influence the microstructure, mechanical characteristics and fatigue strength of low carbon steel 09G2S welded joint. It is established that the application of the adaptive pulse-arc welding method with modulated current (CMW) as compared to the welding method with direct current (DCW) allows one to obtain a welded joint of this steel with high reserve impact strength, dynamic fracture toughness and fatigue strength of metallic structures at operation temperatures up to -60°C.

  12. Micro Structural Comparison of Friction Stir Weldment and Shielded Metal Arc Welding in API-X65 Pipe Line

    Directory of Open Access Journals (Sweden)

    Amin Shahinfar

    2015-04-01

    Full Text Available The study was conducted to investigate the microstructure and microhardness properties of the friction stir welded zones and shielded metal arc welded. Microstructural analysis of the weld was carried out using optical microscopy. Under FSW process base metal microstructure fully changed. Different heat inputs were obtained using a fix travel (welding speed in combination with several spindle speeds. Heat input during welding process had a significant influence on the microstructure and mechanical proprieties in the various weld regions.it can be concluded that with decrease in heat input the bainitic structure in the hard zone becomes finer and so hard zone hardness increase.

  13. The influence of electric ARC activation on the speed of heating and the structure of metal in welds

    Directory of Open Access Journals (Sweden)

    Savytsky Oleksandr M.

    2016-01-01

    Full Text Available This paper presents the results of a research related to the impact of electric arc activation onto drive welding energy and metal weld heating speed. It is confirmed that ATIG and AMIG methods, depending on metal thickness, single pass weldability and chemical composition of activating flux, enable the reduction of welding energy by 2-6 times when compared to conventional welding methods. Additionally, these procedures create conditions to increase metal weld heating speed up to 1,500-5,500°C/s-1. Steel which can be rapidly heated, allows for a hardened structure to form (with carbon content up to 0.4%, together with a released martensitic structure or a mixture of bainitic-martensitic structures. Results of the research of effectiveness of ATIG and AMIG welding showed that increase in the penetration capability of electric arc, which increases welding productivity, is the visible side of ATIG and AMIG welding capabilities.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-11-01

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

  15. Effect of A-TIG Welding Process on the Weld Attributes of Type 304LN and 316LN Stainless Steels

    Science.gov (United States)

    Vasudevan, M.

    2017-03-01

    The specific activated flux has been developed for enhancing the penetration performance of TIG welding process for autogenous welding of type 304LN and 316LN stainless steels through systematic study. Initially single-component fluxes were used to study their effect on depth of penetration and tensile properties. Then multi-component activated flux was developed which was found to produce a significant increase in penetration of 10-12 mm in single-pass TIG welding of type 304LN and 316LN stainless steels. The significant improvement in penetration achieved using the activated flux developed in the present work has been attributed to the constriction of the arc and as well as reversal of Marangoni flow in the molten weld pool. The use of activated flux has been found to overcome the variable weld penetration observed in 316LN stainless steel with welds compared to that of the welds produced by conventional TIG welding on the contrary the transverse strength properties of the 304LN and 316LN stainless steel welds produced by A-TIG welding exceeded the minimum specified strength values of the base metals. Improvement in toughness values were observed in 316LN stainless steel produced by A-TIG welding due to refinement in the weld microstructure in the region close to the weld center. Thus, activated flux developed in the present work has greater potential for use during the TIG welding of structural components made of type 304LN and 316LN stainless steels.

  16. Effect of A-TIG Welding Process on the Weld Attributes of Type 304LN and 316LN Stainless Steels

    Science.gov (United States)

    Vasudevan, M.

    2017-02-01

    The specific activated flux has been developed for enhancing the penetration performance of TIG welding process for autogenous welding of type 304LN and 316LN stainless steels through systematic study. Initially single-component fluxes were used to study their effect on depth of penetration and tensile properties. Then multi-component activated flux was developed which was found to produce a significant increase in penetration of 10-12 mm in single-pass TIG welding of type 304LN and 316LN stainless steels. The significant improvement in penetration achieved using the activated flux developed in the present work has been attributed to the constriction of the arc and as well as reversal of Marangoni flow in the molten weld pool. The use of activated flux has been found to overcome the variable weld penetration observed in 316LN stainless steel with welds compared to that of the welds produced by conventional TIG welding on the contrary the transverse strength properties of the 304LN and 316LN stainless steel welds produced by A-TIG welding exceeded the minimum specified strength values of the base metals. Improvement in toughness values were observed in 316LN stainless steel produced by A-TIG welding due to refinement in the weld microstructure in the region close to the weld center. Thus, activated flux developed in the present work has greater potential for use during the TIG welding of structural components made of type 304LN and 316LN stainless steels.

  17. Structure and Properties of `Steel 08kp + ChNMSh Iron' Bimetal Obtained by Explosion Welding

    Science.gov (United States)

    Denisov, I. V.

    2017-05-01

    The structure of a bimetal from structural steel 08kp and low-alloy iron ChNMSh obtained by explosion welding is studied. The effect of different heat treatments on the structure and properties of the bimetal is determined, and expedient modes of heat treatment for reliving the internal stresses in the zone of joining, which do not worsen the operating properties of the welded materials, are suggested.

  18. Temperature Histories of Structural Steel Welds Calculated Using Solidification-Boundary Constraints

    Science.gov (United States)

    Lambrakos, S. G.

    2016-09-01

    Temperature histories of structural steel deep-penetration welds are presented, which are calculated using numerical-analytical basis functions and solidification-boundary constraints. These weld temperature histories can be adopted as input data to various types of computational procedures, which include numerical models for prediction of solid-state phase transformations and mechanical response. In addition, these temperature histories can be used parametrically for inverse thermal analysis of welds corresponding to other welding processes whose process conditions are within similar regimes. The present study applies an inverse thermal analysis procedure that uses three-dimensional constraint conditions whose two-dimensional projections are mapped within transverse cross sections of experimentally measured solidification boundaries. In addition, the present study uses experimentally measured estimates of the heat effect zone edge to examine the consistency of calculated temperature histories for steel welds.

  19. Robust design of spot welds in automotive structures: A decision-making methodology

    Science.gov (United States)

    Ouisse, M.; Cogan, S.

    2010-05-01

    Automotive structures include thousands of spot welds whose design must allow the assembled vehicle to satisfy a wide variety of performance constraints including static, dynamic and crash criteria. The objective of a standard optimization strategy is to reduce the number of spot welds as much as possible while satisfying all the design objectives. However, a classical optimization of the spot weld distribution using an exhaustive search approach is simply not feasible due to the very high order of the design space and the subsequently prohibitive calculation costs. Moreover, even if this calculation could be done, the result would not necessarily be very informative with respect to the design robustness to manufacturing uncertainties (location of welds and defective welds) and to the degradation of spot welds due to fatigue effects over the lifetime of the vehicle. In this paper, a decision-making methodology is presented which allows some aspects of the robustness issues to be integrated into the spot weld design process. The starting point is a given distribution of spot welds on the structure, which is based on both engineering know-how and preliminary critical numerical results, in particular criteria such as crash behavior. An over-populated spot weld distribution is then built in order to satisfy the remaining design criteria, such as static torsion angle and modal behavior. Then, an efficient optimization procedure based on energy considerations is used to eliminate redundant spot welds while preserving as far as possible the nominal structural behavior. The resulting sub-optimal solution is then used to provide a decision indicator for defining effective quality control procedures (e.g. visual post-assembly inspection of a small number of critical spot welds) as well as designing redundancy into critical zones. The final part of the paper is related to comparing the robustness of competing designs. Some decision-making indicators are presented to help the

  20. An Improved Plasticity-Based Distortion Analysis Method for Large Welded Structures

    Science.gov (United States)

    Yang, Yu-Ping; Athreya, Badrinarayan P.

    2013-05-01

    The plasticity-based distortion prediction method was improved to address the computationally intensive nature of welding simulations. Plastic strains, which are typically first computed using either two-dimensional (2D) or three-dimensional (3D) thermo-elastic-plastic analysis (EPA) on finite element models of simple weld geometry, are mapped to the full structure finite element model to predict distortion by conducting a linear elastic analysis. To optimize welding sequence to control distortion, a new theory was developed to consider the effect of weld interactions on plastic strains. This improved method was validated with experimental work on a Tee joint and tested on two large-scale welded structures—a light fabrication and a heavy fabrication—by comparing against full-blown distortion predictions using thermo-EPA. 3D solid and shell models were used for the heavy and light fabrications, respectively, to compute plastic strains due to each weld. Quantitative comparisons between this method and thermo-EPA indicate that this method can predict distortions fairly accurately—even for different welding sequences—and is roughly 1-2 orders of magnitude faster. It was concluded from these findings that, with further technical development, this method can be an ideal solver for optimizing welding sequences.

  1. FE Simulation Models for Hot Stamping an Automobile Component with Tailor-Welded High-Strength Steels

    Science.gov (United States)

    Tang, Bingtao; Wang, Qiaoling; Wei, Zhaohui; Meng, Xianju; Yuan, Zhengjun

    2016-05-01

    Ultra-high-strength in sheet metal parts can be achieved with hot stamping process. To improve the crash performance and save vehicle weight, it is necessary to produce components with tailored properties. The use of tailor-welded high-strength steel is a relatively new hot stamping process for saving weight and obtaining desired local stiffness and crash performance. The simulation of hot stamping boron steel, especially tailor-welded blanks (TWBs) stamping, is more complex and challenging. Information about thermal/mechanical properties of tools and sheet materials, heat transfer, and friction between the deforming material and the tools is required in detail. In this study, the boron-manganese steel B1500HS and high-strength low-alloy steel B340LA are tailor welded and hot stamped. In order to precisely simulate the hot stamping process, modeling and simulation of hot stamping tailor-welded high-strength steels, including phase transformation modeling, thermal modeling, and thermal-mechanical modeling, is investigated. Meanwhile, the welding zone of tailor-welded blanks should be sufficiently accurate to describe thermal, mechanical, and metallurgical parameters. FE simulation model using TWBs with the thickness combination of 1.6 mm boron steel and 1.2 mm low-alloy steel is established. In order to evaluate the mechanical properties of the hot stamped automotive component (mini b-pillar), hardness and microstructure at each region are investigated. The comparisons between simulated results and experimental observations show the reliability of thermo-mechanical and metallurgical modeling strategies of TWBs hot stamping process.

  2. Structure and Microhardness of Cu-Ta Joints Produced by Explosive Welding

    Directory of Open Access Journals (Sweden)

    Iu. N. Maliutina

    2013-01-01

    Full Text Available The structure and microhardness of Cu-Ta joints produced by explosive welding were studied. It was found that, during explosive welding, an intermediate layer 20⋯40 μm thick with a finely dispersed heterophase structure, formed between the welded copper and tantalum plates. The structure of the layer was studied by scanning and transmission electron microscopy. Microvolumes with tantalum particles distributed in a copper matrix and microvolumes of copper particles in a tantalum matrix were detected. The tantalum particles in copper have a size of 5⋯500 nm, with a predominance of 5⋯50 nm particles. A mechanism for the formation of the finely dispersed heterophase structure in explosive welding is proposed. The microhardness of interlayers with the heterophase structure reaches 280 HV, which far exceeds the microhardness of copper (~130 HV and tantalum (~160 HV. Many twins of deformation origin were found in the structure of the copper plate. The effect of heating temperature in the range from 100 to 900∘C on the microhardness of copper, tantalum, and the Cu-Ta welded joint was studied. Upon heating to 900∘C, the microhardness of the intermediate layer decreases from 280 to 150 HV. The reduction in the strength properties of the weld material is mainly due to structural transformations in copper.

  3. Structure and microhardness of cu-ta joints produced by explosive welding.

    Science.gov (United States)

    Maliutina, Iu N; Mali, V I; Bataev, I A; Bataev, A A; Esikov, M A; Smirnov, A I; Skorokhod, K A

    2013-01-01

    The structure and microhardness of Cu-Ta joints produced by explosive welding were studied. It was found that, during explosive welding, an intermediate layer 20⋯40  μ m thick with a finely dispersed heterophase structure, formed between the welded copper and tantalum plates. The structure of the layer was studied by scanning and transmission electron microscopy. Microvolumes with tantalum particles distributed in a copper matrix and microvolumes of copper particles in a tantalum matrix were detected. The tantalum particles in copper have a size of 5⋯500 nm, with a predominance of 5⋯50 nm particles. A mechanism for the formation of the finely dispersed heterophase structure in explosive welding is proposed. The microhardness of interlayers with the heterophase structure reaches 280 HV, which far exceeds the microhardness of copper (~130 HV) and tantalum (~160 HV). Many twins of deformation origin were found in the structure of the copper plate. The effect of heating temperature in the range from 100 to 900°C on the microhardness of copper, tantalum, and the Cu-Ta welded joint was studied. Upon heating to 900°C, the microhardness of the intermediate layer decreases from 280 to 150 HV. The reduction in the strength properties of the weld material is mainly due to structural transformations in copper.

  4. Effect of width of repair welding on stress distribution of dissimilar metal butt weld of nuclear piping

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Won Shik; Lee, Hwee Seung; Huh, Nam Su [Seoul National Univ. of Science and Technology, Seoul (Korea, Republic of)

    2013-10-15

    In the present work, the welding residual stress due to repair welding and the stress redistribution behavior due to primary pressure are investigated via 2-dimensional non-linear finite element analyses. In particular, the effect of repair welding width on stress distribution is emphasized. Although, large tensile residual stresses are produced at the PWSCC sensitive region due to repair welding, these stresses are highly reduced due to stress redistribution caused by primary load. Based on the present finite element results, it has been revealed that the effect of width of repair welding on stress distribution is not significant. In the past few years, many numerical and experimental works have been made to assess a structural integrity of cracked components subjected to primary water stress corrosion cracking in dissimilar metal weld (DMW) using Alloys 82/182 in nuclear industries worldwide. These works include a prediction of weld residual stresses in dissimilar metal weld by either numerical or experimental works since an accurate estimation of residual stress distribution in dissimilar metal weld is the most important element for integrity assessment of components subjected to primary water stress corrosion cracking. During an actual welding process, in general, a repair welding is often performed when a defect indication is detected during post-welding inspection. It has been revealed that such a repair welding could lead to higher tensile residual stress in dissimilar metal weld, which is detrimental to the crack growth due to primary water stress corrosion cracking. Thus, the prediction of residual stress considering a repair welding is needed, and then many efforts were made on this issue. In the present work, the effect of width of repair welding on stress distribution of dissimilar metal butt weld of nuclear piping is evaluated based on the detailed 2-dimensional non-linear finite element analyses. For this purpose, the welding residual stress due to

  5. Residual stress simulation of circumferential welded joints

    Directory of Open Access Journals (Sweden)

    Melicher R.

    2007-11-01

    Full Text Available Residual stresses are an important consideration in the component integrity and life assessment of welded structure. The welding process is very complex time dependent physical phenomenon with material nonlinearity. The welding is a thermal process with convection between fluid flow and welding body, between welding bodyand environment. Next type of boundary conditions is radiation and thermo-mechanical contact on the outer surface of gas pipe in the near of weld. The temperature variation so obtained is utilised to find the distribution of the stress field.In this paper, a brief review of weld simulation and residual stress modelling using the finite element method (FEM by commercial software ANSYS is presented. Thermo-elastic-plastic formulations using a von Mises yield criterion with nonlinear kinematics hardening has been employed. Residual axial and hoop stresses obtained from the analysis have been shown. The commercial FEM code ANSYS was used for coupled thermalmechanical analysis.

  6. Research on Ultrasonic Flaw Detection of Steel Weld in Spatial Grid Structure

    Science.gov (United States)

    Du, Tao; Sun, Jiandong; Fu, Shengguang; Zhang, Changquan; Gao, Qing

    2017-06-01

    The welding quality of spatial grid member is an important link in quality control of steel structure. The paper analyzed the reasons that the welding seam of small-bore pipe with thin wall grid structure is difficult to be detected by ultrasonic wave from the theoretical and practical aspects. A series of feasible detection methods was also proposed by improving probe and operation approaches in this paper, and the detection methods were verified by project cases. Over the years, the spatial grid structure is widely used the engineering by virtue of its several outstanding characteristics such as reasonable structure type, standard member, excellent space integrity and quick installation. The wide application of spatial grid structure brings higher requirements on nondestructive test of grid structure. The implementation of new Code for Construction Quality Acceptance of Steel Structure Work GB50205-2001 strengthens the site inspection of steel structure, especially the site inspection of ultrasonic flaw detection in steel weld. The detection for spatial grid member structured by small-bore and thin-walled pipes is difficult due to the irregular influence of sound pressure in near-field region of sound field, sound beam diffusion generated by small bore pipe and reduction of sensitivity. Therefore, it is quite significant to select correct detecting conditions. The spatial grid structure of welding ball and bolt ball is statically determinate structure with high-order axial force which is connected by member bars and joints. It is welded by shrouding or conehead of member bars and of member bar and bolt-node sphere. It is obvious that to ensure the quality of these welding positions is critical to the quality of overall grid structure. However, the complexity of weld structure and limitation of ultrasonic detection method cause many difficulties in detection. No satisfactory results will be obtained by the conventional detection technology, so some special

  7. Intermetallic alloy welding wires and method for fabricating the same

    Science.gov (United States)

    Santella, M.L.; Sikka, V.K.

    1996-06-11

    Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined. 4 figs.

  8. Structure and Hardness of 01570 Aluminum Alloy Friction Stir Welds Processed Under Different Conditions

    Science.gov (United States)

    Il'yasov, R. R.; Avtokratova, E. V.; Markushev, M. V.; Predko, P. Yu.; Konkevich, V. Yu.

    2015-10-01

    Structure and hardness of the 01570 aluminum alloy joints processed by friction stir welding at various speeds are investigated. It is shown that increasing the traverse tool speed lowers the probability of macrodefect formation in the nugget zone; however, this can lead to anomalous grain growth in the zone of contact with the tool shoulder. Typical "onion-like" structure of the weld consisting of rings that differ by optical contrast is formed for all examined welding regimes. It is demonstrated that this contrast is caused by the difference in the grain sizes in the rings rather than by their chemical or phase composition. Mechanisms of transformation of the alloy structure during friction stir welding are discussed.

  9. Influence of process parameters on the weld lines of a micro injection molded component

    DEFF Research Database (Denmark)

    Tosello, Guido; Gava, Alberto; Hansen, Hans Nørgaard;

    2007-01-01

    was designed and manufactured by µEDM (Electro Discharge Machining). Weld lines were quantitatively characterized both in the two-dimensional (direction and position) and three-dimensional range (surface topography characterization). Results showed that shape and position of weld lines are mainly influenced...

  10. Predicting welding distortion in a panel structure with longitudinal stiffeners using inherent deformations obtained by inverse analysis method.

    Science.gov (United States)

    Liang, Wei; Murakawa, Hidekazu

    2014-01-01

    Welding-induced deformation not only negatively affects dimension accuracy but also degrades the performance of product. If welding deformation can be accurately predicted beforehand, the predictions will be helpful for finding effective methods to improve manufacturing accuracy. Till now, there are two kinds of finite element method (FEM) which can be used to simulate welding deformation. One is the thermal elastic plastic FEM and the other is elastic FEM based on inherent strain theory. The former only can be used to calculate welding deformation for small or medium scale welded structures due to the limitation of computing speed. On the other hand, the latter is an effective method to estimate the total welding distortion for large and complex welded structures even though it neglects the detailed welding process. When the elastic FEM is used to calculate the welding-induced deformation for a large structure, the inherent deformations in each typical joint should be obtained beforehand. In this paper, a new method based on inverse analysis was proposed to obtain the inherent deformations for weld joints. Through introducing the inherent deformations obtained by the proposed method into the elastic FEM based on inherent strain theory, we predicted the welding deformation of a panel structure with two longitudinal stiffeners. In addition, experiments were carried out to verify the simulation results.

  11. Predicting Welding Distortion in a Panel Structure with Longitudinal Stiffeners Using Inherent Deformations Obtained by Inverse Analysis Method

    Directory of Open Access Journals (Sweden)

    Wei Liang

    2014-01-01

    Full Text Available Welding-induced deformation not only negatively affects dimension accuracy but also degrades the performance of product. If welding deformation can be accurately predicted beforehand, the predictions will be helpful for finding effective methods to improve manufacturing accuracy. Till now, there are two kinds of finite element method (FEM which can be used to simulate welding deformation. One is the thermal elastic plastic FEM and the other is elastic FEM based on inherent strain theory. The former only can be used to calculate welding deformation for small or medium scale welded structures due to the limitation of computing speed. On the other hand, the latter is an effective method to estimate the total welding distortion for large and complex welded structures even though it neglects the detailed welding process. When the elastic FEM is used to calculate the welding-induced deformation for a large structure, the inherent deformations in each typical joint should be obtained beforehand. In this paper, a new method based on inverse analysis was proposed to obtain the inherent deformations for weld joints. Through introducing the inherent deformations obtained by the proposed method into the elastic FEM based on inherent strain theory, we predicted the welding deformation of a panel structure with two longitudinal stiffeners. In addition, experiments were carried out to verify the simulation results.

  12. The interfacial structure of plated copper alloy resistance spot welded joint

    Science.gov (United States)

    Wu, Jingwei; Zhai, Guofu; Chen, Qing; Wang, Jianqi; Ren, Gang

    2008-09-01

    Plated copper alloys are widely used in electron industry. The plating lay caused the farther decreasing of the welding property of copper alloys, whose intrinsic weldability was poor. In this paper, the bronze and brass specimens with nickel-tin double plating layer were joined by resistance spot welding method. The microstructure and peel strength of the joints were investigated. The experiment results show that a sandwich-like structure was obtained in the faying surface after welding, and the nickel plating layer thickness had severe effect on the reliability of the joints.

  13. The interfacial structure of plated copper alloy resistance spot welded joint

    Energy Technology Data Exchange (ETDEWEB)

    Wu Jingwei [Xiamen Hongfa Electroacoustic Co., Ltd, 361021 Xiamen (China); Harbin Institute of Technology, 150001 Harbin (China)], E-mail: jingweiwu.hit@gmail.com; Zhai Guofu [Harbin Institute of Technology, 150001 Harbin (China); Chen Qing; Wang Jianqi; Ren Gang [Xiamen Hongfa Electroacoustic Co., Ltd, 361021 Xiamen (China)

    2008-09-15

    Plated copper alloys are widely used in electron industry. The plating lay caused the farther decreasing of the welding property of copper alloys, whose intrinsic weldability was poor. In this paper, the bronze and brass specimens with nickel-tin double plating layer were joined by resistance spot welding method. The microstructure and peel strength of the joints were investigated. The experiment results show that a sandwich-like structure was obtained in the faying surface after welding, and the nickel plating layer thickness had severe effect on the reliability of the joints.

  14. Optimization of Filler Metals Consumption in the Production of Welded Steel Structures

    Directory of Open Access Journals (Sweden)

    Pańcikiewicz K.

    2016-03-01

    Full Text Available The paper presents the some aspects of the optimization of filler metals consumption in the production of welded steel structures. Correct choice of beveling method can allow to decrease cost of production and increase quality. The review of calculation methods of filler metal consumption at the design stage was carried out. Moreover, the practical examples of amount of filler metals calculation were presented and analyzed. The article also contain examples of mobile apps which are makes it easy to see welding costs in just a few seconds. Apps as well as simple excel spreadsheets with correct mathematic equations allows to optimize welding process.

  15. Film videorecording and image processing systems: structural element welding

    Science.gov (United States)

    Konovalov, Nikolai A.; Veselovsky, Vladimir B.; Kovalenko, Vladimir I.; Lakhno, Nikolay I.; Skorik, Alexander D.; Furmanov, Valeri B.; Polyakov, Gennadiy A.

    1999-06-01

    With the aim of technological process automatization and control for high-frequency welding of different diameters pipes the machine-program complex (APC) was designed. APC gives the opportunity to create the cine- and telerecording of process in production conditions at the mill '159 - 529' of Novomoskovsky Tube Rolling Mill, Ukraine). With the help of APC in real functioning mill conditions the character of flashing zone length changing and the angle of convergence depending on pipe welding speed was investigated, also the zone of jumpers is defined. The comparison of theoretical and experimental data gave an opportunity to define a welding rate which is optimal for the most qualitative values of welded joints in the range of pipe products of mill '159 - 529.'

  16. Cold welding of copper nanowires with single-crystalline and twinned structures: A comparison study

    Science.gov (United States)

    Huang, Rao; Shao, Gui-Fang; Wen, Yu-Hua

    2016-09-01

    In this article, molecular simulations were adopted to explore the cold welding processes of copper nanowires with both single-crystalline and fivefold twinned structures. It was verified that the twinned nanowires exhibited enhanced strength but lowered elastic limit and ductility. Both nanowires could be successfully welded through rather small loadings, although their stress-strain responses toward compression were different. Meanwhile, more stress was accumulated in the twinned nanowire due to repulsive force of the twin boundaries against the nucleation and motions of dislocations. Moreover, by characterizing the structure evolutions in the welding process, it can be ascertained that perfect atomic order was finally built at the weld region in both nanowires. This comparison study will be of great importance to future mechanical processing of metallic nanowires.

  17. Hybrid Visual Servoing Control for Robotic Arc Welding Based on Structured Light Vision

    Institute of Scientific and Technical Information of China (English)

    XUDe; WANGLin-Kun; TUZhi-Guo; TANMin

    2005-01-01

    A novel hybrid visual servoing control method based on structured light vision is proposed for robotic arc welding with a general six degrees of freedom robot. It consists of a position control inner-loop in Cartesian space and two outer-loops. One is position-based visual control inCartesian space for moving in the direction of weld seam, i.e., weld seam tracking, another is imagebased visual control in image space for adjustment to eliminate the errors in the process of tracking.A new Jacobian matrix from image space of the feature point on structured light stripe to Cartesian space is provided for differential movement of the end-effector. The control system model is simplified and its stability is discussed. An experiment of arc welding protected by gas CO2 for verifying is well conducted.

  18. Feasibility Study on Welding Structure of the HT-7U Toroidal Field Coil Case

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Toroidal Field (TF) coil case of the HT-7U superconducting tokamak device is made of austenitic stainless steel 316LN and is designed to operate at cryogenic temperature (4 K). 316LN can retain high strength and fracture toughness at 4 K. Feasibility study on technical process of welding has been experimentally considered as a hopeful joint method for suppression of post-welding deformation and reduction of over-heating. Meanwhile the final range of stress in- tensity and the stress intensity factor (K) for pre-cracks of welding structure have been determined by using J-integral. These related results are optimistic and have shown that there's no problem in strength and fracture toughness at the vicinity of the pre-crack tip. This paper introduces the welding structure of TF coil case in detail.

  19. Holographic interferometry as a method to detect welding failures on ribbed iron structures

    Science.gov (United States)

    Vincitorio, F. M.; Budini, N.; Mulone, C.; Freyre, C.; Spector, M.; López Díaz, A. J.; Ramil Rego, A.; Yañez Casal, A.

    2013-11-01

    Metallic structures made of ribbed iron bars (ADN-420) are of common use in sheds and supporting structures. Usually, trusses are constructed with many pieces of ribbed iron bars, combined together through a welding process. Although ribbed iron manufacturers do not recommend this type of structure it is still frequently used. The main weakness of these trusses is the welding point because ribbed iron is not a material suitable for welding. This work presents results obtained from an analysis of welding points between ribbed iron bars extracted from a collapsed truss, by means of conventional (optical) and digital holographic interferometry (HI and DHI, respectively). The experiments were divided in two different series of studies. The first series were performed by HI on metallographic samples while the second series were done by DHI on different welding points. These results were complemented by metallographic analysis made in an external laboratory. DHI indicated that the bars did not have important failures but evidenced defects in one of the welding points under analysis. This information together with metallographic results allowed inferring that the collapse was probably due to an error in the design of the structure, since the iron bars were out of standard compliance.

  20. Flaws detection and localization in weld structure using the topological energy method

    Science.gov (United States)

    Lubeigt, Emma; Mensah, Serge; Rakotonarivo, Sandrine; Chaix, Jean-François; Gobillot, Gilles; Baqué, François

    2017-02-01

    The non-destructive testing of austenitic welds using ultrasound plays an important role in the assessment of the structural integrity and safety of critical structures in a nuclear reactor. The bedspring and the deck are complex welded structures of very restricted access; the ability to reliably detect and locate defects like cracks is therefore a difficult challenge. Ultrasonic testing is a well-recognized non-invasive technique which exhibits high characterization performances in homogeneous media (steel). However, its capabilities are hampered when operating in heterogeneous and anisotropic austenitic welds because of deviation and splitting of the ultrasonic beam. In order to rise to this important challenge, a model-based method is proposed, which takes into account a prior knowledge corresponding to the welding procedure specifications that condition the austenitic grains orientation within the weld and thus the wave propagation. The topological imaging method implemented is a differential approach which, compares signals from the reference defect-free medium to the inspected medium. It relies on combinations of two computed ultrasonic fields, one forward and one adjoint. Numerical simulations and experiments have been carried out to validate the practical relevance of this approach to detect and locate a flaw in a weld.

  1. Friction welding of TiAl intermetallics and structural steel by applying Inconel 718 as interlayer

    Institute of Scientific and Technical Information of China (English)

    Li Jinglong; Wang Zhongping; Xiong Jiangtao; Zhang Fusheng; Wang Yanfang

    2005-01-01

    lnconel 718 with thickness ranged from 0. 1 - 1.7 mm was chosen as interlayer to promote weldability in friction welding of TiAl intermetallics and structural steel such as AISI 4140, in which the welded joint presents single fin showing less welding deformation on TiAl side. The correlations between tensile strength and the interlayer thickness were analyzed and fitted to a model. It indicates an optimum interlayer thickness ranged from 0. 9 - 1.1 mm where the tensile strength reaches as high as 360 MPa. Otherwise, while the interlayer thickness decreases to 0. 1 mm, brittle compounds of TiC, Al2 Ti4 C2 and M7 C3 are formed in the welded zone so that the tensile strength decays. Thicker interlayer should be also avoided as double joints may occur at TiAl - Inconel 718 and Inconel 718 -AISI 4140, respectively, which lowers the tensile strength to some extent.

  2. Welding sequences optimization of box structure based on genetic algorithm method

    Institute of Scientific and Technical Information of China (English)

    CUI Xiao-fang; MA Jun; MENG Kai; ZHAO Wen-zhong; ZHAO Hai-yan

    2006-01-01

    In this article, The genetic algorithm method was proposed, that is, to establish the box structure's nonlinear three-dimension optimization numerical model based on thermo-mechanical coupling algorithm, and the objective function of welding distortion has been utilized to determine an optimum welding sequence by optimization simulation. The validity of genetic algorithm method combining with the thermo-mechanical nonlinear finite element model is verified by comparison with the experimental data where available. By choosing the appropriate objective function for the considered case, an optimum welding sequence is determined by a genetic algorithm. All done in this study indicates that the new method presented in this article will have important practical application for designing the welding technical parameters in the future.

  3. GMA-laser Hybrid Welding of High-strength Fine-grain Structural Steel with an Inductive Preheating

    Science.gov (United States)

    Lahdo, Rabi; Seffer, Oliver; Springer, André; Kaierle, Stefan; Overmeyer, Ludger

    The industrial useof GMA-laser hybrid welding has increased in the last 10 years, due to the brilliant quality of the laser beam radiation, and higher laser output powers. GMA-laser hybrid welding processes operate in a common molten pool. The combination of the laser beam and the arc results in improved welding speed, penetration depth, heat affected zone and gap bridgeability. Single-layer, GMA-laser hybrid welding processes have been developed for high-strength fine-grain structural steels with a grade of S690QL and a thickness of 15 mm and 20 mm. In addition, the welding process is assisted by an integrated, inductive preheating process to improve the mechanical properties of the welding seam. By using the determined parameters regarding the energy per unit length, and the preheating temperature, welding seams with high quality can be achieved.

  4. Friction stir weld tools having fine grain structure

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-15

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

  5. Effects of LSP on micro-structures and residual stresses in a 4 mm CLAM steel weld joints

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xizhang, E-mail: chenxizhang@wzu.edu.cn [School of Mechanical and Electrical Engineering, Wenzhou University., Wenzhou 325035 (China); School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China); Fang, Yuanyuan [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China); Zhang, Shuyan; Kelleher, Joe F. [ISIS, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Zhou, Jianzhong [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China)

    2015-05-15

    The effects of laser shock processing (LSP) on the distribution of residual stress and micro-structure of China Low Activation Martensitic (CLAM) steel weldment were investigated via neutron diffraction and optical microscope (OM). A pair of 4 mm CLAM steel plates joined by GTA welding. Special attention is paid to the generation of high level compressive residual stresses introduced by LSP. Residual stress in longitudinal, normal and transversal direction at weldment surface and longitudinal stress through thickness are evaluated via neutron diffraction. Compressive residual stress after LSP occurred at more than 90% areas within the weld joint, it is almost double the areas of compressive stress compare to weldment surface before LSP. The maximum compressive normal residual stress becomes to −183 MPa after LSP from −63 MPa before LSP. The Modification of surface micro-structures including weld zone (WZ), heat affected zone (HAZ) and base metal (BM) are also discussed. Results to date demonstrate that laser shock processing has been a great potential method for the improvement of mechanical performance of components.

  6. Effect of welding parameters of the Nd:YAG laser on the penetration depth of cobalt chromium alloys.

    Science.gov (United States)

    Vlachogianni, V; Clark, R K F; Juszczyk, A S; Radford, D R

    2012-03-01

    The aim of the investigation was to study the effect of the laser welding parameters of energy and spot diameter on the penetration depth of the weld of cast Co-Cr alloy when a single weld was performed. Within the limitations of the study as voltage increased and the spot diameter decreased, penetration depth increased. However, SEM investigation showed more defects in the welded area under these circumstances. The clinical significance is that during selection of the welding parameters the thickness of the components to be welded should be considered to achieve an extended welded area without the induction of micro-structural defects.

  7. Effect of Thermal and Diffusion Processes on Formation of the Structure of Weld Metal in Laser Welding of Dissimilar Materials

    Science.gov (United States)

    Turichin, G. A.; Klimova, O. G.; Babkin, K. D.; Pevzner, Ya. B.

    2014-01-01

    The thermal and diffusion processes in laser welding of dissimilar materials are simulated. The active LaserCAD model for welding of dissimilar materials is amended. The developed model is verified for the Fe - Cu system. The microstructure of a weld of tin bronze and low-carbon steel is studied and the elements in the diffusion zone are analyzed. The computed and experimental data for laser and electron-beam welding are shown to agree well.

  8. Novel concepts in weld metal science: Role of gradients and composite structure

    Energy Technology Data Exchange (ETDEWEB)

    Matlock, D.K.; Olson, D.L.

    1991-12-01

    The effects of compositional and microstructural gradients on weld metal properties are being investigated. Crack propagation is solidified alloy structures is being characterized as to solidification orientation and the profile of the compositional variations. The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a compositional gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Special techniques to produce laboratory samples with microstructures which simulate the composition and microstructure gradients in solidified weld metal are used, along with appropriate mathematical models, to evaluate the properties of the composite weld metals. The composite modeling techniques are being applied to describe the effects of compositional and microstructural gradients on weld metal properties in Ni-Cu alloys. The development of metal matrix composition weld deposits on austenitic stainless steels has been studied. The particulate metal matrix composites were produced with ceramic or refractory metal powder filled cored wire, which was gas tungsten arc and gas metal arc welded.

  9. Effect of Structural Heterogeneity on In Situ Deformation of Dissimilar Weld Between Ferritic and Austenitic Steel

    Science.gov (United States)

    Ghosh, M.; Santosh, R.; Das, S. K.; Das, G.; Mahato, B.; Korody, J.; Kumar, S.; Singh, P. K.

    2015-08-01

    Low-alloy steel and 304LN austenitic stainless steel were welded using two types of buttering material, namely 309L stainless steel and IN 182. Weld metals were 308L stainless steel and IN 182, respectively, for two different joints. Cross-sectional microstructure of welded assemblies was investigated. Microhardness profile was determined perpendicular to fusion boundary. In situ tensile test was performed in scanning electron microscope keeping low-alloy steel-buttering material interface at the center of gage length. Adjacent to fusion boundary, low-alloy steel exhibited carbon-depleted region and coarsening of matrix grains. Between coarse grain and base material structure, low-alloy steel contained fine grain ferrite-pearlite aggregate. Adjacent to fusion boundary, buttering material consisted of Type-I and Type-II boundaries. Within buttering material close to fusion boundary, thin cluster of martensite was formed. Fusion boundary between buttering material-weld metal and weld metal-304LN stainless steel revealed unmixed zone. All joints failed within buttering material during in situ tensile testing. The fracture location was different for various joints with respect to fusion boundary, depending on variation in local microstructure. Highest bond strength with adequate ductility was obtained for the joint produced with 309L stainless steel-buttering material. High strength of this weld might be attributed to better extent of solid solution strengthening by alloying elements, diffused from low-alloy steel to buttering material.

  10. An Approach to Maximize Weld Penetration During TIG Welding of P91 Steel Plates by Utilizing Image Processing and Taguchi Orthogonal Array

    Science.gov (United States)

    Singh, Akhilesh Kumar; Debnath, Tapas; Dey, Vidyut; Rai, Ram Naresh

    2016-06-01

    P-91 is modified 9Cr-1Mo steel. Fabricated structures and components of P-91 has a lot of application in power and chemical industry owing to its excellent properties like high temperature stress corrosion resistance, less susceptibility to thermal fatigue at high operating temperatures. The weld quality and surface finish of fabricated structure of P91 is very good when welded by Tungsten Inert Gas welding (TIG). However, the process has its limitation regarding weld penetration. The success of a welding process lies in fabricating with such a combination of parameters that gives maximum weld penetration and minimum weld width. To carry out an investigation on the effect of the autogenous TIG welding parameters on weld penetration and weld width, bead-on-plate welds were carried on P91 plates of thickness 6 mm in accordance to a Taguchi L9 design. Welding current, welding speed and gas flow rate were the three control variables in the investigation. After autogenous (TIG) welding, the dimension of the weld width, weld penetration and weld area were successfully measured by an image analysis technique developed for the study. The maximum error for the measured dimensions of the weld width, penetration and area with the developed image analysis technique was only 2 % compared to the measurements of Leica-Q-Win-V3 software installed in optical microscope. The measurements with the developed software, unlike the measurements under a microscope, required least human intervention. An Analysis of Variance (ANOVA) confirms the significance of the selected parameters. Thereafter, Taguchi's method was successfully used to trade-off between maximum penetration and minimum weld width while keeping the weld area at a minimum.

  11. Comparative analysis of the friction stir welded aluminum-magnesium alloy joint grain structure

    Science.gov (United States)

    Zaikina, A. A.; Sizova, O. V.; Novitskaya, O. S.

    2015-10-01

    A comparative test of the friction stir welded aluminum-magnesium alloy joint microstructure for plates of a different thickness was carried out. Finding out the structuring regularities in the weld nugget zone, that is the strongest zone of the weld, the effects of temperature-deformational conditions on the promotion of a metal structure refinement mechanism under friction stir welding can be determined. In this research friction stir welded rolled plates of an AMg5M alloy; 5 and 8 mm thick were investigated. Material fine structure pictures of the nugget zone were used to identify and measure subgrain and to define a second phase location. By means of optical microscopy it was shown that the fine-grained structure developed in the nugget zone. The grain size was 5 flm despite the thickness of the plates. In the sample 5.0 mm thick grains were coaxial, while in the sample 8.0 mm thick grains were elongate at a certain angle to the tool travel direction.

  12. Friction Stir Lap Welding: material flow, joint structure and strength

    Directory of Open Access Journals (Sweden)

    Z.W. Chen

    2012-12-01

    Full Text Available Friction stir welding has been studied intensively in recent years due to its importance in industrial applications. The majority of these studies have been based on butt joint configuration and friction stir lap welding (FSLW has received considerably less attention. Joining with lap joint configuration is also widely used in automotive and aerospace industries and thus FSLW has increasingly been the focus of FS research effort recently. number of thermomechancal and metallurgical aspects of FSLW have been studied in our laboratory. In this paper, features of hooking formed during FSLW of Al-to-Al and Mg-to-Mg will first be quantified. Not only the size measured in the vertical direction but hook continuity and hooking direction have been found highly FS condition dependent. These features will be explained taking into account the effects of the two material flows which are speed dependent and alloy deformation behaviour dependent. Strength values of the welds will be presented and how strength is affected by hook features and by alloy dependent local deformation behaviours will be explained. In the last part of the paper, experimental results of FSLW of Al-to-steel will be presented to briefly explain how joint interface microstructures affect the fracturing process during mechanical testing and thus the strength. From the results, tool positioning as a mean for achieving maximum weld strength can be suggested.

  13. Structure formation and properties of a copper-aluminum joint produced by ultrasound-assisted explosive welding

    Science.gov (United States)

    Kuz'min, E. V.; Peev, A. P.; Kuz'min, S. V.; Lysak, V. I.

    2017-08-01

    The effect of ultrasound-assisted explosive welding on the structure formation and the properties of copper-aluminum joints is studied. Ultrasound-assisted explosive welding improves the quality of formed copper-aluminum joints, i.e., enhances their strength and significantly reduces the amount of fused metal over the entire weldability range. It is shown that ultrasound-assisted explosive welding can noticeably extend the weldability range of the copper-aluminum pair to obtain equal-in-strength joints with minimum structural heterogeneity in the wide welding range.

  14. Work in progress on fatigue of welded structures in the Nordic countries

    DEFF Research Database (Denmark)

    Samuelsson, Jack; Haagensen, Per; Agerskov, Henning

    2006-01-01

    on fatigue of welded structures progressing in this region, but it does provide a cross-section of those activities that has been brought to the attention of the national societies. Several of the issues reported here represent sub-tasks within the project Q-FAB: Quality and Cost of Fabricated Advanced......Close international cooperation has been an important characteristic of the research on fatigue of welded structures in the Nordic countries. Cooperative projects were initiated already in the mid-1980's and have continued for nearly 20 years. This report is by no means exhaustive of all the work...... Welded Structures, which is partially funded by the Nordic Innovation Centre and numerous national funding agencies. The project has 10 industry companies, 5 universities and one research centre as partners....

  15. Structure of the welding zone between titanium and orthorhombic titanium aluminide for explosion welding: II. Local melting zones

    Science.gov (United States)

    Grinberg, B. A.; Ivanov, M. A.; Rybin, V. V.; Kuz'min, S. V.; Lysak, V. I.; Elkina, O. A.; Patselov, A. M.; Antonova, O. V.; Inozemtsev, A. V.

    2011-10-01

    The structure and chemical composition of the local melting zones that form during explosion welding of orthorhombic titanium aluminide with commercial-purity titanium near a wavy interface between them are studied. The Rayleigh number is estimated to propose a possible mechanism for the formation of a concentric structure in these zones. Titanium aluminide fragments are detected near the zone boundaries. It is assumed that the fragmentation in the transition zone is caused by the division of a material into loosely coupled microvolumes under the action of a strong external action in a time comparable with the explosion time. Outside the transition zone, fragmentation occurs via a traditional way beginning from dislocation accumulation. Both processes occur in titanium aluminide and only one process (banded structure formation) takes place in titanium.

  16. Possibility of Inducing Compressive Residual Stresses in Welded Joints of SS400 Steels

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Since the welded constructions produce easily stress corrosion cracking (SCC) or fatigue disruption in corrosive medium or under ripple load, two methods inducing compressive stress on structural surfaces by anti-welding-heating treatment (AWHT) and explosion treatment (ET) are presented. The results show that they are good ways to resisting SCC on the welded SS400 steel or other components.

  17. 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.

  18. Structured Functional Principal Component Analysis

    Science.gov (United States)

    Shou, Haochang; Zipunnikov, Vadim; Crainiceanu, Ciprian M.; Greven, Sonja

    2015-01-01

    Summary Motivated by modern observational studies, we introduce a class of functional models that expand nested and crossed designs. These models account for the natural inheritance of the correlation structures from sampling designs in studies where the fundamental unit is a function or image. Inference is based on functional quadratics and their relationship with the underlying covariance structure of the latent processes. A computationally fast and scalable estimation procedure is developed for high-dimensional data. Methods are used in applications including high-frequency accelerometer data for daily activity, pitch linguistic data for phonetic analysis, and EEG data for studying electrical brain activity during sleep. PMID:25327216

  19. Finite Element Modeling for the Structural Analysis of Al-Cu Laser Beam Welding

    Science.gov (United States)

    Hartel, Udo; Ilin, Alexander; Bantel, Christoph; Gibmeier, Jens; Michailov, Vesselin

    Laser beam welding of aluminum and copper (Al-Cu) materials is a cost efficient joining technology to produce e.g. connector elements for battery modules. Distortion low connections can be achieved, which have electrical favorable properties. Numerical simulation of the laser beam welding process of Al-Cu dissimilar materials can provide further insight into principal process mechanisms and mechanical response of the joint parts. In this paper a methodology is introduced to investigate the structural behavior of Al-Cu joints in overlap joint with respect to welding distortions and residual stresses. First the material model of the homogeneous base materials are validated. Next, a generic material model approach is used to simulate the structural behavior of heterogeneous Al-Cu connections.

  20. Numerical estimation of structure composition in laser-arc hybrid welded joints

    Directory of Open Access Journals (Sweden)

    W. Piekarska

    2010-10-01

    Full Text Available This work presents results of numerical estimation of the structure composition in laser-arc hybrid welded joints. Temperature field wasobtained by the solution of the heat transfer equation with activity of inner heat sources. Convective motion of liquid metal in the welding pool, latent heat of fusion and latent heat of phase transformation were taken into account in the algorithms for numerical analysis of the temperature field. The volumetric fractions of arising phases were determined on the basis of Johnson - Mehl - Avrami (JMA model for diffusive transformations and Koistinen - Marburger (KM model for martensitic transformation. On the basis of calculated temperature distribution the structure composition in welded joint was numerically estimated, taking into account CHT and CCT diagrams for S355 steel.

  1. Optimization of structures and components

    CERN Document Server

    Muñoz-Rojas, Pablo Andrés

    2013-01-01

    Written by an international group of active researchers in the field, this volume presents innovative formulations and applied procedures for sensitivity analysis and structural design optimization. Eight chapters discuss subjects ranging from recent developments in the determination and application of topological gradients, to the use of evolutionary algorithms and meta-models to solve practical engineering problems. With such a comprehensive set of contributions, the book is a valuable source of information for graduate students and researchers entering or working in the matter.

  2. Generalized Structured Component Analysis with Latent Interactions

    Science.gov (United States)

    Hwang, Heungsun; Ho, Moon-Ho Ringo; Lee, Jonathan

    2010-01-01

    Generalized structured component analysis (GSCA) is a component-based approach to structural equation modeling. In practice, researchers may often be interested in examining the interaction effects of latent variables. However, GSCA has been geared only for the specification and testing of the main effects of variables. Thus, an extension of GSCA…

  3. Influence of pin structure on microstructure and mechanical properties of friction stir welded AA 6063 (AlMgSi 0.5) aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sayer, S.; Ceyhun, V. [Ege Univ., Izmir (Turkey)

    2008-07-01

    In this study, AA 6063 (AlMgSi0.5) Aluminum alloy plates were welded by a solid state welding procedure, friction stir welding (FSW). The influence of pin structure on the microstructure of the weld region and the mechanical properties of the joints were studied. It has been seen that the helical structure on pinscrew has an effective role on the formation of a zigzag line in the weld region. While rather long and uninterrupted zigzag lines in the weld region are obtained when right helical pinscrew is used, left helical pinscrew gave rise to shorter zigzag lines. While the zigzag line has no effect on the mechanical properties of the as-welded joint, heat treatment after the welding (PWHT) procedure seriously affects the strength of the joint due to the zigzag line formed in the weld region. The mechanical strength decreases with right helical pinscrew in PWHT, whereas, left helical pinscrew causes an increase in mechanical strength. (orig.)

  4. Preliminary evaluation of collagen as a component in the thermally induced 'weld'

    Science.gov (United States)

    Lemole, G. M., Jr.; Anderson, R. Rox; DeCoste, Sue

    1991-06-01

    A simple thermodynamic approach to tissue 'welding' was studied. Fresh bovine tendon (67% type I collagen) was sectioned into disk shaped pieces, pairs of which were inserted between bowed glass coverslips and wrapped in aluminum foil. The packets were heated in a waterbath according to two protocols. In group I, packets were tested for four minutes at temperatures between 55-65 degree(s)C, in 1 degree(s)C intervals. In group II, the packets were kept at 62 degree(s)C for 4 minutes while the rate of cooling was altered. The force necessary to separate the tendon disks was then measured. The optimal temperature for tissue bonding (group I) was 62 degree(s)C (598 gm/in2). Stress values below 250 gm/in2 could be achieved without heat application and were considered non-welds. Group II showed that the faster the sample cools, the stronger the bond. Several conclusions can be postulated. The narrow temperature region necessary for tissue 'welding' strongly suggests that melting of type I collagen fibrils is involved. Bonding presumably occurs at 62 degree(s)C by allowing (alpha) -strands from the collagen super-helix molecule to form new, random connections. Group II results suggest that trans-incisional reannealing of unraveled helices does not play a role in tissue bonding. Rapid cooling allows less time for extended helix reformation; same-side a-helix reannealing may inhibit effective welds by reducing sites for trans-incisional visco-elastic bonding. Although the exact nature and optimization of thermal tissue 'welds' remains unclear, the behavior of collagen appears to play a central role.

  5. Explosive welding method for manufacturing ITER-grade 316L(N)/CuCrZr hollow structural member

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Rui, E-mail: mr9980@163.com [PLA University of Science and Technology, Nanjing 210007 (China); Wang, Yaohua [PLA University of Science and Technology, Nanjing 210007 (China); Wu, Jihong [Southwestern Institute of Physics, Chengdu 610041 (China); Duan, Mianjun [PLA University of Science and Technology, Nanjing 210007 (China)

    2014-12-15

    Highlights: • Develop a new explosive welding method to fabricate the cooling channel of FW. • Utilize effective energy model to accurately calculate optimal welding parameters. • Provide an efficient way for manufacturing high-ductility hollow structural member. - Abstract: In this study, a new explosive welding method provided an effective way for manufacturing ITER-grade 316L(N)/CuCrZr hollow structural member. The welding parameters (stand-off distance and explosion rate) were calculated respectively using equivalent frontal collision wave model and effective energy model. The welded samples were subject to two step heat treatment cycles (solution annealing and aging). Optical microscopy (OM) and scanning electron microscopy (SEM) were utilized to analyze the microstructure of bonding interface. The mechanical properties of the welded samples were evaluated through microhardness test and tensile test. Moreover, the sealing property of the welded specimens was measured through helium leak test. Microstructural analysis showed that the welded sample using effective energy model had an ideal wavy interface. The results of microhardness test revealed an increase in hardness for both sides near to the bonding interface. And the hardening phenomenon of interface region disappeared after the solution annealing. SEM observation indicated that the samples with the post heat treatments exhibited a ductile fracture with dimple features after tensile test. After the specimens undergo aging strengthening, there was an obvious increase in the strength for all specimens. The helium leak test results have proven that the welded specimens are soundness.

  6. Welding of girders to insert plates of composite steel-concrete structure of tower in Kuwait

    OpenAIRE

    A. Lisiecki; J. Szlek; A. Klimpel

    2007-01-01

    Purpose: A study of influence of preheating and MMA welding technique of tee-joints of plate girders to insert plates of a composite steel-concrete structure of the telecommunication tower, on the properties and quality of the concrete in the region of the insert plate has been carried out.Design/methodology/approach: Studies of thermo-mechanical phenomena during manual arc welding MMA of tee-joints between plate girders and insert plates were carried out to identify possible sources of the ...

  7. Welding of girders to insert plates of composite steel-concrete structure

    OpenAIRE

    A. Klimpel; A. Lisiecki; J. Szlek

    2007-01-01

    Purpose: of this paper: A study of influence of preheating and MMA welding technique of tee-joints of plate girders to insert plates of a composite steel-concrete structure of the telecommunication tower, on the properties and quality of the concrete in the region of the insert plate has been carried out.Design/methodology/approach: Studies of thermo-mechanical phenomena during manual arc welding MMA of tee-joints between plate girders and insert plates were carried out to identify possible s...

  8. Effects of mechanical force on grain structures of friction stir welded oxide dispersion strengthened ferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Han, Wentuo, E-mail: hanwentuo@hotmail.com [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Tsuda, Naoto [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Serizawa, Hisashi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Chen, Dongsheng [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Je, Hwanil [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Ha, Yoosung [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Morisada, Yoshiaki [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Noto, Hiroyuki [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2014-12-15

    The weldability of oxide dispersion strengthened (ODS) ferritic steels is a critical obstructive in the development and use of these steels. Friction stir welding has been considered to be a promising way to solve this problem. The main purpose of this work was to reveal the effects of mechanical force on grain structures of friction stir welded ODS ferritic steel. The grain appearances and the misorientation angles of grain boundaries in different welded zones were investigated by the electron backscatter diffraction (EBSD). Results showed that the mechanical force imposed by the stir tool can activate and promote the recrystallization characterized by the transformation of boundaries from LABs to HABs, and contribute to the grain refinement. The type of recrystallization in the stir zone can be classified as the continuous dynamic recrystallization (CDRX)

  9. Particulate and gaseous emissions when welding aluminum alloys.

    Science.gov (United States)

    Cole, Homer; Epstein, Seymour; Peace, Jon

    2007-09-01

    Fabrication and repair of aluminum components and structures commonly involves the use of electric arc welding. The interaction of the arc and the metal being welded generates ultraviolet radiation, metallic oxides, fumes, and gases. Aluminum is seldom used as the pure metal but is often alloyed with other metals to improve strength and other physical properties. Therefore, the exact composition of any emissions will depend on the welding process and the particular aluminum alloy being welded. To quantify such emissions, The Aluminum Association sponsored several studies to characterize arc welding emissions by the gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) processes for various combinations of base and filler alloys. In all cases, the tests were conducted under conditions that could be found in a production weld shop without forced ventilation. The concentrations of each analyte that a welder could be exposed to were greatly affected by the welding process, the composition of the base and filler alloys, the position of the welder, and the welding helmet. The results obtained can be used by employers to identify and control potential hazards associated with the welding of aluminum alloys and can provide the basis for hazard communication to employees involved in the welding of these alloys.

  10. Detecting the bonding state of explosive welding structures based on EEMD and sensitive IMF time entropy

    Science.gov (United States)

    Si, Yue; Zhang, Zhousuo; Liu, Qiang; Cheng, Wei; Yuan, Feichen

    2014-07-01

    With the increasing application of explosive welding structures in many engineering fields, interface bonding state detection has become more and more significant to avoid catastrophic accidents. However, the complexity of the interface bonding state makes this task challenging. In this paper, a new method based on ensemble empirical mode decomposition (EEMD) and sensitive intrinsic mode function (IMF) time entropy is proposed for this task. As a self-adaptive non-stationary signal analysis method, EEMD can decompose a complicated signal into a set of IMFs with truly physical meaning, which is beneficial to allocate the structural vibration response signal containing a wealth of bonding state information to certain IMFs. Then, the time entropies of these IMFs are calculated to quantitatively assess the bonding state of the explosive welding structure. However, the IMF time entropies have different sensitivities to the bonding state. Therefore, the most sensitive IMF time entropy is selected based on a distance evaluation technique to detect the bonding state of explosive welding structures. The proposed method is applied to bonding state detection of explosive welding pipes in three cases, and the results demonstrate its effectiveness.

  11. Structure and properties of fixed joints formed by ultrasonic-assisted friction-stir welding

    Energy Technology Data Exchange (ETDEWEB)

    Fortuna, S. V., E-mail: s-fortuna@ispms.ru; Ivanov, K. V., E-mail: ikv@ispms.ru; Eliseev, A. A., E-mail: alan@ispms.ru [Institute of Strength Physics and Materials ScienceTomsk, 634055 (Russian Federation); Tarasov, S. Yu., E-mail: tsy@ispms.ru; Ivanov, A. N., E-mail: ivan@ispms.ru; Rubtsov, V. E., E-mail: rvy@ispms.ru; Kolubaev, E. A., E-mail: eak@ispms.ru [Institute of Strength Physics and Materials ScienceTomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    This paper deals with structure and properties of aluminum alloy 7475 and its joints obtained by friction stir welding including under ultrasonic action. Microhardness measurements show that ultrasonic action increases strength properties of the joints. Optical and transmission electron microscopy reveals that this effect is related to the precipitation of tertiary coherent S-and T-phase particles.

  12. Mechanical properties of full austenitic welding joint at cryogenic temperature for the ITER toroidal field coil structure

    Energy Technology Data Exchange (ETDEWEB)

    Iguchi, M., E-mail: iguchi.masahide@jaea.go.jp [Japan Atomic Energy Agency, ITER Superconducting Magnet Technology Group, 801-1 Mukoyama, Naka, Ibaraki 311-0193 Japan (Japan); Saito, T.; Kawano, K.; Chida, Y.; Nakajima, H. [Japan Atomic Energy Agency, ITER Superconducting Magnet Technology Group, 801-1 Mukoyama, Naka, Ibaraki 311-0193 Japan (Japan); Ogawa, T.; Katayama, Y.; Ogata, H.; Minemura, T. [Toshiba Cooperation, Power Systems Company, 2-4, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 2300-0045 (Japan); Tokai, D.; Niimi, K. [Kawasaki Heavy Industries, LTD., Plant and Infrastructure Company, Production Center, 8, Niijima, Harima-cho, Kako-gun, Hyogo 675-0180 (Japan)

    2013-10-15

    Highlights: • No significant distribution of tensile strengths at 4 K, 77 K and room temperature along welding thickness of 200 mm manufactured by one side narrow gap TIG welding with FMYJJ1. • Tensile strengths at cryogenic temperature of welded joint are increased with increasing of C + N contents of base material. • In the case that welded joint is manufactured by combination of different base materials, strength at 4 K of welded joints are below strength of base material having higher C + N contents. -- Abstract: ITER toroidal field coil (TFC) structures are large welding structures composed of coil case and support structures made of heavy thick high strength and high toughness stainless steels. Japan Atomic Energy Agency plans to apply narrow gap Tungsten Inert Gas (TIG) welding with FMYJJ1 (0.03C–10Mn–12Cr–14Ni–5Mo–0.13N) which is full austenitic stainless filler material. In order to evaluate effect of base material thickness and combinations of base material on tensile properties, tensile tests were performed at room temperature, 77 K and 4 K by using tensile specimens taken from 200 mm thickness welded joints of two combinations of base materials and 40 mm thickness welded joints of four combinations of base materials. As the results, it was confirmed that there were no large distribution of yield and tensile strength along the thickness of welded joints of 200 mm thickness and yield and tensile strengths of welded joints were decreased with decreasing of C + N contents of base material.

  13. Effective modelling, analysis and fatigue assessment of welded structures; Effektive Modellbildung, Analyse und Bewertung fuer die rechnerische Lebensdaueranalyse geschweisster Strukturen

    Energy Technology Data Exchange (ETDEWEB)

    Rauch, R.; Schiele, S. [CADFEM GmbH, Stuttgart (Germany); Rother, K.

    2007-07-01

    Analysis of welded structures is a challenge for the analyst. Improvements of Soft- and Hardware enable an analysis containing full assemblies. Especially for welded structures these possibilities show significant benefits leading to more detailed descriptions of the flux of forces and reducing the effort for the engineer. This paper covers the method for modeling, structural analysis and assessment of welded structures using Finite Element Analysis. A hierarchical concept to localize highly stressed regions using a global model and a local approach according to a notch stress analysis will be presented. (orig.)

  14. 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 plasti...... as a knowledge handbook for laser welding of plastic components. This document should provide the information for all aspects of plastic laser welding and help the design engineers to take all critical issues into consideration from the very beginning of the design phase....

  15. Technique for the residual life assessment of high temperature components based on creep-rupture testing on welded miniature specimens

    Energy Technology Data Exchange (ETDEWEB)

    Garzillo, A.; Guardamagna, C.; Moscotti, L.; Ranzani, L. [Ente Nazionale per l`Energia Elettrica, Milan (Italy)

    1995-06-01

    Following the present trend in the development of advanced methodologies for residual life assessment of high temperature components operating in power plants, particularly in non destructive methods, a testing technique has been set up at ENEL-CRAM based on creep-rupture testa in an argon on welded miniature specimens. Five experimental systems for creep-rupture tests in an argon atmosphere have been set up which include high accuracy systems, vacuum chambers and exrwnsometer devices. With the aim of establishing and validating the suitability of the experimental methodology, creep-rupture and interrupted creep testing programmes have been performed on miniature specimens (2 mm diameter and 10 mm gauge lenght). On the basis of experience gathered by various European research laboratories, a miniature specimen construction procedure has been developed using a laser welding technique for joining threaded heads to sample material. Low alloy ferritic steels, such as virgin 2.25CrlMo, 0.5Cr 0.5Mo 0.25V, and IN 738 superalloy miniature specimens have been investigated and the results, compared with those from standard specimens, show a regular trend in deformation vs time. Additional efforts to provide guidelines for material sampling from each plant component will be required in order to reduce uncertainties in residual life prediction.

  16. Joining Technology of Dissimilar Materials for Automotive Components(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Meung Ho Rhee; Jong Ho Song; Woo Young Chung; Young Myoung Kim

    2004-01-01

    Joining techniques of dissimilar materials for lightweight multi-material automotive body structure were discussed. The joining of 1 .4 mm thickness steel and 2 mm thickness of Al were performed by the new method that is hybrid laser welding system. After aluminum and steel were welded by laser hybrid welding process, the micro-structure investment and the micro-hardness test were carried out. Hybrid laser welding promises a bright future in joining technology of dissimilar materials for automotive components.

  17. Mechanical property variation within Inconel 82/182 dissimilar metal weld between low alloy steel and 316 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Changheui [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)], E-mail: chjang@kaist.ac.kr; Lee, Jounghoon [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Sung Kim, Jong; Eun Jin, Tae [Korea Power Engineering Company, 360-9 Mabuk-ri, Guseong-eup, Yongin-si, Gyeonggi-do 449-713 (Korea, Republic of)

    2008-09-15

    In several locations of pressurized water reactors, dissimilar metal welds using Inconel welding wires are used to join the low alloy steel components to stainless-steel pipes. Because of the existence of different materials and chemistry variation within welds, mechanical properties, such as tensile and fracture properties, are expected to show spatial variation. For design and integrity assessment of the dissimilar welds, these variations should be evaluated. In this study, dissimilar metal welds composed of low alloy steel, Inconel 82/182 weld, and stainless steel were prepared by gas tungsten arc welding and shielded metal arc welding techniques. Microstructures were observed using optical and electron microscopes. Typical dendrite structures were observed in Inconel 82/182 welds. Tensile tests using standard and mini-sized specimens and micro-hardness tests were conducted to measure the variation in strength along the thickness of the weld as well as across the weld. In addition, fracture toughness specimens were taken at the bottom, middle, and top of the welds and tested to evaluate the spatial variation along the thickness. It was found that while the strength is about 50-70 MPa greater at the bottom of the weld than at the top of the weld, fracture toughness values at the top of the weld are about 70% greater than those at the bottom of the weld.

  18. Reliability assessment of fatigue critical welded details in wind turbine jacket support structures

    DEFF Research Database (Denmark)

    Branner, Kim; Stensgaard Toft, Henrik; Haselbach, Philipp Ulrich;

    2013-01-01

    This paper describes a probabilistic approach to reliability assessment of fatigue critical welded details in jacket support structures for offshore wind turbines. The analysis of the jacket response to the operational loads is performed using Finite Element Method (FEM) simulations in SIMULIA...... Abaqus. Fatigue stress cycles are computed on the jacket members by applying tower top loads from an aeroelastic simulation with superimposed marine loads and in accordance to the IEC-61400-3 guidelines for operational conditions. The combined effect of the hydrodynamic loads and the rotor loads...... on the jacket structure is analyzed in a de-coupled scheme, but including the structural dynamics of the support structure. The failure prediction of the welded joints, connecting the individual members of the support structure is based on SN-curves and Miners rule according to ISO 19902 and DNV-RP-C203/DNV...

  19. Influence of pin geometry on mechanical and structural properties of butt friction stir welded 2024-T351 aluminum alloy

    Directory of Open Access Journals (Sweden)

    Radisavljević Igor Z.

    2015-01-01

    Full Text Available The aim of this work was to investigate the combined effect of small difference in pin geometry, together with rotation and welding speed on the weldability, mechanical and structural properties of FSW 2024-T351 Al plates. The only difference in tool pin design was the shape of thread: regular and rounded. Specimens were welded using rotation rate of 750 rev/min and welding speeds of 73 and 93 mm/min. In all four cases, specimens were defect free, with good or acceptable weld surface. Modification in pin design showed strong influence on macro structure and hardness distribution. Weak places are identified as low hardness zone, close to the nugget zone and are in good agreement with fracture location in tensile testing. Weld efficiency, as a measure of weld quality, are better in case of 310 tool, while UTS values can differ up to 13% for the equal welding parameters. Therefore, it can be assumed that small modification in tool design, particularly in pin geometry, can have great influence on weld formation and mechanical properties.

  20. Innovative Tools Advance Revolutionary Weld Technique

    Science.gov (United States)

    2009-01-01

    The iconic, orange external tank of the space shuttle launch system not only contains the fuel used by the shuttle s main engines during liftoff but also comprises the shuttle s backbone, supporting the space shuttle orbiter and solid rocket boosters. Given the tank s structural importance and the extreme forces (7.8 million pounds of thrust load) and temperatures it encounters during launch, the welds used to construct the tank must be highly reliable. Variable polarity plasma arc welding, developed for manufacturing the external tank and later employed for building the International Space Station, was until 1994 the best process for joining the aluminum alloys used during construction. That year, Marshall Space Flight Center engineers began experimenting with a relatively new welding technique called friction stir welding (FSW), developed in 1991 by The Welding Institute, of Cambridge, England. FSW differs from traditional fusion welding in that it is a solid-state welding technique, using frictional heat and motion to join structural components without actually melting any of the material. The weld is created by a shouldered pin tool that is plunged into the seam of the materials to be joined. The tool traverses the line while rotating at high speeds, generating friction that heats and softens but does not melt the metal. (The heat produced approaches about 80 percent of the metal s melting temperature.) The pin tool s rotation crushes and stirs the plasticized metal, extruding it along the seam as the tool moves forward. The material cools and consolidates, resulting in a weld with superior mechanical properties as compared to those weld properties of fusion welds. The innovative FSW technology promises a number of attractive benefits. Because the welded materials are not melted, many of the undesirables associated with fusion welding porosity, cracking, shrinkage, and distortion of the weld are minimized or avoided. The process is more energy efficient, safe

  1. Metallic layered composite materials produced by explosion welding: Structure, properties, and structure of the transition zone

    Science.gov (United States)

    Mal'tseva, L. A.; Tyushlyaeva, D. S.; Mal'tseva, T. V.; Pastukhov, M. V.; Lozhkin, N. N.; Inyakin, D. V.; Marshuk, L. A.

    2014-10-01

    The structure, morphology, and microhardness of the transition zone in multilayer metallic composite joints are studied, and the cohesion strength of the plates to be joined, the mechanical properties of the formed composite materials, and fracture surfaces are analyzed. The materials to be joined are plates (0.1-1 mm thick) made of D16 aluminum alloy, high-strength maraging ZI90-VI (03Kh12N9K4M2YuT) steel, BrB2 beryllium bronze, and OT4-1 titanium alloy. Composite materials made of different materials are shown to be produced by explosion welding. The dependence of the interface shape (smooth or wavelike) on the physicomechanical properties of the materials to be joined is found. The formation of a wavelike interface is shown to result in the formation of intense-mixing regions in transition zones. Possible mechanisms of layer adhesion are discussed.

  2. MICROSTRUCTURE AND FATIGUE PROPERTIES OF DISSIMILAR SPOT WELDED JOINTS OF AISI 304 AND AISI 1008

    Directory of Open Access Journals (Sweden)

    Nachimani Charde

    2013-06-01

    Full Text Available Carbon steel and stainless steel composites are being more frequently used for applications requiring a corrosion resistant and attractive exterior surface and a high strength structural substrate. Spot welding is a potentially useful and efficient jointing process for the production of components consisting of these two materials. The spot welding characteristics of weld joints between these two materials are discussed in this paper. The experiment was conducted on dissimilar weld joints using carbon steel and 304L (2B austenitic stainless steel by varying the welding currents and electrode pressing forces. Throughout the welding process; the electrical signals from the strain sensor, current transducer and terminal voltage clippers are measured in order to understand each and every millisecond of the welding process. In doing so, the dynamic resistances, heat distributions and forging forces are computed for various currents and force levels within the good welds’ regions. The other process controlling parameters, particularly the electrode tip and weld time, remained constant throughout the experiment. The weld growth was noted for the welding current increment, but in the electrode force increment it causes an adverse reaction to weld growth. Moreover, the effect of heat imbalance was clearly noted during the welding process due to the different electrical and chemical properties. The welded specimens finally underwent tensile, hardness and metallurgical testing to characterise the weld growth.

  3. End-effector for robotic assembly of welded truss structures in space

    Science.gov (United States)

    Brewer, William V.

    1991-01-01

    In June 1987, work was initiated at LaRC on end-effectors and preloaded joints for robotic truss assembly. This is part of an on-going research effort centered on a test facility that assembles 1 inch x 2 m identical struts into an 8 m diameter x 1.5 m deep platform truss. A detailed description of the test facility was published. The end-effector being used for the LaRC assembly demonstration is quite suitable for the Precision Segmented Reflector or other precision applications. These require high stiffness provided by mechanical joint preloads. Stiffness obtained in this manner is only required and provided over a load range far less than the ultimate strength of the strut tubes. Beyond this useful range, truss behavior is somewhat unpredictable. Mechanically preloaded joints of this type are less suitable for applications such as the Aero Brake where predictable strength and stiffness are required over a greater fraction of the load bearing capacity of component parts. Preliminary studies of the Aerobrake support truss indicate that struts of at least 3 different diameters and various lengths would improve performance. The double-ended end-effector currently in service is designed for only one diameter and length. Anticipated single-ended versions can accommodate varying lengths but not multiple diameters. Tradeoff considerations for welded joints relative to their mechanically preloaded counterparts are presented. Conclusions from this research are as follows: (1) repair by cut and re-weld on the original weld site should be research; (2) welded joints, though repairable, should not be used where high repair frequencies are anticipated; and (3) welded joints should be considered for an Aero Brake truss.

  4. Role of the micro/macro structure of welds in crack nucleation and propagation in aerospace aluminum-lithium alloy

    Science.gov (United States)

    Talia, George E.

    1996-01-01

    Al-Li alloys offer the benefits of increased strength, elastic modulus and lower densities as compared to conventional aluminum alloys. Martin Marietta Laboratories has developed an Al-Li alloy designated 2195 which is designated for use in the cryogenic tanks of the space shuttle. The Variable Polarity Plasma Arc (VPPA) welding process is currently being used to produce these welds [1]. VPPA welding utilizes high temperature ionized gas (plasma) to transfer heat to the workpiece. An inert gas, such as Helium, is used to shield the active welding zone to prevent contamination of the molten base metal with surrounding reactive atmospheric gases. [1] In the Space Shuttle application, two passes of the arc are used to complete a butt-type weld. The pressure of the plasma stream is increased during the first pass to force the arc entirely through the material, a practice commonly referred to as keyholing. Molten metal forms on either side of the arc and surface tension draws this liquid together as the arc passes. 2319 Al alloy filler material may also be fed into the weld zone during this pass. During the second pass, the plasma stream pressure is reduced such that only partial penetration of the base material is obtained. Al 2319 filler material is added during this pass to yield a uniform, fully filled welded joint. This additional pass also acts to alter the grain structure of the weld zone to yield a higher strength joint.

  5. 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

  6. Finite Element Simulation of Plasma Transferred ARC Welding [PTAW] of Structural Steel

    Directory of Open Access Journals (Sweden)

    PV Senthiil

    2014-10-01

    Full Text Available Plasma transferred Arc welding is one of the most widely used welding process, in which the metals are fused just above the melting point, and makes the metal to fuse. It is employed in many applications like tool die and metal casting, strip metal welding etc. This investigation is to analyze temperature distribution residual stress and distortion by varying the heat source parameter in SYSWELD, and compared the results with ANSYS. The simulation of Plasma Transferred Arc welding was of structural steel plate performed using a non-linear transient heat transfer analysis. Heat losses due to convection and variation of material properties with temperature were considered in this analysis. To incorporate the heat developed the Gaussian distribution was considered. Finite element simulations were performed using ANSYS Parametric Design Language (APDL code and using SYSWELD. The temperatures obtained were compared with experimental results for validation. It was found that the predicted values of temperature agree very well with the experimental values. Residual Stress and Distortion were also predicted for various heat Input. The effect of heat input on residual stress and distortion was investigated.

  7. Self-Reacting Friction Stir Welding for Aluminum Alloy Circumferential Weld Applications

    Science.gov (United States)

    Bjorkman, Gerry; Cantrell, Mark; Carter, Robert

    2003-01-01

    Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation. The high weld forge force is reacted against an anvil and a stout tool structure. A variation of friction stir welding currently being evaluated is self-reacting friction stir welding. Self-reacting friction stir welding incorporates two opposing shoulders on the crown and root sides of the weld joint. In self-reacting friction stir welding, the weld forge force is reacted against the crown shoulder portion of the weld pin tool by the root shoulder. This eliminates the need for a stout tooling structure to react the high weld forge force required in the typical friction stir weld process. Therefore, the self-reacting feature reduces tooling requirements and, therefore, process implementation costs. This makes the process attractive for aluminum alloy circumferential weld applications. To evaluate the application of self-reacting friction stir welding for aluminum alloy circumferential welding, a feasibility study was performed. The study consisted of performing a fourteen-foot diameter aluminum alloy circumferential demonstration weld using typical fusion weld tooling. To accomplish the demonstration weld, weld and tack weld development were performed and fourteen-foot diameter rings were fabricated. Weld development consisted of weld pin tool selection and the generation of a process map and envelope. Tack weld development evaluated gas tungsten arc welding and friction stir welding for tack welding rings together for circumferential welding. As a result of the study, a successful circumferential demonstration weld was produced leading

  8. Recover the story of a component or the determination of the welding residual stresses; Parcourir l`histoire d`un composant ou la determination des contraintes residuelles de soudage

    Energy Technology Data Exchange (ETDEWEB)

    Genette, P. [Electricite de France (EDF), 69 - Villeurbanne (France). Service Etudes et Projets Thermiques et Nucleaires; Dupas, Ph. [Electricite de France, 77 - Moret sur Loing (France). Dept. Mecanique et Technologie des Composants; Waeckel, F. [Electricite de France (EDF), 92 - Clamart (France). Dept. Mecanique et Modeles Numerique

    1998-10-01

    Mechanical components in nuclear power plants can keep track of the welding processes they had undergone before to entrying into service. The memory of these past events can postpone or enhance possible damage phenomena on these components. Nowadays, numerical simulation software, such as the Code ASTER, enable to reproduce numerically these welding processes so that their mechanical consequences be retrieved. (authors)

  9. Effect of Heat Treatment on the Structure and Properties of Explosion Welded Bimetal Kh20N80 + AD1

    Science.gov (United States)

    Shmorgun, V. G.; Arisova, V. N.; Slautin, O. V.; Taube, A. O.; Bakuntseva, V. M.

    2017-05-01

    Results of a study of the effect of heat treatment on the microhardness, structure and phase composition of diffusion zone in explosion-welded `refractory nickel alloy Kh20N80 + aluminum alloy AD1' bimetal are presented.

  10. Structure and properties of explosion-welded composite from steels 12Kh18N10T and 20

    Science.gov (United States)

    Gladkovskii, S. V.; Trunina, T. A.; Kokovikhin, E. A.; Vichuzhanin, D. I.; Golubkova, I. A.

    2009-09-01

    Special features of structure formation, mechanical properties, and microstructure of fractures of "austenitic steel 12Kh18N10T + low-carbon steel 20" composite after explosive welding and subsequent cold rolling are studied.

  11. Special Features of Structure Formation in an Explosion-Welded Magnesium-Aluminum Composite Under Deformation and Subsequent Heat Treatment

    Science.gov (United States)

    Gurevich, L. M.; Arisova, V. N.; Trykov, Yu. P.; Ponomareva, I. A.; Trudov, A. F.

    2016-07-01

    The effect of bending deformation and subsequent heat treatment on the variation of microhardness and structure of explosion-welded magnesium-aluminum layered composite material MA2-1 - AD1 is studied.

  12. Modification of Structure and Strength Properties of Permanent Joints Under Laser Beam Welding with Application of Nanopowder Modifiers

    Science.gov (United States)

    Cherepanov, A. N.; Orishich, A. M.; Malikov, A. G.; Ovcharenko, V. E.

    2016-08-01

    In the paper we present the results of experimental study of specially prepared nanosize metal-ceramic compositions impact upon structure, microhardness and mechanical properties of permanent joints produced by laser-beam welding of steel and titanium alloy plates.

  13. Investigation of the structure and properties of the material of various zones of the welded joint of the austenitic nitrogen-containing steel upon elastoplastic deformation

    Science.gov (United States)

    Gorkunov, E. S.; Putilova, E. A.; Zadvorkin, S. M.; Makarov, A. V.; Pecherkina, N. L.; Kalinin, G. Yu.; Mushnikova, S. Yu.; Fomina, O. V.

    2016-11-01

    The structural, mechanical, and magnetic properties of metal cut out from the welded joint and from the near-weld zone of the welded joint of high-strength nitrogen-containing 04Kh20N6G11M2AFB austenitic steel have been investigated. The behavior of the magnetic parameters of materials under study subjected to various schemes of loading, such as tension, torsion, internal pressure, and combination of tension and torsion have been investigated. It has been established that the metal of the welded joint and near-weld zone of the welded joint, just as the base metal, has a stable phase composition and magnetic properties under various loading conditions. It has been concluded that 04Kh20N6G11M2AFB steel can be used in the fabrication of welded parts and elements of welded constructions that require low magnetization and high stability of magnetic characteristics under the force action.

  14. Field application of phased array ultrasonic testing for structural weld overlay on dissimilar welds of pressurizer nozzles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Hoi; Kim, Yong Sik [Korea Hydro and Nuclear Power Company Ltd., Central Research Institute, Daejeon (Korea, Republic of)

    2015-08-15

    Weld overlay was first used in power plants in the US in the early 1980s as an interim method of repairing the welds of flawed piping joints. Weld overlaid piping joints in nuclear power plants must be examined periodically using ultrasonic examination technology. Portable phased array ultrasonic technology has recently become available. Currently, the application of preemptive weld overlays as a mitigation technique and/as a method to improve the examination surface condition for more complex configurations is becoming more common. These complex geometries may require several focused conventional transducers for adequate inspection of the overlay, the original weld, and the base material. Alternatively, Phased array ultrasonic probes can be used to generate several inspection angles simultaneously at various focal depths to provide better and faster coverage than that possible by conventional methods. Thus, this technology can increase the speed of examinations, save costs, and reduce radiation exposure. In this paper, we explain the general sequence of the inspection of weld overlay and the results of signal analysis for some PAUT (phased array ultrasonic testing) signals detected in on-site inspections.

  15. A Review: Welding Of Dissimilar Metal Alloys by Laser Beam Welding & Friction Stir Welding Techniques

    Directory of Open Access Journals (Sweden)

    Ms. Deepika Harwani

    2014-12-01

    Full Text Available Welding of dissimilar metals has attracted attention of the researchers worldwide, owing to its many advantages and challenges. There is no denial in the fact that dissimilar welded joints offer more flexibility in the design and production of the commercial and industrial components. Many welding techniques have been analyzed to join dissimilar metal combinations. The objective of this paper is to review two such techniques – Laser welding and Friction stir welding. Laser beam welding, a high power density and low energy-input process, employs a laser beam to produce welds of dissimilar materials. Friction stir welding, a solid-state joining process, is also successfully used in dissimilar welding applications like aerospace and ship building industries. This paper summarizes the trends and advances of these two welding processes in the field of dissimilar welding. Future aspects of the study are also discussed.

  16. Application of Submerged Arc Welding Without Back Chipping in Steel Structure Industry%埋弧焊免清根技术在钢结构行业的应用∗

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    在建筑钢结构制作行业,埋弧焊焊接工艺应用非常普遍。埋弧焊以生产效率高,焊接质量稳定,劳动条件好等优势在钢结构加工行业占有一席之地。埋弧焊免清根技术的应用,对钢结构焊接中的成本控制有着举足轻重的作用。介绍了埋弧焊免清根技术的优点及施工难点,并进行试件试验分析了其施工参数及技术要点。%In the structural steelwork fabrication industry, submerged arc welding is widely used. The submerged arc welding has high production efficiency with stable welding quality and good working condition, thus making it take a place in this industry. With the application of submerged arc welding without back gouging technology, it will play a significant role in the cost control of structural steelwork welding. This paper introduces the advantages and difficulties. Then through components test the construction parameters and technical keys of submerged arc welding are analyzed.

  17. Structural materials for ITER in-vessel component design

    Science.gov (United States)

    Kalinin, G.; Gauster, W.; Matera, R.; Tavassoli, A.-A. F.; Rowcliffe, A.; Fabritsiev, S.; Kawamura, H.

    1996-10-01

    The materials proposed for ITER in-vessel components have to exhibit adequate performance for the operating lifetime of the reactor or for specified replacement intervals. Estimates show that maximum irradiation dose to be up to 5-7 dpa (for 1 MWa/m 2 in the basic performance phase (BPP)) within a temperature range from 20 to 300°C. Austenitic SS 316LN-ITER Grade was defined as a reference option for the vacuum vessel, blanket, primary wall, pipe lines and divertor body. Conventional technologies and mill products are proposed for blanket, back plate and manifold manufacturing. HIPing is proposed as a reference manufacturing method for the primary wall and blanket and as an option for the divertor body. The existing data show that mechanical properties of HIPed SS are no worse than those of forged 316LN SS. Irradiation will result in property changes. Minimum ductility has been observed after irradiation in an approximate temperature range between 250 and 350°C, for doses of 5-10 dpa. In spite of radiation-induced changes in tensile deformation behavior, the fracture remains ductile. Irradiation assisted corrosion cracking is a concern for high doses of irradiation and at high temperatures. Re-welding is one of the critical issues because of the need to replace failed components. It is also being considered for the replacement of shielding blanket modules by breeding modules after the BPP. Estimates of radiation damage at the locations for re-welding show that the dose will not exceed 0.05 dpa (with He generation of 1 appm) for the manifold and 0.01 dpa (with He generation 0.1 appm) for the back plate for the BPP of ITER operation. Existing experimental data show that these levels will not result in property changes for SS; however, neutron irradiation and He generation promote crack formation in the heat affected zone during welding. Cu based alloys, DS-Cu (Glidcop A125) and PHCu CuCrZr bronze) are proposed as a structural materials for high heat flux

  18. Design aspects of high strength steel welded structures improved by high frequency mechanical impact (HFMI) treatment

    OpenAIRE

    Yildirim, Halid Can

    2013-01-01

    This doctoral study is concerned with the fatigue strength of welded steel structures which are improved by high frequency mechanical impact (HFMI) treatment. A comprehensive evaluation of 417 HFMI test data obtained from the literature and 24 HFMI fatigue data tested as a part of this work are studied. According to the statistical analyses an S-N slope of five (5) is proposed. A yield strength correction procedure which relates the material yield strength (fy) to fatigue is presented and ver...

  19. Evidence of superior ferroelectricity in structurally welded ZnSnO3 nanowire arrays.

    Science.gov (United States)

    Datta, Anuja; Mukherjee, Devajyoti; Kons, Corisa; Witanachchi, Sarath; Mukherjee, Pritish

    2014-10-29

    Highly packed LN-type ZnSnO3 NW arrays are grown on ZnO:Al/Si substrates using a hybrid pulsed laser deposition and solvothermal process. Unique "welding" mechanism structurally joins adjacent ZnSnO3 NWs to form a nearly impervious 20 μm thick nanostructured film that shows high P r of 30 μC/cm(2) at a low E c of 25 kV/cm for the first time.

  20. In-Space Friction Stir Welding Machine Project

    Data.gov (United States)

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

  1. Coil Welding Aid

    Science.gov (United States)

    Wiesenbach, W. T.; Clark, M. C.

    1983-01-01

    Positioner holds coil inside cylinder during tack welding. Welding aid spaces turns of coil inside cylinder and applies contact pressure while coil is tack-welded to cylinder. Device facilitates fabrication of heat exchangers and other structures by eliminating hand-positioning and clamping of individual coil turns.

  2. The effect of welding fixtures on welding distortions

    OpenAIRE

    2007-01-01

    Purpose: of this paper is to examine the effect of welding fixture used to prevent the distortions duringcooling process utilizing a robot controlled gas metal arc welding method on cooling rate and distortions ofwelded structures.Design/methodology/approach: Using a specially designed welding fixture for a welded steel structure, sixdifferent types of AISI 1020 steel specimens are tested in three different welding speeds and two differentcooling conditions either at fixture or without using ...

  3. Microheterogeneous Structure of Local Melted Zones in the Process of Explosive Welding

    Science.gov (United States)

    Greenberg, Bella A.; Ivanov, Mikhail A.; Inozemtsev, Alexei V.; Patselov, Alexander M.; Pushkin, Mark S.; Vlasova, Alisa M.

    2015-08-01

    The dispersed structures formed in the process of explosive welding and solidification after melting were investigated in areas near the interface. It was shown that melting can be initiated by particles flying away as a result of granulating fragmentation. This is the fastest process during explosive welding, which is similar to fragmentation in conventional explosions with the formation of fragments but occurring in the presence of a barrier. The reaction between the particles and their environment may lead to local heating sufficient for melting. This is confirmed by the observation of numerous particles of the refractory phase within the local melted zones. In the absence of mutual solubility of the initial phases, the solidified local melted zones are to a certain extent analogous to colloidal solutions of immiscible liquids. Correlations between the typical temperatures were obtained that determine the conditions for the formation of various types of colloidal solutions.

  4. Features of misoriented structures in a copper-copper bilayer plate obtained by explosive welding

    Science.gov (United States)

    Rybin, V. V.; Ushanova, E. A.; Zolotorevskii, N. Yu.

    2013-09-01

    Structures induced by deformation in the narrow zone of a contact between two copper plates that is prepared by explosive welding are systematically investigated at the micro-, meso-, and macrolevels. Plastic jets, regions of metal plastic flow anomalous localization, are discovered in areas adjacent to the contact surface. The defect structure of the plastic jets is examined by transmission electron microscopy and electron backscatter diffraction. It is shown that at the mesolevel the plastic jets are regions with a heavily fragmented structure. The statistics of the fragment distribution over misorientations and transverse sizes is studied.

  5. Numerical modelling of welding distortion redistribution due to the change of self-constraint in a T-joint welded structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao; Kim, Yong Rae; Kim, Jae Woong [Yeungnam University, Kyongsan (Korea, Republic of)

    2016-06-15

    Finite element method (FEM) is a powerful tool for analysing the potential deformation during a material removal process. After the removal of material, re-establishment of equilibrium within the remaining part of the structure causes distortion due to the relief of residual stress in the removed materials. In this study, commercial FEM software (MSC.Marc) was used to simulate material removal, and the accuracy was evaluated by comparison with results from machining experiments. The effect of cutting height on the distortion redistribution and the kerf width in a T-joint welded structure is discussed, and the distortion differences at the centre line of the bottom were compared between the calculated and experimental results. The results demonstrate that the developed model is useful and efficient for simulating the redistribution of welding distortion due to material removal.

  6. Component Representation for Shock Qualified Foundation Structure

    Directory of Open Access Journals (Sweden)

    Timothy Coats

    2003-01-01

    Full Text Available Navy ship foundations are typically designed for shock using the Navy's Dynamic Design Analysis Method. The NAVSEA 0908-LP-000-3010, Rev. 1 manual states that a component modeled as a lumped mass with rigid links should not provide constraint to the support structure. This ensures foundations are designed to withstand all shock loads without accounting for additional stiffness provided by the component. Investigations are provided herein to illustrate the trade-offs and consequences of several approaches for component representations. The observations reinforce the notion that one must give careful consideration for the system being modeled, the expected modal characteristics, and compliance with NAVSEA 0908-LP-000-3010, Rev. 1.

  7. Modeling structural dynamic behavior of SSME components

    Science.gov (United States)

    Kiefling, Larry A.; Saxon, J. B.; Prickett, T. L.

    1991-01-01

    FEM studies are presented of the nozzle and the low-pressure fuel-pump inducer designs for the Space Shuttle Main Engine (SSME) to analyze the effects of structural vibrations. FEM preprocessing software based on a CAD system is employed to develop a model of the component's sophisticated geometry. The nozzle geometry is also defined by means of the preprocessing technique and subsequently analyzed with respect to time-transient loading. The analysis is conducted with a Cray supercomputer using the SPAR/EAL FEM program. The investigation of the nozzle demonstrates the advantageous use of symmetry in the determination of nozzle response to SSME start-up transients. Plots of time vs strain are developed for gages on the nozzle wall and steerhorn tubing. The results of the inducer modeling are found to be adequate for investigating the component's principle modes, and the nozzle results indicate the suitability of the FEM techniques for optimizing the design of engine components.

  8. Welded Kimberlite?

    Science.gov (United States)

    van Straaten, B. I.; Kopylova, M. G.; Russell, J. K.; Scott Smith, B. H.

    2009-05-01

    settings. In this contribution we explore the possible welded origin for dark and competent kimberlite facies from the Victor Northwest pipe (Northern Ontario, Canada). This volumetrically extensive facies superficially resembles a coherent rock. The following observations on the dark and competent facies are suggestive of a pyroclastic, rather than intrusive or extrusive coherent origin: The facies is completely enveloped by pyroclastic facies; has gradational contacts with adjacent pyroclastic facies above and below; contains faint outlines of primary pyroclasts; shows diffuse grain size variations and rare bedding; shows systematic changes in components from the underlying pyroclastic facies to the dark and competent facies to the overlying pyroclastic facies implying a lack of a depositional break in this succession; and shows a faint, generally subhorizontal fabric despite the presence of an equant grain shape population. In addition, we present evidence that the original inter-clast porosity has been reduced or eliminated by syn-depositional welding rather than by precipitation of secondary minerals in the inter-clast pore spaces. We feel that the latter process (i.e., alteration) is highly unlikely because: The kimberlite package contains intervals with well crystallized groundmass similar to coherent kimberlite, this texture simply cannot be produced by alteration; the kimberlite is in fact the freshest rock within the pipe, containing mostly fresh olivines; and the dark and competent kimberlite does not show a patchy or vein-related heterogeneity typical of alteration. In summary, these deposits likely represent a variably welded succession of proximal spatter/fire fountaining kimberlite deposits.

  9. Analysis of the misoriented structures in the model copper-copper compound formed by explosion welding

    Science.gov (United States)

    Rybin, V. V.; Zolotorevskii, N. Yu.; Ushanova, E. A.

    2014-12-01

    The existing concepts of the mechanisms of forming fragmented structures under the conditions of severe plastic deformation of crystalline solids are analytically reviewed. The translational and rotational plasticity modes that develop at micro- and mesoscopic structural levels, respectively, are sequentially taken into account. This allows us to correctly describe the morphological features of the evolution of fragmented structures, to predict misorientation spectra for various fragmentation mechanisms, and to determine the partial contribution of each mechanism in the cases where several deformation grain refinement mechanisms are involved in fragmentation. The computer simulation of deformation-induced misorientation spectra that was developed using these concepts is a new method for studying the physical nature of structure formation processes, and this method can be applied for various materials, temperature-rate deformation conditions, and technological loading schemes. As an example, we comprehensively consider the formation of fragmented structures under the extreme conditions of explosion welding of commercial-purity copper plates. A comparison of the model misorientation spectra calculated for a reference structure and the fragmented structure in the near-contact zone of the welded joint with the existing experimental data demonstrates the efficiency and reliability of the proposed method.

  10. Weld line optimization on thermoplastic elastomer micro injection moulded components using 3D focus variation optical microscopy

    DEFF Research Database (Denmark)

    Hasnaes, F.B.; Elsborg, R.; Tosello, G.;

    2015-01-01

    The presented study investigates weld line depth development across a micro suspension ring. A focus variation microscope was used to obtain 3D images of the weld line area. Suspension rings produced with different micro injection moulding process parameters were examined to identify the correlat...

  11. Guidelines for Friction Stir Welding

    Science.gov (United States)

    2011-03-29

    in a large void at the termination point of the weld, the effects the exit hole will have on structural integrity must be considered. The...3.6 Cavity. A void -type discontinuity within a solid-state weld. See Figure 3.4. 3.7 Complex weld joint. A continuous weld...except as affected by corner radii. 3.61 Underfill . A depression resulting when the weld face is below the adjacent parent material surface. See

  12. Structured automated code checking through structural components and systems engineering

    NARCIS (Netherlands)

    Coenders, J.L.; Rolvink, A.

    2014-01-01

    This paper presents a proposal to employ the design computing methodology proposed as StructuralComponents (Rolvink et al [6] and van de Weerd et al [7]) as a method to perform a digital verification process to fulfil the requirements related to structural design and engineering as part of a buildin

  13. High Power Laser Welding. [of stainless steel and titanium alloy structures

    Science.gov (United States)

    Banas, C. M.

    1972-01-01

    A review of recent developments in high power, carbon dixoide laser welding is presented. Deep penetration welding in stainless steel to 0.5-in. thick, high speed welding in thin gage rimmed steel and gas shielded welding in Ti-6Al-4V alloy are described. The effects of laser power, power density, focusing optics, gas-shielding techniques, material properties and weld speed on weld quality and penetration are discussed. It is shown that laser welding performance in thin materials is comparable to that of electron beams. It is further shown that high quality welds, as evidenced by NDT, mechanical and metal-lographic tests, can be achieved. The potential of the laser for industrial welding applications is indicated.

  14. Knowledge-based System Prototype in Structural Component Design Based on FM

    Institute of Scientific and Technical Information of China (English)

    JIANG; Tao; LI; Qing-fen; LI; Ming; FU; Wei

    2002-01-01

    A knowledge-based system in structural component design based on fracture mechanics is developed in this paper. The system consists of several functional parts: a general inference engine, a set of knowledge bases and data-bases, an interpretation engine, a bases administration system and the interface. It can simulate a human expert to make analysis and design scheme mainly for four kinds of typical structural components widely used in shipbuilding industry: pressure vessels, huge rotation constructions, pump-rod and welded structures. It is an open system which may be broadened and perfected to cover a wider range of engineering application through the modification and enlargement of knowledge bases and data-bases. It has a natural and friendly interface that may be easily operated. An on-line help service is also provided.

  15. Thermoplastics Reinforced with Self-Welded Short Carbon Fibers: Nanoparticle-Promoted Structural Evolution.

    Science.gov (United States)

    Zhang, Dongge; Liu, Yaohua; Lin, Yu; Wu, Guozhang

    2016-07-27

    The large volume of currently available fiber-reinforced polymer composites critically limits the intrinsic versatility of fibers such as high mechanical strength, heat resistance, and excellent thermal/electrical conductivity. We proposed a facile and widely applicable strategy to promote self-organization of randomly dispersed short carbon fibers (CFs) into a three-dimensionally continuous scaffold. The morphological evolution and structural reinforcement of the self-welded CF-polyamide 6 (PA6) scaffold in polystyrene (PS) matrix were investigated, with carbon black (CB) or titanium dioxide (TiO2) nanoparticles (NPs) selectively localized in the PA6 domains. Surprisingly, all of the PA6 droplets once dispersed in the PS matrix can migrate and evenly encapsulate onto the CF surface when 5.8 wt % CB is incorporated, whereas in the TiO2-filled system, the PA6 droplets preferentially segregate at the junction point of CFs to fasten the self-welded CF structure. In addition, a remarkable increase in the interfacial adhesive work between PA6 and CF was observed only when TiO2 is added, and a loading of even less than 0.8 wt % can effectively abruptly strengthen the self-welded CF scaffold. We clarified that the structural evolution is promoted by the nature of self-agglomeration of NPs. CB is highly capable of self-networking in the PA6 domain, resulting in high encapsulation of PA6, although the capillary force for preferential segregation of PA6 at the junction point of CFs is reduced. By contrast, the TiO2 particles tend to form compact aggregates. Such an agglomeration pattern, together with enhanced interfacial affinity, must contribute to a strong capillary force for the preferential segregation of PA6.

  16. Lightweight Thermoformed Structural Components and Optics

    Science.gov (United States)

    Zeiders, Glenn W.; Bradford, Larry J.

    2004-01-01

    A technique that involves the use of thermoformed plastics has been developed to enable the design and fabrication of ultra-lightweight structural components and mirrors for use in outer space. The technique could also be used to produce items for special terrestrial uses in which minimization of weight is a primary design consideration. Although the inherent strengths of thermoplastics are clearly inferior to those of metals and composite materials, thermoplastics offer a distinct advantage in that they can be shaped, at elevated temperatures, to replicate surfaces (e.g., prescribed mirror surfaces) precisely. Furthermore, multiple elements can be bonded into structures of homogeneous design that display minimal thermal deformation aside from simple expansion. The design aspect of the present technique is based on the principle that the deflection of a plate that has internal structure depends far more on the overall thickness than on the internal details; thus, a very stiff, light structure can be made from thin plastic that is heatformed to produce a sufficiently high moment of inertia. General examples of such structures include I beams and eggcrates.

  17. A maxillary laser-welded component removable partial denture: a clinical report.

    Science.gov (United States)

    Domagala, Daniel M; Waliszewski, Michael P

    2009-01-01

    Component removable partial dentures (RPDs) are fabricated in pieces and assembled on the definitive cast. The treatment modality described is believed by the authors to optimize the passive fit and frictional retention of the RPD. Increased frictional retention and stability is believed to improve the clinical performance of the RPD. Patients may thereby benefit from more esthetic and more durable prostheses.

  18. 焊接温度对铸铁件焊补区组织和性能的影响%Effects of Welding Temperature on the Structure and Property of Welding-mend Zone of Grey Iron

    Institute of Scientific and Technical Information of China (English)

    赵书林; 翟秋亚; 董立社; 罗秋利

    2001-01-01

    The effects of a variet welding temperature on the structure andproperty of welding-mend zone of grey iron (HT250) plank is tested under produce condition using mutti-alloying cast iron homogeneous are cold welding electrode.The results shows that on-chill welding-mend zone can be obtained by the biger welding electric current and continuous welding at 200℃.The structure of welding zone is composed of pealite and a few ferri te and fine flake graphit the hardness is 176 HB for the welding zone and 198 HB for the semimelting zone.Moreove the welding mend zone has high resistance of crack and exellent machinability and be satisfied with welding cylinder typical iron casting.%在生产条件下使用多元微合金化铸铁同质电弧冷焊焊条对HT250板材进行不同温度下的焊接试验。结果表明,200℃大电流连续焊接可获得无白口的焊补区,焊缝由珠光体、少量铁素体加细小的片墨构成。焊缝与熔合区硬度分别为176HB和198HB,机加工性能良好,抗裂性好,熔敷金属强度高,能够满足缸体类铸铁件焊补需要。

  19. Welding of nickel free high nitrogen stainless steel: Microstructure and mechanical properties

    Directory of Open Access Journals (Sweden)

    Raffi Mohammed

    2017-04-01

    Full Text Available High nitrogen stainless steel (HNS is a nickel free austenitic stainless steel that is used as a structural component in defence applications for manufacturing battle tanks as a replacement of the existing armour grade steel owing to its low cost, excellent mechanical properties and better corrosion resistance. Conventional fusion welding causes problems like nitrogen desorption, solidification cracking in weld zone, liquation cracking in heat affected zone, nitrogen induced porosity and poor mechanical properties. The above problems can be overcome by proper selection and procedure of joining process. In the present work, an attempt has been made to correlate the microstructural changes with mechanical properties of fusion and solid state welds of high nitrogen steel. Shielded metal arc welding (SMAW, gas tungsten arc welding (GTAW, electron beam welding (EBW and friction stir welding (FSW processes were used in the present work. Optical microscopy, scanning electron microscopy and electron backscatter diffraction were used to characterize microstructural changes. Hardness, tensile and bend tests were performed to evaluate the mechanical properties of welds. The results of the present investigation established that fully austenitic dendritic structure was found in welds of SMAW. Reverted austenite pools in the martensite matrix in weld zone and unmixed zones near the fusion boundary were observed in GTA welds. Discontinuous ferrite network in austenite matrix was observed in electron beam welds. Fine recrystallized austenite grain structure was observed in the nugget zone of friction stir welds. Improved mechanical properties are obtained in friction stir welds when compared to fusion welds. This is attributed to the refined microstructure consisting of equiaxed and homogenous austenite grains.

  20. Wave formation during explosive welding: the relaxation of a nonequilibrium structure

    Science.gov (United States)

    Greenberg, B. A.; Ivanov, M. A.; Kuz'min, S. V.; Lysak, V. I.; Pushkin, M. S.; Inozemtsev, A. V.; Patselov, A. M.; Pasheev, A. V.

    2016-12-01

    The sequence of the transition states of the interface in the process of explosion welding has been studied. The self-organization of splash-shaped cusps first into a quasi-wave surface and, then into a perfect wavy surface has been revealed. A similarity between a quasi-wave surface and the periodic surface relief, which has been observed in the well-known experiments of G. R. Abrahamson, of a steel bullet after collision with a target has been found. Simulation tests have been performed in order to find possible methods of the relaxation of a nonequilibrium structure that possess excess area.

  1. Effect of heat treatment of formation of columnar ferrite structure in explosively welded titanium/hypoeutectoid steel joints

    Energy Technology Data Exchange (ETDEWEB)

    Morizono, Y. [Shock Wave and Condensed Matter Research Center, Kumamoto Univ., Kumamoto (Japan); Nishida, M.; Chiba, A.; Yamamuro, T. [Dept. of Mechanical Engineering and Materials Science, Kumamoto Univ., Kumamoto (Japan)

    2004-07-01

    Explosive welding of titanium to hypoeutectoid steel (SS 400, 0.09 mass% C) was carried out, and interfacial aspects of as-welded and heat treated states have been investigated with a focus on microstructures of the steel. In as-welded joint, plastic flow occurred by high velocity collision was observed in the vicinity of the interface. The steel in the joints retained equiaxed structure consisting of ferrite and pearlite even after prolonged heat treatment up to 1173 K. Columnar grains were generated in the steel near the interface by the heat treatment at 1223 K and above. Although the region of the columnar ferrite structure increased with increasing heating temperature and holding time, texture with specific crystal orientation was not confirmed. It was found that such a microstructural change in the steel was closely related to constituent phases formed at the bonding interface. The formation mechanism of the columnar structure was also discussed. (orig.)

  2. Laser micro welding of copper and aluminum

    Science.gov (United States)

    Mys, Ihor; Schmidt, Michael

    2006-02-01

    Aluminum combines comparably good thermal and electrical properties with a low price and a low material weight. These properties make aluminum a promising alternative to copper for a large number of electronic applications, especially when manufacturing high volume components. However, a main obstacle for a wide use of this material is the lack of a reliable joining process for the interconnection of copper and aluminum. The reasons for this are a large misalignment in the physical properties and even more a poor metallurgical affinity of both materials that cause high crack sensitivity and the formation of brittle intermetallic phases during fusion welding. This paper presents investigations on laser micro welding of copper and aluminum with the objective to eliminate brittle intermetallic phases in the welding structure. For these purposes a combination of spot welding, a proper beam offset and special filler material are applied. The effect of silver, nickel and tin filler materials in the form of thin foils and coatings in a thickness range 3-100 μm has been investigated. Use of silver and tin filler materials yields to a considerable improvement of the static and dynamic mechanical stability of welded joints. The analysis of the weld microstructure shows that an application even of small amounts of suitable filler materials helps to avoid critical, very brittle intermetallic phases on the interface between copper and solidified melt in the welded joints.

  3. Structure of the transition zone and its influence on the strength of copper-tantalum joint (Explosion welding)

    Science.gov (United States)

    Greenberg, B. A.; Ivanov, M. A.; Rybin, V. V.; Elkina, O. A.; Patselov, A. M.; Antonova, O. V.; Inozemtsev, A. V.; Salishchev, G. A.; Kozhevnikov, V. E.

    2012-10-01

    The joint of copper and tantalum, metals without mutual solubility, formed by explosion welding is studied. The mechanism of the influence of mutual solubility on the structure of the transition zone is established. It is demonstrated that the interface contains heterogeneities, and their role in the strength of the materials joint is revealed. A microheterogeneous structure of the joint zones is detected.

  4. Time-domain fatigue response and reliability analysis of offshore wind turbines with emphasis on welded tubular joints and gear components

    OpenAIRE

    DONG, WENBIN

    2012-01-01

    Presently fixed support structures are mainly used in the offshore wind industry, e.g. monopile, tripod, gravity base, et al., where the water depth are usually less than 30 m. Research work is ongoing for deeper water depth. Jacket substructure is very competitive in moderate water depth like 40-100m, due to its light weight, high stiffness and efficient construction. Due to the harsh offshore environments, the fatigue performance of welded connections in jacket support structure is therefor...

  5. Exploring material flow in friction stir welding using stacked structure of 2024 and 606 1 aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    马正斌; 董春林; 李继忠; 陈巍; 栾国红

    2014-01-01

    An experimental technique based on stacked structures was developed to observe the material flow behavior ofthe friction stir welding (FSW)process.Analysis ofsection views along different directions revealed important new details ofthe material flow in FSW process.In this work,a general flow model ofFSW was constructed based on the analysis ofdifferent static section views ofstacked structure weld.The formation ofonion rings was found to be a geometric effect due to layered deposition and the extrusion occurred at the interface between flow arm (FA)and stirring zone (SZ).

  6. StructuralComponents: a software system for conceptual structural design

    NARCIS (Netherlands)

    Van de Weerd, B.; Rolvink, A.; Coenders, J.L.

    2012-01-01

    Conceptual design is the starting point of the design process. The conceptual design stage comprises the formation of several ideas or design concepts to meet the imposed constraints. StructuralComponents is a software application that attempts to provide the designing engineer with a suitable set o

  7. Advanced welding for closed structure. Pt. 3 The thermal approach

    Energy Technology Data Exchange (ETDEWEB)

    Sacripanti, A.; Bonanno, G.; Paoloni, M.; Sagratella, G. [ENEA Centro Ricerche Casaccia, Rome (Italy). Dipt. Innovazione; Arborino, A.; Varesi, R.; Antonucci, A. [DUNE, (Italy)

    1999-07-01

    This report describes the activities developed for the European Contract BRITE AWCS III to study the use of thermal sensing techniques to obtain an accurate detection of the internal reinforcement of the closed steel structures employed in the shipbuilding industry. After a description of the methods, normally developed in Russia, about the techniques and problems, for the thermal testing of materials in the conventional approach, a new thermal detector was utilized, a new bolometric thermo camera is introduced with a special software for the on line image analysis, there are also shown the experimental tests and results. The obtained conclusion shows that the thermal non destructive testing techniques with the new detector should be useful to assemble a complete sensing system with one ultrasonic head. [Italian] Questo rapporto descrive le attivita' sperimentali sviluppate nell'ambito del contratto europeo BRITE AWCS III, in cui si sono utilizzate tecniche termiche per ottenere un preciso rilevamento dei rinforzi interni di strutture metalliche chiuse utilizzate nell'industria delle costruzioni navali. Dopo la descrizione dei metodi sviluppati essenzialmente in Russia, circa le tecniche e i problemi riguardanti il testing termico dei materiali, e' stato introdotto un approccio innovativo basato su un nuovo sensore: una termocamera bolometrica connessa con un software dedicato per l'analisi online del setto; vengono inoltre mostrati i risultati sperimentali ottenuti. Le conclusioni ottenute mostrano che nel nuovo approccio, il testing termico non distruttivo dovrebbe essere utile per assemblare un sistema sensoriale completo che utilizzi anche un sensore di tipo ultrasonico.

  8. Formation and structure of vortex zones arising upon explosion welding of carbon steels

    Science.gov (United States)

    Bataev, I. A.; Bataev, A. A.; Mali, V. I.; Burov, V. G.; Prikhod'ko, E. A.

    2012-03-01

    Presented are the results of investigation of vortex zones arising upon explosion welding of thin plates of steel 20. Specific features of the structure of the vortices and zones of the deformed material adjacent to them have been revealed by methods of structure analysis. It has been shown that in the process of explosive loading the central regions of the vortices characterized by an enhanced carbon content were in the molten state. The microhardness in the region of vortex zones reaches 5700 MPa. The character of the arrangement of ferrite grains and martensite microvolumes in peripheral regions of vortices is caused by intense rotation of the material. The intense intermixing of materials in different states of aggregation in vortex zones is one of the factors responsible for the formation of cavities, whose volume exceeds the volume shrinkage occurring upon casting of carbon steels. It has been established that traces of vortex zones are retained even after one-hour annealing of welded packets at 800°C.

  9. Electron Beam Welding to Join Gamma Titanium Aluminide Articles

    Science.gov (United States)

    Kelly, Thomas Joseph (Inventor)

    2008-01-01

    A method is provided for welding two gamma titanium aluminide articles together. The method includes preheating the two articles to a welding temperature of from about 1700 F to about 2100 F, thereafter electron beam welding the two articles together at the welding temperature and in a welding vacuum to form a welded structure, and thereafter annealing the welded structure at an annealing temperature of from about 1800 F to about 2200 F, to form a joined structure.

  10. 振动时效在大型焊接结构件中的应用%Application of Stress Relief by Vibration on Large Welded Structure

    Institute of Scientific and Technical Information of China (English)

    杨新华; 杨国华

    2012-01-01

    The influences of VSR on welding residual stress were studied through measuring the welding residual stress of welding lines in the pre-weld and post-weld by blind-hole method, and the feasibility and effectiveness of VSR process was employed, which can provide technology reference for production of large welded structures.%通过盲孔法对轨道焊缝振动时效前后残余应力的测量对比,研究振动时效工艺对焊接残余应力的影响,总结振动时效(VSR)工艺的可行性和有效性,从而为大型焊接结构件的生产提供技术参考.

  11. Fine structure at the diffusion welded interface of Fe3Al/Q235 dissimilar materials

    Indian Academy of Sciences (India)

    Wang Juan; Li Yajiang; Wu Huiqiang

    2001-12-01

    The interface of Fe3Al/Q235 dissimilar materials joint, which was made by vacuum diffusion welding, combines excellently. There are Fe3Al, FeAl phases and -Fe (Al) solid solution at the interface of Fe3Al/Q235. Aluminum content decreases from 28% to 1.5% and corresponding phase changes from Fe3Al with DO3 type body centred cubic (bcc) structure to -Fe (Al) solid solution with B2 type bcc structure. All phases are present in sub-grain structure level and there is no obvious brittle phases or micro-defects such as pores and cracks at the interface of Fe3Al/Q235 diffusion joint.

  12. Model of Layered Weld Formation Under Narrow Gap Pulse Welding

    Science.gov (United States)

    Krampit, A. G.

    2016-04-01

    The model parameters of narrow gap pulse welding can be divided into input, internal and output ones. The breadth of gap, that is, clearance breadth between upright edges is one of key parameters securing high quality of a weld joint. The paper presents theoretical outcomes for the model of layered weld formation under narrow gap pulse welding. Based on these studies is developed model of processes, which occur in the weld pool under pulse grove welding. It comprises the scheme of liquid metal motion in the weld pool, scheme of fusion with the side edge and in the bottom part, and the scheme of welding current impulse effect on the structure of a weld joint.

  13. [Change in the composition and structure of the metal in the zone of the welded seam of dental drill blanks].

    Science.gov (United States)

    Altareva, G I; Bazhukhin, V I; Gerasev, G P; Matukhnov, V M; Shmyreva, T P

    1982-01-01

    Composition and structure of metals in the meld zone connecting a dental burr handpiece made of hard alloy BK-6 with a shank made of steel 20X13 are examined by the X-ary microanalyzer MS-46 and the X-ray diffractometer "dPOH-2". Representative interdiffusion processes of alloy components into steel and, converserly, iron from steel into hard alloy are found. After melding, the transition layer has been shown to represent the cobalt-iron solid solution with variable concentration of the components through the layer, tungsten carbid particles being uniformly spread all over the metallic matrix. The phasic composition change is analysed in the course of material welding. The enrichment of stell melt with carbon of tungsten carbid results in the formation of gamma-Fe phase in the meld zone. The failure of burr blanks is noted to occur at the interface of the second (10-20 micrometer) and the first (130-140 micrometer) zones. The increase in the concentration of both iron and iron-containing phases--alpha-Fe, gamma-Fe, Fe3W3C--at the surface of steel fracture is responsible for the failures.

  14. Residual Stresses in Thick Bi-metallic Fusion Welds: a Neutron Diffraction Study

    NARCIS (Netherlands)

    Ohms, C.

    2013-01-01

    Welding is applied in many industrial sectors to join components, and has become an important manufacturing process because it enables the fabrication of structures that could not otherwise be constructed. Weld regions have inhomogeneous microstructures and are more susceptible to crack initiation a

  15. Residual Stresses in Thick Bi-metallic Fusion Welds: a Neutron Diffraction Study

    NARCIS (Netherlands)

    Ohms, C.

    2013-01-01

    Welding is applied in many industrial sectors to join components, and has become an important manufacturing process because it enables the fabrication of structures that could not otherwise be constructed. Weld regions have inhomogeneous microstructures and are more susceptible to crack initiation a

  16. Residual Stresses in Thick Bi-metallic Fusion Welds: a Neutron Diffraction Study

    NARCIS (Netherlands)

    Ohms, C.

    2013-01-01

    Welding is applied in many industrial sectors to join components, and has become an important manufacturing process because it enables the fabrication of structures that could not otherwise be constructed. Weld regions have inhomogeneous microstructures and are more susceptible to crack initiation

  17. The role and performance of certified welding inspector in steel structure welding process%焊接检验师在海洋钢结构焊接过程中的角色与行为

    Institute of Scientific and Technical Information of China (English)

    张相军; 景迪; 张吉合; 任胜汉

    2011-01-01

    welding is extremely important process during steel structure production. As the important part of welding quality assurance, certified welding inspectors are playing key roles during quality control of steel structure fabrication. The requirement of welding quality for offshore steel structure shall be much higher than others because of the effect of hydrology and climate. It has been described that role and performance of certified welding inspector in steel structure welding process,and excellent certified welding inspectors perform as "especial reporter" for communicating with project engineer,welding engineer,fabrication director,welding leader,and welder even,and so that issues about quality could be avoided or solved during the fabrication process. It has been highlighted that how to act as an excellent certified welding inspector,and in final prospected that excellent certified welding inspector will play more and more important role in offshore steel structure engineering projects. And it will be definitely the international trend that have been agreed gradually.%焊接是钢结构形成过程中一个极其重要的环节,作为焊接质量的重要保证,焊接检验师在钢结构生产的焊接质量控制中扮演着关键角色.由于海洋钢结构受到水文、气候等诸多因素影响,焊接质量要求更高.结合海洋钢结构工程项目中检验监理的亲身经历,阐述了焊接检验师在钢结构焊接过程中担当的角色和行为,称职的焊接检验师在项目焊接质量控制中担当着"特殊通讯员"的角色,需要与项目工程师、设计人员、工艺工程师、建造经理、焊接领班甚至焊工就质量问题进行沟通,提前采取措施以避免可预见的问题产生.未来优秀的焊接检验师在大型海洋钢结构工程中必然会发挥越来越重要的作用.

  18. FLUXES FOR MECHANIZED ELECTRIC WELDING,

    Science.gov (United States)

    WELDING FLUXES, WELDING ), (* WELDING , WELDING FLUXES), ARC WELDING , WELDS, STABILITY, POROSITY, WELDING RODS, STEEL, CERAMIC MATERIALS, FLUXES(FUSION), TITANIUM ALLOYS, ALUMINUM ALLOYS, COPPER ALLOYS, ELECTRODEPOSITION

  19. Numerical Modelling Of Thermal And Structural Phenomena In Yb:YAG Laser Butt-Welded Steel Elements

    Directory of Open Access Journals (Sweden)

    Kubiak M.

    2015-06-01

    Full Text Available The numerical model of thermal and structural phenomena is developed for the analysis of Yb:YAG laser welding process with the motion of the liquid material in the welding pool taken into account. Temperature field and melted material velocity field in the fusion zone are obtained from the numerical solution of continuum mechanics equations using Chorin projection method and finite volume method. Phase transformations in solid state are analyzed during heating and cooling using classical models of the kinetics of phase transformations as well as CTA and CCT diagrams for welded steel. The interpolated heat source model is developed in order to reliably reflect the real distribution of Yb:YAG laser power obtained by experimental research on the laser beam profile.

  20. Characterisation of Dynamic Mechanical Properties of Resistance Welding Machines

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    2005-01-01

    The dynamic mechanical properties of a resistance welding machine have significant influence on weld quality, which must be considered when simulating the welding process numerically. However, due to the complexity of the machine structure and the mutual coupling of components of the machine system...... characterizing the dynamic mechanical characteristics of resistance welding machines is suggested, and a test set-up is designed determining the basic, independent machine parameters required in the model. The model is verified by performing a series of mechanical tests as well as real projection welds......., it is very difficult to measure or calculate the basic, independent machine parameters required in a mathematical model of the machine dynamics, and no test method has so far been presented in literature, which can be applied directly in an industrial environment. In this paper, a mathematical model...

  1. Characterisation of Dynamic Mechanical Properties of Resistance Welding Machines

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    2005-01-01

    The dynamic mechanical properties of a resistance welding machine have significant influence on weld quality, which must be considered when simulating the welding process numerically. However, due to the complexity of the machine structure and the mutual coupling of components of the machine system......, it is very difficult to measure or calculate the basic, independent machine parameters required in a mathematical model of the machine dynamics, and no test method has so far been presented in literature, which can be applied directly in an industrial environment. In this paper, a mathematical model...... characterizing the dynamic mechanical characteristics of resistance welding machines is suggested, and a test set-up is designed determining the basic, independent machine parameters required in the model. The model is verified by performing a series of mechanical tests as well as real projection welds....

  2. Two dimensional Coupled Eulerian Lagrangian (CEL) model for banded structure prediction in friction stir welding with trigonal tool

    Science.gov (United States)

    Tongne, A.; Robe, H.; Desrayaud, C.; Jahazi, M.; Feulvarch, E.

    2016-10-01

    A finite element model has been developed by means of a coupled Eulerian-Lagrangian approach. The banded structure which is related to the periodical material deposition is predicted in two dimensions as the experimental investigation shows that, during FSW with trigonal tool, the material flow operates mainly in the welded plates plan.

  3. Creep and Creep-Fatigue Crack Growth at Structural Discontinuities and Welds

    Energy Technology Data Exchange (ETDEWEB)

    Dr. F. W. Brust; Dr. G. M. Wilkowski; Dr. P. Krishnaswamy; Mr. Keith Wichman

    2010-01-27

    The subsection ASME NH high temperature design procedure does not admit crack-like defects into the structural components. The US NRC identified the lack of treatment of crack growth within NH as a limitation of the code and thus this effort was undertaken. This effort is broken into two parts. Part 1, summarized here, involved examining all high temperature creep-fatigue crack growth codes being used today and from these, the task objective was to choose a methodology that is appropriate for possible implementation within NH. The second part of this task, which has just started, is to develop design rules for possible implementation within NH. This second part is a challenge since all codes require step-by-step analysis procedures to be undertaken in order to assess the crack growth and life of the component. Simple rules for design do not exist in any code at present. The codes examined in this effort included R5, RCC-MR (A16), BS 7910, API 579, and ATK (and some lesser known codes). There are several reasons that the capability for assessing cracks in high temperature nuclear components is desirable. These include: (1) Some components that are part of GEN IV reactors may have geometries that have sharp corners - which are essentially cracks. Design of these components within the traditional ASME NH procedure is quite challenging. It is natural to ensure adequate life design by modeling these features as cracks within a creep-fatigue crack growth procedure. (2) Workmanship flaws in welds sometimes occur and are accepted in some ASME code sections. It can be convenient to consider these as flaws when making a design life assessment. (3) Non-destructive Evaluation (NDE) and inspection methods after fabrication are limited in the size of the crack or flaw that can be detected. It is often convenient to perform a life assessment using a flaw of a size that represents the maximum size that can elude detection. (4) Flaws that are observed using in-service detection

  4. Creep and Creep-Fatigue Crack Growth at Structural Discontinuities and Welds

    Energy Technology Data Exchange (ETDEWEB)

    Dr. F. W. Brust; Dr. G. M. Wilkowski; Dr. P. Krishnaswamy; Mr. Keith Wichman

    2010-01-27

    The subsection ASME NH high temperature design procedure does not admit crack-like defects into the structural components. The US NRC identified the lack of treatment of crack growth within NH as a limitation of the code and thus this effort was undertaken. This effort is broken into two parts. Part 1, summarized here, involved examining all high temperature creep-fatigue crack growth codes being used today and from these, the task objective was to choose a methodology that is appropriate for possible implementation within NH. The second part of this task, which has just started, is to develop design rules for possible implementation within NH. This second part is a challenge since all codes require step-by-step analysis procedures to be undertaken in order to assess the crack growth and life of the component. Simple rules for design do not exist in any code at present. The codes examined in this effort included R5, RCC-MR (A16), BS 7910, API 579, and ATK (and some lesser known codes). There are several reasons that the capability for assessing cracks in high temperature nuclear components is desirable. These include: (1) Some components that are part of GEN IV reactors may have geometries that have sharp corners - which are essentially cracks. Design of these components within the traditional ASME NH procedure is quite challenging. It is natural to ensure adequate life design by modeling these features as cracks within a creep-fatigue crack growth procedure. (2) Workmanship flaws in welds sometimes occur and are accepted in some ASME code sections. It can be convenient to consider these as flaws when making a design life assessment. (3) Non-destructive Evaluation (NDE) and inspection methods after fabrication are limited in the size of the crack or flaw that can be detected. It is often convenient to perform a life assessment using a flaw of a size that represents the maximum size that can elude detection. (4) Flaws that are observed using in-service detection

  5. Application of welding simulation to block joints in shipbuilding and assessment of welding-induced residual stresses and distortions

    Directory of Open Access Journals (Sweden)

    Fricke Wolfgang

    2014-06-01

    Full Text Available During ship design, welding-induced distortions are roughly estimated as a function of the size of the component as well as the welding process and residual stresses are assumed to be locally in the range of the yield stress. Existing welding simulation methods are very complex and time-consuming and therefore not applicable to large structures like ships. Simplified methods for the estimation of welding effects were and still are subject of several research projects, but mostly concerning smaller structures. The main goal of this paper is the application of a multi-layer welding simulation to the block joint of a ship structure. When welding block joints, high constraints occur due to the ship structure which are assumed to result in accordingly high residual stresses. Constraints measured during construction were realized in a test plant for small-scale welding specimens in order to investigate their and other effects on the residual stresses. Associated welding simulations were successfully performed with fine-mesh finite element models. Further analyses showed that a courser mesh was also able to reproduce the welding-induced reaction forces and hence the residual stresses after some calibration. Based on the coarse modeling it was possible to perform the welding simulation at a block joint in order to investigate the influence of the resulting residual stresses on the behavior of the real structure, showing quite interesting stress distributions. Finally it is discussed whether smaller and idealized models of definite areas of the block joint can be used to achieve the same results offering possibilities to consider residual stresses in the design process.

  6. Calculation of residual stresses by means of a 3D numerical weld simulation

    Energy Technology Data Exchange (ETDEWEB)

    Nicak, Tomas; Huemmer, Matthias [AREVA NP GmbH, Postfach 1109 (Germany)

    2008-07-01

    The numerical weld simulation has developed very fast in recent years. The problem complexity has increased from simple 2D models to full 3D models, which can describe the entire welding process more realistically. As recent research projects indicate, a quantitative assessment of the residual stresses by means of a 3D analysis is possible. The structure integrity can be assessed based on the weld simulation results superimposed with the operating load. Moreover, to support the qualification of welded components parametric studies for optimization of the residual stress distribution in the weld region can be performed. In this paper a full 3D numerical weld simulation for a man-hole drainage nozzle in a steam generator will be presented. The residual stresses are calculated by means of an uncoupled transient thermal and mechanical FE analysis. The paper will present a robust procedure allowing reasonable predictions of the residual stresses for complex structures in industrial practice. (authors)

  7. Technical Letter Report, An Evaluation of Ultrasonic Phased Array Testing for Reactor Piping System Components Containing Dissimilar Metal Welds, JCN N6398, Task 2A

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Aaron A.; Cinson, Anthony D.; Crawford, Susan L.; Anderson, Michael T.

    2009-11-30

    Research is being conducted for the U.S. Nuclear Regulatory Commission at the Pacific Northwest National Laboratory to assess the effectiveness and reliability of advanced nondestructive examination (NDE) methods for the inspection of light-water reactor components. The scope of this research encom¬passes primary system pressure boundary materials including dissimilar metal welds (DMWs), cast austenitic stainless steels (CASS), piping with corrosion-resistant cladding, weld overlays, inlays and onlays, and far-side examinations of austenitic piping welds. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in steel components that challenge standard and/or conventional inspection methodologies. This interim technical letter report provides a summary of a technical evaluation aimed at assessing the capabilities of phased-array (PA) ultrasonic testing (UT) methods as applied to the inspection of small-bore DMW components that exist in the reactor coolant systems (RCS) of pressurized water reactors (PWRs). Operating experience and events such as the circumferential cracking in the reactor vessel nozzle-to-RCS hot leg pipe at V.C. Summer nuclear power station, identified in 2000, show that in PWRs where primary coolant water (or steam) are present under normal operation, Alloy 82/182 materials are susceptible to pressurized water stress corrosion cracking. The extent and number of occurrences of DMW cracking in nuclear power plants (domestically and internationally) indicate the necessity for reliable and effective inspection techniques. The work described herein was performed to provide insights for evaluating the utility of advanced NDE approaches for the inspection of DMW components such as a pressurizer surge nozzle DMW, a shutdown cooling pipe DMW, and a ferritic (low-alloy carbon steel)-to-CASS pipe DMW configuration.

  8. Comparison of Post Weld Treatment of High Strength Steel Welded Joints in Medium Cycle Fatigue

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Melters; Mouritsen, Ole Ø.; Hansen, Michael Rygaard

    2010-01-01

    the stress range can exceed the yield-strength of ordinary structural steel, especially when considering positive stress ratios (R > 0). Fatigue experiments and qualitative evaluation of the different post-weld treatments leads to the selection of TIG dressing. The process of implementing TIG dressing......This paper presents a comparison of three post-weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post-weld treatment for implementation in mass production of certain crane components manufactured from very high-strength steel....... The processes investigated are: burr grinding, TIG dressing and ultrasonic impact treatment. The focus of this investigation is on the so-called medium cycle area, i.e. 10 000-500 000 cycles and very high stress ranges. In this area of fatigue design, the use of very high strength steel becomes necessary, since...

  9. Control of Structure in Conventional Friction Stir Welds through a Kinematic Theory of Metal Flow

    Science.gov (United States)

    Rubisoff, H.A.; Schneider, J.A.; Nunes, A.C.

    2009-01-01

    In friction stir welding (FSW), a rotating pin is translated along a weld seam so as to stir the sides of the seam together. Metal is prevented from flowing up the pin, which would result in plowing/cutting instead of welding, by a shoulder on the pin. In conventional FSW, the weld metal rests on an "anvil", which supports the heavy "plunge" load on the tool. In this study, both embedded tungsten wires along and copper plating on the faying surfaces were used to trace the flow of AA2219 weld metal around the C-FSW tool. The effect of tool rotational speed, travel speed, plunge load, and pin thread pitch on the resulting weld metal flow was evaluated. Plan, longitudinal, and transverse section x-ray radiographs were examined to trace the metal flow paths. The results are interpreted in terms of a kinematic theory of metal flow in FSW.

  10. Microstructures and Mechanical Properties of Friction Tapered Stud Overlap Welding for X65 Pipeline Steel Under Wet Conditions

    Science.gov (United States)

    Xu, Y. C.; Jing, H. Y.; Han, Y. D.; Xu, L. Y.

    2017-08-01

    This paper exhibits a novel in situ remediation technique named friction tapered stud overlap welding (FTSOW) to repair a through crack in structures and components in extremely harsh environments. Furthermore, this paper presents variations in process data, including rotational speed, stud displacement, welding force, and torque for a typical FTSOW weld. In the present study, the effects of welding parameters on the microstructures and mechanical properties of the welding joints were investigated. Inapposite welding parameters consisted of low rotational speeds and welding forces, and when utilized, they increased the occurrence of a lack of bonding and unfilled defects within the weld. The microstructures with a welding zone and heat-affected zone mainly consisted of upper bainite. The hardness value was highest in the welding zone and lowest in the base material. During the pull-out tests, all the welds failed in the stud. Moreover, the defect-free welds broke at the interface of the lap plate and substrate during the cruciform uniaxial tensile test. The best tensile test results at different depths and shear tests were 721.6 MPa and 581.9 MPa, respectively. The favorable Charpy impact-absorbed energy was 68.64 J at 0 °C. The Charpy impact tests revealed a brittle fracture characteristic with a large area of cleavage.

  11. Influence of the parameters of a high-frequency acoustic wave on the structure, properties, and plastic flow of metal in the zone of a joint of materials welded by ultrasound-assisted explosive welding

    Science.gov (United States)

    Peev, A. P.; Kuz'min, S. V.; Lysak, V. I.; Kuz'min, E. V.; Dorodnikov, A. N.

    2017-05-01

    The results of an investigation of the influence of the parameters of high-frequency acoustic wave on the structure and properties of the zone of joint of homogeneous metals bonded by explosive welding under the action of ultrasound have been presented. The influence of the frequency and amplitude of ultrasonic vibrations on the structure and properties of the explosively welded joints compared with the samples welded without the application of ultrasound has been established. The action of high-frequency acoustic waves on the metal leads to a reduction in the dynamic yield stress, which changes the properties of the surface layers of the metal and the conditions of the formation of the joint of the colliding plates upon the explosive welding. It has been shown that the changes in the length and amplitude of waves that arise in the weld joint upon the explosive welding with the simultaneous action of ultrasonic vibrations are connected with a decrease in the magnitude of the deforming pulse and time of action of the compressive stresses that exceed the dynamic yield stress beyond the point of contact.

  12. Welding technology for rails. Rail no setsugo gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Okumura, M.; Karimine, K. (Nippon Steel Corp., Tokyo (Japan)); Uchino, K.; Sugino, K. (Nippon Steel Corp., Kitakyushu, Fukuoka (Japan). Technical Research Inst. of Yawata Works); Ueyama, K. (JR Railway Technical Research Inst., Tokyo (Japan))

    1993-08-01

    The rail joining technology is indispensable for making long welded rails. Flush butt welding, gas welding, enclosed arc welding, and thermit welding are used properly as the welding methods. A method for improving the joint reliability by controlling the residual stress distribution of welded joint is investigated to prepare high carbon component weld metal similar to the rail. Problems with each of the welding methods and the newly developed technology to solve the problems are outlined. Composition of the coating is improved also, and a high C system welding rod is developed which has satisfactory weldability. High performance and high efficient new enclosed arc welding technology not available by now is developed which utilizes high carbon welding metal as a new EA welding work technology, and put to practical use. As a result of this study, useful guides are obtained for the establishment of satisfactory thermit welding technology. 17 refs., 16 figs., 1 tab.

  13. Studies of welded joints

    Directory of Open Access Journals (Sweden)

    J. M. Krupa

    2010-07-01

    Full Text Available Studies of a welded joint were described. The joint was made as a result of the reconstruction of a truss and one of the possible means to make a repair. The studies were of a simulation character and were targeted at the detection of welding defects and imperfections thatshould be eliminated in a real structure. A model was designed and on this model the tests and examinations were carried out. The modelwas made under the same conditions as the conditions adopted for repair. It corresponded to the real object in shape and dimensions, and in the proposed technique of welding and welding parameters. The model was composed of five plates joined together with twelve beads.The destructive and non-destructive tests were carried out; the whole structure and the respective welds were also examined visually. Thedefects and imperfections in welds were detected by surface methods of inspection, penetration tests and magnetic particle flaw detection.The model of the welded joint was prepared by destructive methods, a technique that would never be permitted in the case of a realstructure. For the investigations it was necessary to cut out the specimens from the welded joint in direction transverse to the weld run. The specimens were subjected to metallographic examinations and hardness measurements. Additionally, the joint cross-section was examined by destructive testing methods to enable precise determination of the internal defects and imperfections. The surface methods were applied again, this time to determine the severity of welding defects. The analysis has proved that, fabricated under proper conditions and with parameters of the welding process duly observed, the welded joint has good properties and repairs of this type are possible in practice.

  14. Systems and Methods for Fabricating Structures Including Metallic Glass-Based Materials Using Ultrasonic Welding

    Science.gov (United States)

    Hofmann, Douglas C. (Inventor); Roberts, Scott N. (Inventor)

    2017-01-01

    Systems and methods in accordance with embodiments of the invention fabricate objects including metallic glass-based materials using ultrasonic welding. In one embodiment, a method of fabricating an object that includes a metallic glass-based material includes: ultrasonically welding at least one ribbon to a surface; where at least one ribbon that is ultrasonically welded to a surface has a thickness of less than approximately 150.mu.m; and where at least one ribbon that is ultrasonically welded to a surface includes a metallic glass-based material.

  15. An adaptive sliding mode control technology for weld seam tracking

    Science.gov (United States)

    Liu, Jie; Hu, Youmin; Wu, Bo; Zhou, Kaibo; Ge, Mingfeng

    2015-03-01

    A novel adaptive sliding mode control algorithm is derived to deal with seam tracking control problem of welding robotic manipulator, during the process of large-scale structure component welding. The proposed algorithm does not require the precise dynamic model, and is more practical. Its robustness is verified by the Lyapunov stability theory. The analytical results show that the proposed algorithm enables better high-precision tracking performance with chattering-free than traditional sliding mode control algorithm under various disturbances.

  16. Friction Stir Welding of HT9 Ferritic-Martensitic Steel: An Assessment of Microstructure and Properties

    Science.gov (United States)

    2013-06-01

    to 17.79kN) for a ferrous alloy , which is likely due to the small tool shoulder diameter (0.44in/1.12cm) [56]. The normal force increased with...structural components. Joining of these new alloys poses a challenge and limits their application in nuclear reactors. Traditionally, fusion welding has...been used to join alloy components. Unfortunately, fusion welding of components can result in a number of problems such as loss of strength, stress

  17. Relationship between image plates physical structure and quality of digital radiographic images in weld inspections

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Davi F.; Silva, Aline S.S.; Machado, Alessandra S.; Gomes, Celio S.; Nascimento, Joseilson; Lopes, Ricardo T., E-mail: davi@lin.ufrj.br.br, E-mail: aline@lin.ufrj.br, E-mail: celio@lin.ufrj.br, E-mail: alemachado@lin.ufrj.br, E-mail: joseilson@lin.ufrj.br, E-mail: ricardo@lin.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Instrumentacao Nuclear

    2015-07-01

    In the last decades a new type of detector which is based on photostimulable luminescence was developed. There are currently many kinds of image plates (IPs) available on the market, originating from different manufacturers. Each kind of plate distinguishes itself from the others by its peculiar physical structure and composition, two factors which have a direct influence upon the quality of the digital radiographic images obtained through them. For this study, several kinds of IPs were tested in order to determine in which way such influence takes place. For this purpose, each kind of IP has been characterized and correlated to its response in the final image. The aim of this work was to evaluate procedures for employing Computed Radiography (CR) to welding inspections in laboratory conditions using the Simple Wall Simple Image Technique (SWSI). Tests were performed in steel welded joins of thickness 5.33, 12.70 and 25.40 mm, using CR scanner and IPs available on the market. It was used an X-Ray equipment as radiation source. The image quality parameters Basic Spatial Resolution (BSR), Normalized Signal-to-Noise Ratio (SNR{sub N}), contrast and detectability were evaluated. In order to determine in which way the IPs' properties are correlated to its response in the final image, the thickness of the sensitive layer was determined and the grain size and the elemental composition of this layer were evaluated. Based on the results drawn from this study, it is possible to conclude that the physical characteristics of image plates are essential for determining the quality of the digital radiography images acquired with them. Regarding the chemical composition of the plates, it was possible to determine that, apart from the chemical elements that were expected to be found (Ba, I and Br), only two plates, with high resolution, do not have fluorine in their composition; the presence of Strontium was also detected in the chemical composition of the plates supplied by a

  18. EB-welding of the copper canister for the nuclear waste disposal. Final report of the development programme 1994-1997

    Energy Technology Data Exchange (ETDEWEB)

    Aalto, H. [Outokumpu Oy Poricopper, Pori (Finland)

    1998-10-01

    During 1994-1997 Posiva Oy and Outokumpu Poricopper Oy had a joint project Development of EB-welding method for massive copper canister manufacturing. The project was part of the national technology program `Weld 2000` and it was supported financially by Technology Development Centre (TEKES). The spent fuel from Finnish nuclear reactors is planned to be encapsulated in thick-walled copper canisters and placed deep into the bedrock. The thick copper layer of the canister provides a long time corrosion resistance and prevents deposited nuclear fuel from contact with water. The quality requirements of the copper components are high because of the designed long lifetime of the canister. The EB-welding technology has proved to be applicable method for the production of the copper canisters and the EB-welding technique is needed at least when the lids of the copper canister will be closed. There are a number of parameters in EB-welding which affect weldability. However, the effect of the welding parameters and their optimization has not been extensively studied in welding of thick copper sections using conventional high vacuum EB-welding. One aim of this development work was to extensively study effect of welding parameters on weld quality. The final objective was to minimise welding defects in the main weld and optimize slope out procedure in thick copper EB-welding. Welding of 50 mm thick copper sections was optimized using vertical and horizontal EB-welding techniques. As a result two full scale copper lids were welded to a short cylinder successfully. The resulting weld quality with optimised welding parameters was reasonable good. The optimised welding parameters for horizontal and vertical beam can be applied to the longitudinal body welds of the canister. The optimal slope out procedure for the lid closure needs some additional development work. In addition of extensive EB-welding program ultrasonic inspection and creep strength of the weld were studied. According

  19. EB-welding of the copper canister for the nuclear waste disposal. Final report of the development programme 1994-1997

    Energy Technology Data Exchange (ETDEWEB)

    Aalto, H. [Outokumpu Oy Poricopper, Pori (Finland)

    1998-10-01

    During 1994-1997 Posiva Oy and Outokumpu Poricopper Oy had a joint project Development of EB-welding method for massive copper canister manufacturing. The project was part of the national technology program `Weld 2000` and it was supported financially by Technology Development Centre (TEKES). The spent fuel from Finnish nuclear reactors is planned to be encapsulated in thick-walled copper canisters and placed deep into the bedrock. The thick copper layer of the canister provides a long time corrosion resistance and prevents deposited nuclear fuel from contact with water. The quality requirements of the copper components are high because of the designed long lifetime of the canister. The EB-welding technology has proved to be applicable method for the production of the copper canisters and the EB-welding technique is needed at least when the lids of the copper canister will be closed. There are a number of parameters in EB-welding which affect weldability. However, the effect of the welding parameters and their optimization has not been extensively studied in welding of thick copper sections using conventional high vacuum EB-welding. One aim of this development work was to extensively study effect of welding parameters on weld quality. The final objective was to minimise welding defects in the main weld and optimize slope out procedure in thick copper EB-welding. Welding of 50 mm thick copper sections was optimized using vertical and horizontal EB-welding techniques. As a result two full scale copper lids were welded to a short cylinder successfully. The resulting weld quality with optimised welding parameters was reasonable good. The optimised welding parameters for horizontal and vertical beam can be applied to the longitudinal body welds of the canister. The optimal slope out procedure for the lid closure needs some additional development work. In addition of extensive EB-welding program ultrasonic inspection and creep strength of the weld were studied. According

  20. Structural integrity and management of aging in internal components of BWR reactors; Integridad estructural y manejo del envejecimiento en componentes internos de reactores BWR

    Energy Technology Data Exchange (ETDEWEB)

    Arganis J, C.R. [Instituto Nacional de Investigaciones Nucleares, Km 36.5 Carretera Mexico, Toluca Salazar Edo. de Mexico (Mexico)]. E-mail: craj@nuclear.inin.mx

    2004-07-01

    Presently work the bases to apply structural integrity and the handling of the aging of internal components of the pressure vessel of boiling water reactors of water are revised and is carried out an example of structural integrity in the horizontal welding H4 of the encircling one of the core of a reactor, taking data reported in the literature. It is also revised what is required to carry out the handling program or conduct of the aging (AMP). (Author)

  1. 弯曲箱型结构焊接顺序对残余应力的影响%Influence of Welding Sequence of Bend Box Structure on Welding Residual Stress

    Institute of Scientific and Technical Information of China (English)

    韩双宗; 王发展

    2016-01-01

    Finite element model of bend box structure was established.Different welding schemes were analyzed by local to whole hierarchical optimization method.The influence laws of welding sequence on the residual stress were studied,and then the optimum welding scheme was proposed.The results show that the welding sequence which can reduce transient heat input concentration could reduce the maximum residual tensile stress prominently for single weld bead,and the reduction rate is 17.7%.The change of welding sequence and direction could control the residual stress for dissimilar weld beads to some degree.But,the change of whole welding sequence could not change the value and distribution of residual stress prominently.%建立了弯曲箱形结构的有限元模型,采用从局部到整体的逐层优化法,对不同焊接方案进行分析,研究了焊接顺序对残余应力的影响规律,进而提出最优焊接方案.结果表明:对于单条焊道,减少瞬时热输入集中的焊接顺序能大幅降低残余拉应力的最大值,降低率达到17.7%;改变焊道间的焊接顺序及焊接方向也能在一定程度上控制残余应力,但是整体焊接顺序的变化并没有显著改变残余应力的大小和分布状况.

  2. Prediction Models on Distribution of Inherent Strains in T Type Welding Structure

    Institute of Scientific and Technical Information of China (English)

    Peng HE; Jicai FENG; Jiecai HAN; Yiyu QIAN

    2003-01-01

    A fundamental theory for the analysis of residual welding stresses and deformation based on the inherent strain distribution along the welded joint is introduced. The method of predicting maximum hardness Hv(y, z) and maximum inherent strain gmax is given

  3. Validation of Temperature Histories for Structural Steel Welds Using Estimated Heat-Affected-Zone Edges

    Science.gov (United States)

    2016-10-12

    used parametrically for inverse thermal analysis of welds corresponding to other welding processes whose process conditions are within similar...regimes. The present study applies an inverse thermal analysis procedure that uses three-dimensional constraint conditions whose two-dimensional...projections are mapped within transverse cross sections of experimentally measured solidification boundaries. In addition, the present study uses

  4. Acoustic determination of cracks in welded joints. [by resonant structural vibration measurements

    Science.gov (United States)

    Baltanoiu, M.; Criciotoiu, E.

    1974-01-01

    The acoustic analysis method permits detection of any cracks that might take place and their manner of propagation. The study deals with the cracks produced in experiments to determine the welding technology for a welded gray cast iron workpiece by using piezoelectric transducers to determine vibration acceleration.

  5. 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.…

  6. 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

  7. Microstructure and Martensitic Transformation Behaviors of Explosively Welded NiTi/NiTi Laminates

    Institute of Scientific and Technical Information of China (English)

    YAN Zhu; CUI Li-shan; ZHENG Yan-jun

    2007-01-01

    The study is a first attempt to prepare bulk NiTi/NiTi shape memory alloy (SMA) laminates with a macroscopic heterogeneous composition by explosive welding and investigate their microstructures and martensitic transformation behaviors. After explosive welding, a perfect interfacial bonding between the two components and a reversible martensitic transformation are realized in the tandem.Results show achievement of a fine granular structure and the maximum value of microhardness near the welding interface because of the excessive cold plastic deformation and the high impact velocity during the explosive welding. Meanwhile, the effects of aging on the transformation of the welded tandem are investigated by differential scanning calorimeter (DSC) and subject to discussion. The transformation temperatures of NiTi/NiTi SMAs increase with the rise of the aging temperature. The experimental results indicate the shape memory properties of NiTi/NiTi SMA fabricated by explosive welding can be improved by optimizing the aging technology.

  8. A welding document management software package based on a Client/Server structure

    Institute of Scientific and Technical Information of China (English)

    魏艳红; 杨春利; 王敏

    2003-01-01

    According to specifications for Welding Procedure Qualification of ASME IX Section and Chinese code, JB 4708-2000, a software package for managing welding documents has been rebuilt. Consequently, the new software package can be used in a Limited Area Network (LAN) with 4 different levels of authorities for different users. Therefore, the welding documents, including DWPS (Design for Welding Procedure Specifications), PQRs (Procedure Qualification Records) and WPS (Welding Procedure Specifications) can be shared within a company. At the same time, the system provides users various functions such as browsing, copying, editing, searching and printing records, and helps users to make decision of whether a new PQR test is necessary or not according to the codes above as well. Furthermore, super users can also browse the history of record modification and retrieve the records when needed.

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

    Science.gov (United States)

    Al-Sarraf, Z.; Lucas, M.

    2012-08-01

    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.

  10. Effect of weld heat input on toughness and structure of HAZ of a new super-high strength steel

    Indian Academy of Sciences (India)

    Wang Juan; Li Yajiang; Liu Peng

    2003-04-01

    Fracture morphology and fine structure in the heat-affected zone (HAZ) of HQ130 super-high strength steel are studied by means of SEM, TEM and electron diffraction technique. Test results indicated that the structure of HAZ of HQ130 steel was mainly lath martensite (ML), in which there were a lot of dislocations in the sub-structure inside ML lath, the dislocation density was about (0.3 ∼ 0.9) × 1012/cm2. No obvious twin was observed in the HAZ under the condition of normal weld heat input. By controlling weld heat input ($E \\leq$ 20 kJ/cm), the impact toughness in the HAZ can be assured.

  11. Rheomorphism of welded tuffs

    Science.gov (United States)

    Wolff, J. A.; Wright, J. V.

    1981-05-01

    Peralkaline welded tuffs from the islands of Gran Canaria, Canary Islands, and Pantelleria, Italy, show abundant evidence for post-depositional flow. It is demonstrated that rheomorphism, or secondary mass flowage, can occur in welded tuffs of ignimbrite and air-fall origin. The presence of a linear fabric is taken as the diagnostic criterion for the recognition of the process. Deposition on a slope is an essential condition for the development of rheomorphism after compaction and welding. Internal structures produced during rheomorphic flow can be studied by the methods of structural geology and show similar dispositions to comparable features in sedimentary slump sheets. It is shown that secondary flowage can occur in welded tuffs emplaced on gentle slopes, provided that the apparent viscosity of the magma is sufficiently low. Compositional factors favor the development of rheomorphism in densely welded tuffs of peralkaline type.

  12. Crack initiation and growth in welded structures; Amorcage et propagation de la fissuration dans les jonctions soudees

    Energy Technology Data Exchange (ETDEWEB)

    Assire, A

    2000-10-13

    This work concerns the remaining life assessment of a structure containing initial defects of manufacturing. High temperature crack initiation and growth are studied for austenitic stainless steels, and defect assessment methods are improved in order to take into account welded structures. For these one, the probability to have a defect is significant. Two kinds of approaches are commonly used for defect assessment analysis. Fracture mechanics global approach with an energetic criterion, and local approach with a model taking into account the physical damage mechanism. For both approaches mechanical fields (stress and strain) have to be computed everywhere within the structure. Then, Finite Element computation is needed. The first part of the thesis concerns the identification of non linear kinematic and isotropic constitutive models. A pseudo-analytical method is proposed for a 'Two Inelastic Strain' model. This method provides a strategy of identification with a mechanical meaning, and this enables to associate each parameter to a physical phenomenon. Existing identifications are improved for cyclic plasticity and creep on a large range of stress levels. The second part concerns high temperature crack initiation and growth in welded structures. Finite Element analysis on plate and tube experimental configuration enable to understand the phenomenons of interaction between base metal and weld metal under mechanical and thermal loading. Concerning global approach, criteria based on C* parameter (Rice integral for visco-plasticity) are used. Finite Element computations underline the fact that for a defect located in the weld metal, C* values strongly depend on the base metal creep strain rate, because widespread visco-plasticity is located in both metals. A simplified method, based on the reference stress approach, is proposed and validated with Finite Element results. Creep crack growth simplified assessment is a quite good validation of the experimental

  13. Methods for reliability based design optimization of structural components

    OpenAIRE

    Dersjö, Tomas

    2012-01-01

    Cost and quality are key properties of a product, possibly even the two most important. Onedefinition of quality is fitness for purpose. Load-bearing products, i.e. structural components,loose their fitness for purpose if they fail. Thus, the ability to withstand failure is a fundamentalmeasure of quality for structural components. Reliability based design optimization(RBDO) is an approach for development of structural components which aims to minimizethe cost while constraining the probabili...

  14. A Brief Introduction to the Theory of Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2008-01-01

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

  15. Structure of MMCs with SiC Particles after Gas-tungsten Arc Welding

    Directory of Open Access Journals (Sweden)

    Przełożyńska E.

    2015-12-01

    Full Text Available The gas-tungsten arc (GTA welding behaviors of a magnesium matrix composite reinforced with SiC particles were examined in terms of microstructure characteristics and process efficiencies. This study focused on the effects of the GTAW process parameters (like welding current in the range of 100/200 A on the size of the fusion zone (FZ. The analyses revealed the strong influence of the GTA welding process on the width and depth of the fusion zone and also on the refinement of the microstructure in the fusion zone. Additionally, the results of dendrite arm size (DAS measurements were presented.

  16. CHARACTERIZATION OF DEFECTS IN ALLOY 152, 52 AND 52M WELDS

    Energy Technology Data Exchange (ETDEWEB)

    Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.; Seffens, Rob J.; Efsing, Pal G.

    2009-08-27

    Defect distributions have been documented by optical metallography, scanning electron microscopy and electron backscatter diffraction in alloy 152 and 52 mockups welds, alloy 52 and 52M overlay mockups and an alloy 52M inlay. Primary defects were small cracks at grain boundaries except for more extensive cracking in the dilution zone of an alloy 52 overlay on 304SS. Detailed characterizations of the dilution zone cracks were performed by analytical transmission electron microscopy identifying grain boundary titanium-nitride precipitation associated with the intergranular separations. I. INTRODUCTION Weldments continue to be a primary location of stress-corrosion cracking (SCC) in light-water reactor systems. While problems related to heat-affected-zone (HAZ) sensitization and intergranular (IG) SCC of austenitic stainless alloys in boiling-water reactors (BWRs) have been significantly reduced, SCC has now been observed in HAZs of non-sensitized materials and in dissimilar metal welds where Ni-base alloy weld metals are used. IGSCC in weld metals has been observed in both BWRs and pressurized water reactors (PWRs) with recent examples for PWR pressure vessel penetrations producing the most concern. This has led to the replacement of alloy 600/182/82 welds with higher Cr, more corrosion-resistant replacement materials (alloy 690/152/52/52M). Complicating this issue has been a known susceptibility to cracking during welding [1-7] of these weld metals. There is a critical need for an improved understanding of the weld metal metallurgy and defect formation in Ni-base alloy welds to effectively assess long-term performance. A series of macroscopic to microscopic examinations were performed on available mockup welds made with alloy 52 or alloy 152 plus selected overlay and inlay mockups. The intent was to expand our understanding of weld metal structures in simulated LWR service components with a focus on as-welded defects. Microstructural features, defect distributions

  17. 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.

  18. Factor structure underlying components of allostatic load.

    Directory of Open Access Journals (Sweden)

    Jeanne M McCaffery

    Full Text Available Allostatic load is a commonly used metric of health risk based on the hypothesis that recurrent exposure to environmental demands (e.g., stress engenders a progressive dysregulation of multiple physiological systems. Prominent indicators of response to environmental challenges, such as stress-related hormones, sympatho-vagal balance, or inflammatory cytokines, comprise primary allostatic mediators. Secondary mediators reflect ensuing biological alterations that accumulate over time and confer risk for clinical disease but overlap substantially with a second metric of health risk, the metabolic syndrome. Whether allostatic load mediators covary and thus warrant treatment as a unitary construct remains to be established and, in particular, the relation of allostatic load parameters to the metabolic syndrome requires elucidation. Here, we employ confirmatory factor analysis to test: 1 whether a single common factor underlies variation in physiological systems associated with allostatic load; and 2 whether allostatic load parameters continue to load on a single common factor if a second factor representing the metabolic syndrome is also modeled. Participants were 645 adults from Allegheny County, PA (30-54 years old, 82% non-Hispanic white, 52% female who were free of confounding medications. Model fitting supported a single, second-order factor underlying variance in the allostatic load components available in this study (metabolic, inflammatory and vagal measures. Further, this common factor reflecting covariation among allostatic load components persisted when a latent factor representing metabolic syndrome facets was conjointly modeled. Overall, this study provides novel evidence that the modeled allostatic load components do share common variance as hypothesized. Moreover, the common variance suggests the existence of statistical coherence above and beyond that attributable to the metabolic syndrome.

  19. Welding for testability: An approach aimed at improving the ultrasonic testing of thick-walled austenitic and dissimilar metal welds

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Sabine; Dugan, Sandra [Materials Testing Institute University of Stuttgart (MPA), Pfaffenwaldring 32, 70569 Stuttgart (Germany); Barth, Martin; Schubert, Frank; Köhler, Bernd [Fraunhofer Institute for Nondestructive Testing, Dresden Branch (IZFP-D), Maria-Reiche-Str. 2, 01109 Dresden (Germany)

    2014-02-18

    Austenitic and dissimilar welds in thick walled components show a coarse grained, dendritic microstructure. Therefore, ultrasonic testing has to deal with beam refraction, scattering and mode conversion effects. As a result, the testing techniques typically applied for isotropic materials yield dissatisfying results. Most approaches for improvement of ultrasonic testing have been based on modeling and improved knowledge of the complex wave propagation phenomena. In this paper, we discuss an alternative approach: is it possible to use a modified welding technology which eliminates the cause of the UT complications, i.e. the large-grained structure of the weld seams? Various modification parameters were tested, including: TIG current pulsing, additional DC and AC magnetic fields, and also additional external vibrations during welding. For all welds produced under different conditions, the grain structure of the weld seam was characterized by optical and GIUM microstructure visualizations on cross sections, wave field propagation measurements, and ultrasonic tests of correct detectability of flaws. The mechanical properties of the welds were also tested.

  20. Polymer matrix nanocomposites for automotive structural components

    Science.gov (United States)

    Naskar, Amit K.; Keum, Jong K.; Boeman, Raymond G.

    2016-12-01

    Over the past several decades, the automotive industry has expended significant effort to develop lightweight parts from new easy-to-process polymeric nanocomposites. These materials have been particularly attractive because they can increase fuel efficiency and reduce greenhouse gas emissions. However, attempts to reinforce soft matrices by nanoscale reinforcing agents at commercially deployable scales have been only sporadically successful to date. This situation is due primarily to the lack of fundamental understanding of how multiscale interfacial interactions and the resultant structures affect the properties of polymer nanocomposites. In this Perspective, we critically evaluate the state of the art in the field and propose a possible path that may help to overcome these barriers. Only once we achieve a deeper understanding of the structure-properties relationship of polymer matrix nanocomposites will we be able to develop novel structural nanocomposites with enhanced mechanical properties for automotive applications.

  1. Polymer matrix nanocomposites for automotive structural components.

    Science.gov (United States)

    Naskar, Amit K; Keum, Jong K; Boeman, Raymond G

    2016-12-06

    Over the past several decades, the automotive industry has expended significant effort to develop lightweight parts from new easy-to-process polymeric nanocomposites. These materials have been particularly attractive because they can increase fuel efficiency and reduce greenhouse gas emissions. However, attempts to reinforce soft matrices by nanoscale reinforcing agents at commercially deployable scales have been only sporadically successful to date. This situation is due primarily to the lack of fundamental understanding of how multiscale interfacial interactions and the resultant structures affect the properties of polymer nanocomposites. In this Perspective, we critically evaluate the state of the art in the field and propose a possible path that may help to overcome these barriers. Only once we achieve a deeper understanding of the structure-properties relationship of polymer matrix nanocomposites will we be able to develop novel structural nanocomposites with enhanced mechanical properties for automotive applications.

  2. Optimisation of component performance via structuring

    Directory of Open Access Journals (Sweden)

    Psyk Verena

    2015-01-01

    Full Text Available Ecological and economic reasons are forcing industry to improve efficiency and to save energy and resources by reducing product weight. In current product designs often insufficient geometric stiffness of the part prohibits exploiting the full potential of weight reduction offered by modern materials. Ideally adapting the geometry to the load profile by implementing appropriate structures often allows a wall thickness and weight reduction and improves the acoustic properties. To enable a target-oriented design, structures manufactured by working media and working energy based forming technologies were analysed.

  3. Procedure for Computing Residual Stresses from Neutron Diffraction Data and its Application to Multi-Pass Dissimilar Weld

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei [ORNL; Feng, Zhili [ORNL; Crooker, Paul [Electric Power Research Institute (EPRI)

    2011-01-01

    Neutron diffraction is a powerful tool for non-destructive measurement of internal residual stresses of welded structures. The conventional approach for determination of residual stresses requires the knowledge of stress-free lattice spacing a priori. For multiple-pass dissimilar metal welds common to nuclear reactor pipeline systems, the stress-free lattice parameter is a complex function of position due to the chemistry inhomogeneity in the weld region and can be challenging to determine experimentally. This paper presents a new approach to calculate the residual stress field in dissimilar welds without the use of stress-free lattice parameter. The theoretical basis takes advantage of the fact that the normal component of welding residual stresses is typically small for thin plate or pipe welds. The applicability of the new approach is examined and justified in a multi-pass dissimilar metal weld consisting of a stainless steel plate and a nickel alloy filler metal. The level of uncertainties associated with this new approach is assessed. Neutron diffraction experiment is carried out to measure the lattice spacing at various locations in the dissimilar weld. A comb-shaped specimen, electro-discharge machined from a companion weld, is used to determine the stress-free lattice spacing. The calculated results from the new approach are consistent with those from the conventional approach. The new approach is found to be a practical method for determining the two in-plane residual stress components in thin plate or pipe dissimilar metal welds.

  4. Structured Observation Component. Secondary Teacher Education Program.

    Science.gov (United States)

    Berger, Michael L.; Keen, Phyllis A.

    A format is presented for use of student teachers in structuring their classroom observation techniques. Fifteen classroom and school activities are listed with a comprehensive questionnaire accompanying each. These questionnaires guide the student on what behaviors to observe and suggest objective and subjective responses to these behaviors to be…

  5. Fatigue life estimation of welded joints of an aluminium alloy under superimposed random load waves (follow-up report). Effects o high frequency components; Jujo random kajuka ni okeru aluminium gokin yosetsu tsugite no hiro jumyo suitei (zokuho). Koshuha seibun no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, K.; Maenaka, H.; Takada, A. [Ship Research Inst., Tokyo (Japan)

    1996-06-01

    In the previous paper, fatigue tests of fillet welded T-joints of JIS A 5083P-O Al-Mg alloy for structural members of ship body were conducted under superimposed random load waves in which the secondary fluctuating waveform superimposes on the primary one, to verify the effectiveness of various fatigue life estimation methods. The T-joints used as specimens had welded toes finished by grinder. In this study, boxing welded joints were used. The residual stress measurements, static loading tests, elastic finite element analysis, and fatigue tests were conducted under both constant amplitude and random loads. These tests were conducted under more common conditions. As a result, conclusions obtained are as follows. A reference stress, which was determined as the stress at a distance of 5 mm from a boxing weld toe, was proved effective in reducing the amount of scattering in the fatigue test results, and in improving the accuracy of fatigue life estimation. With regard to the high frequency components, it was required to express the fatigue life using a representative frequency for each stress. 4 refs., 21 figs., 4 tabs.

  6. Investigation of microstructure and mechanical properties of explosively welded ITER-grade 316L(N)/CuCrZr hollow structural member

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Rui, E-mail: mr9980@163.com [PLA University of Science and Technology, Nanjing 210007 (China); Navy Command Academy, Nanjing 210007 (China); Wang, Yaohua [PLA University of Science and Technology, Nanjing 210007 (China); Wu, Jihong [Southwestern Institute of Physics, Chengdu 610041 (China); Duan, Mianjun [PLA University of Science and Technology, Nanjing 210007 (China)

    2015-04-15

    Highlights: • Develop a new explosive welding method to fabricate the hollow structural member. • Effects of solution annealing on microstructure of welding interface researched. • Influence of heat treatments on hardness evolution in welding interface studied. • The ultimate strength and elongation were increased after solution annealing. • The interface of samples was exhibited ductile fracture after solution annealing. - Abstract: In this study, a new explosive welding method furnished an effective way for manufacturing ITER-grade 316L(N) stainless steel/CuCrZr alloy hollow structural member. In order to recover some hardening effects, caused by plastic deformation during explosion welding in the materials bonding interface region, the welded samples were subject to the solution annealing (SA) treatment at 970 °C for 30 min. The SA heat-treated samples were then aged at 580 °C for 2 h. Optical microscopy (OM) and electron microscopy (SEM) were used to analyze the microstructure of bonding interface. Energy dispersive spectroscopy (EDS) analysis was performed to investigate the diffusion zone formed in the interface region after the solution annealing (SA) treatment. Moreover, the mechanical properties of the welded samples were evaluated through microhardness test and tensile strength test. Microstructural analysis showed that the welded sample had a wavy interface, and there was no melting zone and intermetallic layer formed in the interface. The result of microhardness test revealed an increase in hardness for both sides near to the bonding interface; this is due to more severe plastic deformation in these regions during the explosive welding. After the tensile test, obvious necking was observed in the fracture cross section of samples. SEM observation indicated that the samples with the post solution annealing treatment exhibited a ductile fracture with dimple features after tensile test.

  7. Gradient approach for the evaluation of the fatigue limit of welded structures under complex loading

    Directory of Open Access Journals (Sweden)

    Y. Nadot

    2017-07-01

    Full Text Available Welded ‘T-junctions’ are tested at different load ratio for constant and variable amplitude loading. Fatigue results are analyzed through the type of fatigue mechanisms depending on the loading type. A gradient approach (WSG: Welded Stress Gradient is used to evaluate the fatigue limit and the comparison with experimental results shows a relative good agreement. Nonlinear cumulative damage theory is used to take into account the variable amplitude loading.

  8. Comparison between hybrid laser-MIG welding and MIG welding for the invar36 alloy

    Science.gov (United States)

    Zhan, Xiaohong; Li, Yubo; Ou, Wenmin; Yu, Fengyi; Chen, Jie; Wei, Yanhong

    2016-11-01

    The invar36 alloy is suitable to produce mold of composite materials structure because it has similar thermal expansion coefficient with composite materials. In the present paper, the MIG welding and laser-MIG hybrid welding methods are compared to get the more appropriate method to overcome the poor weldability of invar36 alloy. According to the analysis of the experimental and simulated results, it has been proved that the Gauss and cone combined heat source model can characterize the laser-MIG hybrid welding heat source well. The total welding time of MIG welding is 8 times that of hybrid laser-MIG welding. The welding material consumption of MIG welding is about 4 times that of hybrid laser-MIG welding. The stress and deformation simulation indicate that the peak value of deformation during MIG welding is 3 times larger than that of hybrid laser-MIG welding.

  9. Mechanical properties and structure of friction stir welds of rolled Zr-modified AA5083 alloy

    Science.gov (United States)

    Malopheyev, S.; Mironov, S.; Kaibyshev, R.

    2016-11-01

    Microstructure and mechanical properties of friction stir welds of Zr-modified AA5083 aluminum sheets were studied. The sheets were produced by cold or hot rolling with a total reduction of 80%. In both rolled conditions, the average high angle boundary spacing was 17-18 µm. The density of free dislocations was ˜5.6 × 1013 and ˜3.5 × 1014 m-2 in hot rolled and cold rolled conditions, respectively. The volume fraction of incoherent Al6Mn dispersoids with an average diameter of ˜25 nm was measured to be ˜0.076%. Defect-free welds were produced by double-side friction stir welding (FSW). Friction stir welding led to the formation of fully recrystallized microstructures with the average grain size about 2.5 µm and low dislocation density in the stir zone in both conditions. The average size and volume fraction of Al6Mn particles increased to ˜25 nm and ˜0.1%, respectively. The joint efficiency of the friction stir welds for ultimate tensile strength was found to be 74 and 94% in the cold-rolled and hot-rolled preprocessed material conditions. The relatively low weld strength was attributed to the elimination of dislocation substructure strengthening during FSW.

  10. SNL/SRNL Joint Project on degradation of mechanical properties in structural metals and welds for GTS reservoirs.

    Energy Technology Data Exchange (ETDEWEB)

    Ronevich, Joseph Allen [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Balch, Dorian K. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); San Marchi, Christopher W. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); West, Scott [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Morgan, Mike [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-12-01

    This project was intended to enable SNL-CA to produce appropriate specimens of relevant stainless steels for testing and perform baseline testing of weld heat-affected zone and weld fusion zone. One of the key deliverables in this project was to establish a procedure for fracture testing stainless steel weld fusion zone and heat affected zones that were pre-charged with hydrogen. Following the establishment of the procedure, a round robin was planned between SNL-CA and SRNL to ensure testing consistency between laboratories. SNL-CA and SRNL would then develop a comprehensive test plan, which would include tritium exposures of several years at SRNL on samples delivered by SNL-CA. Testing would follow the procedures developed at SNL-CA. SRNL will also purchase tritium charging vessels to perform the tritium exposures. Although comprehensive understanding of isotope-induced fracture in GTS reservoir materials is a several year effort, the FY15 work would enabled us to jump-start the tests and initiate long-term tritium exposures to aid comprehensive future investigations. Development of a procedure and laboratory testing consistency between SNL-CA and SNRL ensures reliability in results as future evaluations are performed on aluminum alloys and potentially additively-manufactured components.

  11. Prediction of solidification and phase transformation in weld metals for welding of high performance stainless steels; Kotaishoku kotainetsu stainless koyo yosetsu kinzoku no gyoko hentai no yosoku gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Koseki, T.; Inoue, H.; Morimoto, H.; Okita, S. [Nippon Steel Corp., Tokyo (Japan)

    1995-02-28

    Prediction technology is introduced on the solidification and transformation of weld metals used for high performance stainless steel. A model has been developed which uses Thermo Calc, a multiple balanced calculation program, as a means to analyze the solidification of multi-component alloys including the polyphase solidification such as eutectic and peritectic. Verification has been in progress concerning the adequacy of this model and the adaptability as a practical steel. The following are the prediction technologies for solidification and transformation which have been derived from experiments and applied to welding techniques: the effects of nitrogen on the solidification mode and residual {gamma}quantity of a welding metal that is required for controlling the welding/solidification of high nitrogen content {gamma}system stainless steel; the structural control of weld metal for high corrosion resistance high Mo stainless steel, in which high Ni and high Mo contents are indispensable for attaining the optimum structure; the structural control of weld metal for two-phase stainless steel containing Mo and N, in which it is essential to secure a high nitrogen content and a {delta}/{gamma}phase balance in a weld metal; and the precipitation prediction of intermetallic compound in a high alloy weld metal for a high alloy stainless steel, for which an explanation is there by Cieslak et al. based on the phase stability theory. 22 refs., 16 figs.

  12. 点焊对钢桥细部焊接结构疲劳寿命的影响%Effect of spot welding on the fatigue life of small welded structures of orthotropic steel bridge

    Institute of Scientific and Technical Information of China (English)

    吕彭民; 周小进; 李大涛

    2015-01-01

    To research the effect of spot welding on the fatigue life of small welded structures of or-thotropic steel bridge, the fatigue specimens of bridge cover and U-rib with spot welding, with pol-ished spot welding and without spot welding were designed and produced. Fatigue tests were per-formed by arranging strain gauges around weld roots and weld toe to obtain the fatigue life and crack position of the specimens. The elaborate finite element calculation was carried out for the fatigue specimens, and the following results were obtained. The stress at the weld toe with spot welding is significantly greater than that at the weld root, and the stress concentration of the specimens with polished spot welding is reduced obviously. And the analysis results show that the finite element a-nalysis results were consistent with the experimental results, and the position of fatigue cracks changed with spot welding which led to the decrease of fatigue life obviously. The fatigue life of the specimens with polished spot welding was almost the same as that of those without spot welding.Comparing the fatigue test data with the specifications for steel structure, the following advices can be given:for the specimens without spot welding or with polished spot welding, it is recommended to use detail category 100 of Eurocode3 specification or detail category Ⅶ in the code for design of steel structure of railway bridge;for the samples with spot welding, the fatigue curve should be downgrad-ed, and detail category 100 of Eurocode3 specification or detail category E of BS5400 specification is suggested to be used. To improve the fatigue life of small welded structures, it is necessary to mini-mize spot welding or polish the spot welding.%为了研究点焊对正交异性钢桥细部焊接结构疲劳寿命的影响,制作了桥面板与U肋细部构造疲劳试样,试样分为有点焊、点焊打磨和无点焊三种形式。在试样的焊缝根部和焊趾位置周围布置应变片

  13. The structure and properties of filler metal-free laser beam welded joints in steel S700MC subjected to TMCP

    Science.gov (United States)

    Górka, Jacek; Stano, Sebastian

    2016-12-01

    The research-related tests aimed to determine the effect of filer-metal free laser beam welding on the structure and properties of 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP). The nondestructive tests revealed that the welded joints represented quality level B according to the requirements of standard 13919-1. The destructive tests revealed that the joints were characterised by tensile strength being by approximately 5% lower than that of the base material. The tests of thin foils performed using a high-resolution scanning transmission electron microscope revealed that filler metal-free welding led to the increased amount of alloying microagents (Ti and Nb) in the weld (particularly near fusion line) in comparison with welding performed using a filler metal. The significant content of hardening phases in the welds during cooling resulted in considerable precipitation hardening through finedispersive (Ti,Nb)(C,N) type precipitates (several nm in size) leading to the deterioration of plastic properties. The destructive tests revealed that the joints were characterised by tensile strength being by approximately 5% lower than that of the base material. The increase in the concentration of microagents responsible for steel hardening (Ti and Nb) also contributed to the decrease in weld toughness being below the allowed value of 25 J/cm2.

  14. Structural integrity and life extension of high-temperature components

    Institute of Scientific and Technical Information of China (English)

    WANG Chun; SHEN Shi-ming

    2005-01-01

    Four different topics for high-temperature components, namely the development of the assessment codes for the structural integrity of high-temperature components, the application of continuous damage mechanics and probabilistic damage mode on the life assessment of high-temperature components, the life extension for high-tem perature components and a proposed strategy for remanufacturing of high-temperature components were discussed in this paper. These topics should provide some important insights for the design and re-design of high- temperature components.

  15. Laser welding and post weld treatment of modified 9Cr-1MoVNb steel.

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z. (Nuclear Engineering Division)

    2012-04-03

    Laser welding and post weld laser treatment of modified 9Cr-1MoVNb steels (Grade P91) were performed in this preliminary study to investigate the feasibility of using laser welding process as a potential alternative to arc welding methods for solving the Type IV cracking problem in P91 steel welds. The mechanical and metallurgical testing of the pulsed Nd:YAG laser-welded samples shows the following conclusions: (1) both bead-on-plate and circumferential butt welds made by a pulsed Nd:YAG laser show good welds that are free of microcracks and porosity. The narrow heat affected zone has a homogeneous grain structure without conventional soft hardness zone where the Type IV cracking occurs in conventional arc welds. (2) The laser weld tests also show that the same laser welder has the potential to be used as a multi-function tool for weld surface remelting, glazing or post weld tempering to reduce the weld surface defects and to increase the cracking resistance and toughness of the welds. (3) The Vicker hardness of laser welds in the weld and heat affected zone was 420-500 HV with peak hardness in the HAZ compared to 240 HV of base metal. Post weld laser treatment was able to slightly reduce the peak hardness and smooth the hardness profile, but failed to bring the hardness down to below 300 HV due to insufficient time at temperature and too fast cooling rate after the time. Though optimal hardness of weld made by laser is to be determined for best weld strength, methods to achieve the post weld laser treatment temperature, time at the temperature and slow cooling rate need to be developed. (4) Mechanical testing of the laser weld and post weld laser treated samples need to be performed to evaluate the effects of laser post treatments such as surface remelting, glazing, re-hardening, or tempering on the strength of the welds.

  16. Molecular Component Structures Mediated Formation of Self-assemblies

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Molecular recognition directed self-assemblies from complementary molecular components, melamine and barbituric acid derivatives were studied by means of NMR, fluorescence, and TEM. It was found that both the process of the self-assembly and the morphologies of the result ed self-assemblies could be mediated by modifying the structures of the molecular components used. The effect of the structures of the molecular components on the formation of the self-as semblies was discussed in terms of intermolecular interactions.

  17. Cracking generated by arc welding; La fissuration consecutive a l'operation de soudage a l'arc

    Energy Technology Data Exchange (ETDEWEB)

    Carpreau, J.M. [LaMSID UMR EDF-CNRS-CEA 2832, 78 - Chatou (France)

    2010-07-01

    During welding, rapid localized heat transients lead to thermal cycles, resulting in changes in the local metallurgy and mechanical loading of the components to be joined. Depending on the materials, these changes may generate cracks, making the weld structure unable to resist in-service loading. Analysis of various cracking mechanisms showed the role of the thermomechanical loading of the weld or HAZ during cooling after arc welding. Hence, prediction of cracking is based on the calculation of the thermomechanical stress, which often gives an estimated range, or from a mechanistically-based phenomenological approach. (author)

  18. Thick SS316 materials TIG welding development activities towards advanced fusion reactor vacuum vessel applications

    Science.gov (United States)

    Kumar, B. Ramesh; Gangradey, R.

    2012-11-01

    Advanced fusion reactors like ITER and up coming Indian DEMO devices are having challenges in terms of their materials design and fabrication procedures. The operation of these devices is having various loads like structural, thermo-mechanical and neutron irradiation effects on major systems like vacuum vessel, divertor, magnets and blanket modules. The concept of double wall vacuum vessel (VV) is proposed in view of protecting of major reactor subsystems like super conducting magnets, diagnostic systems and other critical components from high energy 14 MeV neutrons generated from fusion plasma produced by D-T reactions. The double walled vacuum vessel is used in combination with pressurized water circulation and some special grade borated steel blocks to shield these high energy neutrons effectively. The fabrication of sub components in VV are mainly used with high thickness SS materials in range of 20 mm- 60 mm of various grades based on the required protocols. The structural components of double wall vacuum vessel uses various parts like shields, ribs, shells and diagnostic vacuum ports. These components are to be developed with various welding techniques like TIG welding, Narrow gap TIG welding, Laser welding, Hybrid TIG laser welding, Electron beam welding based on requirement. In the present paper the samples of 20 mm and 40 mm thick SS 316 materials are developed with TIG welding process and their mechanical properties characterization with Tensile, Bend tests and Impact tests are carried out. In addition Vickers hardness tests and microstructural properties of Base metal, Heat Affected Zone (HAZ) and Weld Zone are done. TIG welding application with high thick SS materials in connection with vacuum vessel requirements and involved criticalities towards welding process are highlighted.

  19. Welding Process for Q345C Main Arm of Underground LHD%Q345C铲运机大臂的焊接工艺

    Institute of Scientific and Technical Information of China (English)

    张少伍; 范湘生; 贺龙明; 胡智君

    2012-01-01

    The CO2 gas shielded arc welding was selected to weld the Q345C main arm of underground LHD by analyzing its complex structure and mechanical characteristics. Adopting the rational welding parameters, welding technology and fixture can effectively prevent welding defects and ensure the welding quality of the arm, which can provide references for the welding of large size and complicated forces components.%通过对铲运机大臂材料Q345C的焊接性分析,选择CO2气体保护焊方法,采用合理的焊接参数、焊接工艺和工装,可有效防止其产生焊接缺陷,保证了大臂的焊接质量.也为其它结构尺寸大、受力复杂构件的焊接提供了参考.

  20. Overview on the welding technologies of CLAM steel and the DFLL TBM fabrication

    Directory of Open Access Journals (Sweden)

    Junyu Zhang

    2016-12-01

    Full Text Available Dual Functional Lithium Lead (DFLL blanket was proposed for its advantages of high energy exchange efficiency and on-line tritium extraction, and it was selected as the candidate test blanket module (TBM for China Fusion Engineering Test Reactor (CFETR and the blanket for Fusion Design Study (FDS series fusion reactors. Considering the influence of high energy fusion neutron irradiation and high heat flux thermal load on the blanket, China Low Activation Martensitic (CLAM steel was selected as the structural material for DFLL blanket. The structure of the blanket and the cooling internal components were pretty complicated. Meanwhile, high precision and reliability were required in the blanket fabrication. Therefore, several welding techniques, such as hot isostatic pressing diffusion bonding, tungsten inner gas welding, electron beam welding and laser beam welding were developed for the fabrication of cooling internals and the assembly of the blanket. In this work, the weldability on CLAM steel by different welding methods and the properties of as-welded and post-weld heat-treated joints were investigated. Meanwhile, the welding schemes and the assembly strategy for TBM fabrication were raised. Many tests and research efforts on scheme feasibility, process standardization, component qualification and blanket assembly were reviewed.

  1. Characterization of the structural details of residual austenite in the weld metal of a 9Cr1MoNbV welded rotor

    Institute of Scientific and Technical Information of China (English)

    Xia Liu; Hui-jun Ji; Peng Liu; Peng Wang; Feng-gui Lu; Yu-lai Gao

    2014-01-01

    The existence of residual austenite in weld metal plays an important role in determining the properties and dimensional accuracy of welded rotors. An effective corrosive agent and the metallographic etching process were developed to clearly reveal the characteristics of residual austenite in the weld metal of a 9Cr1MoNbV welded rotor. Moreover, the details of the distribution, shape, length, length-to-width ratio, and the content of residual austenite were systematically characterized using the Image-Pro Plus image analysis software. The results revealed that the area fraction of residual austenite was approximately 6.3% in the observed weld seam; the average area, length, and length-to-width ratio of dispersed residual austenite were quantitatively evaluated to be (5.5 ± 0.1)μm2, (5.0 ± 0.1)μm, and (2.2 ± 0.1), re-spectively. The newly developed corrosive agent and etching method offer an appropriate approach to characterize residual austenite in the weld metal of welded rotors in detail.

  2. CO2 laser welding of magnesium alloys

    Science.gov (United States)

    Dhahri, Mohammed; Masse, Jean Eric; Mathieu, J. F.; Barreau, Gerard; Autric, Michel L.

    2000-02-01

    Metallic alloys with a low mass density can be considered to be basic materials in aeronautic and automotive industry. Magnesium alloys have better properties than aluminum alloys in respect of their low density and high resistance to traction. The main problems of magnesium alloy welding are the inflammability, the crack formation and the appearance of porosity during the solidification. The laser tool is efficient to overcome the difficulties of manufacturing by conventional processing. Besides, the laser processing mainly using shielding gases allows an effective protection of the metal against the action of oxygen and a small heat affected zone. In this paper, we present experimental results about 5 kW CO2 laser welding of 4 mm-thick magnesium alloy plates provided by Eurocopter France. The focused laser beam has about 0.15 mm of diameter. We have investigated the following sample: WE43, alloy recommended in aeronautic and space applications, is constituted with Mg, Y, Zr, rare earth. More ductile, it can be used at high temperatures until 250 degrees Celsius for times longer than 5000 hours without effects on its mechanical properties. A sample of RZ5 (French Norm: GZ4TR, United States Norm ZE41) is composed of Mg, Zn, Zr, La, rare earth. This alloy has excellent properties of foundry and it allows to the realization of components with complex form. Also, it has a good resistance and important properties of tightness. The parameters of the process were optimized in the following fields: laser power: 2 to 5 kW, welding speed: 1 to 4.5 m/min, focal position: -3 mm to +3 mm below or on the top of the metal surface, shielding gas: helium with a flow of 10 to 60 l/min at 4 bars. Metallurgical analyses and mechanical control are made (macroscopic structure, microscopic structure, interpretations of the structures and localization of possible defects, analyse phases, chemical composition, hardness, tensile test etc.) to understand the parameters influence of welding

  3. Thermal Recovery of Plastic Deformation in Dissimilar Metal Weld

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Dongxiao [Tsinghua Univ., Beijing (China); Yu, Xinghua [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhang, Wei [The Ohio State Univ., Columbus, OH (United States); Crooker, Paul [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); David, Stan A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Feng, Zhili [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-05-23

    Stainless steel has been widely used in challenging environments typical to nuclear power plant structures, due its excellent corrosion resistance. Nickel filler metals containing high chromium concentration, including Alloy 82/182, are used for joining stainless steel to carbon steel components to achieve similar high resistance to stress corrosion cracking. However, the joint usually experience weld metal stress corrosion cracking (SCC), which affects the safety and structural integrity of light water nuclear reactor systems. A primary driving force for SCC is the high tensile residual stress in these welds. Due to large dimension of pressure vessel and limitations in the field, non-destructive residual stress measurement is difficult. As a result, finite element modeling has been the de facto method to evaluate the weld residual stresses. Recent studies on this subject from researchers worldwide report different residual stress value in the weldments [5]. The discrepancy is due to the fact that most of investigations ignore or underestimate the thermal recovery in the heat-affect zone or reheated region in the weld. In this paper, the effect of heat treatment on thermal recovery and microhardness is investigated for materials used in dissimilar metal joint. It is found that high equivalent plastic strains are predominately accumulated in the buttering layer, the root pass, and the heat affected zone, which experience multiple welding thermal cycles. The final cap passes, experiencing only one or two welding thermal cycles, exhibit less plastic strain accumulation. Moreover, the experimental residual plastic strains are compared with those predicted using an existing weld thermo-mechanical model with two different strain hardening rules. The importance of considering the dynamic strain hardening recovery due to high temperature exposure in welding is discussed for the accurate simulation of weld residual stresses and plastic strains. In conclsuion, the

  4. Trends in Development of Weld Overlaying During The 21ST Century

    Directory of Open Access Journals (Sweden)

    Nikolov Mitko

    2014-08-01

    Full Text Available The present article discusses the trends in the development of welding and weld overlaying on the threshold of the new millennium and during it. It presents the trends in the production of welding materials for welding and weld overlaying in industrially developed and developing countries. The structure of welding methods is also shown, giving priority to its development until 2020.

  5. Identifying the Component Structure of Satisfaction Scales by Nonlinear Principal Components Analysis

    NARCIS (Netherlands)

    Manisera, M.; Kooij, A.J. van der; Dusseldorp, E.

    2010-01-01

    The component structure of 14 Likert-type items measuring different aspects of job satisfaction was investigated using nonlinear Principal Components Analysis (NLPCA). NLPCA allows for analyzing these items at an ordinal or interval level. The participants were 2066 workers from five types of social

  6. 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…

  7. Optimization of friction stir welding parameters for improved corrosion resistance of AA2219 aluminum alloy joints

    Directory of Open Access Journals (Sweden)

    G. Rambabu

    2015-12-01

    Full Text Available The aluminium alloy AA2219 (Al–Cu–Mg alloy is widely used in the fabrication of lightweight structures with high strength-to-weight ratio and good corrosion resistance. Welding is main fabrication method of AA2219 alloy for manufacturing various engineering components. Friction stir welding (FSW is a recently developed solid state welding process to overcome the problems encountered in fusion welding. This process uses a non-consumable tool to generate frictional heat on the abutting surfaces. The welding parameters, such as tool pin profile, rotational speed, welding speed and axial force, play major role in determining the microstructure and corrosion resistance of welded joint. The main objective of this work is to develop a mathematical model to predict the corrosion resistance of friction stir welded AA2219 aluminium alloy by incorporating FSW process parameters. In this work a central composite design with four factors and five levels has been used to minimize the experimental conditions. Dynamic polarization testing was carried out to determine critical pitting potential in millivolt, which is a criteria for measuring corrosion resistance and the data was used in model. Further the response surface method (RSM was used to develop the model. The developed mathematical model was optimized using the simulated annealing algorithm optimizing technique to maximize the corrosion resistance of the friction stir welded AA2219 aluminium alloy joints.

  8. FEM Simulation of Welding Quafity in Porthole Die Extrusion

    Institute of Scientific and Technical Information of China (English)

    HE Youfeng; XIE Shuisheng; CHENG Lei; HUANG Guojie; FU Yao

    2011-01-01

    The effects of die structure such as the height of the welding, the welding angle and chamber the shape of the bridge on the welding quality of profiles were investigated by means of the commercial software DEFORM-3D. The numerical simulation results show that the welding quality of the hollow profiles has great sensitive to the die structure. With increasing the welding chamber height and decreasing the welding angle of the die leg can improve the welding quality. In addition, the welding quality index k of the new designed shape of the die leg is little down from 4.1 to 3.9 comparing the standard leg.

  9. Modeling Long-term Creep Performance for Welded Nickel-base Superalloy Structures for Power Generation Systems

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Chen [GE Global Research, NIskayuna, NY (United States); Gupta, Vipul [GE Global Research, NIskayuna, NY (United States); Huang, Shenyan [GE Global Research, NIskayuna, NY (United States); Soare, Monica [GE Global Research, NIskayuna, NY (United States); Zhao, Pengyang [GE Global Research, NIskayuna, NY (United States); Wang, Yunzhi [GE Global Research, NIskayuna, NY (United States)

    2017-02-28

    The goal of this project is to model long-term creep performance for nickel-base superalloy weldments in high temperature power generation systems. The project uses physics-based modeling methodologies and algorithms for predicting alloy properties in heterogeneous material structures. The modeling methodology will be demonstrated on a gas turbine combustor liner weldment of Haynes 282 precipitate-strengthened nickel-base superalloy. The major developments are: (1) microstructure-property relationships under creep conditions and microstructure characterization (2) modeling inhomogeneous microstructure in superalloy weld (3) modeling mesoscale plastic deformation in superalloy weld and (4) a constitutive creep model that accounts for weld and base metal microstructure and their long term evolution. The developed modeling technology is aimed to provide a more efficient and accurate assessment of a material’s long-term performance compared with current testing and extrapolation methods. This modeling technology will also accelerate development and qualification of new materials in advanced power generation systems. This document is a final technical report for the project, covering efforts conducted from October 2014 to December 2016.

  10. Misunderstanding and Understanding of Primary Water Stress Corrosion Cracking of Structural Components in the Primary System of PWRs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Suk; Kim, Sung Soo; Kim, Dae Whan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    All the structural components in the primary system of pressurized water reactors that are in contact with primary water are made of austenitic Ni-Cr-Fe alloys which are known to be corrosion resistant. Nevertheless, these Ni-Cr-Fe alloys such as Alloy 600, weld 182/82, austenitic stainless steels suffer from intergranular stress corrosion cracking (IGSCC) after their 10 year operation in reactors although the environment to which they have been exposed is almost pure water of pH 6.9 to 7.2, which is called primary water stress corrosion cracking (PWSCC). Given that the underlying mechanism of PWSCC remains unidentified so far, there are many misunderstandings related to PWSCC of the structural components, which may lead to unreasonable mitigation measures. The aim of this work is to highlight understanding and misunderstanding of PWSCC related to austenitic Ni-Cr-Fe alloys.

  11. SHADOW: a new welding technique

    Science.gov (United States)

    Kramer, Thorsten; Olowinsky, Alexander M.; Durand, Friedrich

    2002-06-01

    The new welding technique 'SHADOW ' is introduced. SHADOW means the use of a single pulse to generate a quasi continuous weld of several millimeters in length. HET processing time is defined by the pulse duration of the pulsed laser. At present, a state-of-the-art laser is capable of a maximum pulse duration of 20 ms. The variation of the laser power depend on time is a vital capability of the pulsed laser to adapt the energy deposition into the workpiece. Laser beam welds of several watch components were successfully performed. Similar metals like crowns and axes made out of stainless steel have been welded using pulsed laser radiation. Applying a series of about 130 single pulses for the crown-axis combination the total energy accumulates to 19.5 J. The use of the SHADOW welding technique reduces the energy to 2.5 J. While welding dissimilar metals like stainless steel and bras, the SHADOW welding reduces drastically the contamination as well as the distortion. Laser beam welding of copper has a low process reliability due to the high reflection and the high thermal conductivity. SHADOW welds of 3.6 mm length were performed on 250 micrometers thick copper plates with very high reproducibility. As a result, a pilot plant for laser beam welding of copper plates has been set up. The work to be presented has partly been funded by the European Commission in a project under the contract BRPR-CT-0634.

  12. 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.

  13. Structure-property relationships of dissimilar friction stir welded aluminum alloys

    Science.gov (United States)

    Quinones, Rogie Irwin Rodriguez

    In this work, the relationship between microstructure and mechanical properties of dissimilar friction stir welded AA6061-to-AA7050 aluminum alloys were evaluated. Experimental results from this study revealed that static strength increased with the tool rotational speed and was correlated with the material intermixing. Fully-reversed low cycle fatigue experimental results showed an increase in the strain hardening properties as well as the number of cycles-to-failure as the tool rotational speed was increased. Furthermore, under both static and cyclic loading, fracture of the joint was dominated by the AA6061 alloy side of the weld. In addition, inspection of the fatigue surfaces revealed that cracks initiated from intermetallic particles located near the surface. In order to determine the corrosion resistance of the dissimilar joint, corrosion defects were produced on the crown surface of the weld by static immersion in 3.5% NaCl for various exposure times. Results revealed localized corrosion damage in the thermo-mechanically affected and heat affected zones. Results demonstrated a decrease in the fatigue life, with evidence of crack initiation at the corrosion defects; however, the fatigue life was nearly independent of the exposure time. This can be attributed to total fatigue life dominated by incubation time. Furthermore, two types of failure were observed: fatigue crack initiation in the AA6061 side at high strain amplitudes (>0.3%); and fatigue crack initiation in the AA7050 side at low strain amplitudes (friction stir welded joints in order to capture the crack initiation and propagation in as-welded and pre-corroded conditions. Good correlation between experimental fatigue results and the model was achieved based on the variation in the initial defect size, microstructure, and mechanical properties of the dissimilar friction stir welded AA6061-to-AA7050 aluminum alloys.

  14. 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...

  15. Resistance welding

    DEFF Research Database (Denmark)

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

    2003-01-01

    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......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...

  16. Graphite composite truss welding and cap section forming subsystems. Volume 1: Executive summary. [large space structures

    Science.gov (United States)

    1980-01-01

    A rolltrusion process was developed for forming of a hybrid, single-ply woven graphite and glass fiber cloth, impregnated with a polysulfone resin and coated with TI02 pigmented P-1700 resin into strips for the on-orbit fabrication of triangular truss segments. Ultrasonic welding in vacuum showed no identifiable effects on weld strength or resin flow characteristics. An existing bench model cap roll forming machine was modified and used to roll form caps for the prototype test truss and for column test specimens in order to test local buckling and torsional instability characteristics.

  17. Microstructure and Crystallographic Texture Variations in the Friction-Stir-Welded Al-Al2O3-B4C Metal Matrix Composite Produced by Accumulative Roll Bonding

    Science.gov (United States)

    Mohammadnezhad, Mahyar; Shamanian, Morteza; Zabolian, Azam; Taheri, Mahshid; Javaheri, Vahid; Navidpour, Amir Hossein; Nezakat, Majid; Szpunar, Jerzy A.

    2015-12-01

    In this research, ultrafine-grained sheets of aluminum matrix composite (Al-Al2O3-B4C) were produced by accumulative roll bonding ARB technique. As-received, ultrafine-grained aluminum composite sheets were joined by friction-stir welding. The microstructure, crystallographic texture, and Vickers hardness in the weld zones were investigated. Electron backscattered diffraction results revealed occurrence of dynamic recrystallization and demonstrated existence of different grain orientations within the weld nugget. Produced composite plates illustrated rotated cubic texture. Moreover, in the nugget, a well-recrystallized grain structure having characteristic strong shear texture component finally developed. However, the texture result in the heat-affected zone illustrated rotated cubic and Goss components that related to the effect of heat input. Friction-stir welding refined the grain size in the weld zone. The hardness also improved with the peak hardness being observed towards the advancing stir welding side.

  18. Materials participation in welded joints manufacturing

    Science.gov (United States)

    Ghenghea, L. D.

    2016-08-01

    Management of materials dilution to form a joint with higher features asked by complex metallic structures is a problem that took attention and efforts of welding processes researchers and this communication will give a little contribution presenting some scientific and experimental results of dilution processes studied by Welding Research Group from Iasi, Romania, TCM Department. Liquid state welding processes have a strong dependence related to dilution of base and filler materials, the most important are for automatic joining using welding. The paper presents a review of some scientific works already published and their contributions, results of dilution coefficient evaluation using weighing, graphics and software applied for shielded metal arc welding process. Paper results could be used for welders’ qualification, welding procedure specification and other welding processes researchers’ activities. The results of Welding Research Group from Iasi, Romania, TCM Department, show dilution coefficient values between 20-30 % of base material and 70-80 % of filler material for studied welding process.

  19. Block-Krylov component synthesis method for structural model reduction

    Science.gov (United States)

    Craig, Roy R., Jr.; Hale, Arthur L.

    1988-01-01

    A new analytical method is presented for generating component shape vectors, or Ritz vectors, for use in component synthesis. Based on the concept of a block-Krylov subspace, easily derived recurrence relations generate blocks of Ritz vectors for each component. The subspace spanned by the Ritz vectors is called a block-Krylov subspace. The synthesis uses the new Ritz vectors rather than component normal modes to reduce the order of large, finite-element component models. An advantage of the Ritz vectors is that they involve significantly less computation than component normal modes. Both 'free-interface' and 'fixed-interface' component models are derived. They yield block-Krylov formulations paralleling the concepts of free-interface and fixed-interface component modal synthesis. Additionally, block-Krylov reduced-order component models are shown to have special disturbability/observability properties. Consequently, the method is attractive in active structural control applications, such as large space structures. The new fixed-interface methodology is demonstrated by a numerical example. The accuracy is found to be comparable to that of fixed-interface component modal synthesis.

  20. Optimization of weld bead geometry in the activated GMA welding process via a grey-based Taguchi method

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Hsuan Liang [National Kaohsiung Normal University, Kaohsiung (China); Yan, Jia Ching [National Chiao Tung University, Hsinchu (China)

    2014-08-15

    We optimized the weld bead geometry of 6061 aluminum alloy welds pre-coated with activating flux before gas metal arc (GMA) welding. In this activated GMA welding process, there were five single component fluxes used in the initial experiment to evaluate the penetration capability of bead-on-plate GMA welds. Based on the higher penetration of weld bead, two single component fluxes were selected to create mixed component flux in next stage. The grey-based Taguchi method was employed to obtain the optimal welding parameters that were considered with multiple quality characteristics such as penetration, depth-to-width ratio (DWR) and fusion area of GMA welds. The experimental procedure of the proposed approach not only increases penetration of 6061 aluminum alloy welds, but also improves the DWR and fusion area of GMA butt-joint welds simultaneously.

  1. 镁合金轮椅小轮轴套焊接结构改进%Structure Improvement of Small Wheel Sleeve Welding on Mg Alloy Wheelchair

    Institute of Scientific and Technical Information of China (English)

    牛丽媛; 孙大仁; 林继兴; 华学兵

    2012-01-01

    The structure of small wheel sleeve welding on magnesium alloy wheelchair were investigated by altering small wheel sleeve welding position, and altering the location and direction of weld bead, which can contribute to the stress release, then the fatigue strength on the welding position was improved. The results show that there is a certain relationship between weld bead and fatigue strength, when the length of weld bead is more than 25 mm, the fatigue life can reach more than 210,000 times, which can meet wheelchair using requirements according to GB/T13800-2009.%研究了镁合金轮椅小轮轴套焊接部位的结构,改变了焊道的部位和方向,大大降低了焊接部位应力集中,有效地提高了焊接部位的疲劳强度.结果表明:焊道长度与疲劳性能有一定的关系,当焊道长度大于25mm时,其疲劳寿命可达21万次以上,根据GB/T 13800-2009标准测试满足轮椅的使用要求.

  2. Novel concepts in weld metal science: Role of gradients and composite structure. Annual technical progress report, January 1, 1991--December 31, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Matlock, D.K.; Olson, D.L.

    1991-12-01

    The effects of compositional and microstructural gradients on weld metal properties are being investigated. Crack propagation is solidified alloy structures is being characterized as to solidification orientation and the profile of the compositional variations. The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a compositional gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Special techniques to produce laboratory samples with microstructures which simulate the composition and microstructure gradients in solidified weld metal are used, along with appropriate mathematical models, to evaluate the properties of the composite weld metals. The composite modeling techniques are being applied to describe the effects of compositional and microstructural gradients on weld metal properties in Ni-Cu alloys. The development of metal matrix composition weld deposits on austenitic stainless steels has been studied. The particulate metal matrix composites were produced with ceramic or refractory metal powder filled cored wire, which was gas tungsten arc and gas metal arc welded.

  3. Deformation Control of Thin-Walled Structure Welded by Electron Beam%柔性薄壁结构电子束焊接的变形控制

    Institute of Scientific and Technical Information of China (English)

    龚荣清; 杨锡龙

    2015-01-01

    Based on electron beam welding method, the deformation control method of vacuum elec-tron beam welding process of PTO flexible thin-walled structures is explored. The deformation control method combined with comprehensive application of the minimum weld heat input, reducing the overlap angle, reasonable welding assembly and heat radiation is proposed. The welding deformation is controlled effectively and the man-ufacturing of PTO lfexible thin-walled is achieved by using electron beam welding.%基于电子束焊接方法,探讨了功率分出轴柔性薄壁结构真空电子束焊接过程中的变形控制方法,提出了综合应用最小焊接热输入、减小焊接重叠角度和合理焊接装配及散热相结合的变形控制方法,有效地控制了焊接变形,实现了电子束焊接柔性薄壁结构的制造。

  4. 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.

  5. Gas metal arc welding in refurbishment of cobalt base superalloys

    Science.gov (United States)

    Shahriary, M. S.; Miladi Gorji, Y.; Kolagar, A. M.

    2017-01-01

    Refurbishments of superalloys which are used in manufacturing gas turbine hot components usually consists of removing cracks and other defects by blending and then repair welding in order to reconstruct damaged area. In this study, the effects of welding parameters on repair of FSX-414 superalloy, as the most applicable cobalt base superalloy in order to manufacture gas turbine nozzles, by use of Gas Metal Arc Welding (GMAW) technic were investigated. Results then were compared by Gas Tungsten Arc Welding (GTAW). Metallographic and SEM studies of the microstructure of the weld and HAZ showed that there are no noticeable defects in the microstructure by use of GMAW. Also, chemical analysis and morphologies of carbide in both methods are similar. Hardness profile of the GM AW structure then also compared with GTAW and no noticeable difference was observed between the profiles. Also, proper tensile properties, compared with GTAW, can be achieved by use of optimum parameters that can be obtained by examining the current and welding speed. Tensile properties of optimized condition of the GMAW then were compared with GTAW. It was seen that the room and high temperature tensile properties of the GMAW structure is very similar and results confirmed that changing the technic did not have any significant influence on the properties.

  6. Engine structures analysis software: Component Specific Modeling (COSMO)

    Science.gov (United States)

    McKnight, R. L.; Maffeo, R. J.; Schwartz, S.

    1994-08-01

    A component specific modeling software program has been developed for propulsion systems. This expert program is capable of formulating the component geometry as finite element meshes for structural analysis which, in the future, can be spun off as NURB geometry for manufacturing. COSMO currently has geometry recipes for combustors, turbine blades, vanes, and disks. Component geometry recipes for nozzles, inlets, frames, shafts, and ducts are being added. COSMO uses component recipes that work through neutral files with the Technology Benefit Estimator (T/BEST) program which provides the necessary base parameters and loadings. This report contains the users manual for combustors, turbine blades, vanes, and disks.

  7. Immunohistochemical Analysis of the Structure of Injured Peripheral Nerve Neuroma after Electrosurgical Welding Intervention.

    Science.gov (United States)

    Korsak, A V; Chaikovskii, Yu B

    2015-10-01

    Immunohistochemical analysis of changes in neuroma after surgical treatment of damaged peripheral nerve with the use of high frequency electrosurgical device for high frequency current welding of soft tissues was carried out. No adverse effects of this technology and the bipolar instrument on degeneration and regeneration of damaged nerve stem were detected.

  8. Structural considerations in friction welding of hybrid Al2O3-reinforced aluminum composites

    Institute of Scientific and Technical Information of China (English)

    In-Duck PARK; Choon-Tae LEE; Hyur-Soo KIM; Woo-Jin CHOI; Myung-Chang KANG

    2011-01-01

    Comparative studies on the relationship between the welding parameters and joining efficiency in the friction welding of hybrid Al2O3-reinforced aluminum composites were conducted. Metal matrix composites (MMCs) with 37% (volume fraction)aluminum particle were joined by friction welding. The results show that the effects of the rotation speed on the reduction rate of particle size are greater than those of the upset pressure, and the area of the MMC weld zone decreases as the joining efficiency increases, while it is considered that the joining efficiency does not increase as the reduction rate of particle size decreases. During the macro-examination of the bonding interface. a gray discolored region was observed on the bonding interface, and the center of the region was dark gray. After the micro-examination of the bonding interface, base metal made some second particulate formed by condensed alumina particulate but discoloration part distributed minute alumina particulate without second particulate. Consequently,it was also observed that rotational speed of 3 000 r/min and upset pressure of 63.6 MPa showed a very good joint.

  9. Effect of Weld Properties on the Crush Strength of the PWR Spacer Grid

    Directory of Open Access Journals (Sweden)

    Kee-nam Song

    2012-01-01

    Full Text Available Mechanical properties in a weld zone are different from those in the base material because of different microstructures. A spacer grid in PWR fuel is a structural component with an interconnected and welded array of slotted grid straps. Previous research on the strength analyses of the spacer grid was performed using base material properties owing to a lack of mechanical properties in the weld zone. In this study, based on the mechanical properties in the weld zone of the spacer grid recently obtained by an instrumented indentation technique, the strength analyses considering the mechanical properties in the weld zone were performed, and the analysis results were compared with the previous research.

  10. Stripe-PZT Sensor-Based Baseline-Free Crack Diagnosis in a Structure with a Welded Stiffener

    Directory of Open Access Journals (Sweden)

    Yun-Kyu An

    2016-09-01

    Full Text Available This paper proposes a stripe-PZT sensor-based baseline-free crack diagnosis technique in the heat affected zone (HAZ of a structure with a welded stiffener. The proposed technique enables one to identify and localize a crack in the HAZ using only current data measured using a stripe-PZT sensor. The use of the stripe-PZT sensor makes it possible to significantly improve the applicability to real structures and minimize man-made errors associated with the installation process by embedding multiple piezoelectric sensors onto a printed circuit board. Moreover, a new frequency-wavenumber analysis-based baseline-free crack diagnosis algorithm minimizes false alarms caused by environmental variations by avoiding simple comparison with the baseline data accumulated from the pristine condition of a target structure. The proposed technique is numerically as well as experimentally validated using a plate-like structure with a welded stiffener, reveling that it successfully identifies and localizes a crack in HAZ.

  11. Narrow gap mechanised arc welding in nuclear components manufactured by AREVA NP; Le soudage mecanise a l'arc en chanfrein etroit dans les constructions nucleaires realisees par AREVA NP

    Energy Technology Data Exchange (ETDEWEB)

    Peigney, A. [Departement Soudage AREVA Centre Technique - 71380 Saint-Marcel (France)

    2007-07-01

    Nuclear components require welds of irreproachable and reproducible quality. Moreover, for a given welding process, productivity requirements lead to reduce the volume of deposited metal and thus to use narrow gap design. In the shop, narrow gap Submerged Arc Welding process (SAW) is currently used on rotating parts in flat position for thicknesses up to 300 mm. Welding is performed with one or two wires in two passes per layer. In Gas Tungsten Arc Welding process (GTAW), multiple applications can be found because this process presents the advantage of allowing welding in all positions. Welding is performed in one or two passes per layer. The process is used in factory and on the nuclear sites for assembling new components but also for replacing components and for repairs. Presently, an increase of productivity of the process is sought through the use of hot wire and/or two wires. Concerning Gas Metal Arc Welding process (GMAW), its use is growing for nuclear components, including narrow gap applications. This process, limited in its applications in the past on account of the defects it generated, draws benefit from the progress of the welding generators. Then it is possible to use this efficient process for high security components such as those of nuclear systems. It is to be noted that the process is applicable in the various welding positions as it is the case for GTAW, while being more efficient than the latter. This paper presents the state of the art in the use of narrow gap mechanised arc welding processes by AREVA NP units. (author) [French] Les constructions nucleaires necessitent des soudures de qualite irreprochable et reproductible. Par ailleurs les imperatifs de productivite conduisent, pour un procede donne, a reduire le volume de metal a deposer et donc a utiliser des chanfreins etroits. En atelier, le soudage fil-flux en chanfrein etroit est couramment utilise sur des pieces tournantes en position a plat pour des epaisseurs atteignant 300 mm. On

  12. An ultrasonic methodology for in-service inspection of shell weld of core support structure in a sodium cooled fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Anish, E-mail: anish@igcar.gov.in; Rajkumar, K.V.; Sharma, Govind K.; Dhayalan, R.; Jayakumar, T.

    2015-02-15

    Highlights: • We demonstrate a novel ultrasonic methodology for in-service inspection of shell weld of core support structure in a sodium cooled fast breeder reactor. • The methodology comprises of the inspection of shell weld immersed in sodium from the outside surface of the main vessel using ultrasonic guided wave. • The formation and propagation of guided wave modes are validated by finite element simulation of the inspection methodology. • A defect down to 20% of 30 mm thick wall (∼6 mm) in the shell weld can be detected reliably using the developed methodology. - Abstract: The paper presents a novel ultrasonic methodology developed for in-service inspection (ISI) of shell weld of core support structure of main vessel of 500 MWe prototype fast breeder reactor (PFBR). The methodology comprises of the inspection of shell weld immersed in sodium from the outsider surface of the main vessel using a normal beam longitudinal wave ultrasonic transducer. Because of the presence of curvature in the knuckle region of the main vessel, the normal beam longitudinal wave enters the support shell plate at an angle and forms the guided waves by mode conversion and multiple reflections from the boundaries of the shell plate. Hence, this methodology can be used to detect defects in the shell weld of the core support structure. The successful demonstration of the methodology on a mock-up sector made of stainless steel indicated that an artificial defect down to 20% of 30 mm thick wall (∼6 mm) in the shell weld can be detected reliably.

  13. Cladding Effects on Structural Integrity of Nuclear Components

    Energy Technology Data Exchange (ETDEWEB)

    Sattari-Far, Iradi; Andersson, Magnus [lnspecta Technology AB, Stockholm (Sweden)

    2006-06-15

    Based on this study, the following conclusions and recommendations can be made: Due to significant differences in the thermal and mechanical properties between the austenitic cladding and the ferritic base metal, residual stresses are induced in the cladding and the underlying base metal. These stresses are left in clad components even after Post-Weld Heat Treatment (PWHT). The different restraint conditions of the clad component have a minor influence on the magnitude of the cladding residual stresses in the cladding layer. The thickness of the clad object is the main impacting geometrical dimension in developing cladding residual stresses. A clad object having a base material thickness exceeding 10 times the cladding thickness would be practically sufficient to introduce cladding residual stresses of a thick reactor pressure vessel. For a clad component that received PWHT, the peak tensile stress is in the cladding layer, and the residual stresses in the underlying base material are negligible. However, for clad components not receiving PWHT, for instance the repair welding of the cladding, the cladding residual stresses of tensile type exist even in the base material. This implies a higher risk for underclad cracking for clad repairs that received no PWHT. For certain clad geometries, like nozzles, the profile of the cladding residual stresses depends on the clad thickness and position, and significant tensile stresses can also exist in the base material. Based on different measurements reported in the literature, a value of 150 GPa can be used as Young's Modulus of the austenitic cladding material at room temperature. The control measurements of small samples from the irradiated reactor pressure vessel head did not reveal a significant difference of Young's Modulus between the irradiated and the unirradiated cladding material condition. No significant differences between the axial and tangential cladding residual stresses are reported in the

  14. Weldability of AISI 304 to copper by friction welding

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-06-01

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

  15. Residual stress analysis of an overlay weld on a dissimilar metal weld

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kang Soo; Lee, Ho Jin; Lee, Bong Sang (Korea Atomic Energy Research Institute, Daejeon (Korea)); Jung, I.C.; Byeon, J.G.; Park, K.S. (Doosan Heavy Industries and Construction Co., Changwon (Korea)), e-mail: kskim5@kaeri.re.kr

    2009-07-01

    In recent years, a dissimilar metal, Alloy 82/182 welds used to connect stainless steel piping and low alloy steel or carbon steel components in nuclear reactor piping system have experienced a cracking due to a primary water stress corrosion (PWSCC). It is well known that one reason for the cracking is the residual stress by the weld. But, it is difficult to estimate the weld residual stress exactly due to many parameters of a welding. In this paper, the analysis of 3 FEM models is performed to estimate the weld residual stress on a dissimilar metal weld exactly

  16. 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

  17. 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…

  18. Numerical simulation of welding for the bogie structure of rolling stock based on SYSWELD%基于SYSWELD的列车转向架结构焊接数值模拟

    Institute of Scientific and Technical Information of China (English)

    孙传政; 潘亦苏; 罗征志

    2012-01-01

    列车的转向架是保证车辆运行品质与运行安全的关键部件,构架又是其最重要的组成承载部件.因此,研究列车转向架焊接构架残余应力与结构强度的关系,具有非常重要的意义.根据列车转向架构架建立其几何模型、划分网格、设置热源参数,采用ESI焊接专业软件SYSWELD对列车转向架构架结构焊接进行数值计算分析.为优化工艺措施,调整应用多种焊接顺序工况进行模拟,并进行对比.%the bogie of rolling stock is a key part to ensure riding quality and operation security of a train, of which the frame is the most important bearing component. It makes a lot of sense to research welding and the relation between welding residual stress and structural strength of the frame of the bogie. After building its three-dimensional model, mesh and setting the heat source parameter, it is performed with SYSWELD software to simulate numerically welding for the bogie structure of rolling stock, and the result matches with experimental results well. To optimize the technology, there are some kinds of welding process simulated and compared with others to show the optimum one.

  19. Protein structure similarity from principle component correlation analysis

    Directory of Open Access Journals (Sweden)

    Chou James

    2006-01-01

    Full Text Available Abstract Background Owing to rapid expansion of protein structure databases in recent years, methods of structure comparison are becoming increasingly effective and important in revealing novel information on functional properties of proteins and their roles in the grand scheme of evolutionary biology. Currently, the structural similarity between two proteins is measured by the root-mean-square-deviation (RMSD in their best-superimposed atomic coordinates. RMSD is the golden rule of measuring structural similarity when the structures are nearly identical; it, however, fails to detect the higher order topological similarities in proteins evolved into different shapes. We propose new algorithms for extracting geometrical invariants of proteins that can be effectively used to identify homologous protein structures or topologies in order to quantify both close and remote structural similarities. Results We measure structural similarity between proteins by correlating the principle components of their secondary structure interaction matrix. In our approach, the Principle Component Correlation (PCC analysis, a symmetric interaction matrix for a protein structure is constructed with relationship parameters between secondary elements that can take the form of distance, orientation, or other relevant structural invariants. When using a distance-based construction in the presence or absence of encoded N to C terminal sense, there are strong correlations between the principle components of interaction matrices of structurally or topologically similar proteins. Conclusion The PCC method is extensively tested for protein structures that belong to the same topological class but are significantly different by RMSD measure. The PCC analysis can also differentiate proteins having similar shapes but different topological arrangements. Additionally, we demonstrate that when using two independently defined interaction matrices, comparison of their maximum

  20. 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.

  1. Microstructural, Micro-hardness and Sensitization Evaluation in HAZ of Type 316L Stainless Steel Joint with Narrow Gap Welds

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Faisal Shafiqul; Jang, Changheui [KAIST, Daejeon (Korea, Republic of); Kang, Shi Chull [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2015-10-15

    From Micro-hardness measurement HAZ zone was found approximately 1-1.5 mm in NGW and DL-EPR test confirmed that 316L NGW HAZ was not susceptible to sensitization as DOS <1% according to sensitization criteria based on reference. In nuclear power plants 316L stainless steels are commonly used material for their metallurgical stability, high corrosion resistance, and good creep and ductility properties at elevated temperatures. Welding zone considered as the weakest and failure initiation source of the components. For safety and economy of nuclear power plants accurate and dependable structural integrity assessment of main components like pressure vessels and piping are need as it joined by different welding process. In similar and dissimilar metal weld it has been observed that weld microstructure cause the variation of mechanical properties through the thickness direction. In the Heat Affected Zone (HAZ) relative to the fusion line face a unique thermal experience during welding.

  2. Structural Weight Optimization of Aircraft Wing Component Using FEM Approach.

    OpenAIRE

    Arockia Ruban M,; Kaveti Aruna

    2015-01-01

    One of the main challenges for the civil aviation industry is the reduction of its environmental impact by better fuel efficiency by virtue of Structural optimization. Over the past years, improvements in performance and fuel efficiency have been achieved by simplifying the design of the structural components and usage of composite materials to reduce the overall weight of the structure. This paper deals with the weight optimization of transport aircraft with low wing configuratio...

  3. 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)

  4. A Finite Element Method for Cracked Components of Structures

    Institute of Scientific and Technical Information of China (English)

    刘立名; 段梦兰; 秦太验; 刘玉标; 柳春图; 余建星

    2003-01-01

    In this paper, a method is developed for determining the effective stiffness of the cracked component. The stiffness matrix of the cracked component is integrated into the global stiffness matrix of the finite element model of the global platform for the FE calculation of the structure in any environmental conditions. The stiffness matrix equation of the cracked component is derived by use of the finite variation principle and fracture mechanics. The equivalent parameters defining the element that simulates the cracked component are mathematically presented, and can be easily used for the FE calculation of large scale cracked structures together with any finite element program. The theories developed are validated by both lab tests and numerical calculations, and applied to the evaluation of crack effect on the strength of a fixed platform and a self-elevating drilling rig.

  5. No Longer the Outlier: Updating the Air Component Structure

    Science.gov (United States)

    2016-06-23

    4 | Air & Space Power Journal No Longer the Outlier Updating the Air Component Structure Lt Gen CQ Brown Jr., USAF Lt Col Rick Fournier, USAF...This article may be reproduced in whole or in part without permission. If it is reproduced, the Air and Space Power Journal requests a courtesy...COCOM) with a highly competent air component that is capable of con- ducting and supporting air , space , and cyberspace operations within its assigned

  6. Stress Distribution in the Dissimilar Metal Butt Weld of Nuclear Reactor Piping due to the Simulation Technique for the Repair Welding

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hweeseung; Huh, Namsu [Seoul Nat' l Univ. of Science and Technology, Seoul (Korea, Republic of); Kim, Jinsu; Lee, Jinho [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2013-05-15

    During welding, the dissimilar metal butt welds of nuclear piping are typically subjected to repair welding in order to eliminate defects that are found during post-weld inspection. It has been found that the repair weld can significantly increase the tensile residual stress in the weldment, and therefore, accurate estimation of the weld residual stress due to repair weld, especially for dissimilar metal welds using Ni-based alloy 82/182 in nuclear components, is of great importance in order to assess susceptibility to primary water stress corrosion cracking. In the present study, the stress distributions of dissimilar metal butt welds in nuclear reactor piping subjected to repair weld were investigated based on detailed nonlinear finite element analyses. Particular emphasis was placed on the variation of the stress distribution in the dissimilar metal butt weld according to the finite element welding analysis sequence for the repair welding process.

  7. Residual Stresses in Inertia-Friction-Welded Dissimilar High-Strength Steels

    Science.gov (United States)

    Moat, R. J.; Hughes, D. J.; Steuwer, A.; Iqbal, N.; Preuss, M.; Bray, S. E.; Rawson, M.

    2009-09-01

    The welding of dissimilar alloys is seen increasingly as a way forward to improve efficiencies in modern aeroengines, because it allows one to tailor varying material property demands across a component. Dissimilar inertia friction welding (IFW) of two high-strength steels, Aermet 100 and S/CMV, has been identified as a possible joint for rotating gas turbine components and the resulting welds are investigated in this article. In order to understand the impact of the welding process and predict the life expectancy of such structures, a detailed understanding of the residual stress fields present in the welded component is needed. By combining energy-dispersive synchrotron X-ray diffraction (EDSXRD) and neutron diffraction, it has been possible to map the variations in lattice spacing of the ferritic phase on both sides of two tubular Aermet 100-S/CMV inertia friction welds (as-welded and postweld heat-treated condition) with a wall thickness of 37 mm. Laboratory-based XRD measurements were required to take into account the variation in the strain-free d-spacing across the weld region. It was found that, in the heat-affected zone (HAZ) slightly away from the weld line, residual stress fields showed tensile stresses increasing most dramatically in the hoop direction toward the weld line. Closer to the weld line, in the plastically affected zone, a sharp drop in the residual stresses was observed on both sides, although more dramatically in the S/CMV. In addition to residual stress mapping, synchrotron XRD measurements were carried out to map microstructural changes in thin slices cut from the welds. By studying the diffraction peak asymmetry of the 200- α diffraction peak, it was possible to demonstrate that a martensitic phase transformation in the S/CMV is responsible for the significant stress reduction close to the weld line. The postweld heat treatment (PWHT) chosen to avoid any overaging of the Aermet 100 and to temper the S/CMV martensite resulted in little

  8. Effect of activating fluxes on weld mechanical properties in TIG welding

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Activating TIG (A-TIG) welding has received many attentions worldwide since the end of 1990s. Compared with conventional TIG welding A-TIG welding can greatly improve the welding productivity and reduce the welding cost without altering the equipments under the same welding procedures and is considered as a innovative variant of conventional TIG welding. The materials applied by A-TIG welding have ranged from original titanium alloy to stainless steel, carbon steel, high temperature alloy steel and so forth. The effects of activating fluxes with single component on weld mechanical properties such as tensile strength, hardness and elastics during A-TIG welding of stainless steel are discussed in this paper. The experimental results show that different fluxes have different effects on the weld mechanical properties. Among these fluxes the flux SiO2 is the best in the performance of tensile strength and ductility, while flux Cr2O3 is the best in the performance of weld hardness compared with conventional TIG welding. These experiments provide the foundation for selecting the most suitable fluxes for stainless steel in practical welding production.

  9. Effects of Friction Stir Welding Speed on AA2195 alloy

    Directory of Open Access Journals (Sweden)

    Lee Ho-Sung

    2016-01-01

    Full Text Available The application of friction stir welding (FSW to aerospace has grown rapidly due to the high efficiency and environmental friendly nature of the process. FSW is achieved by plastic flow of frictionally heated material in solid state and offers many advantages of avoiding hot cracking and limiting component distortion. Recently low density, high modulus and high strength AA2195 are used as substitute for conventional aluminum alloys since the weight saving is critical in aerospace applications. One of the problems for this alloy is weld metal porosity formation leading to hot cracking. Combination of FSW and AA2195 provides synergy effect to improve mechanical properties and weight saving of aerospace structure such as cryogenic fuel tanks for launch systems. The objective of this paper is to investigate the effect of friction stir welding speed on mechanical and microstructural properties of AA2195. The friction stir welded materials were joined with four different tool rotation speeds (350~800 rpm and five welding speeds (120~360 mm/min, which are the two prime welding parameters in this process.

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

    Science.gov (United States)

    2013-01-01

    Sheet) Continuation for Block 13 ARO Report Number Friction Stir Weld Failure Mechanisms in Alumin Block 13: Supplementary Note © 2013 . Published in...nose, steel jacketed, hard tungsten core (1400 Hv), armor piercing (AP) projectile (Ref 1). As mentioned above, this failure mechanism is often...zones being impacted with blunt, lower hardness projectiles [e.g., 20-mm caliber, 53 g, blunt, chamfered right circular cylindrical steel fragment

  11. Study of mechanism of activating flux increasing weld penetration of AC A-TIG welding for aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    HUANG Yong; FAN Ding; FAN Qinghua

    2007-01-01

    When multi-component flux AF305 is used as surface activating flux for an aluminum alloy, the weld penetration of activating flux-tungsten inert-gas (A-TIG)welding is over two times more than that of conventional TIG welding. Using A-TIG welding with the modes of alternating current (AC), direct current electrode negative (DCEN) and direct current electrode positive (DCEP), respectively, the flux differently affects weld penetration when the polarity is different. After studied the effect of compelled arc constriction on weld penetration of AC welding, it is believed that the constriction of the whole arc root is not the main mechanism that flux AF305 dramatically improves weld penetration. The penetration has a relationship with the separate distribution of slag on the weld surface. Then, an observation of scanning electron microscopy (SEM) and an electronic data systems (EDS) analysis of slag were performed respectively. The separate distribution of slag on the weld pool during welding and the great constriction of arc spots were confirmed by TIG welding with helium shielding gas. The relationship between slag distribution and weld penetration was studied by adding aluminum powder into flux AF305 to change the distribution of slag. During welding, the separate distribution of slag on the weld pool results in the great constriction of arc spots, an increase in arc spot force, and an increase in Lorentz force within the arc and weld pool. Finally, the weld penetration is increased.

  12. Fine micro-welding of thin metal sheet by high speed laser scanning

    Science.gov (United States)

    Okamoto, Yasuhiro; Gillner, Arnold; Olowinsky, Alexander; Gedicke, Jens; Uno, Yoshiyuki

    2007-05-01

    Recently, since the size of component becomes smaller, then the welding of thin metal sheet has been required. Besides, the flexibility of process is important according to the accessibility especially for small components. Fraunhofer Institute for Laser Technology had developed the SHADOW ® welding technology, in which the high speed joining with small distortion is possible using pulsed Nd:YAG laser. The possibility of high speed and high quality welding had been reported by using single-mode fiber laser. The combination of micro beam and high speed laser scanning has the advantages for thin metal sheet welding. Therefore, the characteristics of micro-welding for thin metal sheet were investigated by high speed laser scanning, in which the welding was carried out by high speed scanner system with single-mode fiber laser and pulsed Nd:YAG laser. The proper welding region was narrow by the laser beam with a large focus diameter of 160 μm without pulse control, while a small focus diameter of 22 μm can control the welding state widely. A small focus diameter can perform the excellent welding seam from the extreme beginning without pulse control. The penetration depth can be controlled by the energy density with a small focus diameter of 22 μm at the energy densities less than 1 J/mm2. Besides, the unique periodic structure appeared at the high velocity of beam scanning with a small focus diameter. Moreover, the overlap welding of 25 μm thickness sheet can be performed regardless of small gap distance between two sheets by the laser beam with a small focus diameter of 22 μm.

  13. Improvement of reliability of welding by in-process sensing and control (development of smart welding machines for girth welding of pipes). Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hardt, D.E.; Masubuchi, K.; Paynter, H.M.; Unkel, W.C.

    1983-04-01

    Closed-loop control of the welding variables represents a promising, cost-effective approach to improving weld quality and therefore reducing the total cost of producing welded structures. The ultimate goal is to place all significant weld variables under direct closed-loop control; this contrasts with preprogrammed machines which place the welding equipment under control. As the first step, an overall strategy has been formulated and an investigation of weld pool geometry control for gas tungsten arc process has been completed. The research activities were divided into the areas of arc phenomena, weld pool phenomena, sensing techniques and control activities.

  14. The Advantage of Sensor Sealing Laser Welding

    Institute of Scientific and Technical Information of China (English)

    YAN Yezhi; XU yu

    2007-01-01

    @@ Laser Welding Inevitably Applied in Sen sor Production Certain kinds of sensors such as pressure sensor,temperature sensor, optic-electronic sensor etc. utilize welding seal according to different application environment. With precision components and IC which is isolated by inert gas inside, these sensors should be sealed and able to resist the pressure. So the welding process must avoid distortion and harm to the components and IC.

  15. Numerical modelling of steel arc welding; Modelisation numerique du soudage a l'arc des aciers

    Energy Technology Data Exchange (ETDEWEB)

    Hamide, M

    2008-07-15

    Welding is a highly used assembly technique. Welding simulation software would give access to residual stresses and information about the weld's microstructure, in order to evaluate the mechanical resistance of a weld. It would also permit to evaluate the process feasibility when complex geometrical components are to be made, and to optimize the welding sequences in order to minimize defects. This work deals with the numerical modelling of arc welding process of steels. After describing the industrial context and the state of art, the models implemented in TransWeld (software developed at CEMEF) are presented. The set of macroscopic equations is followed by a discussion on their numerical implementation. Then, the theory of re-meshing and our adaptive anisotropic re-meshing strategy are explained. Two welding metal addition techniques are investigated and are compared in terms of the joint size and transient temperature and stresses. The accuracy of the finite element model is evaluated based on experimental results and the results of the analytical solution. Comparative analysis between experimental and numerical results allows the assessment of the ability of the numerical code to predict the thermomechanical and metallurgical response of the welded structure. The models limitations and the phenomena identified during this study are finally discussed and permit to define interesting orientations for future developments. (author)

  16. Mechanical Characteristics of Welded Joints of Aluminum Alloy 6061 T6 Formed by Arc and Friction Stir Welding

    Science.gov (United States)

    Astarita, A.; Squillace, A.; Nele, L.

    2016-01-01

    Butt welds formed by arc welding in inert gas with nonconsumable electrode (tungsten inert gas (TIG) welding) and by friction stir welding (FSW) from aluminum alloy AA6061 T6 are studied. Comparative analysis of the structures and mechanical properties of the welded joints is performed using the results of optical and electron microscopy, tensile tests, tests for residual bending ductility, and measurements of microhardness. The changes in the microstructure in different zones and the degrees of degradation of the mechanical properties after the welding are determined. It is shown that the size of the tool for the friction stir welding affects the properties of the welds. Quantitative results showing the relation between the microscopic behavior of the alloy and the welding-induced changes in the microstructure are obtained. Friction stir welding is shown to provide higher properties of the welds.

  17. Predicting welding residual stresses in a dissimilar metal girth welded pipe using 3D finite element model with a simplified heat source

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Dean, E-mail: deandeng@cqu.edu.c [College of Materials Science and Engineering, Chongqing University, Shazheng Street 174, Shapingba, Chongqing 400044 (China); Kiyoshima, Shoichi [Research Center of Computational Mechanics, Inc., Togoshi NI-Bldg., 1-7-1 Togoshi, Shinagawa-ku, Tokyo 142-0041 (Japan); Ogawa, Kazuo [Japan Nuclear Energy Safety Organization, TOKYU REIT Toranomon Bldg, 3-17-1, Toranomon, Minato-ku, Tokyo 105-0001 (Japan); Yanagida, Nobuyoshi [Hitachi Ltd. 1-1, Saiwa-cho 3-chome, Hitachi-shi, Ibaraki-ken 317-8511 (Japan); Saito, Koichi [Hitachi-GE Nuclear Energy, Ltd. 2-2, Omika-cho, 5-chome, Hitachi-shi, Ibaraki-ken 319-1221 (Japan)

    2011-01-15

    Research highlights: Welding residual stresses have asymmetrical distributions in the dissimilar metal pipe. Variable length heat source model can largely save computing time. Besides welding, other thermal processes also affect residual stresses. - Abstract: Dissimilar metal welds are commonly used in nuclear power plants to connect low alloy steel components and austenitic stainless steel piping systems. The integrity assessment and life estimation for such welded structures require consideration of residual stresses induced by manufacturing processes. Because the fabrication process of dissimilar metal weld joints is considerably complex, it is very difficult to accurately predict residual stresses. In this study, both numerical simulation technology and experimental method were used to investigate welding residual stress distribution in a dissimilar metal pipe joint with a medium diameter, which were performed by a multi-pass welding process. Firstly, an experimental mock-up was fabricated to measure the residual stress distributions on the inside and the outside surfaces. Then, a time-effective 3-D finite element model was developed to simulate welding residual stresses through using a simplified moving heat source. The simplified heat source method could complete the thermo-mechanical analysis in an acceptable time, and the simulation results generally matched the measured data near the weld zone. Through comparing the simulation results and the experimental measurements, we can infer that besides the multi-pass welding process other key manufacturing processes such as cladding, buttering and heat treatment should also be taken into account to accurately predict residual stresses in the whole range of the dissimilar metal pipe.

  18. Structural ECM components in the premetastatic and metastatic niche

    DEFF Research Database (Denmark)

    Høye, Anette M; Erler, Janine T

    2016-01-01

    The aim of this review is to give an overview of the extracellular matrix (ECM) components that are important for creating structural changes in the premetastatic and metastatic niche. The successful arrival and survival of cancer cells that have left the primary tumor and colonized distant sites...

  19. Nominal and Structural Subtyping in Component-Based Programming

    DEFF Research Database (Denmark)

    Ostermann, Klaus

    2007-01-01

    type. We analyze structural and different flavors of nominal subtyping from the perspective of component-based programming, where issues such as blame assignment and modular extensibility are important. Our analysis puts various existing subtyping mechanisms into a common frame of reference...

  20. Investigation on the stepping arc stud welding process

    Institute of Scientific and Technical Information of China (English)

    Chi Qiang; Zhang Jianxun; Fu Jifei; Zhang Youquan

    2005-01-01

    Through the investigation on traditional arc stud welding process, a new welding gun and its control system were developed in this paper. The stepping arc stud welding gun was mainly made by a stepping motor as actuating unit and a screw-driven device as moving unit. A control system with a MCS-51 single-chip microcomputer as main control component was used to realize the new stud welding procedure. This new welding process with stepping stud welding gun is named as stepping arc stud welding. In the new welding process, the stud action can be looked as constituted by some micro steps. The setting and adjusting of the stepping arc welding gun behavior parameters are accomplished independently. It is indicated from the results of process tests and bending test that the stepping arc stud welding process is practicable.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-05

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

  2. The hardiness of numerical simulation of TIG welding. Application to stainless steel 316L structures; La robustesse de la simulation numerique du soudage TIG. Application sur des structures en acier 316L

    Energy Technology Data Exchange (ETDEWEB)

    El-Ahmar, Walid; Jullien, Jean-Francois [INSA-Lyon, LaMCoS, CNRS UMR 551, 20 Avenue Albert Einstein, 69621 Villeurbanne, (France); Gilles, Philippe [AREVA NP, 92084 Paris La Defense, (France); Taheri, Said [EDF, 92141 Clamart, (France); Boitout, Frederic [ESI-GROUP, 69458 Lyon, (France)

    2006-07-01

    The welding numerical simulation is considered as one of the mechanics problems the most un-linear on account of the great number of the parameters required. The analysis of the hardiness of the welding numerical simulation is a current questioning whose expectation is to specify welding numerical simulation procedures allowing to guarantee the reliability of the numerical result. In this work has been quantified the aspect 'uncertainties-sensitivity' imputable to different parameters which occur in the simulation of stainless steel 316L structures welded by the TIG process: that is to say the mechanical and thermophysical parameters, the types of modeling, the adopted behaviour laws, the modeling of the heat contribution.. (O.M.)

  3. Structure analysis of active components of traditional Chinese medicines

    DEFF Research Database (Denmark)

    Zhang, Wei; Sun, Qinglei; Liu, Jianhua

    2013-01-01

    Traditional Chinese Medicines (TCMs) have been widely used for healing of different health problems for thousands of years. They have been used as therapeutic, complementary and alternative medicines. TCMs usually consist of dozens to hundreds of various compounds, which are extracted from raw...... samples. NMR, on the other hand, provides not only information of primary structures but also information of higher order structures, complementing the components structure analysis by HPLC-MS. The most recent progress in the analysis of the commonly used TCMs will be summarized...

  4. Field Evaluations of Low-Frequency SAFT-UT on Cast Stainless Steel and Dissimilar Metal Weld Components

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Aaron A.; Harris, R. V.; Doctor, Steven R.

    2008-11-01

    This report documents work performed at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, and at the Electric Power Research Institute's (EPRI) Nondestructive Examination (NDE) Center in Charlotte, North Carolina, on evalutating a low frequency ultrasonic inspection technique used for examination of cast stainless steel (CSS) and dissimilar metal (DMW) reactor piping components. The technique uses a zone-focused, multi-incident angle, low frequency (250-450 kHz) inspection protocol coupled with the synthetic aperture focusing technique (SAFT). The primary focus of this work is to provide information to the United States Nuclear Regulatory Commission on the utility, effectiveness and reliability of ultrasonic testing (UT) inspection techniques as related to the inservice ultrasonic inspection of coarse grained primary piping components in pressurized water reactors (PWRs).

  5. Crystal structure of the RNA component of bacterial ribonuclease P

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Larios, Alfredo; Swinger, Kerren K.; Krasilnikov, Andrey S.; Pan, Tao; Mondragon, Alfonso (NWU); (UC)

    2010-03-08

    Transfer RNA (tRNA) is produced as a precursor molecule that needs to be processed at its 3' and 5' ends. Ribonuclease P is the sole endonuclease responsible for processing the 5' end of tRNA by cleaving the precursor and leading to tRNA maturation. It was one of the first catalytic RNA molecules identified and consists of a single RNA component in all organisms and only one protein component in bacteria. It is a true multi-turnover ribozyme and one of only two ribozymes (the other being the ribosome) that are conserved in all kingdoms of life. Here we show the crystal structure at 3.85 {angstrom} resolution of the RNA component of Thermotoga maritima ribonuclease P. The entire RNA catalytic component is revealed, as well as the arrangement of the two structural domains. The structure shows the general architecture of the RNA molecule, the inter- and intra-domain interactions, the location of the universally conserved regions, the regions involved in pre-tRNA recognition and the location of the active site. A model with bound tRNA is in agreement with all existing data and suggests the general basis for RNA-RNA recognition by this ribozyme.

  6. Crystal structure of the RNA component of bacterial ribonuclease P.

    Science.gov (United States)

    Torres-Larios, Alfredo; Swinger, Kerren K; Krasilnikov, Andrey S; Pan, Tao; Mondragón, Alfonso

    2005-09-22

    Transfer RNA (tRNA) is produced as a precursor molecule that needs to be processed at its 3' and 5' ends. Ribonuclease P is the sole endonuclease responsible for processing the 5' end of tRNA by cleaving the precursor and leading to tRNA maturation. It was one of the first catalytic RNA molecules identified and consists of a single RNA component in all organisms and only one protein component in bacteria. It is a true multi-turnover ribozyme and one of only two ribozymes (the other being the ribosome) that are conserved in all kingdoms of life. Here we show the crystal structure at 3.85 A resolution of the RNA component of Thermotoga maritima ribonuclease P. The entire RNA catalytic component is revealed, as well as the arrangement of the two structural domains. The structure shows the general architecture of the RNA molecule, the inter- and intra-domain interactions, the location of the universally conserved regions, the regions involved in pre-tRNA recognition and the location of the active site. A model with bound tRNA is in agreement with all existing data and suggests the general basis for RNA-RNA recognition by this ribozyme.

  7. Laser vision sensing based on adaptive welding for aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhixiang; SONG Yonglun; ZHANG Jun; ZHANG Wanchun; JIANG Li; XIA Xuxin

    2007-01-01

    A laser vision sensing based on the adaptive tungsten inert gas(TIG)welding system for large-scale aluminum alloy components was established to fit various weld groove conditions.A new type of laser vision sensor was used to precisely measure the weld groove.The joint geometry data,such as the bevel angle,the gap,the area,and the mismatch,etc.,aided in assembling large-scale aerospace components before welding.They were also applied for automatic seam tracking,such as automatic torch transverse alignment and torch height adjustment in welding.An adaptive welding process was realized by automatically adjusting the wire feeding speed and the welding current according to the groove conditions.The process results in a good weld formation and high welding quality,which meet the requirements of related standards.

  8. Milestones in welding technology

    Science.gov (United States)

    Dolby, Richard E.

    2013-09-01

    Sir Alan's PhD thesis describes his research into cracking during arc welding of armour steels. Throughout his career, he had a strong interest in defects of all types, how they formed in metallic structures and how the larger ones could be detected and sized by non-destructive techniques. He was also vitally concerned with how defects impacted on the engineering integrity of welded structures, particularly the risk of fracture in nuclear plant. This study presents a view of some of the major milestones in global welding technology that took place over the 60 or more years of Sir Alan's career and highlights those where he had a personal and direct involvement.

  9. A study of internal structure in components made by additive manufacturing process using 3 D X-ray tomography

    Energy Technology Data Exchange (ETDEWEB)

    Raguvarun, K., E-mail: prajagopal@iitm.ac.in; Balasubramaniam, Krishnan, E-mail: prajagopal@iitm.ac.in; Rajagopal, Prabhu, E-mail: prajagopal@iitm.ac.in [Centre for NDE, Indian Institute of Technology Madras, Chennai 600036, Tamilnadu (India); Palanisamy, Suresh [Swinburne University of Technology, Faculty of Engineering, Science and Technology, Hawthorn, Victoria 3122 Australia and Defence Materials Technology Centre, Hawthorn, Victoria 3122 (Australia); Nagarajah, Romesh; Kapoor, Ajay [Swinburne University of Technology, Faculty of Engineering, Science and Technology, Hawthorn, Victoria 3122 (Australia); Hoye, Nicholas; Curiri, Dominic [University of Wollongong, Faculty of Engineering, New South Wales 2522, Australia and Defence Materials Technology Centre, Hawthorn, Victoria 3122 (Australia)

    2015-03-31

    Additive manufacturing methods are gaining increasing popularity for rapidly and efficiently manufacturing parts and components in the industrial context, as well as for domestic applications. However, except when used for prototyping or rapid visualization of components, industries are concerned with the load carrying capacity and strength achievable by additive manufactured parts. In this paper, the wire-arc additive manufacturing (AM) process based on gas tungsten arc welding (GTAW) has been examined for the internal structure and constitution of components generated by the process. High-resolution 3D X-ray tomography is used to gain cut-views through wedge-shaped parts created using this GTAW additive manufacturing process with titanium alloy materials. In this work, two different control conditions for the GTAW process are considered. The studies reveal clusters of porosities, located in periodic spatial intervals along the sample cross-section. Such internal defects can have a detrimental effect on the strength of the resulting AM components, as shown in destructive testing studies. Closer examination of this phenomenon shows that defect clusters are preferentially located at GTAW traversal path intervals. These results highlight the strong need for enhanced control of process parameters in ensuring components with minimal defects and higher strength.

  10. Investigation of the micro contact profile welding technics

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The cladding preparation technology for the micro contact profile is investigated through the way of seam welding. The effects of the seam welding on different conditions including welding electrical current, welding time, electrode force and electrode material were contrasted through the way of metallographic structure, electron scanning, experiments of rectification and twist fatigue.The parameters of welding several kinds of materials were obtained. As a result, the qualified contact profile can be produced by making a control of the technical conditions: welding current, welding time, electrode force and electrode material.

  11. Effect of pulse duty cycle on Inconel 718 laser welds

    Science.gov (United States)

    McCay, M. H.; McCay, T. D.; Dahotre, N. B.; Sharp, C. M.; Sedghinasab, A.; Gopinathan, S.

    1989-01-01

    Crack sensitive Inconel 718 was laser pulse welded using a 3.0 kW CO2 laser. Weld shape, structure, and porosity were recorded as a function of the pulse duty cycle. Within the matrix studied, the welds were found to be optimized at a high (17 ms on, 7 ms off) duty cycle. These welds were superior in appearance and lack of porosity to both low duty cycle and CW welds.

  12. New trends for the NDT of aeronautic welds

    Science.gov (United States)

    Ithurralde, G.; Simonet, D.; Choffy, J.-P.; Bernard, L.

    2001-04-01

    Recent advances in laser beam welding, electron beam welding and friction stir welding enable to join aeronautic and space alloys (mainly aluminum based) and think about new welded design for structural parts at a lower cost. This paper deals with both the non destructive testing approach implemented for welding process optimization, and the NDT multi-sensors tools selected because of their ability for on-line defect tracking automation.

  13. Microstructural characterization of the A-508/82/182/316L dissimilar metal weld with reinforcement of 52 weld; Caracterizacao microestrutural da solda de metais dissimilares A-508/82/182/316L com reforco de solda 52

    Energy Technology Data Exchange (ETDEWEB)

    Paula, Raphael G.; Figueiredo, Celia A.; Campos, Wagner R.C., E-mail: caf@cdtn.br, E-mail: wrcc@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2011-07-01

    Stress corrosion cracking (SCC) is the major corrosion concern in the plant life management of ageing plants. The main classes of nuclear power plant materials that are potentially subjected to SCC are austenitic stainless steels and nickel based alloys. The nickel alloys 600, 82 and 182, originally selected due to their high corrosion resistance, show after many years of plant operation, susceptibility to SCC. Those alloys are used in steam generators and as dissimilar metal weld materials for nozzles of components such as the reactor pressure vessel and the pressurizer. Several techniques have been developed to mitigate the consequences of SCC in dissimilar metal welds; e. g. deposition of a compatible structural layer over the nozzle external surface, known as weld overlay, to induce compressive stresses on the nozzle critical region and weld repair. The material used in this work is a mock-up of an Angra 1 pressurizer nozzle weld, manufactured at CDTN according to procedures established for nuclear power plants. The weld links the forged 316 stainless steel to the A-508 carbon steel by Inconel 182 weld metal. On the carbon steel side, a buttering layer is applied (alloy 82). Alloy 52 is employed as weld overlay. The objective of this work is to perform a microstructural and metallographic characterization of the mock up materials, which includes an optical microscope analysis of the general structure of the material, microhardness determinations and a microstructure evaluation of selected regions of the mock up. (author)

  14. Influence of Specific Features of Twin Arc Welding on Properties of Weld Joints

    Science.gov (United States)

    Sholokhov, M. A.; Melnikov, A. U.; Fiveyskiy, A. M.

    2016-04-01

    The present article covers the influence of standard and narrow gap twin arc welding on properties of weld joints from high-strength steels. While analyzing microsections we established that distribution of micro structure and phase terms, as well the distribution of micro-hardness, were more homogeneous under narrow gap twin arc welding.

  15. Morphology and structure of various phases at the bonding interface of Al/steel formed by explosive welding

    Science.gov (United States)

    Li; Hashimoto; Sukedai; Zhang; Zhang

    2000-01-01

    The bonding interface of explosively-welded aluminium and steel in three explosive conditions have been investigated by using scanning electron microscopy, transmission electron microscopy, electron diffraction and electron probe microanalysis methods. The results show that all the interfaces have the shape of waves with curled front formed by process of superplasticity and some discontinuous reacted zones. They consist of amorphous and nano sized crystals and quasi-crystals as well as the compounds such as AlFe, Al2Fe, Al3Fe and Al6Fe with various shapes. The basal steel crystal near the interface has structure of martensite and perlite crystals which are deformed by the process of superplasticity. The size of reacted zone becomes large with increasing amount of explosive charge powder and separation of the driver Al plate from the basal steel plate.

  16. Structure and mechanical properties of a multilayer carbide-hardened niobium composite material fabricated by diffusion welding

    Science.gov (United States)

    Korzhov, V. P.; Ershov, A. E.; Stroganova, T. S.; Prokhorov, D. V.

    2016-04-01

    The structure, the bending strength, and the fracture mechanism of an artificial niobium-based composite material, which is fabricated by high-pressure diffusion welding of multilayer stacks assembled from niobium foils with a two-sided carbon coating, are studied. The microstructure of the composite material is found to consist of alternating relatively plastic layers of the solid solution of carbon in niobium and hardening niobium carbide layers. The room-temperature proportional limit of the developed composite material is threefold that of the composite material fabricated from coating-free niobium foils using the proposed technology. The proportional limit of the developed composite material and the stress corresponding to the maximum load at 1100°C are 500 and 560 MPa, respectively. The developed material is considered as an alternative to Ni-Al superalloys.

  17. Structural and wetting properties of fuel cell components

    Science.gov (United States)

    Volfkovich, Yu. M.; Sosenkin, V. E.; Bagotsky, V. S.

    The operation of proton exchange membrane (PEMFC) and direct methanol fuel cells (DMFC) is connected with the flow of different gaseous and liquid components in the cell's membrane-electrode assembly (MEA). The structural and wetting properties of different components of the MEA influence the rate and direction of these flows and hence the fuel cell's efficiency. For a better understanding of the mechanism of all processes influencing the fuel cell efficiency, for a mathematical modelling of these processes, and for a possibility of their optimization, a detailed knowledge of the geometrical structure and wetting properties of all MEA components is necessary. This review describes the results of such investigations performed mainly by using the method of standard contact porosimetry (MSCP). This method gives the possibility to receive information on multicomponent porous and powdered materials hitherto not accessible, viz. their wetting and swelling properties, pore corrugation, and also isotherms of capillary pressure and bond energy. Measurements of MEA components by this method can be performed under exactly the same conditions (temperature, compression degree, contact with water, etc.) as those existing in real fuel cells.

  18. 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…

  19. Mechanical and materials engineering of modern structure and component design

    CERN Document Server

    Altenbach, Holm

    2015-01-01

    This book presents the latest findings on mechanical and materials engineering as applied to the design of modern engineering materials and components. The contributions cover the classical fields of mechanical, civil and materials engineering, as well as bioengineering and advanced materials processing and optimization. The materials and structures discussed can be categorized into modern steels, aluminium and titanium alloys, polymers/composite materials, biological and natural materials, material hybrids and modern nano-based materials. Analytical modelling, numerical simulation, state-of-the-art design tools and advanced experimental techniques are applied to characterize the materials’ performance and to design and optimize structures in different fields of engineering applications.

  20. Structural Weight Optimization of Aircraft Wing Component Using FEM Approach.

    Directory of Open Access Journals (Sweden)

    Arockia Ruban M,

    2015-06-01

    Full Text Available One of the main challenges for the civil aviation industry is the reduction of its environmental impact by better fuel efficiency by virtue of Structural optimization. Over the past years, improvements in performance and fuel efficiency have been achieved by simplifying the design of the structural components and usage of composite materials to reduce the overall weight of the structure. This paper deals with the weight optimization of transport aircraft with low wing configuration. The Linear static and Normal Mode analysis were carried out using MSc Nastran & Msc Patran under different pressure conditions and the results were verified with the help of classical approach. The Stress and displacement results were found and verified and hence arrived to the conclusion about the optimization of the wing structure.

  1. Structural Components of Lifestyle and Beyond: The Case of Hungary

    Directory of Open Access Journals (Sweden)

    Tamás Keller

    2011-06-01

    Full Text Available This paper deals with the question of when and how lifestyle and its components are important in social stratification. There is considerable consensus among scholars about the structure of the society being a consequence of hierarchical dimensions like occupation, income, or wealth. Some thirty years ago, largely based on Bourdieu’s “Distinction”, a new paradigm emerged highlighting the lifestyle components and the value-oriented cultural and material consumption in stratifi cation. The idea refl ects the empirical fi nding that inequality between social classes has largely decreased, giving priority to horizontal lifestyle differentiation instead of vertical inequality dimensions. From a theoretical viewpoint, a challenge in the approach is finding out to what extent lifestyle typology is of a non-vertical character in reality. This social determination of lifestyle is investigated for Hungary when comparing an occupation-based typology with a consumption-based one. On the one hand, results reveal that the effects of structural components on social status are stronger than those of lifestyle. On the other hand, lifestyle turns out to be less independent of social position and the top and bottom levels of the lifestyle typology are particularly predictable by structural measures.

  2. The Vibration Impact Determination of the Helicopter Structural Components

    Directory of Open Access Journals (Sweden)

    Khaksar Zeinab

    2017-01-01

    Full Text Available This paper presents the determination of the vibration impact of the helicopter structural components and skin repairs in terms of frequency characteristics. To address this issue, a 3D Finite Element Method (FEM model of 349 Gazelle helicopter has been developed in ABAQUS and the frequency analysis is conducted. The results on the natural frequencies of the full structure reasonably match with the literature giving confidence in the baseline model. The main advantage of this FEM model is that, it can be used to predict the natural frequencies of the full structure, precisely. In addition, the material properties and conditions of the components can be updated based on the applied conditions during the repair and maintenance period. Thus, the model gives a comprehensive design tool for analysing the frequencies of the helicopter with differing components. The effective variations in the frequency changes due to repair are predicted numerically. The discussion of these results helps in developing leads to improved selection of replacement materials and their properties.

  3. ITER lip seal welding and cutting developments

    Energy Technology Data Exchange (ETDEWEB)

    Levesy, B.; Cordier, J.J.; Jokinen, T. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Kujanpää, V.; Karhu, M. [VTT Technical Research Centre of Finland (Finland); Le Barbier, R. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Määttä, T. [VTT Technical Research Centre of Finland (Finland); Martins, J.P.; Utin, Y. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France)

    2015-10-15

    Highlights: • Different TIG and Laser welding techniques are tested. • Twin spot laser welding techniques is the best. • Limited heat input gives a stable weld pool in all positions. • Penetrations is achieved. • Lip seal welding and cutting with a robotic arm is successfully performed on a representative mock-up. - Abstract: The welded lip seals form part of the torus primary vacuum boundary in between the port plugs and the vacuum vessel, and are classified as Protection Important Component. In order to refurbish the port plugs or the in-vessel components, port plugs have to be removed from the machine. The lip seal design must enable up to ten opening of the vacuum vessel during the life time operation of the ITER machine. Therefore proven, remote reliable cutting and re-welding are essential, as these operations need to be performed in the port cells in a nuclear environment, where human presence will be restricted. Moreover, the combination of size of the components to be welded (∼10 m long vacuum compatible thin welds) and the congested environment close to the core of the machine constraint the type and size of tools to be used. This paper describes the lip seal cutting and welding development programme performed at the VTT Technical Research Centre, Finland. Potential cutting and welding techniques are analyzed and compared. The development of the cutting, TIG and laser welding techniques on samples are presented. Effects of lip seal misalignments and optimization of the 2 welding processes are discussed. Finally, the manufacturing and test of the two 1.2 m × 1 m representative mock-ups are presented. The set-up and use of a robotic arm for the mock-up cutting and welding operations are also described.

  4. Virtual Welded - Joint Design Integrating Advanced Materials and Processing Technology

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhishang; Ludewig, Howard W.; Babu, S. Suresh

    2005-06-30

    Virtual Welede-Joint Design, a systematic modeling approach, has been developed in this project to predict the relationship of welding process, microstructure, properties, residual stress, and the ultimate weld fatique strength. This systematic modeling approach was applied in the welding of high strength steel. A special welding wire was developed in this project to introduce compressive residual stress at weld toe. The results from both modeling and experiments demonstrated that more than 10x fatique life improvement can be acheived in high strength steel welds by the combination of compressive residual stress from the special welding wire and the desired weld bead shape from a unique welding process. The results indicate a technology breakthrough in the design of lightweight and high fatique performance welded structures using high strength steels.

  5. Damage Tolerance Assessment of Friction Pull Plug Welds

    Science.gov (United States)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process developed and patented by The Welding Institute in Cambridge, England. Friction stir welding has been implemented in the aerospace industry in the fabrication of longitudinal welds in pressurized cryogenic propellant tanks. As the industry looks to implement friction stir welding in circumferential welds in pressurized cryogenic propellant tanks, techniques to close out the termination hole associated with retracting the pin tool are being evaluated. Friction pull plug welding is under development as a one means of closing out the termination hole. A friction pull plug weld placed in a friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite, plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size in the test or service environments. Test data relating residual strength capability to flaw size in two aluminum alloy friction plug weld configurations is presented.

  6. Hybrid Friction Stir Welding of High-carbon Steel

    Institute of Scientific and Technical Information of China (English)

    Don-Hyun Choi; Seung-Boo Jung; Chang-Yong Lee; Byung-Wook Ahn; Jung-Hyun Choi; Yun-Mo Yeon; Keun Song; Seung-Gab Hong; Won-Bae Lee; Ki-Bong Kang

    2011-01-01

    A high-carbon steel joint, SK5 (0.84 wt% C), was successfully welded by friction stir welding (FSW), both without and with a gas torch, in order to control the cooling rate during welding. After welding, the weld zone comprised gray and black regions, corresponding to microstructural variation: a martensite structure and a duplex structure of ferrite and cementite, respectively. The volume fraction of the martensite structure and the Vickers hardness in the welds were decreased with the using of the gas torch, which was related with the lower cooling rate.

  7. Evolution of a Laser Hybrid Welding Map

    Science.gov (United States)

    Kaplan, Alexander F. H.; Frostevarg, Jan; Ilar, Torbjörn; Bang, Hee-Seon; Bang, Han-Sur

    Laser arc hybrid welding combines the advantages but also the complex physical mechanisms of gas metal arc welding and laser keyhole welding. From manifold mainly experimental but also theoretical research results a map with versatile functions was initiated for the first time. The purpose is to survey the overall context and to facilitate navigation to the various phenomena that are shown through case studies accompanied by theoretical explanations and guidelines for optimization. Though not complete, the map enables systematic and graphical navigation to relevant publications. Based on a fundamental structure of the map, which was decided early, it is inherently extendable in the future by adding existing and new knowledge, also from other research groups, enabling evolution. The fundament of the map structure comprises gouge thickness, joint type and metal grade, in coherence with product and weld designers' starting points. The next hierarchy level of the map offers options in the joint type as well as in hybrid welding techniques. The latter contains techniques like double-sided welding, pulse shaping management of the arc or laser, CMT arcs, tandem arcs, or remelting of undercuts. In addition to laser-arc hybrid welding, other hybrid laser techniques like multilayer hot-wire laser welding of narrow gaps or hybrid laser friction stir welding can be taken into account. At the other end of the hierarchy, the map offers via a database-like archive electronic navigation to research results like weld macrographs, high speed imaging or numerical simulation results of the welding process.

  8. Weld bonding of stainless steel

    DEFF Research Database (Denmark)

    Santos, I. O.; Zhang, Wenqi; Goncalves, V.M.

    2004-01-01

    This paper presents a comprehensive theoretical and experimental investigation of the weld bonding process with the purpose of evaluating its relative performance in case of joining stainless steel parts, against alternative solutions based on structural adhesives or conventional spot...

  9. An Electrochemical Evaluation on the Corrosion of Weld Zone in Cold Arc Welding of the Cast Iron

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Kyung Man; Lee, Myung Hoon; Kim, Ki Joon [Korea Maritime University, Busan (Korea, Republic of); Kim, Jin Gyeong [Korea Institute of Marine and Frsheries Technology, Busan (Korea, Republic of)

    2008-04-15

    Cold arc welding of cast iron has been widely used with repair welding of metal structures. However its welding is often resulted in the galvanic corrosion between weld metal zone and heat affected zone(HAZ) due to increasing of hardness. In this study, corrosion properties such as hardness, corrosion potential, surface microstructures, and variation of corrosion current density of welding zone with parameters of used electrodes for cast iron welding were investigated with an electrochemical evaluation. Hardness of HAZ showed the highest value compared to other welding zone regardless of kinds of used electrodes for cast iron welding. And its corrosion potential was also shifted to more negative direction than other welding zone. In addition, corrosion current density of WM in polarization cures was qualitatively smaller than that of HAZ. Therefore galvanic corrosion may be apparently observed at HAZ. However galvanic corrosion may be somewhat controlled by using an optimum welding electrode.

  10. FEATURES OF WELDED TITANIUM STRUCTURE ELEMENT DESTRUCTION (RIBBED PANELS UNDER VIBRATION LOADS

    Directory of Open Access Journals (Sweden)

    Mr. Pavel V. Bakhmatov

    2016-12-01

    Full Text Available The article presents data on the experimental studies results of welded ribbed panel vibration load of the BT-20 titanium alloy. It was established that in the areas of attachment, there is elevated dynamic alternating stress, which in combination with the "hard" of the sample holder creates favorable conditions for the emergence and development of fatigue cracks, and stress concentrators greatly reduce the time before the formation of the hearth destruction. An exception in these zones of superficial defects do not affect the nature and kinetics of destruction. Construction of titanium alloys made in the application of gas-laser cutting blanks for optimal regimes in the technical environment of nitrogen and subsequent heat treatment on vibration reliability is not inferior to design, made by traditional technology.

  11. Structural design optimization of vehicle components using Cuckoo Search Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Yildiz, Ali Riza [Bursa Technical Univ., Bursa (Turkey). Dept. of Mechanical Engineering; Durgun, Ismail

    2012-07-01

    In order to meet today's vehicle design requirements and to improve the cost and fuel efficiency, there is an increasing interest to design light-weight and cost-effective vehicle components. In this research, a new optimization algorithm, called the Cuckoo Search Algorithm (CS) algorithm, is introduced for solving structural design optimization problems. This research is the first application of the CS to the shape design optimization problems in the literature. The CS algorithm is applied to the structural design optimization of a vehicle component to illustrate how the present approach can be applied for solving structural design problems. Results show the ability of the CS to find better optimal structural design. [German] Um heutige Anforderungen an das Fahrzeugdesign zu beruecksichtigen und um die Kosten- und Kraftstoffeffektivitaet zu erhoehen, nimmt das Interesse am Design leichter und kosteneffektiver Fahrzeugkomponenten weiterhin zu. In der diesem Beitrag zugrunde liegenden Studie wurde ein neuer Optimierungsalgorithmus angewendet, der so genannte Cuckoo Suchalgorithmus (CS). Es handelt sich um die erste CS-Applikation fuer das Formdesign in der Literatur. Der CS-Algorithmus wird hierbei zur Strukturdesignoptimierung einer Fahrzeugkomponente angewendet, um zu zeigen, wie er bei der Loesung von Strukturdesignaufgaben angewendet werden kann. Die Ergebnisse zeigen, wie damit ein verbessertes Design erreicht werden kann.

  12. Study on unified fatigue strength assessment method for welded structure. Hot spot stress evaluating method for various combinations of plate thickness and weld leg length; Yosetsu kozo no toitsutekina hiro kyodo hyokaho ni kansuru kenkyu. Itaatsu to yosetsu ashinaga no kumiawase ni taisuru hot spot oryoku sanshutsu ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Nihei, K.; Inamura, F.; Koe, S. [Kawasaki Heavy Industries, Ltd., Kobe (Japan)

    1996-12-31

    There has been tried to apply unified assessment method using hot spot stress, which is effective to evaluate fatigue strength of fillet welded structures for ships and marine structures. This method can be applied to complicated structures and is independent of welding processes. In this study, first, stress analysis has been conducted for two-dimensional fillet welded joint models with various combinations of plate thickness and weld leg length of general fillet structures by means of boundary element method. Then, critical position, which is not affected by local stress concentration due to bead, was determined from the detailed stress distribution in the vicinity of weld toe. As a result, a general equation has been proposed to estimate the hot spot stress by one-point representative method. Second, the fatigue tests of typical fillet welded joints have been conducted by applying this method. Consequently, it was demonstrated that the unified fatigue strength can be evaluated by the S-N data based on hot spot stress range determined from the proposed equation, independent of structural stress concentration. 22 refs., 14 figs.

  13. 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.

  14. Structure learning by pruning in independent component analysis

    DEFF Research Database (Denmark)

    Nielsen, Andreas Brinch; Hansen, Lars Kai

    2008-01-01

    We discuss pruning as a means of structure learning in independent component analysis (ICA). Learning the structure is attractive in both signal processing and in analysis of abstract data, where it can assist model interpretation, generalizability and reduce computation. We derive the relevant s...... based methods and Bayesian methods, for both small and large samples. The Bayesian information criterion (BIC) seems to outperform both AIC and test sets as tools for determining the optimal dimensionality....... saliency expressions and compare with magnitude based pruning and Bayesian sparsification. We show in simulations that pruning is able to identify underlying structures without prior knowledge on the dimensionality of the model. We find, that for ICA, magnitude based pruning is as efficient as saliency...

  15. 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

  16. Towards Real Time Diagnostics of Hybrid Welding Laser/GMAW

    Energy Technology Data Exchange (ETDEWEB)

    Timothy Mcjunkin; Dennis C. Kunerth; Corrie Nichol; Evgueni Todorov; Steve Levesque; Feng Yu; Robert Danna Couch

    2013-07-01

    Methods are currently being developed towards a more robust system real time feedback in the high throughput process combining laser welding with gas metal arc welding. A combination of ultrasonic, eddy current, electronic monitoring, and visual techniques are being applied to the welding process. Initial simulation and bench top evaluation of proposed real time techniques on weld samples are presented along with the concepts to apply the techniques concurrently to the weld process. Consideration for the eventual code acceptance of the methods and system are also being researched as a component of this project. The goal is to detect defects or precursors to defects and correct when possible during the weld process.

  17. Towards real time diagnostics of Hybrid Welding Laser/GMAW

    Energy Technology Data Exchange (ETDEWEB)

    McJunkin, T. R.; Kunerth, D. C.; Nichol, C. I. [Idaho National Laboratory, Idaho Falls, ID 83415-3570 (United States); Todorov, E.; Levesque, S. [Edison Welding Institute, Columbus, OH (United States)

    2014-02-18

    Methods are currently being developed towards a more robust system real time feedback in the high throughput process combining laser welding with gas metal arc welding. A combination of ultrasonic, eddy current, electronic monitoring, and visual techniques are being applied to the welding process. Initial simulation and bench top evaluation of proposed real time techniques on weld samples are presented along with the concepts to apply the techniques concurrently to the weld process. Consideration for the eventual code acceptance of the methods and system are also being researched as a component of this project. The goal is to detect defects or precursors to defects and correct when possible during the weld process.

  18. Differences between Laser and Arc Welding of HSS Steels

    Science.gov (United States)

    Němeček, Stanislav; Mužík, Tomáš; Míšek, Michal

    Conventional welding processes often fail to provide adequate joints in high strength steels with multiphase microstructures. One of the promising techniques is laser beam welding: working without filler metal and with sufficient capacity for automotive and transportation industry (where the amount of AHSS steels increases each year, as well as the length of laser welds). The paper compares microstructures and properties of HSS (high strength steel) joints made by MAG (Metal Active Gas) and laser welding. The effects of main welding parameters (heat input, welding speed and others) are studied on multiphase TRIP 900 steel tubes and martensitic sheets DOCOL 1200, advanced materials for seat frames and other automotive components. Whereas the strength of conventional welds is significantly impaired, laser welding leaves strength of the base material nearly unaffected. As the nature of fracture changes during loading and depending on the welding method, failure mechanisms upon cross tension tests have been studied as well.

  19. Genesis of the microstructures during friction stir welding of aluminium alloys of the series 2000 and 5000 and resulting mechanical behavior; Genese des microstructures lors du soudage par friction malaxage d'alliages d'aluminium de la serie 2000 et 5000 et comportement mecanique resultant

    Energy Technology Data Exchange (ETDEWEB)

    Genevois, C.

    2004-09-15

    The 2024 alloy (Al-Cu-Mg) is used for minimizing the weight of structural components in the transportation industry. However, this alloy is not easy to weld by traditional techniques. Friction stir welding (FSW) is a recently developed solid state process which removes the solidification defects. In this study, the microstructures of FSW welds of this alloy were finely characterized by SAXS, DSC, TEM, SEM, EBSD and optical microscopy. In order to highlight the interactions between deformation, precipitation and recrystallization, which all take place during the welding of the 2024 alloy, model experiments were carried out as well as a comparative study between the alloys 5251 and 2024. The combination of the welding characterisation and the model experiments allow to define the metallurgical phenomena controlling the mechanical strength of the welded joints and their microstructure. In addition, a detailed characterisation of the mechanical behaviour of the welded joints was carried out, validated by a finite element model. (author)

  20. Analysis methods for structure reliability of piping components

    Energy Technology Data Exchange (ETDEWEB)

    Schimpfke, T.; Grebner, H.; Sievers, J. [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Koeln (Germany)

    2004-07-01

    In the frame of the German reactor safety research program of the Federal Ministry of Economics and Labour (BMWA) GRS has started to develop an analysis code named PROST (PRObabilistic STructure analysis) for estimating the leak and break probabilities of piping systems in nuclear power plants. The long-term objective of this development is to provide failure probabilities of passive components for probabilistic safety analysis of nuclear power plants. Up to now the code can be used for calculating fatigue problems. The paper mentions the main capabilities and theoretical background of the present PROST development and presents some of the results of a benchmark analysis in the frame of the European project NURBIM (Nuclear Risk Based Inspection Methodologies for Passive Components). (orig.)

  1. Investigation of the structure and properties of titanium-stainless steel permanent joints obtained by laser welding with the use of intermediate inserts and nanopowders

    Science.gov (United States)

    Cherepanov, A. N.; Orishich, A. M.; Pugacheva, N. B.; Shapeev, V. P.

    2015-03-01

    Results of an experimental study of the structure, the phase composition, and the mechanical properties of laser-welded joints of 3-mm thick titanium and 12Kh18N10T steel sheets obtained with the use of intermediate inserts and nanopowdered modifying additives are reported. It is shown that that such parameters as the speed of welding, the radiation power, and the laser-beam focal spot position all exert a substantial influence on the welding-bath process and on the seam structure formed. In terms of chemical composition, most uniform seams with the best mechanical strength are formed at a 1-m/min traverse speed of laser and 2.35-kW laser power, with the focus having been positioned at the lower surface of the sheets. Under all other conditions being identical, uplift of the focus to workpiece surface or to a higher position results in unsteady steel melting, in a decreased depth and reduced degree of the diffusion-induced mixing of elements, and in an interpolate connection formed according to the soldering mechanism in the root portion of the seam. The seam material is an over-saturated copper-based solid solution of alloying elements with homogeneously distributed intermetallic disperse particles (Ti(Fe, Cr)2 and TiCu3) contained in this alloy. Brittle fracture areas exhibiting cleavage and quasi-cleavage facets correspond to coarse Ti(Fe, Cr)2 intermetallic particles or to diffusion zones primarily occurring at the interface with the titanium alloy. The reported data and the conclusions drawn from the numerical calculations of the thermophysical processes of welding of 3-mm thick titanium and steel sheets through an intermediate copper insert are in qualitative agreement with the experimental data. The latter agreement points to adequacy of the numerical description of the melting processes of contacting materials versus welding conditions and focal-spot position in the system.

  2. Impact properties and hardening behavior of laser and electron-beam welds of V-4Cr-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Strain, R.V.; Tsai, H.C.; Park, J.H.; Smith, D.L. [Argonne National Lab., IL (United States)

    1996-10-01

    The authors are conducting a program to develop an optimal laser welding procedure that can be applied to large-scale fusion-reactor structural components to be fabricated from vanadium-base alloys. Results of initial investigation of mechanical properties and hardening behavior of laser and electron-beam (EB) welds of the production-scale heat of V-4Cr-4Ti (500-kg Heat 832665) in as-welded and postwelding heat-treated (PWHT) conditions are presented in this paper. The laser weld was produced in air using a 6-kW continuous CO{sub 2} laser at a welding speed of {approx}45 mm/s. Microhardness of the laser welds was somewhat higher than that of the base metal, which was annealed at a nominal temperature of {approx}1050{degrees}C for 2 h in the factory. In spite of the moderate hardening, ductile-brittle transition temperatures (DBTTs) of the initial laser ({approx}80{degrees}C) and EB ({approx}30{degrees}C) welds were significantly higher than that of the base metal ({approx}{minus}170{degrees}C). However, excellent impact properties, with DBTT < {minus}80{degrees}C and similar to those of the base metal, could be restored in both the laser and EB welds by postwelding annealing at 1000{degrees}C for 1 h in vacuum.

  3. Quality control of laser tailor welded blanks

    Science.gov (United States)

    Yan, Qi

    2008-03-01

    Tailor welded blanks were widely used in the automobile industry for their special advantages. A combination of different materials, thickness, and coatings could be welded together to form a blank for stamping car body panels. With the gradually growing consciousness on safety requirement of auto body structural, the business of laser tailor welded blanks is developing rapidly in China. Laser tailor welded blanks were just the semi products between steel factory and automobile manufacturers. As to the laser welding defects such as convexity and concavity, automobile industry had the strict requirement. In this paper, quality standard on laser tailor welded blanks were discussed. As for the production of laser tailor welded blanks, online quality control of laser tailor welded blanks was introduced. The image processing system for welding laser positioning and weld seam monitoring were used in the production of laser tailor welded blanks. The system analyzes images from the individual cameras and transmits the results to the machine control system via a CAN bus.

  4. MATHEMATICAL SIMULATION OF WELDING DISTORTIONS IN THIN PLATES

    Directory of Open Access Journals (Sweden)

    Afshin Kheidari Monfared

    2011-01-01

    Full Text Available Welding is a crucial manufacturing process and widely used for manufacturing various products including ships, automobiles, trains and bridges. Welding distortions often occur in welded structures of thin plates due to relatively low stiffness and result in their warpage during assembly process and high manufacturing cost. Therefore, prediction and reduction of welding distortions are important in order to improve quality of welded structures. Welding distortion during the assembly process is caused not only by local shrinkage due to rapid heating and cooling. 3-D thermo-elastic-plastic finite element method (FEM has been used to simulate single-bead-on-plate welding with 1 mm thickness. Experiments have been carried out to prove the simulated results. Comparison of the experimental results and FEM simulation results has confirmed that the proposed method efficiently  predicts level of  welding distortions while making single-bead-on-plate welding with 1 mm thickness.

  5. Novel Process Revolutionizes Welding Industry

    Science.gov (United States)

    2008-01-01

    Glenn Research Center, Delphi Corporation, and the Michigan Research Institute entered into a research project to study the use of Deformation Resistance Welding (DRW) in the construction and repair of stationary structures with multiple geometries and dissimilar materials, such as those NASA might use on the Moon or Mars. Traditional welding technologies are burdened by significant business and engineering challenges, including high costs of equipment and labor, heat-affected zones, limited automation, and inconsistent quality. DRW addresses each of those issues, while drastically reducing welding, manufacturing, and maintenance costs.

  6. Structural ECM components in the premetastatic and metastatic niche.

    Science.gov (United States)

    Høye, Anette M; Erler, Janine T

    2016-06-01

    The aim of this review is to give an overview of the extracellular matrix (ECM) components that are important for creating structural changes in the premetastatic and metastatic niche. The successful arrival and survival of cancer cells that have left the primary tumor and colonized distant sites depends on the new microenvironment they encounter. The primary tumor itself releases factors into the circulation that travel to distant organs and then initiate structural changes, both non-enzymatic and enzymatic, to create a favorable niche for the disseminating tumor cells. Therapeutic strategies aimed at targeting cell-ECM interactions may well be one of the best viable approaches to combat metastasis and thus improve patient care.

  7. Multigroup Moderation Test in Generalized Structured Component Analysis

    Directory of Open Access Journals (Sweden)

    Angga Dwi Mulyanto

    2016-05-01

    Full Text Available Generalized Structured Component Analysis (GSCA is an alternative method in structural modeling using alternating least squares. GSCA can be used for the complex analysis including multigroup. GSCA can be run with a free software called GeSCA, but in GeSCA there is no multigroup moderation test to compare the effect between groups. In this research we propose to use the T test in PLS for testing moderation Multigroup on GSCA. T test only requires sample size, estimate path coefficient, and standard error of each group that are already available on the output of GeSCA and the formula is simple so the user does not need a long time for analysis.

  8. Structures and components in galaxy clusters: observations and models

    CERN Document Server

    Bykov, A M; Ferrari, C; Forman, W R; Kaastra, J S; Klein, U; Markevitch, M; de Plaa, J

    2015-01-01

    Clusters of galaxies are the largest gravitationally bounded structures in the Universe dominated by dark matter. We review the observational appearance and physical models of plasma structures in clusters of galaxies. Bubbles of relativistic plasma which are inflated by supermassive black holes of AGNs, cooling and heating of the gas, large scale plasma shocks, cold fronts, non-thermal halos and relics are observed in clusters. These constituents are reflecting both the formation history and the dynamical properties of clusters of galaxies. We discuss X-ray spectroscopy as a tool to study the metal enrichment in clusters and fine spectroscopy of Fe X-ray lines as a powerful diagnostics of both the turbulent plasma motions and the energetics of the non-thermal electron populations. The knowledge of the complex dynamical and feedback processes is necessary to understand the energy and matter balance as well as to constrain the role of the non-thermal components of clusters.

  9. Detection of Component Failures for Smart Structure Control Systems

    Science.gov (United States)

    Okubo, Hiroshi

    Uncertainties in the dynamics model of a smart structure are often of significance due to model errors caused by parameter identification errors and reduced-order modeling of the system. Design of a model-based Failure Detection and Isolation (FDI) system for smart structures, therefore, needs careful consideration regarding robustness with respect to such model uncertainties. In this paper, we proposes a new method of robust fault detection that is insensitive to the disturbances caused by unknown modeling errors while it is highly sensitive to the component failures. The capability of the robust detection algorithm is examined for the sensor failure of a flexible smart beam control system. It is shown by numerical simulations that the proposed method suppresses the disturbances due to model errors and markedly improves the detection performance.

  10. Structure Learning by Pruning in Independent Component Analysis

    DEFF Research Database (Denmark)

    Kjems, Andreas; Hansen, Lars Kai

    2006-01-01

    We discuss pruning as a means of structure learning in independent component analysis. Sparse models are attractive in both signal processing and in analysis of abstract data, they can assist model interpretation, generalizability and reduce computation. We derive the relevant saliency expression...... methods, for both small and large samples. The Bayesian information criterion (BIC) seems to outperform both AIC and test sets as tools for determining the optimal degree of sparsity....... and compare with magnitude based pruning and Bayesian sparsification. We show in simulations that pruning is able to identify underlying sparse structures without prior knowledge on the degree of sparsity. We find that for ICA magnitude based pruning is as efficient as saliency based methods and Bayesian...

  11. Magnons in one-dimensional k-component Fibonacci structures

    Science.gov (United States)

    Costa, C. H.; Vasconcelos, M. S.

    2014-05-01

    We have studied the magnon transmission through of one-dimensional magnonic k-component Fibonacci structures, where k different materials are arranged in accordance with the following substitution rule: Sn(k)=Sn-1(k)Sn-k(k) (n ≥k=0,1,2,…), where Sn(k) is the nth stage of the sequence. The calculations were carried out in exchange dominated regime within the framework of the Heisenberg model and taking into account the RPA approximation. We have considered multilayers composed of simple cubic spin-S Heisenberg ferromagnets, and, by using the powerful transfer-matrix method, the spin wave transmission is obtained. It is demonstrated that the transmission coefficient has a rich and interesting magnonic pass- and stop-bands structures, which depends on the frequency of magnons and the k values.

  12. Magnons in one-dimensional k-component Fibonacci structures

    Energy Technology Data Exchange (ETDEWEB)

    Costa, C. H., E-mail: carloshocosta@hotmail.com [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Vasconcelos, M. S. [Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil)

    2014-05-07

    We have studied the magnon transmission through of one-dimensional magnonic k-component Fibonacci structures, where k different materials are arranged in accordance with the following substitution rule: S{sub n}{sup (k)}=S{sub n−1}{sup (k)}S{sub n−k}{sup (k)} (n≥k=0,1,2,…), where S{sub n}{sup (k)} is the nth stage of the sequence. The calculations were carried out in exchange dominated regime within the framework of the Heisenberg model and taking into account the RPA approximation. We have considered multilayers composed of simple cubic spin-S Heisenberg ferromagnets, and, by using the powerful transfer-matrix method, the spin wave transmission is obtained. It is demonstrated that the transmission coefficient has a rich and interesting magnonic pass- and stop-bands structures, which depends on the frequency of magnons and the k values.

  13. Braze welding of cobalt with a silver–copper filler

    Directory of Open Access Journals (Sweden)

    Everett M. Criss

    2015-01-01

    Full Text Available A new method of joining cobalt by braze-welding it with a silver–copper filler was developed in order to better understand the residual stresses in beryllium–aluminum/silicon weldments which are problematic to investigate because of the high toxicity of Be. The base and filler metals of this new welding system were selected to replicate the physical properties, crystal structures, and chemical behavior of the Be–AlSi welds. Welding parameters of this surrogate Co–AgCu system were determined by experimentation combining 4-point bending tests and microscopy. Final welds are 5 pass manual TIG (tungsten inert gas, with He top gas and Ar back gas. Control of the welding process produces welds with full penetration melting of the cobalt base. Microscopy indicates that cracking is minimal, and not through thickness, whereas 4-point bending shows failure is not by base-filler delamination. These welds improve upon the original Be–AlSi welds, which do not possess full penetration, and have considerable porosity. We propose that utilization of our welding methods will increase the strength of the Be–AlSi weldments. The specialized welding techniques developed for this study may be applicable not only for the parent Be–AlSi welds, but to braze welds and welds utilizing brittle materials in general. This concept of surrogacy may prove useful in the study of many different types of exotic welds.

  14. Dependence of the mechanical properties of joints welded according to the parameters of the metal active gas (MAG welding regime

    Directory of Open Access Journals (Sweden)

    D. Dobrotă

    2015-10-01

    Full Text Available The main objective followed in the realization of welded structures is to obtain superior mechanical characteristics for these structures. The research aimed at setting ranges of values for the welding voltage (Uw, respectively for the welding current (Iw so as to obtain superior mechanical features for welded constructions. The research was carried out using E 36-4 steel as base material and SG2 wire as filler material, whereas the applied welding process was MAG. The optimization was done with the help of a number of 31 test bars considering various welding procedures for each test bar, and the experimental data were processed using the STATISTCA program.

  15. Nondestructive Ultrasonic Inspection of Friction Stir Welds

    Science.gov (United States)

    Tabatabaeipour, M.; Hettler, J.; Delrue, S.; Van Den Abeele, K.

    Friction Stir Welding (FSW) is a relatively new solid-state welding procedure developed at The Welding Institute (TWI-UK) and the technique is widely employed for welding aluminum alloys in various applications. In order to examine the quality of the welds and to detect a variety of welding flaws such as wormholes and root-flaws, it is required to develop a methodical inspection technique that can be used for the identification and localization of such defects. The most prevalent and risky defect in this type of welding is the barely visible root flaw with a length varying from 100-700 μm. Due to the extreme characteristics of the flaw, off-the-shelf ultrasonic weld inspection methods are not always able to readily detect this type of minute defect feature. Here, we propose a novel approach to characterize root flaws using an oblique incident ultrasonic C-scan backscattering analysis. The implementation consists of an immersion ultrasonic testing method in pulse echo (i.e. backscatter) mode with a 3.5 MHz transducer, and makes use of an empirical procedure to engender of a shear wave dominated excitation at the root surface, and to properly gate the received signal for root flaw examination. By scanning the surface above the welded component, a C-scan image displaying the backscatter response from the root surface of the nugget zone can be obtained which allows a simple interpretation of the root flaw status of the weld.

  16. Effect of pulsed current and post weld aging treatment on tensile properties of argon arc welded high strength aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Balasubramanian, V. [Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar, Tamil Nadu 608002 (India)], E-mail: visvabalu@yahoo.com; Ravisankar, V. [Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar, Tamil Nadu 608002 (India); Reddy, G. Madhusudhan [Metal Joining Section, Defence Metallurgical Research Laboratory, Kanchanbag (P.O.), Hyderabad 560058 (India)

    2007-06-25

    This paper reveals the effect of pulsed current and post weld aging treatment on tensile properties of argon arc welded AA7075 aluminium alloy. This alloy has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW) and (iv) pulsed current GMAW (PCGMAW) processes. As welded joint strength is much lower than the base metal strength and hence, a simple aging treatment has been given to improve the tensile strength of the joints. Current pulsing leads to relatively finer and more equi-axed grain structure in GTA and GMA welds. In contrast, conventional continuous current welding resulted in predominantly columnar grain structures. Post weld aging treatment is accompanied by an increase in tensile strength and tensile ductility.

  17. Residual strength evaluation of concrete structural components under fatigue loading

    Indian Academy of Sciences (India)

    A Rama Chandra Murthy; G S Palani; Nagesh R Iyer; Smitha Gopinath; B K Raghu Prasad

    2012-02-01

    This paper presents methodologies for residual strength evaluation of concrete structural components using linear elastic and nonlinear fracture mechanics principles. The effect of cohesive forces due to aggregate bridging has been represented mathematically by employing tension softening models. Various tension softening models such as linear, bilinear, trilinear, exponential and power curve have been described with appropriate expressions. These models have been validated by predicting the remaining life of concrete structural components and comparing with the corresponding experimental values available in the literature. It is observed that the predicted remaining life by using power model and modified bi-linear model is in good agreement with the corresponding experimental values. Residual strength has also been predicted using these tension softening models and observed that the predicted residual strength is in good agreement with the corresponding analytical values in the literature. In general, it is observed that the variation of predicted residual moment with the chosen tension softening model follows the similar trend as in the case of remaining life. Linear model predicts large residual moments followed by trilinear, bilinear and power models.

  18. Numerical evaluation of multipass welding temperature field in API 5L X80 steel welded joints

    Directory of Open Access Journals (Sweden)

    J Nóbrega

    2016-10-01

    Full Text Available Many are the metallurgical changes suffered by materials when subjected to welding thermal cycle, promoting a considerable influence on the welded structures thermo mechanical properties. In project phase, one alternative for evaluating the welding cycle variable, would be the employment of computational methods through simulation. So, this paper presents an evaluation of the temperature field in a multipass welding of API 5L X80 steel used for oil and gas transportation, using the ABAQUS ® software, based on Finite Elements Method (FEM. During the simulation complex phenomena are considerable including: Variation in physical and mechanical properties of materials as a function of temperature, welding speed and the different mechanisms of heat exchange with the environment (convection and radiation were used. These considerations allow a more robust mathematical modeling for the welding process. An analytical heat source proposed by Goldak, to model the heat input in order to characterize the multipass welding through the GTAW (Gas Tungsten Arc Welding process on root and the SMAW (Shielded Metal Arc Welding process for the filling passes were used. So, it was possible to evaluate the effect of each welding pass on the welded joint temperature field, through the temperature peaks and cooling rates values during the welding process.

  19. Welding in space and the construction of space vehicles by welding; Proceedings of the Conference, New Carrollton, MD, Sept. 24-26, 1991

    Science.gov (United States)

    The present conference discusses such topics in spacecraft welding as the NASA Long Duration Exposure Facility's evidence on material properties degradation, EVA/telerobotic construction techniques, welding of the superfluid helium on-orbit transfer flight demonstration tanks and hardware, electron-beam welding of aerospace vehicles, variable-polarity plasma arc keyhole welding of Al, aircraft experiments of low-gravity fusion welding, flash-butt welding of Al alloys, and a computer-aided handbook for space welding fabrication. Also discussed are the welded nozzle extension for Ariane launch vehicles, the existence of on-orbit cold-welding, structural materials performance in long-term space service, high-strength lightweight alloys, steels, and heat-resistant alloys for aerospace welded structures, the NASA-Goddard satellite repair program, and the uses of explosion welding and cutting in aerospace engineering.

  20. Mechanical Properties of Welded Deformed Reinforcing Steel Bars

    Directory of Open Access Journals (Sweden)

    Ghafur H. Ahmed

    2015-05-01

    Full Text Available Reinforcement strength, ductility and bendability properties are important components in design of reinforced concrete members, as the strength of any member comes mainly from reinforcement. Strain compatibility and plastic behaviors are mainly depending on reinforcement ductility. In construction practice, often welding of the bars is required. Welding of reinforcement is an instant solution in many cases, whereas welding is not a routine connection process. Welding will cause deficiencies in reinforcement bars, metallurgical changes and re-crystallization of microstructure of particles. Weld metal toughness is extremely sensitive to the welding heat input that decreases both of its strength and ductility. For determining the effects of welding in reinforcement properties, 48 specimens were tested with 5 different bar diameters, divided into six groups. Investigated parameters were: properties of un-welded bars; strength, ductility and density of weld metal; strength and ductility reduction due to heat input for bundled bars and transverse bars; welding effect on bars’ bending properties; behavior of different joint types; properties of three weld groove shapes also the locations and types of failures sections. Results show that, strength and elongation of the welded bars decreased by (10-40% and (30-60% respectively. Cold bending of welded bars and groove welds shall be prevented.

  1. Irradiation-induced structural changes in surveillance material of VVER 440-type weld metal

    Science.gov (United States)

    Grosse, M.; Denner, V.; Böhmert, J.; Mathon, M.-H.

    2000-01-01

    The irradiation-induced microstructural changes in surveillance materials of the VVER 440-type weld metal Sv-10KhMFT were investigated by small angle neutron scattering (SANS) and anomalous small angle X-ray scattering (SAXS). Due to the high fluence, a strong effect was found in the SANS experiment. No significant effect of the irradiation is detected by SAXS. The reason for this discrepancy is the different scattering contrast of irradiation-induced defects for neutrons and X-rays. An analysis of the SAXS shows that the scattering intensity is mainly caused by vanadium-containing (VC) precipitates and grain boundaries. Both types of scattering defects are hardly changed by irradiation. Neutron irradiation rather produces additional scattering defects of a few nanometers in size. Assuming these defects are clusters containing copper and other foreign atoms with a composition according to results of atom probe field ion microscopy (APFIM) investigations, both the high SANS and the low SAXS effect can be explained.

  2. Welded repair joints of boiler steels following operation in creep conditions exceeding the design time of operation

    Energy Technology Data Exchange (ETDEWEB)

    Dobrzanski, J.; Paszkowska, H.; Zielinski, A. [Institute for Ferrous Metallurgy, Gliwice (Poland)

    2010-07-01

    The assessment of suitability for further operation for materials and welded repair joints of thick-walled main steam pipeline components, made of steel 14MoV63, as well as steam superheater outlet headers made of steel X20CrMoV121 following operation in creep conditions in time periods considerably longer than the specified calculated time of operation. Strength properties, impact strength and transition temperature into brittle condition, as well as structure condition have been evaluated. On the basis of shortened creep tests, the residual life and disposable residual life of materials and welded joints have been determined. Material properties following operation and those of fabricated circumferential welded repair joints have been compared. The condition of examined components and suitability of the fabricated welded repair joints for further operation have been assessed. (orig.)

  3. Microstructural evolutions of friction stir welded F82H steel for fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Sang Hoon; Shim, Jae Won; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Tani Gawa, Hiro Yasu [JAEA, Rokasho (Japan); Fujii, Hideto Shi [Osaka Univ., Osaka (Japan); Kim Ura, Aki Hiko [Kyoto Univ., Kyoto (Japan)

    2012-10-15

    A blanket is the most important component functionalized as plasma confining, tritium breeding, heat exchanging, and irradiation shielding from severe thermo neutron loads in a fusion reactor. Its structure consists of first walls, side walls, a back board, and coolant channels mainly made of reduced activation ferritic/martensitic (RAFM) steel, which is the most promising candidate as a structural material for fusion reactors. To fabricate this blanket structure, some welding and joining methods have being carefully applied. However, when fusion welding, such as tungsten inert gas (TIG) welding, electron beam, and laser welding was performed between F82H and itself, the strength of welds significantly deteriorated due to the development of {delta} ferrite and precipitate dissolution. Post welding heat treatment (PWHT) should be followed to restore the initial microstructure. Nevertheless, microstructural discontinuity inevitably occurs between the weld metal, heat affected zone and base metal and this seriously degrades the entire structural stability under pulsed operation at high temperature in test blanket module (TBM). A phase transformation can also be an issue to be solved, which leads to a difficult replacement of the blanket module. Therefore, a reliable and field applicable joining technique should be developed not to accompany with PWHT after the joining process. Friction stir welding (FSW) is one of the solid state processes that does not create a molten zone at the joining area, so the degradation of the featured microstructures may be avoided or minimized. In this study, FSW was employed to join F82H steels to develop a potential joining technique for RAFM steel. The microstructural features on the joint region were investigated to evaluate the applicability of the FSW.

  4. THE INFLUENCE OF WELD SEAM SHAPE AND THE FATIGUE IN CASE OF THE FILLET WELDS

    Directory of Open Access Journals (Sweden)

    Claudiu BABIS

    2015-12-01

    Full Text Available The stress concentrators at MA/MB welding joint will increase by the cross sectional convexity of the fillet weld. Therefore, for variable loaded structures, based on a satisfactory fatigue life, concave fillet welds are preferred likely to ensure low stress concentrators at the MA/MB welding joint due to a smooth passing from the fillet weld to the basic material. The present paper aims is analyse the fatigue life duration raising durability curves based on experimental determination and using the Finite Element Analysis Method.

  5. Welding Curtains

    Science.gov (United States)

    1984-01-01

    Concept of transparent welding curtains made of heavy duty vinyl originated with David F. Wilson, President of Wilson Sales Company. In 1968, Wilson's curtains reduced glare of welding arc and blocked ultraviolet radiation. When later research uncovered blue light hazards, Wilson sought improvement of his products. He contracted Dr. Charles G. Miller and James B. Stephens, both of Jet Propulsion Laboratory (JPL), and they agreed to undertake development of a curtain capable of filtering out harmful irradiance, including ultraviolet and blue light and provide protection over a broad range of welding operation. Working on their own time, the JPL pair spent 3 years developing a patented formula that includes light filtering dyes and small particles of zinc oxide. The result was the Wilson Spectra Curtain.

  6. Analysis of the Mechanism of Longitudinal Bending Deformation Due to Welding in a Steel Plate by Using a Numerical Model

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Rae; Yan, Jieshen; Kim, Jae-Woong [Yeungnam Univ., Gyeongsan (Korea, Republic of); Song, Gyu Yeong [Gyeongbuk Hybrid Technology Institute, Yeongcheon (Korea, Republic of)

    2017-01-15

    Welding deformation is a permanent deformation that is caused in structures by welding heat. Welding distortion is the primary cause of reduced productivity, due to welded structural strength degradation, low dimensional accuracy, and appearance. As a result, research and numerous experiments are being carried out to control welding deformation. The aim of this study is to analyze the mechanism of longitudinal bending deformation due to welding. Welding experiments and numerical analyses were performed for this study. The welding experiments were performed on 4 mm and 8.5 mm thickness steel plates, and the numerical analysis was conducted on the welding deformation using the FE software MSC.marc.

  7. Ultrasonic welding for fast bonding of self-aligned structures in lab-on-a-chip systems

    DEFF Research Database (Denmark)

    Kistrup, Kasper; Poulsen, Carl Esben; Hansen, Mikkel Fougt

    2015-01-01

    Ultrasonic welding is a rapid, promising bonding method for the bonding of polymer chips; yet its use is still limited. We present two lab-on-a-chip applications where ultrasonic welding can be preferably applied: (1) Self-aligned gapless bonding of a two-part chip with a tolerance of 50 um; (2......) bonding of a large area shallow chamber (1.8 cm^2 X 150 um). Using injection moulding combined with ultrasonic welding we achieved a total production and bonding time of 60 s per chip, and a batch of chips could be produced within a day going from design to finished chips. We believe that the technical...

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

    Science.gov (United States)

    Ren, Weiju

    2014-11-11

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

  9. Patterns of residual stresses due to welding

    Science.gov (United States)

    Botros, B. M.

    1983-01-01

    Residual stresses caused by welding result from the nonuniform rate of cooling and the restrained thermal contraction or non-uniform plastic deformation. From the zone of extremely high temperature at the weld, heat flows into both the adjoining cool body and the surrounding atmosphere. The weld metal solidifies under very rapid cooling. The plasticity of the hot metal allows adjustment initially, but as the structure cools the rigidity of the surrounding cold metal inhibits further contraction. The zone is compressed and the weld is put under tensile stresses of high magnitude. The danger of cracking in these structural elements is great. Change in specific volume is caused by the change in temperature.

  10. High-Speed Friction-Stir Welding To Enable Aluminum Tailor-Welded Blanks

    Energy Technology Data Exchange (ETDEWEB)

    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 joining technologies for automotive aluminum alloys 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 has been traditionally 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 welded 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 utilizing 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.

  11. Microstructural investigation of the heat-affected zone of simulated welded joint of P91 steel

    Directory of Open Access Journals (Sweden)

    T. Vuherer

    2013-07-01

    Full Text Available In the process of testing real components exposed to elevated temperature, it is not possible to neglect cracks. The most significant cracks can be induced by welding, which is applied for joining of structural components. Pressure equipment in service is also exposed to high pressure and high stresses. Materials for their manufacturing are designed to resist high stress at elevated temperature, and to meet requirements regarding creep resistance. The objective of this study is to investigate microstructure of different regions of the heat affected zone in T/P91 steels by using thermal simulation instead of welding.

  12. Formability Analysis of Diode-Laser-Welded Tailored Blanks of Advanced High-Strength Steel Sheets

    Science.gov (United States)

    Panda, S. K.; Baltazar Hernandez, V. H.; Kuntz, M. L.; Zhou, Y.

    2009-08-01

    Currently, advances due to tailored blanking can be enhanced by the development of new grades of advanced high-strength steels (HSSs), for the further weight reduction and structural improvement of automotive components. In the present work, diode laser welds of three different grades of advanced high-strength dual-phase (DP) steel sheets (with tensile strengths of 980, 800, and 450 MPa) to high-strength low-alloy (HSLA) material were fabricated by applying the proper welding parameters. Formability in terms of Hecker’s limiting dome height (LDH), the strain distribution on the hemispherical dome surface, the weld line movement during deformation, and the load-bearing capacity during the stretch forming of these different laser-welded blanks were compared. Finite element (FE) analysis of the LDH tests of both the parent metals and laser-welded blanks was done using the commercially available software package LS-DYNA (Livermore Software Technology Corporation, Livermore, CA); the results compared well with the experimental data. It was also found that the LDH was not affected by the soft zone or weld zone properties; it decreased, however, with an increase in a nondimensional parameter, the “strength ratio” (SR). The weld line movement during stretch forming is an indication of nonuniform deformation resulting in a decrease in the LDH. In all the dissimilar weldments, fracture took place on the HSLA side, but the fracture location shifted to near the weld line (at the pole) in tailor-welded blanks (TWBs) of a higher strength ratio.

  13. Fatique Resistant, Energy Efficient Welding Program, Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Egland, Keith; Ludewig, Howard

    2006-05-25

    The program scope was to affect the heat input and the resultant weld bead geometry by synchronizing robotic weave cycles with desired pulsed waveform shapes to develop process parameters relationships and optimized pulsed gas metal arc welding processes for welding fatique-critical structures of steel, high strength steel, and aluminum. Quality would be addressed by developing intelligent methods of weld measurement that accurately predict weld bead geometry from process information. This program was severely underfunded, and eventually terminated. The scope was redirected to investigate tandem narrow groove welding of steel butt joints during the one year of partial funding. A torch was designed and configured to perform a design of experiments of steel butt weld joints that validated the feasability of the process. An initial cost model estimated a 60% cost savings over conventional groove welding by eliminating the joint preparation and reducing the weld volume needed.

  14. X-Aerogels for Structural Components and High Temperature Applications

    Science.gov (United States)

    2005-01-01

    Future NASA missions and space explorations rely on the use of materials that are strong ultra lightweight and able to withstand extreme temperatures. Aerogels are low density (0.01-0.5 g/cu cm) high porosity materials that contain a glass like structure formed through standard sol-gel chemistry. As a result of these structural properties, aerogels are excellent thermal insulators and are able to withstand temperatures in excess of l,000 C. The open structure of aerogels, however, renders these materials extremely fragile (fracturing at stress forces less than 0.5 N/sq cm). The goal of NASA Glenn Research Center is to increase the strength of these materials by templating polymers and metals onto the surface of an aerogel network facilitating the use of this material for practical applications such as structural components of space vehicles used in exploration. The work this past year focused on two areas; (1) the research and development of new templated aerogels materials and (2) process development for future manufacturing of structural components. Research and development occurred on the production and characterization of new templating materials onto the standard silica aerogel. Materials examined included polymers such as polyimides, fluorinated isocyanates and epoxies, and, metals such as silver, gold and platinum. The final properties indicated that the density of the material formed using an isocyanate is around 0.50 g/cc with a strength greater than that of steel and has low thermal conductivity. The process used to construct these materials is extremely time consuming and labor intensive. One aspect of the project involved investigating the feasibility of shortening the process time by preparing the aerogels in the templating solvent. Traditionally the polymerization used THF as the solvent and after several washes to remove any residual monomers and water, the solvent around the aerogels was changed to acetonitrile for the templating step. This process

  15. Local atomic structures of single-component metallic glasses

    Science.gov (United States)

    Trady, Salma; Hasnaoui, Abdellatif; Mazroui, M.'hammed; Saadouni, Khalid

    2016-10-01

    In this study we examine the structural properties of single-component metallic glasses of aluminum. We use a molecular dynamics simulation based on semi-empirical many-body potential, derived from the embedded atom method (EAM). The radial distribution function (RDF), common neighbors analysis method (CNA), coordination number analysis (CN) and Voronoi tessellation are used to characterize the metal's local structure during the heating and cooling (quenching). The simulation results reveal that the melting temperature depends on the heating rate. In addition, atomic visualization shows that the structure of aluminum after fast quenching is in a glassy state, confirmed quantitatively by the splitting of the second peak of the radial distribution function, and by the appearance of icosahedral clusters observed via CNA technique. On the other hand, the Wendt-Abraham parameters are calculated to determine the glass transition temperature (Tg), which depends strongly on the cooling rate; it increases while the cooling rate increases. On the basis of CN analysis and Voronoi tessellation, we demonstrate that the transition from the Al liquid to glassy state is mainly due to the formation of distorted and perfect icosahedral clusters.

  16. Fundamental Study of Micro-Defects in Electropolished EB-Welded and Hydroformed SRF Accelerating Structures

    Energy Technology Data Exchange (ETDEWEB)

    Sumption, Mike

    2014-08-29

    In the area of niobium elecropolishing fundamentals, we focused on understanding the influence of the surface topology, and geometry (with effects from gravity included. The formation of a viscous film is essential for the electropolishing process to take place. The exact nature and composition of the film formed on niobium is still unknown because of its solubility in the electrolyte. Extensive pitting may take place at surface where a stable film cannot form. This has to be taken into consideration while determining the speed with which the SRF cavities are rotated while EP. Hydrodynamic aspects must be taken into consideration while optimizing the polishing parameters. There is improvement in surface finish with polishing time. There is a huge change in surface quality when the EP time is increased from 2 hours to 4 hours but not much change takes place when the time is further increased to 6 hours. So keeping the economic points in view, about 100 um defect layer removal may be sufficient to get the desired performance. In the area of Electropolishing of untreated and treated niobium with Weld Joints we studied untreated and treated Nb, especially for the heat affected areas next to welded bumps, electropolished for different durations. The electropolishing of the untreated Nb caused the formation of pits on the surface at about 15 min but they disappeared when the electropolishing duration was more than 15 min. Electropolishing for 120 min smoothened the surface of untreated Nb by levelling the surface, but the severe formation of pits on the whole surface was found after 240 min. The treatment of Nb significantly changed the Nb surface morphology which was covered by grains of different size that looked light or dark in the optical microscope. The treated Nb was susceptible to pitting during the entire electropolishing starting from 15 min and the dark grains had more susceptibility to pitting than the light grains. In addition, electropolishing for 240 min

  17. The influence of electric ARC activation on the speed of heating and the structure of metal in welds

    National Research Council Canada - National Science Library

    Savytsky Oleksandr M; Savytsky Mychailo M; Bajić Darko R; Shkrabalyuk Yuriy M; Vuherer Tomaž

    2016-01-01

    .... It is confirmed that ATIG and AMIG methods, depending on metal thickness, single pass weldability and chemical composition of activating flux, enable the reduction of welding energy by 2-6 times when...

  18. Structure and Properties of Thick-Walled Joints of Alloy 1570s Prepared by Friction Stir Welding

    Science.gov (United States)

    Velichko, O. V.; Ivanov, S. Yu.; Karkhin, V. A.; Lopota, V. A.; Makhin, I. D.

    2016-09-01

    The microstructure and mechanical properties of thick-walled joints of Al - Mg - Sc alloy 1570S, prepared by friction stir welding are studied. Joint microstructural and mechanical inhomogeneity are revealed.

  19. 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.

  20. Friction Stir Welding in Wrought and Cast Aluminum Alloys: Weld Quality Evaluation and Effects of Processing Parameters on Microstructure and Mechanical Properties

    Science.gov (United States)

    Pan, Yi; Lados, Diana A.

    2017-01-01

    Friction stir welding (FSW) is a solid-state process widely used for joining similar and dissimilar materials for critical applications in the transportation sector. Understanding the effects of the process on microstructure and mechanical properties is critical in design for structural integrity. In this study, four aluminum alloy systems (wrought 6061-T651 and cast A356, 319, and A390) were processed in both as-fabricated and pre-weld heat-treated (T6) conditions using various processing parameters. The effects of processing and heat treatment on the resulting microstructures, macro-/micro-hardness, and tensile properties were systematically investigated and mechanistically correlated to changes in grain size, characteristic phases, and strengthening precipitates. Tensile tests were performed at room temperature both along and across the welding zones. A new method able to evaluate weld quality (using a weld quality index) was developed based on the stress concentration calculated under tensile loading. Optimum processing parameter domains that provide both defect-free welds and good mechanical properties were determined for each alloy and associated with the thermal history of the process. These results were further related to characteristic microstructural features, which can be used for component design and materials/process optimization.

  1. Friction Stir Welding in Wrought and Cast Aluminum Alloys: Weld Quality Evaluation and Effects of Processing Parameters on Microstructure and Mechanical Properties

    Science.gov (United States)

    Pan, Yi; Lados, Diana A.

    2017-04-01

    Friction stir welding (FSW) is a solid-state process widely used for joining similar and dissimilar materials for critical applications in the transportation sector. Understanding the effects of the process on microstructure and mechanical properties is critical in design for structural integrity. In this study, four aluminum alloy systems (wrought 6061-T651 and cast A356, 319, and A390) were processed in both as-fabricated and pre-weld heat-treated (T6) conditions using various processing parameters. The effects of processing and heat treatment on the resulting microstructures, macro-/micro-hardness, and tensile properties were systematically investigated and mechanistically correlated to changes in grain size, characteristic phases, and strengthening precipitates. Tensile tests were performed at room temperature both along and across the welding zones. A new method able to evaluate weld quality (using a weld quality index) was developed based on the stress concentration calculated under tensile loading. Optimum processing parameter domains that provide both defect-free welds and good mechanical properties were determined for each alloy and associated with the thermal history of the process. These results were further related to characteristic microstructural features, which can be used for component design and materials/process optimization.

  2. ARc Welding (Industrial Processing Series).

    Science.gov (United States)

    ARC WELDING , *BIBLIOGRAPHIES), (*ARC WELDS, BIBLIOGRAPHIES), ALUMINUM ALLOYS, TITANIUM ALLOYS, CHROMIUM ALLOYS, METAL PLATES, SPOT WELDING , STEEL...INERT GAS WELDING , MARAGING STEELS, MICROSTRUCTURE, HEAT RESISTANT ALLOYS, HEAT RESISTANT METALS, WELDABILITY, MECHANICAL PROPERTIES, MOLYBDENUM ALLOYS, NICKEL ALLOYS, RESISTANCE WELDING

  3. RECONSTRUCTION OF WELD POOL SURFACE BASED ON SHAPE FROM SHADING

    Institute of Scientific and Technical Information of China (English)

    DU Quanying; CHEN Shanben; LIN Tao

    2006-01-01

    A valid image-processing algorithm of weld pool surface reconstruction according to an input image of weld pool based on shape from shading (SFS) in computer vision is presented. The weld pool surface information is related to the backside weld width, which is crucial to the quality of weldjoint. The image of weld pool is recorded with an optical sensing method. Firstly, the reflectance map model, which specifies the imaging process, is estimated. Then, the algorithm of weld pool surface reconstruction based on SFS is implemented by iteration scheme and speeded by hierarchical structure. The results indicate the accuracy and effectiveness of the approach.

  4. On the Deflexion of Anisotropic Structural Composite Aerodynamic Components

    Directory of Open Access Journals (Sweden)

    J. Whitty

    2014-01-01

    Full Text Available This paper presents closed form solutions to the classical beam elasticity differential equation in order to effectively model the displacement of standard aerodynamic geometries used throughout a number of industries. The models assume that the components are constructed from in-plane generally anisotropic (though shown to be quasi-isotropic composite materials. Exact solutions for the displacement and strains for elliptical and FX66-S-196 and NACA 63-621 aerofoil approximations thin wall composite material shell structures, with and without a stiffening rib (shear-web, are presented for the first time. Each of the models developed is rigorously validated via numerical (Runge-Kutta solutions of an identical differential equation used to derive the analytical models presented. The resulting calculated displacement and material strain fields are shown to be in excellent agreement with simulations using the ANSYS and CATIA commercial finite element (FE codes as well as experimental data evident in the literature. One major implication of the theoretical treatment is that these solutions can now be used in design codes to limit the required displacement and strains in similar components used in the aerospace and most notably renewable energy sectors.

  5. A System for Complex Robotic Welding

    DEFF Research Database (Denmark)

    Madsen, Ole; Sørensen, Carsten Bro; Olsen, Birger

    2002-01-01

    This paper presents the architecture of a system for robotic welding of complex tasks. The system integrates off-line programming, control of redundant robots, collision-free motion planning and sensor-based control. An implementation for pipe structure welding made at Odense Steel Shipyard Ltd......., Denmark, demonstrates the system can be used for automatic welding of complex products in one-of-a-kind production....

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

    Directory of Open Access Journals (Sweden)

    Jingwei Yang

    2017-02-01

    Full Text Available 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.

  7. Through-Thickness Measurements of Residual Stresses in an Overlay Dissimilar Weld Pipe using Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Wan Chuck; EM, Vyacheslav; Lee, Ho Jin; Kim, Kang Soo; Kang, Mi Hyun; Joo, Jong Dae; Seong, Baek Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Byeon, Jin Gwi; Park, Kwang Soo [Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)

    2010-10-15

    The distribution of residual stresses in dissimilar material joints has been extensively studied because of the wide applications of the dissimilar welds in many inevitable complex design structures. Especially the cracking of dissimilar welding has been a long standing issue of importance in many components of the power generation industries such as nuclear power plant, boiling pressure system, and steam generators. In particular, several failure analysis and direct observations have shown that critical fractures have frequently occurred in one side of the dissimilar welded parts. For example, the heat-affected zone on the ferrite steel side is known to critical in many dissimilar welding pipes when ferrite (low carbon steel) and austenite (stainless) steels are joined. The main cause of the residual stresses can be attributed to the mismatch in the coefficient of thermal expansion between the dissimilar metals (ferrite and austenite). Additional cladding over circumferential welds is known to reinforce the mechanical property due to the beneficial compressive residual stress imposed on the weld and heat-affected zone. However, science-based quantitative measurement of the through thickness residual stress distribution is very limited in literature. The deep penetration capability of neutrons into most metallic materials makes neutron diffraction a powerful tool to investigate and map the residual stresses of materials throughout the thickness and across the weld. Furthermore, the unique volume averaged bulk characteristic of materials and mapping capability in three dimensions are suitable for the engineering purpose. Thus, the neutron-diffraction measurement method has been selected as the most useful method for the study of the residual stresses in various dissimilar metal welded structures. The purpose of this study is to measure the distribution of the residual stresses in a complex dissimilar joining with overlay in the weld pipe. Specifically, we measured

  8. Conceptual Design of Structural Components of a Dual Cooled Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung-Kyu; Lee, Young-Ho; Lee, Kang-Hee; Kim, Jae-Yong; Yoon, Kyung-Ho

    2008-01-15

    A dual cooled fuel, featured by an internal as well as an external coolant flow passage of a fuel rod, was suggested to enable a large-scaled power-uprate of PWR plant and launched as one of the National Nuclear R and D Projects in 2007. It is necessary to make the dual cooled fuel be compatible with an OPR-1000 system to maximize the economy. Also, the structural components of the dual cooled fuel should be designed to realize their features. To this end, a conceptual design of a spacer grid, outer and center guide tubes, and top and bottom end pieces has been carried out in the project 'Development of Design Technology for Dual Cooled Fuel Structure'. For the spacer grids, it is suggested that springs and dimples are located at or near the cross points of the straps due to a considerably narrowed rod-to-rod gap. Candidate shapes of the grids were also developed and applied for domestic patents. For the outer and center guide tubes, a dual tube like a fuel rod was suggested to make the subchannel areas around the guide tubes be similar to those around the fuel rods of enlarged diameter. It was applied for the domestic patent as well. For the top and bottom end pieces, the shape and pattern have been changed from the conventional ones reflecting the fuel rods' changes. Technical issues and method of resolution for each components were listed up for a basic design works in the following years.

  9. 基于结构光的机器人弧焊混合视觉伺服控制%Hybrid Visual Servoing Control for Robotic Arc Welding Based on Structured Light Vision

    Institute of Scientific and Technical Information of China (English)

    徐德; 王麟琨; 涂志国; 谭民

    2005-01-01

    A novel hybrid visual servoing control method based on structured light vision is proposed for robotic arc welding with a general six degrees of freedom robot. It consists of a position control inner-loop in Cartesian space and two outer-loops. One is position-based visual control in Cartesian space for moving in the direction of weld seam, i.e., weld seam tracking, another is imagebased visual control in image space for adjustment to eliminate the errors in the process of tracking.A new Jacobian matrix from image space of the feature point on structured light stripe to Cartesian space is provided for differential movement of the end-effector. The control system model is simplified and its stability is discussed. An experiment of arc welding protected by gas CO2 for verifying is well conducted.

  10. Effects of heat input on the microstructure and toughness of the 8 MnMoNi 5 5 shape-welded nuclear steel

    Science.gov (United States)

    Million, Karl; Datta, Ratan; Zimmermann, Horst

    2005-04-01

    A weld metal well proven in the German nuclear industry served as the basis for the certification of a shape-welded steel to be used as base material for manufacture of nuclear primary components. The outstanding properties of this steel are attributed to the extremely fine-grained and stable primary microstructure. Subsequent reheating cycles caused by neighbouring weld beads do neither lead to coarsened brittle structures in the heat-affected zone nor to increase in hardness and decrease in toughness, as is the case with wrought steel materials. One of the largest new reactor vessel design amongst today's advanced reactor projects is considered to be particularly suitable for the use of shape-welded parts in place of forgings. In addition the need for design and development of new shape-welded steel grades for other new generation reactor projects is emphasized, in which the experience gained with this research could make a contribution.

  11. Component

    Directory of Open Access Journals (Sweden)

    Tibor Tot

    2011-01-01

    Full Text Available A unique case of metaplastic breast carcinoma with an epithelial component showing tumoral necrosis and neuroectodermal stromal component is described. The tumor grew rapidly and measured 9 cm at the time of diagnosis. No lymph node metastases were present. The disease progressed rapidly and the patient died two years after the diagnosis from a hemorrhage caused by brain metastases. The morphology and phenotype of the tumor are described in detail and the differential diagnostic options are discussed.

  12. Texture evolution and deformation mechanism in friction stir welding of 2219Al

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S., E-mail: sjchen@bjut.edu.cn; Jiang, X.

    2014-08-26

    Texture evolution and deformation mechanism in the weld zones of friction stir welded 2219Al alloy have been investigated by the electron backscatter diffraction method. The weld zones are characterized by elongated structure in the base material, the heat affected zone and the thermo-mechanically affected zone and rotated elongated structure in the nugget zone. Four main texture components, Cube {001}〈100〉, Goss {011}〈100〉, Brass {011}〈211〉 and Cube ND {001}〈110〉 close to Cube component, were developed in the TMAZ, the HAZ and the nugget zone; S {123}〈634〉 was developed in the nugget zone only with Cube component orientated as their next neighbour and the nugget zone is dominated by Cube, Goss and S texture components. Cube grains in the nugget zone were formed by strain induced boundary migration mechanism (SIBM). Both variants of the texture components have two slip systems with the highest Schmid factors 0.42. Both Cube and Goss components slip on two planes (111) and (1{sup ¯}11). Relatively larger fractions of Σ3, Σ9 twin boundaries and Σ11, Σ29a boundaries have been found in the centre of the weld zone. Materials in the TMAZ have undergone dynamic recovery; geometric dynamic recrystallization (GDRX) occurred in the nugget zone.

  13. Assessment of delta ferrite in multipass TIG welds of 40 mm thick SS 316L: A comparative study of ferrite number (FN) prediction and measurements

    Science.gov (United States)

    Buddu, Ramesh Kumar; Raole, P. M.; Sarkar, B.

    2017-04-01

    Austenitic stainless steels are widely used in the fabrication of fusion reactor major systems like vacuum vessel, divertor, cryostat and other structural components development. Multipass welding is used for the development of thick plates for the structural components fabrication. Due to the repeated weld thermal cycles, the microstructure adversely alters owing to the presence of complex phases like austenite, ferrite and delta ferrite and subsequently influences the mechanical properties like tensile and impact toughness of joints. The present paper reports the detail analysis of delta ferrite phase in welded region of 40 mm thick SS316L plates welded by special design multipass narrow groove TIG welding process under three different heat input conditions. The correlation of delta ferrite microstructure of different type structures acicular and vermicular is observed. The chemical composition of weld samples was used to predict the Ferrite Number (FN), which is representative form of delta ferrite in welds, with Schaeffler’s, WRC-1992 diagram and DeLong techniques by calculating the Creq and Nieq ratios and compared with experimental data of FN from Feritescope measurements. The low heat input conditions (1.67 kJ/mm) have produced higher FN (7.28), medium heat input (1.72 kJ/mm) shown FN (7.04) where as high heat input (1.87 kJ/mm) conditions has shown FN (6.68) decreasing trend and FN data is compared with the prediction methods.

  14. Effect of welding parameters on the mechanical properties of GMA-welded HY-80 steels

    Energy Technology Data Exchange (ETDEWEB)

    Durmusoglu, Senol [Gazi Univ., Ankara (Turkey); Tuerker, Mehmet [RWTH Aachen Univ. (Germany). ISF - Welding and Joining Inst.; Tosun, Murat [Gedik Univ., Istanbul (Turkey)

    2015-07-01

    In this publication, investigations of HY-80 steels joined by gas metal arc welding by using different welding parameters are described. Different samples obtained from the welded joints were subjected to mechanical testing by means of tensile, hardness and impact toughness tests. The tensile test results showed that the strength of weld metal and heat affected zone were higher than of base metal. Similar Charpy impact toughness test results were obtained for weld metal and heat affected zone. Weld metal hardness was almost similar to the base metal hardness, nevertheless, the heat affected zone indicated higher values. The base metal has ferritic-perlitic structure with fine grains. Martensite needles and bainite are seen in the heat affected zone. Weld metal has martensite needles, partial bainite and residual austenite.

  15. Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and -196 °C

    Science.gov (United States)

    Lei, Xuefeng; Deng, Ying; Yin, Zhimin; Xu, Guofu

    2014-06-01

    2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (-196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at -196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled θ (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

  16. 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

    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...... 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...... to plastic flow localization was observed, with a substantial influence on the specimen elongation at the onset of localization and thereby failure. This influence is, however, shown to be strongly affected by the applied boundary conditions. Specimens cut from the welded plate, transverse to the weld line...

  17. Laser Welding in Electronic Packaging

    Science.gov (United States)

    2000-01-01

    The laser has proven its worth in numerous high reliability electronic packaging applications ranging from medical to missile electronics. In particular, the pulsed YAG laser is an extremely flexible and versatile too] capable of hermetically sealing microelectronics packages containing sensitive components without damaging them. This paper presents an overview of details that must be considered for successful use of laser welding when addressing electronic package sealing. These include; metallurgical considerations such as alloy and plating selection, weld joint configuration, design of optics, use of protective gases and control of thermal distortions. The primary limitations on use of laser welding electronic for packaging applications are economic ones. The laser itself is a relatively costly device when compared to competing welding equipment. Further, the cost of consumables and repairs can be significant. These facts have relegated laser welding to use only where it presents a distinct quality or reliability advantages over other techniques of electronic package sealing. Because of the unique noncontact and low heat inputs characteristics of laser welding, it is an ideal candidate for sealing electronic packages containing MEMS devices (microelectromechanical systems). This paper addresses how the unique advantages of the pulsed YAG laser can be used to simplify MEMS packaging and deliver a product of improved quality.

  18. Recognizing genes and other components of genomic structure

    Energy Technology Data Exchange (ETDEWEB)

    Burks, C. (Los Alamos National Lab., NM (USA)); Myers, E. (Arizona Univ., Tucson, AZ (USA). Dept. of Computer Science); Stormo, G.D. (Colorado Univ., Boulder, CO (USA). Dept. of Molecular, Cellular and Developmental Biology)

    1991-01-01

    The Aspen Center for Physics (ACP) sponsored a three-week workshop, with 26 scientists participating, from 28 May to 15 June, 1990. The workshop, entitled Recognizing Genes and Other Components of Genomic Structure, focussed on discussion of current needs and future strategies for developing the ability to identify and predict the presence of complex functional units on sequenced, but otherwise uncharacterized, genomic DNA. We addressed the need for computationally-based, automatic tools for synthesizing available data about individual consensus sequences and local compositional patterns into the composite objects (e.g., genes) that are -- as composite entities -- the true object of interest when scanning DNA sequences. The workshop was structured to promote sustained informal contact and exchange of expertise between molecular biologists, computer scientists, and mathematicians. No participant stayed for less than one week, and most attended for two or three weeks. Computers, software, and databases were available for use as electronic blackboards'' and as the basis for collaborative exploration of ideas being discussed and developed at the workshop. 23 refs., 2 tabs.

  19. 29 CFR 1915.54 - Welding, cutting and heating of hollow metal containers and structures not covered by § 1915.12.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Welding, cutting and heating of hollow metal containers and... STANDARDS FOR SHIPYARD EMPLOYMENT Welding, Cutting and Heating § 1915.54 Welding, cutting and heating of... which have contained flammable substances shall, before welding, cutting, or heating is undertaken...

  20. The fatigue strength of base material and butt welds made of S690 and S1100

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Kolstein, M.H.; Romeijn, A.; Bijlaard, F.S.K.

    2007-01-01

    Modern steel manufacturing techniques make it possible to produce steel with nominal strengths up to 1100 MPa (very high strength steels, VHSS). For the design of cyclic loaded slender VHSS structures, the fatigue strength of both base material and welded components should be known. In a VHSS

  1. The fatigue strength of base material and butt welds made of S690 and S1100

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Kolstein, M.H.; Romeijn, A.; Bijlaard, F.S.K.

    2007-01-01

    Modern steel manufacturing techniques make it possible to produce steel with nominal strengths up to 1100 MPa (very high strength steels, VHSS). For the design of cyclic loaded slender VHSS structures, the fatigue strength of both base material and welded components should be known. In a VHSS fatigu

  2. A Comparative Study on the Laser Welding of Ti6Al4V Alloy Sheets in Flat and Horizontal Positions

    Directory of Open Access Journals (Sweden)

    Baohua Chang

    2017-04-01

    Full Text Available Laser welding has been increasingly utilized to manufacture a variety of components thanks to its high quality and speed. For components with complex shapes, the welding position needs be continuously adjusted during laser welding, which makes it necessary to know the effects of the welding position on the quality of the laser welds. In this paper, the weld quality under two (flat and horizontal welding positions were studied comparatively in the laser welding of Ti6Al4V titanium alloy, in terms of weld profiles, process porosity, and static tensile strengths. Results show that the flat welding position led to better weld profiles, less process porosity than that of the horizontal welding position, which resulted from the different actions of gravity on the molten weld metals and the different escape routes for pores under different welding positions. Although undercuts showed no association with the fracture positions and tensile strengths of the welds, too much porosity in horizontal laser welds led to significant decreases in the strengths and specific elongations of welds. Higher laser powers and travel speeds were recommended, for both flat and horizontal welding positions, to reduce weld porosity and improve mechanical properties.

  3. An Evaluation on the Residual Stresses Induced by EFR Welding of CEDM Nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Ho; Park, Gi Yeol; Kim, Tae Ryong [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2015-10-15

    In this paper, carried out the welding analysis to use the SYSWELD as welding interpretation code based on the reactor upper head nozzle. In this paper, evaluated the residual stress in CEDM nozzle by EFR through the SYSWELD which is the welding interpretation code. The conclusion are same as below. 1) When comparing with Hoop Stress and Axial Stress by J-Groove and EFR, after welding residual stress by EFR is lower than after J-Groove. 2) After EFR, it was confirmed that the tensile stress is reduced after increasing over the point3. The PWSCC of Dissimilar Metal Zone of reactor can degrade the integrity of the main device in nuclear power plant, and according to the power plant stopped for inspection, it can cause an enormous amount of lost sales when the crack is occurred. Various methods have been developed to reduce residual stress to prevent the PWSCC like Weld Overlay (WOL), Mechanical Stress Improvement Process (Msp), Laser Peening, Inlay Weld, etc. Among them, Wol is the most commonly used welding method in nuclear power plant. When performing a Wol, structure rigidity will be increase, and residual stress of welding zone will be changed into compressive stress from the tensile stress. This has the advantage that improved resistance to PWSCC. The most commonly used material in nuclear power plant is Inconel 600. Inconel 600 consist of a Ni-Cr-Fe and it has 14-17% of Cr content, 10% of Fe content and susceptible to PWSCC. The more Cr content is more stronger against PWSCC. Inconel 690 which has 2 times more Cr content than Inconel 600 has very strong resistance to PWSCC than Inconel 600. Embedded Flaw Repair (EFR) has been developed in Westinghouse by 1994. The welding metal with high corrosion resistance is embedded on the surface of component, and could protect cracking part from the PWSCC. It is permanent repair method that isolates the flaw from the environment, eliminating further crack propagation due to PWSCC. EFR method is that at least three layers

  4. Nanostructurization and thermal properties of polyethylenes' welds

    Science.gov (United States)

    Galchun, Anatoliy; Korab, Nikolay; Kondratenko, Volodymyr; Demchenko, Valeriy; Shadrin, Andriy; Anistratenko, Vitaliy; Iurzhenko, Maksym

    2015-03-01

    As it is known, polyethylene (PE) is one of the common materials in the modern world, and PE products take the major share on industrial and trade markets. For example, various types of technical PE like PE-63, PE-80, and PE-100 have wide industrial applications, i.e., in construction, for pipeline systems etc. A rapid development of plastics industry outstrips detailed investigation of welding processes and welds' formation mechanism, so they remain unexplored. There is still no final answer to the question how weld's microstructure forms. Such conditions limit our way to the understanding of the problem and, respectively, prevent scientific approaches to the welding of more complicated (from chemical point of view) types of polymers than PE. Taking into account state-of-the-art, the article presents results of complex studies of PE weld, its structure, thermophysical and operational characteristics, analysis of these results, and basing on that some hypotheses of welded joint and weld structure formation. It is shown that welding of dissimilar types of polyethylene, like PE-80 and PE-100, leads to the formation of better-ordered crystallites, restructuring the crystalline phase, and amorphous areas with internal stresses in the welding zone.

  5. Improving Fatigue Performance of AHSS Welds

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [ORNL; Yu, Xinghua [ORNL; ERDMAN III, DONALD L [ORNL; Wang, Yanli [ORNL; Kelly, Steve [ArcelorMittal USA; Hou, Wenkao [ArcelorMittal USA; Yan, Benda [ArcelorMittal USA; Wang, Zhifeng [Colorado School of Mines, Golden; Yu, Zhenzhen [Colorado School of Mines, Golden; Liu, Stephen [Colorado School of Mines, Golden

    2015-03-01

    Reported herein is technical progress on a U.S. Department of Energy CRADA project with industry cost-share aimed at developing the technical basis and demonstrate the viability of innovative in-situ weld residual stresses mitigation technology that can substantially improve the weld fatigue performance and durability of auto-body structures. The developed technology would be costeffective and practical in high-volume vehicle production environment. Enhancing weld fatigue performance would address a critical technology gap that impedes the widespread use of advanced high-strength steels (AHSS) and other lightweight materials for auto body structure light-weighting. This means that the automotive industry can take full advantage of the AHSS in strength, durability and crashworthiness without the concern of the relatively weak weld fatigue performance. The project comprises both technological innovations in weld residual stress mitigation and due-diligence residual stress measurement and fatigue performance evaluation. Two approaches were investigated. The first one was the use of low temperature phase transformation (LTPT) weld filler wire, and the second focused on novel thermo-mechanical stress management technique. Both technical approaches have resulted in considerable improvement in fatigue lives of welded joints made of high-strength steels. Synchrotron diffraction measurement confirmed the reduction of high tensile weld residual stresses by the two weld residual stress mitigation techniques.

  6. A new method for welding aluminum alloy LY12CZ sheet with high strength

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    From the viewpoint of welding mechanics, a new welding technology-trailing peening was applied firstly to weld aluminum alloy LY12CZ sheet with high susceptibility to hot cracking. Trailing peening can exert a transverse extrusion strain on the metal in brittle temperature region (BTR) which can compensate for the tensioning strain during the cooling procedure post welding. So, welding hot cracking of LY12CZ sheet can be controlled effectively on the special jig for hot cracking experiment, and the phenomenon of hot cracking can't be found in specimens with large dimensions finally. At the same time, welding with trailing peening can decrease welding distortion caused by longitudinal and transverse shrinkage of weld obviously. Due to strengthening the poor position-weld toe during the process of welding, the residual stress distribution of welded joint is more reasonable. Contrast with conventional welding, mechanical properties such as tensile strength, prolongation ratio and cold-bending angle of welded joint with trailing peening can be improved obviously, and rupture position of welded joint transits from weld toe at conventional welding to weld metal at trailing peening. So, welding with trailing peening can be regarded as a dynamic welding method with low stress, little distortion and hot cracking-free really. As far as theoretical analysis is concerned, the technology of trailing peening can be used to weld the materials with high susceptibility to hot cracking such as LY12CZ and LD10, and solve the welding distortion of thin plate-shell welded structures which contain closed welds such as flange. In addition, the technology of trailing peening has many advantages: simple device, high efficiency, low cost and flexible application which make the welding method have widely applied foreground in the field of aeronautics and aerospace.

  7. The reliability of untempered end plug welds on HT9-clad IFR fuel elements

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, D C; Porter, D L

    1987-02-01

    Welding generally leaves residual stresses in transformed weld zones, which can initiate cracks from flaws already present in the weld zones. When HT9 cools from welding temperatures, a martensite phase forms in the weld fusion zone and heat-affected zone. Because this martensite phase is hard and brittle, it is particularly susceptible to cracking aggravated by residual stresses. This causes concern over the use of untempered welds on HT9-clad fuel elements. To determine if residual stresses present in end-plug weld zones would affect fuel pin performance, HT9 capsules with prototypic TIG- and CD-welded end plugs (in the tempered and as-welded conditions) were pressurized to failure at room temperature, 550{sup 0}C, and 600{sup 0}C. None of the capsules failed in a weld zone. To determine the effects of reactor operating temperatures on untempered welds, prototypic TIG welds were tempered at reactor bulk sodium temperature and an expected sodium outlet temperature for various lengths of time. Subsequent tensile and burst tests of these specimens proved that any embrittling effects that may have been induced in these welds were of no consequence. Hardness tests on longitudinal sections of welds indicated the amount of tempering a weld will receive inreactor after relatively short lengths of time. The pressure burst tests proved that untemperted welds on HT9-clad fuel elements are as reliable as tempered welds; any residual stresses in untempered weld zones were of no consequence. The tempering test showed that welds used in the as-welded condition will sufficiently temper in 7 days at 550{sup 0}C, but will not, sufficiently temper in 7 days at bulk sodium temperature. A comparison of the structure of laser welds to those of CD and TIG welds indicated that untempered laser welds will perform and temper in a manner similar to the TIG welds tested in this effort.

  8. 29 CFR 1910.254 - Arc welding and cutting.

    Science.gov (United States)

    2010-07-01

    ..., hoists, and elevators shall not be used to carry welding current. (iv) Where a structure, conveyor, or... following limits shall not be exceeded: (i) Alternating-current machines (A) Manual arc welding and cutting...-current machines (A) Manual arc welding and cutting—100 volts. (B) Automatic (machine or mechanized) arc...

  9. International Round-Robin Test Results for Dissimilar Metal Weld (DMW)

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sung Sik; Kim, Kyung Jo; Jung, Hae Dong [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2009-10-15

    In nuclear power plant, there are many joints to connect pipes, nozzles and structural components. Most of them are welding joint, and it may be a weak point for leakage and cracks. Some cracks were found in dissimilar metal welds (DMW), which are connected with major components of nuclear power plants. Usually, the dissimilar metal welds are consisted of Alloy 600, carbon steel and stainless steel. Since 2000s, most of the cracks are found in welds, especially dissimilar metal welds such as pressurizer safety relief nozzle, reactor head penetration, reactor bottom mounted instrumentation (BMI), and reactor nozzles. Since the cracks are revealed as a primary water stress corrosion cracking (PWSCC), the reliability of non destructive evaluation (NDE) technique becomes more important. To cope with the NDE reliability, PINC (program for inspection of nickel alloy components) international cooperation was organized. The aim of the project was 1) to fabricate representative NDE mock-ups with flaws to simulate PWSCCs, 2) to identify and quantitatively assess NDE methods for accurately detecting, sizing and characterizing PWSCCs, 3) to document the range of locations and morphologies of PWSCCs and 4) to incorporate results with other results of ongoing PWSCC research programs, as appropriate. In this study, as part of the PINC project, international RRT (round robin test) results for DMW will be introduced.

  10. Application of the results of pipe stress analyses into fracture mechanics defect analyses for welds of nuclear piping components; Uebernahme der Ergebnisse von Rohrsystemanalysen (Spannungsanalysen) fuer bruchmechanische Fehlerbewertungen fuer Schweissnaehte an Rohrleitungsbauteilen in kerntechnischen Anlagen

    Energy Technology Data Exchange (ETDEWEB)

    Dittmar, S.; Neubrech, G.E.; Wernicke, R. [TUeV Nord SysTec GmbH und Co.KG (Germany); Rieck, D. [IGN Ingenieurgesellschaft Nord mbH und Co.KG (Germany)

    2008-07-01

    For the fracture mechanical assessment of postulated or detected crack-like defects in welds of piping systems it is necessary to know the stresses in the un-cracked component normal to the crack plane. Results of piping stress analyses may be used if these are evaluated for the locations of the welds in the piping system. Using stress enhancing factors (stress indices, stress factors) the needed stress components are calculated from the component specific sectional loads (forces and moments). For this procedure the tabulated stress enhancing factors, given in the standards (ASME Code, German KTA regulations) for determination and limitation of the effective stresses, are not always and immediately adequate for the calculation of the stress component normal to the crack plane. The contribution shows fundamental possibilities and validity limits for adoption of the results of piping system analyses for the fracture mechanical evaluation of axial and circumferential defects in welded joints, with special emphasis on typical piping system components (straight pipe, elbow, pipe fitting, T-joint). The lecture is supposed to contribute to the standardization of a code compliant and task-related use of the piping system analysis results for fracture mechanical failure assessment. [German] Fuer die bruchmechanische Bewertung von postulierten oder bei der wiederkehrenden zerstoerungsfreien Pruefung detektierten rissartigen Fehlern in Schweissnaehten von Rohrsystemen werden die Spannungen in der ungerissenen Bauteilwand senkrecht zur Rissebene benoetigt. Hierfuer koennen die Ergebnisse von Rohrsystemanalysen (Spannungsanalysen) genutzt werden, wenn sie fuer die Orte der Schweissnaehte im Rohrsystem ausgewertet werden. Mit Hilfe von Spannungserhoehungsfaktoren (Spannungsindizes, Spannungsbeiwerten) werden aus den komponentenweise berechneten Schnittlasten (Kraefte und Momente) die benoetigten Spannungskomponenten berechnet. Dabei sind jedoch die in den Regelwerken (ASME

  11. Structures, Components and Functions of Secretory Tissues in Houttuynia cordata

    Institute of Scientific and Technical Information of China (English)

    Xi-Lu Ni; Li Peng; Wen-Zhe Liu

    2007-01-01

    Houttuynia cordata Thunb., traditionally used as a therapeutic plant in folk medicine, has shown antioxidant and anticancer activities.The species, as a core component of paleoherbs, is normally characterized based on the presence of different types of secretory tissue: oil cells, three types of secretory cells and glandular hairs.The aim of this work was to study the structural, componential, and the functional characteristics of the secretory tissues in both the floral and vegetative parts.The results indicate that oll cells and secretory cells are distributed in all organs of the plant, while glandular hairs are situated on the aerial stems and leaves.Both oil cells and glandular hairs initiate from the protoderm, but their developmental processes are different.Although three types of secretory cells initiate from different primary meristems, the developmental pattems of different secretory cells are the same.Also, although the origins of secretory cells are different from oil cells, their early developmental processes are the same.Histochemical results show that oil cells, secretory cells and glandular hairs produce flavonoids, phenolic compounds, tannins, lipids, aldehyde and ketone-compounds.In addition, there are terpenoids and pectic-like substances in oil cells, alkaloids in secretory cells of aerial stems, and terpenoids and alkaloids in glandular hairs.These compounds play very important roles in protecting plants from being eaten by herbivores (herbivory) and infected by microbial pathogens.The oil cell and secretory cell, as unicellular secretory tissues, are intermediates between the primitive surface glandular and secretory cavity and canal during the evolution of secretory structures.

  12. Structural Stability Analysis of Weld Stainless Steel Subway Car Body%不锈钢点焊地铁车车体结构稳定性分析

    Institute of Scientific and Technical Information of China (English)

    刘婷婷; 刘海涛; 陈秉智

    2013-01-01

    以不锈钢点焊地铁车为载体,应用HYPERMESH软件和有限元分析软件ANSYS进行有限元建模和稳定性计算,得到不锈钢点焊车发生屈曲的部位以及屈曲因子λ.发现该车局部结构失稳现象严重,不能满足设计要求,并提出改进意见,为不锈钢点焊车的在生产和研发提供必要的理论依据.%Using weld stainless steel subway cars as a carrier, the softwares of Hypermesh and Ansys are em-ployed to construct the model and simulate its stability, and the bulking part and factor A of the weld car are obtained. It is found that the instability of local structural is serious, which cannot meet the design require-ments. Thus the improvement opinion is proposed, which can provide the necessary theoretical basis for the re-search and development of the weld cars.

  13. 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...

  14. 基于ANSYS的一种螺旋焊管机座的强度分析%ANSYS-based Strength Analysis of Spiral Welded Pipe Bender Seat

    Institute of Scientific and Technical Information of China (English)

    虞兵; 陈靖芯; 马祥; 秦永法; 竺志大

    2013-01-01

    This paper simply introduces the components of the spiral welded pipe bender ,puts forward a way of structural strength analysis for spiral welded pipe bender seat ,and uses this method to analyse the strength of one spiral welded pipe bender seat .%  简单介绍了螺旋焊管机的组成,提出了一种螺旋焊管机座结构强度分析的计算方法,并且采用该方法对某款螺旋焊管机座进行了结构强度分析。

  15. Development of thick wall welding and cutting tools for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Nakahira, Masataka; Takahashi, Hiroyuki; Akou, Kentaro; Koizumi, Koichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-04-01

    The Vacuum Vessel, which is a core component of International Thermonuclear Experimental Reactor (ITER), is required to be exchanged remotely in a case of accident such as superconducting coil failure. The in-vessel components such as blanket and divertor are planned to be exchanged or fixed. In these exchange or maintenance operations, the thick wall welding and cutting are inevitable and remote handling tools are necessary. The thick wall welding and cutting tools for blanket are under developing in the ITER R and D program. The design requirement is to weld or cut the stainless steel of 70 mm thickness in the narrow space. Tungsten inert gas (TIG) arc welding, plasma cutting and iodine laser welding/cutting are selected as primary option. Element welding and cutting tests, design of small tools to satisfy space requirement, test fabrication and performance tests were performed. This paper reports the tool design and overview of welding and cutting tests. (author)

  16. Resistance Welding of Thermoplastic Composites: Process and Performance

    OpenAIRE

    Shi, H.

    2014-01-01

    Compared to thermoset composites, thermoplastic composites are drawing more and more attention by aircraft industries not only due to their excellent material properties but also due to their potentials to reduce cycle time and structure cost by using low-cost manufacturing technologies such as welding. Resistance welding has been regarded as one of the most promising welding techniques owing to the low energy consumption, simplicity of welding operation and capability for scaling up. Previou...

  17. Vortex Structures in a Rotating BEC Dark Matter Component

    Directory of Open Access Journals (Sweden)

    N. T. Zinner

    2011-01-01

    Full Text Available We study the effects of a dark matter component that consists of bosonic particles with ultralight masses in the condensed state. We compare previous studies for both noninteracting condensates and with repulsive two-body terms and show consistency between the proposals. Furthermore, we explore the effects of rotation on a superfluid dark matter condensate, assuming that a vortex lattice is formed as seen in ultracold atomic gas experiments. The influence of such a lattice in virialization of gravitationally bound structures and on galactic rotation velocity curves is explored. With fine-tuning of the bosonic particle mass and the two-body repulsive interaction strength, we find that one can have substructure on rotation curves that resembles some observations in spiral galaxies. This occurs when the dark matter halo has an array of hollow cylinders. This can cause oscillatory behavior in the galactic rotation curves in similar fashion to the well-known effect of the spiral arms. We also consider how future experiments and numerical simulations with ultracold atomic gases could tell us more about such exotic dark matter proposals.

  18. Study of Welding Distortion and Residual Stress Considering Nonlinear Yield Stress Curves and Multi-constraint Equations

    Science.gov (United States)

    Rong, Youmin; Zhang, Guojun; Huang, Yu

    2016-10-01

    Inherent strain analysis has been successfully applied to predict welding deformations of large-scale structural components, while thermal-elastic-plastic finite element method is rarely used for its disadvantages of long calculation period and large storage space. In this paper, a hybrid model considering nonlinear yield stress curves and multi-constraint equations to thermal-elastic-plastic analysis is further proposed to predict welding distortions and residual stresses of large-scale structures. For welding T-joint structural steel S355JR by metal active gas welding, the published experiment results of temperature and displacement fields are applied to illustrate the credibility of the proposed integration model. By comparing numerical results of four different cases with the experiment results, it is verified that prediction precision of welding deformations and residual stresses is apparently improved considering the power-law hardening model, and computational time is also obviously shortened about 30.14% using multi-constraint equations. On the whole, the proposed hybrid method can be further used to precisely and efficiently predict welding deformations and residual stresses of large-scale structures.

  19. Acoustic emisson and ultrasonic wave characteristics in TIG-welded 316 stainless steel

    Science.gov (United States)

    Lee, Jin Kyung; Lee, Joon Hyun; Lee, Sang Pill; Son, In Su; Bae, Dong Su

    2014-05-01

    A TIG welded 316 stainless steel materials will have a large impact on the design and the maintenance of invessel components including pipes used in a nuclear power plant, and it is important to clear the dynamic behavior in the weld part of stainless steel. Therefore, nondestructive techniques of acoustic emission (AE) and ultrasonic wave were applied to investigate the damage behavior of welded stainless steel. The velocity and attenuation ratio of the ultrasonic wave at each zone were measured, and a 10 MHz sensor was used. We investigated the relationship between dynamic behavior and AE parameters analysis and derived the optimum parameters to evaluate the damage degree of the specimen. By measuring the velocity and the attenuation of an ultrasonic wave propagating each zone of the welded stainless steel, the relation of the ultrasonic wave and metal structure at the base metal, heat affected zone (HAZ) metal and weld metal is also discussed. The generating tendency of cumulated counts is similar to that of the load curve. The attenuation ratios from the ultrasonic test results were 0.2 dB/mm at the base zone, and 0.52 dB/mm and 0.61 dB/mm at the HAZ zone and weld zone, respectively.

  20. Creep behaviour and microstructural evolution in P23/P91 dissimilar welds

    Energy Technology Data Exchange (ETDEWEB)

    Vodarek, V. [Technical Univ. of Ostrava (Czech Republic); Kubon, Z.; Strilkova, L. [MATERIALS AND METALLURGICAL RESEARCH Ltd., Ostrava (Czech Republic); Hainsworth, S.V. [Leicester Univ. (United Kingdom). Dept. of Engineering

    2010-07-01

    The structural integrity of welded components operated at elevated temperatures is of key importance in power plant applications. Long-term creep exposure of dissimilar welds is accompanied by redistribution of interstitial elements which strongly affects microstructural evolution in the vicinity of the fusion zone between low and high alloy materials. This paper summarises results of studies on creep rupture properties and minor phase evolution in the P23/P71 heterogeneous welds duing creep exposure at 500, 550 and 600 C for durations exceeding 60 000 hours. The composition of filler material in Weld A corresponded to that of P91 steel, whilst for Weld B the low alloy filler material of P23 type composition was used. Results of creep rupture tests on the cross weld specimens are close to, or slightly below, the lower limit of the {+-}20% scatter band around the standardized curve for creep strength of the P23 steel. Experimental data on microstructural evolution have been compared with results of thermodynamic and kinetic simulations. The predicted minor phase evolution close to the P23/P91 interface was confirmed by microstructural investigations. Some differences between calculations and experimental studies were found for the P23 steel. It was demonstrated that undissolved fine MX particles in the partly decarburized zone of the P23 (WM23) steel significantly delayed recrystallization of the bainitic matrix. (orig.)

  1. Repair welding of cast iron coated electrodes

    Science.gov (United States)

    Żuk, M.; Górka, J.; Dojka, R.; Czupryński, A.

    2017-08-01

    Welding cast iron is a complex production procedure. Repair welding was used to repair damaged or poorly made castings. This is due to a tendency to cracking of the material during welding as well as after it. Welding cast iron can be carried out on hot or on cold. Hot welding requires high heat material and the use of welding material in the form of cast iron. In the case of cold welding, it is possible to use different materials. Mostly used filler metals are nickel and copper based. The work shows the course of research concerning repairmen of ductile iron with arc welding method. For the reparation process four types of ESAB company coated electrodes dedicated for cast iron were used with diameter 3.2 and 4 mm: ES 18-8-6B (4mm), EB 150 (4mm), OK NiCl, EŻM. In the cast iron examined during the testing grooves were made using plasma methods, in order to simulate the removed casting flaws. Then the welding process with coated electrodes was executed. The process utilized low welding current row of 100A, so there would only be a small amount of heat delivered to the heat affected zone (HAZ). Short stitches were made, after welding it was hammered, in order to remove stresses. After the repair welding the part of studies commenced which purpose was finding surface defects using visual testing (VT) and penetration testing (PT). In the second part, a series of macro and microscopic studies were executed witch the purpose of disclosuring the structure. Then the hardness tests for welds cross sections were performed. An important aspect of welding cast iron is the colour of the padding weld after welding, more precisely the difference between the base material and padding weld, the use of different materials extra gives the extra ability to select the best variant. The research of four types of coated electrode was executed, based on the demands the best option in terms of aesthetic, strength and hardness.

  2. Realizing precision pulse TIG welding with arc length control and visual image sensing based weld detection

    Institute of Scientific and Technical Information of China (English)

    孙振国; 陈念; 陈强

    2003-01-01

    Methods of arc length control and visual image based weld detection for precision pulse TIG welding were investigated. With a particular all-hardware circuit, arc voltage during peak current stage is sampled and integrated to indicate arc length, deviation of arc length and adjusting parameters are calculated and output to drive a step motor directly. According to the features of welding image grabbed with CCD camera, a special algorithm was developed to detect the central line of weld fast and accurately. Then an application system were established, whose static arc length error is ±0.1 mm with 20 A average current and 1 mm given arc length, static detection precision of weld is 0.01 mm, processing time of each image is less than 120 ms. Precision pulse TIG welding of some given thin stainless steel components with complicated curved surface was successfully realized.

  3. 76 FR 74831 - Aging Management of Stainless Steel Structures and Components in Treated Borated Water

    Science.gov (United States)

    2011-12-01

    ... COMMISSION Aging Management of Stainless Steel Structures and Components in Treated Borated Water AGENCY...- ISG-2011-01, ``Aging Management of Stainless Steel Structures and Components in Treated Borated Water... management of stainless steel structures and components exposed to treated borated water. In response to...

  4. Ultrasonic welding for fast bonding of self-aligned structures in lab-on-a-chip systems.

    Science.gov (United States)

    Kistrup, K; Poulsen, C E; Hansen, M F; Wolff, A

    2015-05-07

    Ultrasonic welding is a rapid, promising bonding method for the bonding of polymer chips; yet its use is still limited. We present two lab-on-a-chip applications where ultrasonic welding can be preferably applied: (1) self-aligned gapless bonding of a two-part chip with a tolerance of 50 μm; (2) bonding of a large area shallow chamber (1.8 cm(2) × 150 μm). Using injection moulding combined with ultrasonic welding we achieved a total production and bonding time of 60 s per chip, and a batch of chips could be produced within a day going from design to finished chips. We believe that the technical solutions offered here can significantly help bridge the gap between academia and industry, where the differences in production methods and materials pose a challenge when transferring technology.

  5. Effect of Heat Input on Microstructure and Hardness Distribution of Laser Welded Si-Al TRIP-Type Steel

    Directory of Open Access Journals (Sweden)

    Adam Grajcar

    2014-01-01

    Full Text Available This study is concerned with issues related to laser welding of Si-Al type TRIP steels with Nb and Ti microadditions. The tests of laser welding of thermomechanically rolled sheet sections were carried out using keyhole welding and a solid-state laser. The tests carried out for various values of heat input were followed by macro- and microscopic metallographic investigations as well as by microhardness measurements of welded areas. A detailed microstructural analysis was carried out in the penetration area and in various areas of the heat affected zone (HAZ. Special attention was paid to the influence of cooling conditions on the stabilisation of retained austenite, the most characteristic structural component of TRIP steels. The tests made it possible to determine the maximum value of heat input preventing the excessive grain growth in HAZ and to identify the areas of the greatest hardness reaching 520 HV0.1.

  6. Effects of Thermocapillary Forces during Welding of 316L-Type Wrought, Cast and Powder Metallurgy Austenitic Stainless Steels

    CERN Document Server

    Sgobba, Stefano

    2003-01-01

    The Large Hadron Collider (LHC) is now under construction at the European Organization for Nuclear Research (CERN). This 27 km long accelerator requires 1248 superconducting dipole magnets operating at 1.9 K. The cold mass of the dipole magnets is closed by a shrinking cylinder with two longitudinal welds and two end covers at both extremities of the cylinder. The end covers, for which fabrication by welding, casting or Powder Metallurgy (PM) was considered, are dished-heads equipped with a number of protruding nozzles for the passage of the different cryogenic lines. Structural materials and welds must retain high strength and toughness at cryogenic temperature. AISI 316L-type austenitic stainless steel grades have been selected because of their mechanical properties, ductility, weldability and stability of the austenitic phase against low-temperature spontaneous martensitic transformation. 316LN is chosen for the fabrication of the end covers, while the interconnection components to be welded on the protrud...

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

    NARCIS (Netherlands)

    Lemmen, H.J.K.

    2010-01-01

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

  8. Microstructure analysis in friction welding of copper and aluminum

    Science.gov (United States)

    Wibowo, A. G. Wahyu; Ismail, Rifky; Jamari, J.

    2016-04-01

    The Friction welding is a welding method with utilizing heat generated due to friction. Surfaces of two materials to be joined, one rotates the other being idle, is contacted by a pressure force. Friction on the second contact surface is done continuously so that the heat generated by the continuous friction will continue to rise. With the heat and the pressure force on the second surface to the second meeting of the material reaches its melting temperature then there is the process of welding. This paper examines the influence of the pressure force, rotational speed and contact time on friction welding of Aluminum (Al) and Copper (Cu) to the quality of welded joints. Friction welding process is performed on a friction welding machine that is equipped with the loading mechanism. The parameters used are the pressure force, rotational speed and friction time. Determination of the quality of welding is done by testing the tensile strength, hardness, and micro structure on the weld joint areas. The results showed that the friction welding quality is very good, this is evidenced by the results of a tensile strength test where the fault occurs outside the weld joint and increased violence in the weld joint. On the results visually cuts the welding area did not reveal any porosity so that it can be concluded that each metal contacts have melted perfectly and produce a connection with good quality.

  9. A Review on Solidification and Change in Mechanical Properties Under Vibratory Welding Condition

    Directory of Open Access Journals (Sweden)

    Jyoti Prakash

    2010-04-01

    Full Text Available Welding has been applied to various industries in particular, automotive, aerospace and microelectronics. Thermal cycle produced near weld line generates residual stress and inhomogeneous plastic deformation in weldments. However there are many methods for welding the workpieces and one of the method among these is vibratory welding. It has the advantages of less investment, more convenient operation, less pollution and shorter manufacturing period. In vibratory welding, workpiece vibrates in the whole welding process and it mainly effects the welding solidification to improve the quality. Vibration facilitates the release of dissolved gases and the resulting weld beads greatly exhibit reduced porosity. Mechanical properties of the welds prepared under vibratory conditions are dependent on the structural changes of the welds This paper presents the solidification behaviour and changes occurs in mechanical properties under vibratory welding condition.

  10. Laser welding of stainless steel weld filler metals at high cooling rates

    Energy Technology Data Exchange (ETDEWEB)

    Vitek, J.M.; David, S.A.

    1988-01-01

    Several stainless steels were laser welded under conditions resulting in high cooling rates of the welds. Significant changes in the microstructures, compared to those produced by conventional welding techniques, were found. For alloys 304, 308, 309, 316 and 347, a general decrease in ferrite content with increasing cooling rate was found. For three alloys (304, 308, 347), a fully austenitic structure was obtained at the highest cooling rates. For alloys 312 and 446, the high cooling rates retarded the formation of austenite, resulting in higher ferrite contents and fully ferritic structures at the highest cooling rates. Only for alloy 310 was the microstructure after laser welding comparable to that found after conventional welding. The results are discussed in terms of their impact on the Schaeffler diagram and its applicability to laser welding. 11 refs., 7 figs.

  11. Welding overlay analysis of dissimilar metal weld cracking of feedwater nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Y.L., E-mail: YLTsai@itri.org.t [National Chiao Tung University, Mechanical Engineering Department, 1001 TaHsueh Road, HsinChu, Taiwan 30010 (China); Industrial Technology Research Institute (ITRI), 195 Chung Hsing Rd., Sec.4 Chu Tung, HsinChu, Taiwan 310 (China); Wang, Li. H. [Industrial Technology Research Institute (ITRI), 195 Chung Hsing Rd., Sec.4 Chu Tung, HsinChu, Taiwan 310 (China); Fan, T.W. [Industrial Technology Research Institute (ITRI), 195 Chung Hsing Rd., Sec.4 Chu Tung, HsinChu, Taiwan 310 (China); Chung Hua University, Department of Civil Engineering and Engineering Informatics, 707, Sec.2, WuFu Rd., HsinChu, Taiwan 300 (China); Ranganath, Sam [Industrial Technology Research Institute (ITRI), 195 Chung Hsing Rd., Sec.4 Chu Tung, HsinChu, Taiwan 310 (China); Wang, C.K. [Taiwan Power Company (TPC), No.242, Sec. 3, Roosevelt Rd., Zhongzheng District, Taipei City 100, Taiwan (China); Chou, C.P. [National Chiao Tung University, Mechanical Engineering Department, 1001 TaHsueh Road, HsinChu, Taiwan 30010 (China)

    2010-01-15

    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.

  12. Proceedings of the Symposium on Welding, Bonding, and Fastening. [production engineering for aircraft and spacecraft structures

    Science.gov (United States)

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

    1972-01-01

    Various technological processes to achieve lightweight reliable joining systems for structural elements of aircraft and spacecraft are considered. Joining methods, combinations of them, and nondestructive evaluation and quality assurance are emphasized.

  13. Design strategy of intelligent CAD for welding positioner scheme design

    Institute of Scientific and Technical Information of China (English)

    林三宝; 杨春利; 吴林; 黎明

    2002-01-01

    Traditional CAD technique does not support the design processes such as function definition, conceptual design and preliminary design, which are most creative and play significant roles on the design quality. Because scheme design has close relationship with product structure, performance and technology cost, it is important for applying the intelligent CAD of scheme design to improve the quality and competitive level of the product. The definition and function of welding positioner are discussed in this paper. The new definition of welding positioner extends the research scope of welding positioner to welding fixture and welding positioning motion mechanism. The design process of welding fixture and positioning motion system is described, and the cased-based and knowledge-based design strategy of welding positioner scheme design intelligent CAD is then put forward, which lays foundation for developing proto-type system of welding positioner scheme design.

  14. Geometric model of robotic arc welding for automatic programming

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Geometric information is important for automatic programming of arc welding robot. Complete geometric models of robotic arc welding are established in this paper. In the geometric model of weld seam, an equation with seam length as its parameter is introduced to represent any weld seam. The method to determine discrete programming points on a weld seam is presented. In the geometric model of weld workpiece, three class primitives and CSG tree are used to describe weld workpiece. Detailed data structure is presented. In pose transformation of torch, world frame, torch frame and active frame are defined, and transformation between frames is presented. Based on these geometric models, an automatic programming software package for robotic arc welding, RAWCAD, is developed. Experiments show that the geometric models are practical and reliable.

  15. Strength of Composite Joints in Structural Components and Articles

    Directory of Open Access Journals (Sweden)

    A. A. Bakulin

    2016-01-01

    Full Text Available Currently, the composite materials (CM are widely used in the aerospace technology and mechanical engineering where the key parameters characterizing structural components and articles are related to their weight characteristics as well as their performance under high temperatures.For the experimental investigation of composite-based threaded items, the rod-based 3Dreinforced carbon-carbon composite material (CCCM was chosen.The subject of the research was the metric thread. The test samples were cut of the aforesaid material along one of the reinforcement direction. The following thread sizes were analyzed: М24×1.5; М24×2; М24×3.Dependence of the thread strength on the number of thread turns was determined within the range of 1 to 10 thread turns for М24×2 thread size. The remaining test samples were used to obtain the relationship between the thread load bearing capacity and the thread pitch.The obtained dependence of the thread load bearing capacity on the number of thread turns showed the following:a An increment in the thread load bearing capacity decreases with increasing number of thread turns. However, this effect is less pronounced than that observed for the metal ‘screw/nut’ pair.b With the CCCM material under study, it proved to be impossible to test configurations having only 1 or 2 thread turns.c The wide confidence range (CR of the failure load can be explained by the fact that the material under study features an apparent structural heterogeneity, with a different probability of hitting a unit cell of the matrix and filler of the material. Nevertheless, the confidence range is stable, thus indicating indirectly the possibility of using this test method for further study of composite-based threaded items.There is an explicit correlation between the thread load bearing capacity and the thread pitch. Increase in the thread strength with increasing thread pitch depends on the relationship between the pitch size and the

  16. 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 met

  17. 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.…

  18. Formation, structure, and properties of "welded" h-BN/graphene compounds

    Science.gov (United States)

    Chernozatonskii, L. A.; Demin, V. A.; Artyukh, A. A.

    2016-07-01

    Structures of h-BN/graphene with holes where atoms at the edges are bonded to each other by sp 2 hybridized C-B and C-N bonds and form continuous junctions from layer to layer with topological defects inside holes have been considered. Their formation, as well as the moiré-type stable atomic structure of such compounds (with different rotation angles of graphene with respect to the hexagonal boron nitride monolayer) with closed hexagonal holes in the AA centers of packing of the moiré superlattice, has been studied. The stability, as well as the electronic and mechanical properties, of such bilayer BN/graphene nanomeshes has been analyzed within electron density functional theory. It has been shown that they have semiconducting properties. Their electronic band structures and mechanical characteristics differ from the respective properties of separate monolayer nanomeshes with the same geometry and arrangement of holes.

  19. Laser welding in space

    Science.gov (United States)

    Kaukler, W. F.; Workman, G. L.

    1991-01-01

    Autogenous welds in 304 stainless steel were performed by Nd-YAG laser heating in a simulated space environment. Simulation consists of welding on the NASA KC-135 aircraft to produce the microgravity and by containing the specimen in a vacuum chamber. Experimental results show that the microgravity welds are stronger, harder in the fusion zone, have deeper penetration and have a rougher surface rippling of the weld pool than one-g welds. To perform laser welding in space, a solar-pumped laser concept that significantly increases the laser conversion efficiency and makes welding viable despite the limited power availability of spacecraft is proposed.

  20. Fatigue Reliability Assessment of Correlated Welded Web-frame Joints

    Institute of Scientific and Technical Information of China (English)

    W. Huang; Y. Garbatov; C. Guedes Soares

    2014-01-01

    The objective of this work is to analyze the fatigue reliability of complex welded structures composed of multiple web-frame joints, accounting for correlation effects. A three-dimensional finite element model using the 20-node solid elements is generated. A linear elastic finite element analysis was performed, hotspot stresses in a web-frame joint were analyzed and fatigue damage was quantified employing the S-N approach. The statistical descriptors of the fatigue life of a non-correlated web-frame joint containing several critical hotspots were estimated. The fatigue reliability of a web-frame joint wasmodeled as a series system of correlated components using the Ditlevsen bounds. The fatigue reliability of the entire welded structure with multiple web-frame joints, modeled as a parallel system of non-correlated web-frame joints was also calculated.

  1. Study on intelligent welding mobile robot with the function of auto-searching weld line

    Institute of Scientific and Technical Information of China (English)

    Zhang Ke; Lü Xueqin; Sun Guang; Wu Yixiong

    2006-01-01

    The development of welding robots suitable for specially unstructured working enviroments has been become an important development direction of industrial robot application because large-scale welding structures have been used more and more widely in modern industry. In this paper, an intelligent mobile robot for welding of ship deck with the function of autosearching weld line was presented. A wheeled motion mechanism and a cross adjustment slider are used for the welding robot body. A sensing system based on laser-PSD (position sensitive detector) displacement sensor was developed to obtain two dimensional deviation signals during seam tracking. A full-digital control system based on DSP and CPLD has also been realized to implement complex and high-performance control algorithm s. Furthermore, the system has still the function of auto-searching weld line according to the characteristics information of weld groove and adjusting posture itself to the desired status preparing for welding. The experiment of auto-searching welding line shows that the robot has high tracing accuracy,and can satisfy the requirement of practical welding project.

  2. Advanced Laser Transmission Welding Strategies for Fibre Reinforced Thermoplastics

    Science.gov (United States)

    Wippo, V.; Jaeschke, P.; Brueggmann, M.; Suttmann, O.; Overmeyer, L.

    Laser transmission welding can be used to join endless fibre reinforced thermoplastics. The welding temperature is affected by the heat conduction along carbon fibresand depends on the local orientation of the fibres in the weld seam and the laser welding technique itself. In these investigations the heat development during the welding with quasi-static temperature fields, which is a combination of two laser welding techniques, is evaluated and compared to welding with a homogenized intensity distribution. In order to optimize the temperature distribution over the weld seam width for both linear and curved weld seams, different scanning structures have beenadapted. The experiments were conducted with a diode laser emitting at a wavelength of 940 nm and the process was monitored by aninfrared camera. The used thermoplastics consist of laminates based on unidirectional carbon fibre reinforced polyphenylenesulfide. With the developed scanning structures, a near-homogeneous temperature distribution was generated over the width of the weld seam for curved weld seams, which is not possible by welding with a homogenized laser radiation intensity distribution.

  3. Impact energy analysis of quenched and tempered fine grain structural steel specimens after weld thermal cycle simulation

    Directory of Open Access Journals (Sweden)

    M. Dunđer

    2014-10-01

    Full Text Available The paper presents impact energy results of thermal cycle simulated specimens of quenched and tempered fine grain structural steel S960QL. These results are obtained by examining notched Charpy specimens. Upon performed metallographic analysis and measured hardness, total impact energy is separated into ductile and brittle components.

  4. 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.

  5. Research on Welding Test of Grey Cast Iron and Low-Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Grey cast iron's welding itself is a complex proble m.So proper welding materials must be selected,complex welding techniques such as preheating before weldingslow cooling after welding etc,should be taken. However the carbon component in low-carbon steel is comparatively low,the carbo n of welded joint will diffuse to the low-carbon steel when it is welded with gr ey cast iron,which will cause the component of carbon greatly increased at the low-carbon steel side in HAZ,high carbon martensite and cracks ...

  6. 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

  7. Study of the structure and properties of laser-welded joints of the Al-Mg-Li alloy

    Science.gov (United States)

    Pugacheva, N. B.; Antenorova, N. P.; Senaeva, E. I.

    2015-12-01

    The macro- and microstructures, the distribution of chemical elements and of the values of the microhardness over the width of the zones of remelting and heat-affected zone have been studied after the laser welding of sheets of an Al-Mg-Li alloy. It has been shown that the material of the zone of remelting (1.2 mm thick) represents in itself finely dispersed misoriented dendrites, in the primary branches of which particles of the strengthening δ' phase (Al3Li) with dimensions of no more than 10 nm and in the interdendrite spaces, dispersed particles of the S phase (Al2MgLi and FeAl2) have been revealed. The hardness of the material of the zone of remelting was 108-123 HV 0.05; the hardness of the basic alloy, 150-162 HV 0.05. In the heat-affected zones of thickness 2 mm, the primary recrystallization occurred only in a narrow zone directly at the boundary with the weld. The strength of the welded junction was 470-490 MPa, which corresponds to the regulated degree of strength of the aluminum alloys of this class. The relative elongation of the material of the weld proved to be considerably less than that in the alloy matrix because of the microporosity of the weld material. It is shown that the convective stirring of the melt in the welding pool upon the laser welding made it possible to avoid the appearance of macroscopic defects, but on the microlevel there are observed micropores in the form of spheres with dimensions of 5-50 μm. The solidification of the alloy occurred in such a way that the dendrites had time to grow around the gas bubbles prior to their collapse, forming a sufficiently strong carcass. Inside the dendritic carcass, there have been revealed coarse inclusions (to 200 μm) that consist of oxides (Al2O3, Fe2O3, MgO, SiO2, CaO), of an iron-based alloy, and of the host aluminum alloy.

  8. All-Fiber Components for Micro-Structured Fibers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose new concepts for developing components for high performance space based Lidar systems. While it is generally recognized that photonic crystal fiber...

  9. Economic security and its components in agro business structures

    OpenAIRE

    MUZYKA T.P.

    2011-01-01

    The place and role of economic security of new organization agro business in the national security system, proposed to form the system of economic security agro businesses, which would include public and private components.

  10. Combined Laser Beam Welding and Brazing Process for Aluminium Titanium Hybrid Structures

    Science.gov (United States)

    Möller, F.; Grden, M.; Thomy, C.; Vollertsen, F.

    The current state of the art in light-weight construction is - for the case of aircraft structures - the use of either aluminium or titanium. Whereas aluminium is light-weight and less expensive, titanium offers superior corrosion properties at higher cost. In order to combine the advantages of both materials, a hybrid Ti-Al structure is proposed for e.g. seat-track application. In this paper, an overview of the results from this research work and the accompanying thermo-mechanical simulations will be reported and discussed. On the basis of the development of an appropriate system technology, the process development will be described, focusing on the main influencing parameters of the process on joint properties.

  11. Evolution of the Structure of Local Regions of Fused Metal in Explosion-Welded Nickel-Aluminum Composites Under Heat Treatment

    Science.gov (United States)

    Shmorgun, V. G.; Bogdanov, A. I.; Gurevich, L. M.

    2016-03-01

    The methods of electron, optical, and atomic force microscopy are used to study the structure, morphology and phase composition of local regions of fused metal in an explosion-welded nickel-aluminum composite. It is shown that the diffusion zone formed due to the heat treatment repeats the contour of the fuse in the first stage and then "absorbs" it upon duration of the hold thus leveling the phase composition. ANi2Al3 Aluminide layer forms on the side of nickel and a NiAl3 layer forms on the side of aluminum.

  12. Measurement of residual stresses in the dissimilar metal weld joint of a safe-end nozzle mock-up

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Kazuo (Japan Nuclear Energy Safety Organisation, Tokyo (Japan)); Kingston, E.; Chidwick, L. (VEQTER Ltd., Bristol (United Kingdom)); Smith, D. (Univ. of Bristol (United Kingdom))

    2009-07-01

    Knowledge of the origin, magnitude and distribution of residual stresses generated during the manufacture of nuclear power plants is of vital importance to their structural integrity assessment. The overall aim of this work was to measure welding residual stresses in components prone to primary water stress corrosion cracking in nuclear reactor pressure vessels. This paper describes the on-site application of the Deep-Hole Drilling (DHD) technique to measure the through-thickness residual stress distributions through a safe-end nozzle component containing a dissimilar metal weld joint at different stages of manufacture

  13. Laser-Assisted Stir Welding of 25-mm-Thick HSLA-65 Plate

    Science.gov (United States)

    Williamson, Keith M.

    2002-12-01

    Laser-assisted stir welding is a hybrid process that combines energy from a laser with functional heating and mechanical energy to join materials in the solid state. The technology is an adaptation of friction stir welding which is particularly suited for joining thick plates. Aluminum plates up to 75 mm thick have been successfully joined using friction stir welding. Since joining occurs in the solid state, stir technology offers the capability for fabricating full penetration joints in thick plates with better mechanical properties and less weld distortion than is possible by fusion processes. Currently friction stir welding is being used in several industries to improve productivity, reduce weight, and increase the strength of welded structures. Examples include: (a) the aircraft/aerospace industry where stir technology is currently being used to fabricate the space shuttle's external tank as well as components of the Delta family of rockets; (b) the shipping industry where container manufacturers are using stir technology to produce lighter containers with more payload capacity; and (c) the oil industry where offshore platform manufactures are using automated stir welding plants to fabricate large panels and structures up to 16 meters long with widths as required. In all these cases, stir technology has been restricted to aluminum alloys; however, stainless and HSLA 65 steels have been recently stir welded with friction as the primary heat source. One of the difficulties in adapting stir welding to steel is tool wear aggravated by the high tool rubbing velocities needed to provide frictional heat input into the material. Early work showed that the tool shoulder reached temperatures above 1000 C and the weld seam behind the tool stayed within this temperature range for up to 25 mm behind the tool. Cross sections of stir welded samples showed that the heat-affected zone is relatively wide and follows the profile of the tool shoulder. Besides minimizing the tool

  14. Experimental and numerical studies on the issues in laser welding of light-weight alloys in a zero-gap lap joint configuration

    Science.gov (United States)

    Harooni, Masoud

    It is advantageous for the transportation industry to use lightweight components in the structure in order to save mass and reduce CO2 emissions. One of the lightest structural metals, magnesium, fulfills the need for mass reduction within the automotive industry. Many of the body structure components in the automotive industry are assembled using joining processes such as fusion welding. Furthermore, laser welding offers a low heat impact, high process rate, joining method which is becoming increasingly popular as the cost for laser systems continues to decrease. However, there is a limited body of work investigating the laser welding of magnesium and therefore, in the current study, different techniques and methods for laser welding of magnesium alloys are numerically and experimentally studied in order to optimize process parameters to achieve high quality welds. A feasibility study was designed in order to study the effect of various laser welding process parameters (such as laser power levels and welding speeds) on weld quality. Three regression models were developed to find the best fit model that relates process parameters to the shear load of the weld. Furthermore, to understand the effect of laser welding parameters on temperature distribution in laser welding of AZ31B magnesium alloy, a numerical model was developed. A rotary Gaussian volumetric body heat source was applied in this study to obtain the temperature history during the laser welding process. Cross-sectional views of the weld beads, temperature history recorded by thermocouples, and temperature history recorded by infrared camera were used to validate the numerical model. In order to study the real-time dynamic behavior of the molten pool and the keyhole during the welding process, a high speed charge-coupled device (CCD) assisted with a green laser as an illumination source was used. In order to observe the presence of pores, prior studies destructively evaluated the weld bead however; in the

  15. Development of a Comprehensive Weld Process Model

    Energy Technology Data Exchange (ETDEWEB)

    Radhakrishnan, B.; Zacharia, T.

    1997-05-01

    ORNL. The timing results illustrate the potential of the modified computer model for the analysis of large-scale welding simulations. 2. The kinetics of grain structure evolution in the weld heat affected zone (HAZ) has been simulated with reasonable accuracy by coupling an improved MC grain growth algorithm with a methodology for converting the MC parameters of grain size and time to real parameters. The simulations effectively captured the thermal pinning phenomenon that has been reported in the weld HAZ. 3. A cellular automaton (CA) code has been developed to simulate the solidification microstructure in the weld fusion zone. The simulations effectively captured the epitaxial growth of the HAZ grains, the grain selection mechanism, and the formation of typical grain structures observed in the weld t%sion zone. 4. The point heat source used in the LMES welding code has ben replaced with a distributed heat source to better capture the thermal characteristics and energy distributions in a commercial welding heat source. 5. Coupled thermal-mechanical and metallurgical models have been developed to accurately predict the weld residual stresses, and 6. Attempts have been made to integrate the newly developed computational capabilities into a comprehensive weld design tool.

  16. Residual stress measurement inside a dissimilar metal weld mock-up of the pressurizer safety and relief nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Wagner R.C.; Rabello, Emerson G.; Silva, Luiz L.; Mansur, Tanius R., E-mail: wrcc@cdtn.br, E-mail: egr@cdtn.br, E-mail: silvall@cdtn.br, E-mail: tanius@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte (Brazil). Servico de Integridade Estrutural; Martins, Ketsia S., E-mail: ketshinoda@hotmail.com [Universidade Federal de Minas Gerais (UFMG), Nelo Horizonte (Brazil). Departamento de Engenharia Metalurgica

    2015-07-01

    Residual stresses are present in materials or structural component in the absence of external loads or changes in temperatures. The most common causes of residual stresses being present are the manufacturing or assembling processes. All manufacturing processes, such as casting, welding, machining, molding, heat treatment, among others, introduces residual stresses into the manufactured object. The residual stresses effects could be beneficial or detrimental, depending on its distribution related to the component or structure, its load service and if it is compressive or tensile. In this work, the residual strains and stresses inside a mock-up that simulates the safety and relief nozzle of Angra 1 Nuclear Power Plant pressurizer were studied. The current paper presents a blind hole-drilling method residual stress measurements both at the inner surface of dissimilar metal welds of dissimilar metal weld nozzle mock-up. (author)

  17. Characteristics comparison of weld metal zones welded to cast and forged steels for piston crown material

    Science.gov (United States)

    Moon, Kyung-Man; Kim, Yun-Hae; Lee, Myeong-Hoon; Baek, Tae-Sil

    2015-03-01

    An optimum repair welding for the piston crown which is one of the engine parts exposed to the combustion chamber is considered to be very important to prolong the engine lifetime from an economical point of view. In this study, two types of filler metals such as 1.25Cr-0.5Mo, 0.5Mo were welded with SMAW method and the other two types of filler metals such as Inconel 625 and 718 were welded with GTAW method, respectively, and the used base metals were the cast and forged steels of the piston crown material. The weld metal zones welded with Inconel 625 and 718 filler metals exhibited higher corrosion resistance compared to 1.25Cr-0.5Mo and 0.5Mo filler metals. In particular, the weld metal zone welded with Inconel 718 and 0.5Mo, filler metals indicated the best and worst corrosion resistance, respectively. Consequently, it is suggested that the corrosion resistance of the weld metal zone surely depends on the chemical components of each filler metal and welding method irrespective of the types of piston crown material.

  18. Prediction of welding residual stress of dissimilar metal weld of nozzle using finite element analyses

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Nam Su; Kim, Jong Wook; Choi, Suhn; Kim, Tae Wan [KAERI, Daejeon (Korea, Republic of)

    2008-07-01

    The Primary Water Stress Corrosion Cracking (PWSCC) of dissimilar metal weld based on Alloy 82/182 is one of major issues in material degradation of nuclear components. It is well known that the crack initiation and growth due to PWSCC is influenced by material's susceptibility to PWSCC and distribution of welding residual stress. Therefore, modeling the welding residual stress is of interest in understanding crack formation and growth in dissimilar metal weld. Currently in Korea, a numerical round robin study is undertaken to provide guidance on the welding residual stress analysis of dissimilar metal weld. As a part of this effort, the present paper investigates distribution of welding resisual stress of a ferritic low alloy steel nozzle with dissimilar metal weld using Alloy 82/182. Two-dimensional thermo-mechanical finite element analyses are carried out to simulate multi-pass welding process on the basis of the detailed design and fabrication data. The present results are compared with those from other participants, and more works incorporating physical measurements are going to be performed to quantify the uncertainties relating to modelling assumptions.

  19. Behavior of a crack within a Dissimilar Metal Weld Part by using an Overlay Weld

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kang Soo; Lee, Ho Jin; Lee, Bong Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-05-15

    In recent years, the dissimilar metal welds, Alloy 82/182 welds, used to connect the stainless steel piping and low alloy steel or carbon steel components in a nuclear reactor piping system have experienced a cracking due to a primary water stress corrosion (PWSCC).It is well known that one reason for the cracking is the residual stress by the weld. But, it is difficult to estimate the weld residual stress exactly due to the many parameters for the welding process. In this paper, a Butt model weld specimen was manufactured and the residual stresses of the weld specimen were measured by the X-Ray method and a Hole Drilling Technique. These results were compared with the results of the Butt FEM Model to confirm the confidence of the FEM input. Also, an analysis of the Crack FEM models made by the ABAQUS Code was performed to estimate the behavior of a crack within a Dissimilar Metal Weld Part (DMWP) when an overlay weld on the DMWP was done.

  20. 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.