Showing papers on "Butt welding published in 2004"

Joining of dissimilar materials with friction stir welding

Abstract: The welding and joining of dissimilar metals which have very different properties, such as aluminium and carbon steel, is considered to be a subject for research and development in the welding/joining sector continuing into the 21st century. There are also huge requirements and expectations for this sector.1 Due to the aforementioned, the research and development of welding and joining of dissimilar materials have been carried out over many years; for instance, eutectic bonding of copper pipe and aluminium pipe was developed 30 years ago and this process is still applied for the heat pipes of refrigerators. Recently it has even progressed for applications in joining of wide plate materials of aluminium alloy and stainless steel by means of the vacuum rolling process2 and also for weldments of aluminium alloy and carbon steel joined by means of friction welding and employed as automobile components.3 However, there are problems from aspects of cost and restrictions concerning the configurations fo...

Welding unit and welding method by means of which at least two different welding processes may be combined

Abstract: The invention relates to a welding unit (27), comprising a welding device (1), with a welding torch unit (29) which may be connected thereto by means of a tube group (23, 28). At least one controller (4), a welding power supply (2) and, optionally, a wire supply unit (30) are arranged in the welding device (1). The welding torch unit (29) comprises at least two separate welding burners (10, 35), embodied for carrying out at least two independent separate welding processes. The invention further relates to a welding method, in which at least two different welding processes can be combined. According to the invention, such a welding unit (27) and welding method can be achieved, in which the amount of introduction of additional material and the heat or energy supply into the workpiece (16) may be adjusted as independently from each other as possible, whereby the first welding burner (10) is embodied for carrying out a welding process and at least one second welding burner (35) is embodied for carrying out a cold metal transfer welding process with a back-and-forth movement of a welding rod (32) and for synchronisation of the welding processes carried out with the at least two welding burners (10, 35).

Fabrication and Engineering Technology for Lightweight Ship Structures, Part 1: Distortions and Residual Stresses in Panel Fabrication

Abstract: An increase in shipboard applications of lightweight structures has been evident over the recent years in both military and commercial vessels. Ship panel distortions generated through various stages of production (e.g., material handling, blast and paint, panel fabrication, subassembly, assembly, outfitting, and erection) have emerged as a major obstacle to the cost-effective fabrication of these lightweight structures. This problem is particularly challenging for naval ships that are built with relatively thin plate and require fair surfaces to maximize hydrodynamic performance and minimize radar signature. With a recent major initiative funded by the U.S. Navy, a comprehensive assessment of the lightweight panel fabrication technology has been undertaken. This assessment took into account the residual stresses of thin plate conditions during the material handling, cutting, fitting, and welding processes. A series of test panels with varying degrees of complexity representing the typical shipboard applications were designed and used to quantify dimensional variations through the entire fabrication processes in a production environment. A light detection and ranging (LIDAR) measurement system was used to analyze panel distortion topography resulting from different processes. Welding attributes, stiffener assembly sequence, and material handling methods were systematically monitored and evaluated to identify areas for fabrication improvement. Advanced computational tools were further developed and used to establish the underlying distortion mechanisms and critical process parameters in these panel structures. Some of the major findings include the following: (1) local buckling is the dominant distortion mechanisms in lightweight panel structures; (2) special care must be exercised in material handling of lightweight structures in preventing long-range permanent deformation; (3) dimensional accuracy from thermal cutting can have a significant impact on buckling distortions, particularly for different thickness combinations in complex panels; (4) any effective mitigation techniques for minimizing buckling distortion should either reduce the buckling driving force (fabrication induced stresses) and/or increase the buckling resistance (e.g., panel geometric parameters and assembly procedures); (5) butt welding of plates to make panels requires a low heat input narrow groove process to minimize distortion prior to fillet welding of stiffeners; (6) precision fillet welding process with automatic seam tracking offers the potential to minimize overwelding.

Synchrotron diffraction measurement of residual stresses in friction stir welded 5383-H321 aluminium butt joints and their modification by fatigue cycling

Abstract: This paper presents two-dimensional information on the residual stresses in 8 mm 5383-H321 aluminium plates joined by double pass (DP) friction stir welding (FSW). It considers the inherent variability in residual stress magnitudes along 0.5 m lengths of weld pass, and their modification under a sequence of applied fatigue loads. This represents one of a planned series of experiments aimed at illuminating the effects of fatigue cycling on residual stress fields. In this particular case, the magnitudes of the bending fatigue loads (R = 0.1) were chosen to correlate with the measured proof strengths of the weld metal (approximately 160 MPa) and the parent plate (approximately 260-270 MPa). In four-point bend S-N tests at R = 0.1 on 40 mm wide FS welded specimens of this alloy and plate thickness, these peak stress levels correspond to lives of around 10 5 cycles and 10 7 cycles, respectively. Results from the work indicate that significant variability exists among welded plates in peak compressive stress magnitudes (a range of perhaps -50 MPa to -140 MPa), although peak tensile stresses were relatively low and more consistent (from around 0 to 30 MPa). Fatigue loading accentuates the peak-to-valley stress change and causes an overall translation of the stresses to become more positive. Peak tensile stresses increase several-fold during fatigue cycling.

Ultrasonic Peening and Low Transformation Temperature Electrodes used for Improving the Fatigue Strength of Welded Joints

Abstract: The fatigue strengths of welded joints in welded structures are much lower than those of the base metal because there are stress concentrations and tensile residual stresses at weld toes. Ultrasonic peening treatment and the use of low transformation temperature electrodes are possible methods for improving the fatigue strengths of welded joints. It was thought that the latter might be particularly suitable for longitudinal welds containing high tensile residual stresses. Comparative fatigue tests carried out on treated transverse butt welded joints and on plate specimens with longitudinal fillet welded gussets confirmed this.

Resistance welding fastener electrode and monitor and method of using same

Abstract: A method of monitoring a resistance welding system is provided. The method utilizes a sensor for isolating and determining movement of a pin that typically supports an object to be welded such as a fastener. The movement of the pin is used to determine various present welding operation parameters to reduce cycle time, and increase efficiency and quality of the weld. The present welding operation parameters are compared to learned or stored welding operation parameters, for example, to determine whether a fault should be generated or whether an acceptable weld was achieved.

Seat mounting rail, particularly for a commercial aircraft

Abstract: A seat mounting rail for securing seats to a floor of a passenger aircraft is made of a seat securing upper section and a rail mounting lower section. Both sections are made of different metals. The upper section is made of a titanium alloy for corrosion protection. The lower rail section is made of an aluminum alloy for weight reduction. The interconnection between the two sections is made as a thermal joint for example formed as a laser weld, which is preferably a butt weld to save welding material.

Microstructure and residual stress variations in weld zone of flash-butt welded railroads

Abstract: In the weld zone and base metal contiguous to the weld zone in flash-butt welded rail, the web of the rail has high tensile residual stresses and the head and base of the rail have compressive residual stresses. The web region is susceptible to failure since most of the weld zone of the rail is coarse grained and has porosity, inclusions and defects resulting from rapid solidification of molten metal entrapment in the weld. Efforts to reduce the amount of these tensile residual stresses require recognition of their causes. In this research, microscopic and macroscopic studies were carried out on vertical and horizontal sections of the weld zone in the head, web and base of the rail. Just after flash-butt welding, the temperature of the web between the current carrying copper electrodes is higher than the temperature of the head and base of the rail. Therefore, by cooling the weld zone to room temperature, the amount of web contraction between the electrodes is higher than the amount of base and he...

Welding device and method

Abstract: A welding device and a welding method for butt welding two pipes to be welded are provided. The welding device comprises a welding device body, having an electrode unit with a welding electrode and a fixing clamp for holding the pipes to be welded; and electrode position indicating means for indicating a position of the welding electrode with respect to the pipes to be welded. The electrode position indicating means is capable of irradiating an indicating light to the pipes to be welded at the position corresponding to the welding electrode. Therefore, the positions of the butt edge surfaces of the pipes and the welding electrode can be easily and correctly consistent so as to perform a good welding.

Hybrid layered manufacturing: Direct rapid metal tool-making process

Abstract: The fabrication method for direct metallic tools presented here combines synergic gas metal arc welding and computer numerical control (CNC) machining processes in order to exploit the benefits of both while avoiding their limitations. A programmable logic controller (PLC)-based low-cost three-axis manipulator is fabricated with a stepper motor driver in open-loop control. The tool head will hold the welding torch and milling cutter. At any time, either milling or welding will take place; for that the welding gun can be moved up and down with a pneumatic operation. The welding parameters such as current, voltage and arc length are controlled externally. The framework also consists of a software program which uses the zeroth-order edge approximation uniform slicing strategy to calculate each slice thickness to be deposited with the required metal as successive layers from lower to topmost layer with the welding process. Further it generates the required CNC code for machining from the top to bottom...

Thread control for welding wire

Abstract: A wire feeding control mechanism and method to obtain a certain stick-out of welding wire from a tip of a welding gun.

Development of Two-electrode Electrogas Arc Welding Process

Abstract: Electrogas arc welding (EGW) is used for vertical position welding of sheer strakes and hatch side coamings of container ships because of its higher welding efficiency. However, in ordinary welding processes for ultra-thick steel plates, defects such as the lack of fusion are likely to occur. In order to solve this problem and others, a two-electrode VEGA ® (Vibratory Electrogas Arc Welding) process was developed by the authors. This paper provides an outline thereto and describes the essential characteristics of this newly developed process for vertical position welding on extraheavy-sectioned steel plates. It was demonstrated that the VEGA ® process achieves a stabilized fusion-line profile for ultra-thick steel plates with higher welding efficiency. It was then confirmed that joint performance in this study satisfies regulations such as class NK KEW53 and KEW53Y40.

Computer-aided analysis of repair welding of stamping tools

Abstract: The paper deals with computer-aided repair welding of a damaged metal-working tool, i. e., a stamping tool. To repair an uncomplicated tool, TIG (Tungsten Inert Gas) welding with a filler material was used. In the process of welding, the welding parameters and the temperature at the workpiece were measured. The major part of the paper describes the use of a personal computer as an aid to calculate the temperature distributions in the workpiece in the process of welding and after welding, and the cooling rate after welding. To this end, the Microsoft Excel software was used. The cooling curves obtained for the individual parts of the workpiece after welding were plotted in a TTT (Time Temperature Transformation) diagram to determine the workpiece structure, hardness and, indirectly, other mechanical properties. The most important finding is that the method described permits to find the locations of maximum stresses in the work-piece that may be potential sources of crack formation.

Continous Butt Welding Method Using Plasma and Laser, and Method for Fabricating Metal Tube Using the Same

Abstract: A continuous butt welding method using plasma and laser, and a method for fabricating a metal tube using the butt welding method are disclosed. The butt welding method conducts a laser welding and a plasma welding together against an object to be welded, which has a very narrow butt space. In particular, the plasma is prior to the laser so that the object is preheated by the plasma, and then a preform is melted by a laser beam in order to accomplish the major welding. In addition, a metal sheet is bent to have a circular section so that its both ends are faced with each other, and then the faced both ends are welded using the aforementioned butt welding method, thereby fabricating a metal tube. The butt welding method and the metal tube fabricating method mentioned above remarkably improve a welding speed and productivity of metal tube.

Weld characterization using eddy current sensors and arrays

Abstract: Eddy current sensors and sensor arrays are used to characterize welds and the welding process schedule or parameters. A sensor or sensor array is placed in proximity to the test material, such as a lap joint or a butt weld, and translated over the weld region. Effective properties associated with the test material and sensor, such as an electrical conductivity or lift-off, are obtained for the weld region and the base material at a distant location from the weld region. The effective properties or features obtained from the effective property variation with position across the weld are used to assess the welding process parameters.

Welded joint excellent in resistance to caulking of metallic composite pipe

Abstract: PROBLEM TO BE SOLVED: To impart good resistance to caulking and carburization to a welded joined part in the case reaction pipes for manufacturing ethylene or the like by pyrolyzing naphtha as a raw material are joined by butt welding SOLUTION: The butt welded joint of the metallic composite pipes is composed by laminate-forming of build-up welding layers 14 having resistance to caulking on the inside of the metallic pipe 12 of a base material The inside of the metallic pipe 12 of the base material which is formed by laminating build-up welded layers is welded by using a filler metal (A) containing 36-49% Cr, 35-63% Ni, 05-5% Mo or a filler metal (B) containing 20-49% Cr, 35-80% Ni and one or two kinds of Al and Si of 15-5% in the total of (Al+Si) and also the rest part is welded by using a filler metal having component equal to the metallic pipe 12 of the base material COPYRIGHT: (C)2005,JPO&NCIPI

Method for controlling and/or adjusting a welding process

Abstract: The invention relates to a method for controlling and/or adjusting a welding process, using a melting welding wire (13), wherein after ignition of an electric arc, a welding process is carried out , said welding process being adjusted on the basis of several different welding parameters and being controlled or adjusted by a control device and/or a welding current source. In order to determine the position or distance between the end of the welding wire (13) and the workpiece (16), which is to be processed, in a manner which is as accurate as possible, at least one mechanical adjustment process (41) is carried out during the welding process, enabling the position of said welding wire (13) to be determined, said welding wire (13) being used as a sensor.

Welding power with control means for the welding joint and the welding position

Abstract: A welding device incorporates some means of selection allowing the operator to select, before the start of welding, at least one primary parameter chosen from the type of weld joint, the welding position and their combinations. An independent claim is also included for a method of electric arc welding using this device.

High heat input butt welding joint exhibiting excellent characteristics in resistance to occurrence of brittle fracture

Abstract: A high heat input butt welding joint exhibiting excellent characteristics in the resistance to the occurrence of brittle fracture which is a butt welding joint in a welded structure, characterized in that (a1) a weld metal has a hardness being 110 % or less relative to that of a base material, or (a2) a weld metal has a hardness being 70 to 110 % relative to that of a base material, and optionally, (b) a weld metal has a width being 70 % or less relative to the thickness of a base plate, (c) the region of a weld heat affected zone being so softened as to have a hardness being 95 % or less relative to that of the base material zone not affected by heat has a width of 5 mm or more, and/or (d) the weld-affected zone (HAZ) adjacent to a weld melt line has an old austenite grain diameter of 200 μm or less.

High heat input butt-welded joint excellent in resistance to brittle fracture generation

Abstract: PROBLEM TO BE SOLVED: To form a welded joint which is sufficiently high in fracture toughness value Kc by butt welding a high-strength steel plate for welding for hulls which is of a 460 MPa class in yield strength and is more than 50 mm in plate thickness. SOLUTION: In the butt-welded joint of a welded structure, (a1) hardness of a weld metal is 110% or less of hardness of a base material or (a2) hardness of the weld metal is 70% or more but 110% or less of hardness of the base material, and when needed, a width of the weld metal is 70% or less of a plate thickness of the base material, (c) a width of a region of an affected portion by welding which is softened into hardness of 95% or less of hardness of the base material not affected by heat is 5 mm or more, and/or (d) an austenitic grain size of the affected portion by welding (HAZ) which comes into contact with a weld fusion line is 200 μm or less, by which the high heat input butt-welded joint excellent in resistance to brittle fracture generation is obtained. COPYRIGHT: (C)2005,JPO&NCIPI

Welding method for tube and infusing nozzle for shielding gas for welding

Abstract: PROBLEM TO BE SOLVED: To provide a method for locally sealing a shielding gas for welding into a tube near a butt welding zone of piping, in a system structure in which sealing of a shielding gas is difficult at the time of welding piping or in which no water soluble film can be used. SOLUTION: In butt welding of a pair of pipes in piping 12, columnar dry ice 11 having an outer diameter equal to the inner diameter of the piping is inserted into the piping, forming a wall inside the piping 12 for the purpose of a purge dam of the shielding gas for welding, thereby suppressing air flow in the air space 13 on the non-welding side inside the piping as well as in the air space 14 inside the piping near the welding back bead. A nozzle 16 for infusing the shielding gas is inserted into the piping 12 from a hole drilled in the groove abutting part in the butt welding zone of the piping 12, with the shielding gas 18 infused into space 14 inside the piping to lower the oxygen concentration, to prevent oxidation in the welding back bead on the piping inner face at the time of the welding. In addition, the outer periphery of the piping in which the dry ice is installed is wrapped with a freezing jacket 10 utilizing liquefied carbon dioxide, suppressing vaporization of the dry ice. COPYRIGHT: (C)2004,JPO

Welding device and method for welding workpieces

Abstract: The invention relates to an ultrasonic welding device which comprises a plurality of elements that adjoin each other via coupling surfaces in a non-positive manner. In order to obtain a sufficiently firm connection between the elements while at the same time simplifying their assembly, the superimposed coupling surfaces (40, 42) of at least some of the elements (30, 34) that are linked in a non-positive manner are structured, thereby obtaining a positive connection.

A fatigue and creep study in austenitic stainless steel 316L used in exhaust pipes of naval gas turbines

Abstract: Exhaust pipes of naval gas turbines are made of thin wall tubing of stainless steel grade AISI 316L. The tubes are fabricated by butt welding of different sections with longitudinal and circumferential joints. The plate thickness is about 4.0 mm, and the working temperature varies between 600 °C and 400 °C in the critical zones of the pipe, in the lower and central areas, respectively. The loadings in the tube induce high-temperature fatigue and creep-fatigue cracks have nucleated and propagated in the tube near some welded joints. The paper presents FCGR data obtained in CT specimens of used material taken from the pipes and tested at RT, 3 3 5, 500 and 600°C. Preliminary creep data obtained in tension, in thin-sheet specimens (about 4 mm thickness), also taken from the conduct wall and tested at 500, 550 and 600 °C are also given. These results are crucial to perform a fatigue-creep interaction life assessment of the critical parts of the structure in the near future. Finally, the paper presents results of research work to investigate carbide precipitation and formation in virgin thin-sheet specimens subjected to several types of thermal exposures. In some cases, 3-4 d was the time interval between exposures. Grain size measurements were carried out together with microstructural observations in the SEM. The influence of time, temperature and time interval between thermal exposures was assessed comparing the microstructures.

Method of controlling the welding of a three-dimensional construction by taking a two-dimensional image of the construction and adjusting in real time in the third dimension

Abstract: A method of controlling the welding in a three-dimensional X-Y-Z coordinate system, in which method a welded structure is provided by a number of pieces arranged on a three-dimensional support base (2) in an assembly in accordance with the construction (1) to be welded, the construction (1) to be welded is photographed and a picture map made of the construction (1), by means of which picture map the weld points of the construction (1) are identified and welding parameters are determined therefor, especially the starting point and the weld type as well as the welding method to be used, and these control data are passed to a control system of the welding equipment. The welding is performed so that the control of the welding equipment in the X-Y plane is based on said picture map provided and said control data, and that the level of the surface to be welded in the direction of the Z-axis, i.e. the vertical axis, in the coordinate system is measured continuously and the level information thus determined is passed to the control system of the welding equipment (4) so as to control the welding equipment (4) in real time also in the direction of Z-axis.

Hybrid Nd:YAG laser-mag welding of thick section steel with adaptive control

Abstract: The laser-arc hybrid welding process is characterised by the simultaneous application of a focused laser beam and an arc welding source. The combination of sources can provide several benefits, one of which is to provide an increased gap bridging capability, when compared with that available from the laser source alone. Using on-line monitoring of the joint geometry and adaptive control of the hybrid welding parameters, the tolerance to joint gap and fit-up can be increased and a consistent weld quality and profile can be maintained. This paper describes the results of an exploratory study, to perform adaptive hybrid laser-MAG welding, via on-line control of the process travel speed. The work used feedback from joint gap measurements, acquired from a laser vision system, in an attempt to maintain constant weld quality, particularly in terms of weld profile, when welding samples with varying gaps. When hybrid welding was used to produce square-edge butt welds in 8mm thickness C-Mn steel, a stringent weld quality, as defined for class-B of EN-ISO13919-1, could be achieved for joint gaps as large as 1.2mm, under conditions of adaptive control. Without adaptive control, this stringent quality level could be maintained only when the joint gap was less than 0.8mm.The laser-arc hybrid welding process is characterised by the simultaneous application of a focused laser beam and an arc welding source. The combination of sources can provide several benefits, one of which is to provide an increased gap bridging capability, when compared with that available from the laser source alone. Using on-line monitoring of the joint geometry and adaptive control of the hybrid welding parameters, the tolerance to joint gap and fit-up can be increased and a consistent weld quality and profile can be maintained. This paper describes the results of an exploratory study, to perform adaptive hybrid laser-MAG welding, via on-line control of the process travel speed. The work used feedback from joint gap measurements, acquired from a laser vision system, in an attempt to maintain constant weld quality, particularly in terms of weld profile, when welding samples with varying gaps. When hybrid welding was used to produce square-edge butt welds in 8mm thickness C-Mn steel, a stringent weld q...

Method for manufacturing butt-welded metallic plates by laser

Abstract: PROBLEM TO BE SOLVED: To provide a laser butt welding method capable of forming an improved weld bead at the time of joining metallic plates of a mutually different melting point by laser butt welding, for example, between a steel plate and an aluminum alloy plate, a steel plate and a copper plate, or an ordinary steel plate and a stainless steel plate. SOLUTION: In the method for manufacturing a welded metallic plate by joining metallic plates of a different melting point by butt welding by laser, the emitting laser energy is set larger to the metallic plate of the higher melting point than that of the metallic plate of the lower melting point. COPYRIGHT: (C)2005,JPO&NCIPI

Friction stir welding method and friction stir welding device

Abstract: A welding tool is inserted into an object in a rotation-stopped state, and the welding tool is rotated after insertion, thereby the object is stirred by frictional heat. The welding tool is inserted into the object free of whirling. The welding tool can be prevented from inserting in a position shifted from the target welding position. Namely, the welding tool is precisely inserted in the target welding position and members of the object can be welded in the target welding position free of shifting.

Working arm for construction machine and method of producing the same

Abstract: A wide plate-like material ( 27 ), having thin and thick wall portions in a transverse direction, is prepared by alternately joining one of flat thin plates ( 28, 29 ) and one of thick corner plates ( 30 ) or thick plates ( 31 ). The wide plate-like material ( 27 ) is bent at and along right and left thick corner plates ( 30 ) and formed into a U-shaped structure ( 32 ) which is U-shape in cross section. Separately from the U-shaped structure ( 32 ), a plate-like member ( 33 ) is prepared by butt welding thick plates ( 35 ) to right and left sides of a thin plate ( 34 ). The plate-like member ( 33 ) is welded to a lower side of the U-shaped structure ( 32 ) by laser welding or the like to form a square tubular structure, which is in a square shape in cross section and serves as a major part of an operating arm.