Showing papers on "Submerged arc welding published in 1975"

Short-circuit arc welding with constant beads

Abstract: In short circuit arc welding there are many parameters which influence the automatically controlled welding procedure, but which frequently may affect the quality of the weld. In some circumstances the welding bead which is formed does not flow in to the molten pool of the workpiece, but disintegrates into many small drops around the weld owing to an excessive short-circuit current. The invention proposes methods and arrangements in which certain parameters, such as arc time and a short-circuit current delay time are controlled or maintained constant, so that always a constant bead size is assured owing to a constant power, after which said bead of constant size is first partly introduced into the molten pool and subsequently the short-circuit current for separation is applied.

Fatigue crack propagation in a Type 316 stainless steel weldment

Abstract: The relationship between fatigue crack propagation rate per cycle da/dN and the variation in stress intensity ∆K has been studied for the material in and around a submerged arc weld in an austenitic stainless steel of Type 316L composition. The behaviour observed is correlated with the microstructure of the material, and with the fracture surfaces obtained.

Extended arc furnace and process for melting particulate charge therein

Abstract: The furnace and process disclosed herein comprise an extended arc furnace having at least one electrode with an axial opening therein through which an appropriate gas, such as argon, may be fed into the extended arc, and a substantially vertical reaction zone above the extended arc through which a particulate charge is fed by gravity into the extended arc zone and in its downward course through the reaction zone the particulate charge is heated and, if desired, a reaction such as reduction may be effected. The rate of gas flow upward in the reaction zone is slow enough to permit free falling of the particulate charge but fast enough to suspend the particles for the heating and reaction time desired. The axial electrode opening or openings are of a size to permit creation of a stabilized extended arc and to give reduced electrode consumption, improved current and voltage wave forms, and the furnace power may be modulated by changing either the rate of gas flow or the composition of the gas. The feeding of the gas internally into the arc gives the extended arc a stability not achievable by other methods of feeding the gas to the arc volume.

High intensity radiation source

Abstract: The novel radiation source system of this invention includes a pair of electrodes which are coaxially mounted at each end of a single cylindrical transparent arc chamber. A liquid, such as water, is circulated through the arc chamber with a tangential velocity so as to form a vortexing liquid wall. The main functions of the liquid wall are to cool the periphery of the arc discharge between the electrodes thus constricting the arc diameter, and to absorb ultraviolet and infrared radiation which would otherwise be absorbed by the outer solid wall. This liquid wall produces a positive dynamic impedance for the arc discharge. In addition, a vortexing column of inert gas, injected through the length of the chamber, stabilizes the arc discharge between the electrodes. In one embodiment, the structure of the anode electrode includes an annular constriction which is mounted near the anode surface to constrict the diameter of the arc column near the anode and to form a gas expansion chamber adjacent to the anode surface wherein the inert gas on expansion loses its vortex motion. The arc is therefore no longer vortex stabilized and current density at the anode surface is reduced. In a further embodiment, the anode structure includes an expanding chamber at the anode into which both the liquid and the gas lose their vortex motion. A 3-stage starting and power supply circuit is connected across the electrodes. It includes a pulsing circuit to initiate the arc discharge across the fixed electrodes and a programmed capacitor bank to sustain the arc until such time that the main power supply, with its inherent high inductance, provides sufficient current to the radiation source to maintain the arc.

Apparatus and method for submerged arc strip cladding of metallic work pieces

Abstract: An improved method and apparatus for the submerged arc surfacing of metallic work pieces with metal electrode strips melting in an electric arc while forming welding beads upon the work piece. The apparatus comprises a work piece which is to be surfaced, an electrode strip comprising the cladding material, means operative to move the strip and work piece relative to one another, a DC source, the opposite poles of which are connected to the electrode strip and the work piece, an electro-magnetic means having poles of opposite polarity operatively positioned at opposite sides of the electrode strip and adjacent the pool of molten flux and molten metal lying behind the electrode strip. The current to the electro-magnetic means is pulsed to thereby cause an agitation of the molten slag and weld deposit thereby resulting in a weld bead of extremely high quality, uniform thickness and also a defect-free tie-in between adjacent weld beads.

Fume extraction control for welding gun

Abstract: A welding gun is provided having vacuum fume extraction means wherein the level of vacuum exerted at the arc welding zone is regulated to avoid extracting shielding gas supplied to the welding zone. The vacuum level is regulated by admitting sufficient air to a fume extracting passage provided within the gun to reduce the vacuum to the desired level.

Methods of welding corner joints

Abstract: A method of welding corner joints by means of a multiple electrode submerged-arc welding and adapted to be utilized for the manufacture of a hollow square steel pillar and the like structural frameworks is disclosed. The method of welding is effected under the following three conditions: 1. The distance between first and second electrodes is 30 to 80 mm, 2. The current flowing through the second electrode is 60 to 85% of the current flowing through the first electrode, and 3. The welding heat input H is given by H ≦ 24d.t KJoule/cm where t is a thickness of a steel flange plate in cm and d is a required penetration depth in cm, whereby a weld bead is completed by a single pass of welding.

Method of multiple electrode gas shielded arc welding

Abstract: of the Disclosure In a multiple electode gas shielded arc welding method wherein a plurality of electrodes are arranged along the welding seam line of a piece of metal to be welded and the continuous gas shielded arc welding of the piece is accomplished simultaneously by the electrodes, the chemical composition of a mixed shielding gas fed to the electrodes is selected in such a manner that the chemical composition of the shielding gas fed to the leading electrode or electrode group differs relative to that fed to the trailing electrode or electrode group to have a different active gas volume ratio and in this way the chemical composition of the weld metal layers formed by the preceeding and following welding operations are homogenizing to ensure uniformity of the properties at every positions in the weld zone.

Submerged arc welding internal seam in pipe mfr. - using flexible rows of roller guides to feed electrode wire to burner nozzles

Abstract: Welding device, esp. for the submerged arc welding of internal seams, using a welding head which can be fed into an opening in a workpiece, esp. a pipe, and using roller guides to turn a welding wire travelling parallel to the seam so the wire passes through a burner nozzle located at 90 degrees to the seam. The novelty is that the roller guides consist of several pairs of rollers located on each side of the guide path in holders, the rollers being joined by flexible connections used to alter the direction or curve of the guide path. The holders and connectors pref. consist of a ribbed plate with cheeks on which the roller bearings are mounted, the cheeks being joined by flexible webs; alternately, the ribbed plate may be assembled from separate links. The guide paths for the welding wires are very easy to adjust and a min. radius of curvature of 8 cm achieved, suitable for welding pipes with dia. below 1 metre.

Vertical welding of thick aluminum members

Abstract: An apparatus for and method of welding aluminum members substantially vertically is provided wherein a groove-defining surface is formed on each of the members and such members are positioned adjacent each other with the groove-defining surfaces cooperating to define a substantially vertically extending groove. A gas-metal arc torch having a consumable electrode and means for supplying a shielding gas therearound is placed with the electrode in the groove, whereupon a welding arc is generated and the torch is moved substantially vertically along the groove while holding the torch at a backhand torch angle. The consumable electrode and shielding gas are fed at predetermined rates therefor while moving the torch and welding arc substantially vertically along the groove to produce weld metal in the groove having an outside oxide support skin and the oxide support skin is the only support required for the weld metal during its solidification.

Delivery of welding flux in a method of submerged arc strip cladding of metallic work pieces

Abstract: A method and apparatus is disclosed for feeding welding flux to both the leading and trailing sides of the strip electrode used in a submerged arc strip cladding process. In order to prevent distortion of the bead shape the pressure due to the weight of the flux burden is controlled to be less in the region of the molten metal and slag pools lying directly behind the welding arc. The flux burden is caused to increase from a first depth directly behind the strip to a maximum depth at the trailing edge of the weld crater region where the quantity of liquid metal and liquid slag is a minimum.

Butt welding process and apparatus for effecting same

Abstract: Disclosure is made of a butt welding process, whereby butt ends of articles to be welded together are placed one opposite the other in a chamber containing a shielding medium. The butt ends are then heated until a layer of molten metal is formed on their surfaces, and upset in order to effect their plastic deformation and produce a weld joint. According to the invention, the heating and flashing-off of the butt ends are effected by a low-pressure arc uniformly distributed over the entire butt end surfaces of the articles being welded. The proposed method is effected through the use of an apparatus which, apart from a welding transformer whose secondary winding terminals are connected to articles being welded, comprises, in accordance with the invention, an auxiliary transformer that serves to initiate a low-pressure arc, or, successively, a glow discharge and a low-pressure arc between the butt ends of the articles being welded, as well as to stabilize said low-pressure arc, the secondary winding terminals of the auxiliary transformer being connected to the articles being welded via a valve-type breaker intended for controlling the low-pressure arc. The proposed process and apparatus for effecting this process make it possible to weld articles with different cross-sectional configurations, while making use of small deformations of articles in order to produce a weld joint. The process and apparatus of the present invention also account for a stable welding process.

Method of multiple gas shielded arc welding

Abstract: of the Disclosure In a method of multiple electrode gas shielded arc welding wherein a plurality of electrodes are arranged along the welding seam line of a piece of metal to be welded and the continuous gas shielded arc welding of the piece is accomplished simultaneously by the electrodes, the chemical. composition of the electrode wire of the electrode or electrode group for depositing a proceeding layer or layers is selected to differ from that of the electrode wire of another electrode or electrode group for depositing a subsequent layer or layers, whereby the chemical composition of the weld metal made by the preceed-ing welding operation is brought near to that of the weld metal made by the following welding operation and thus the uniform properties are ensured for the welding metals at the respective positions in the weld zone.

Method of and apparatus for arc welding

Abstract: Method of arc welding in which an electric arc is maintained between a welding wire and a workpiece in a thermally ionized gas which is produced by an electric arc maintained between the workpiece and the inner surface of a nozzle which acts as a non-consumable electrode as a substitute for a separate tungsten electrode.

Automatic arc welding process using a consumable nozzle

Abstract: An automatic arc welding process for welding in a substantially horizontal direction, includes the steps of placing a longitudinal consumable nozzle along the joint line within the weld groove, the nozzle being coated with an insulating material disposed therearound and having a hollow core portion, and continuously feeding a wire through the hollow core portion.

Backing flux for one side arc welding

Abstract: PURPOSE:To provide the subject flux wherein an aqueous dextrin solution which has been prepared in a specific viscosity is mixed and added in the flux thereby to apply the solution on the flux uniformly, and further applying a suitable quantity of calcium stearate on the surface thereof thereby to make it possible to carry out effective welding.

Flux-cored wire for electric arc welding of soft steels or low-alloyed steels

Abstract: Flux-cored wire for automatic or semi-automatic arc welding process, comporting specific powder compositions as detailed in the description, which are high in amounts of metallic powders, mixed with metallic silicate solution to form a paste and baked before its introduction within a low-carbon or low-alloy steel sheath.

Gas tungsten arc welding electrode

Abstract: An improved electrode and electrode working tip for a gas tungsten arc welding apparatus. The face of the working tip of the electrode is formed as a narrow ring coaxial with the electrode and having an area less than the area of electron emission for the operating currents of the electrode. The reduced area of the narrow annular ring forces the area of electron emission to spread to the immediately adjacent walls. The improved electrode working tip provides a more stable and uniform plasma of reduced diameter for improved precision and repeatability in welds which is the ability to consistently reproduce welding parameters. The electrode tip also has a significantly increased working life.

Lay down arc welding method

Abstract: A lay down arc welding electrode with improved weld penetration is described. The welding electrode includes a core wire surrounded by flux, a portion of which has been longitudinally removed or has been otherwise made thinner than the flux surrounding the remainder of the arc wire. The direction of arc is adjusted by varying the shapes of core wire and flux. During welding the arc welding electrode rests on a tack weld. This causes directional angle (α) to the root of the weld to increase and the divergence angle (β) to decrease, resulting in improved penetration of disposed metal. An apparatus is described for continuous lay down arc welding using the described arc welding electrode.

Flux breaker for submerged arc strip cladding of metallic work pieces

Abstract: The invention relates to an improvement in apparatus for carrying out the submerged arc surfacing of metallic work pieces with metal electrode strips melting in an electric arc while forming welding beads upon the work piece. A slag breaker comprising a series of parallel plate portions disposed substantially perpendicular to the surface of the electrode strip is positioned on the leading side of the electrode strip adjacent the region of the electric arc. The slag breaker serves to break up an accumulation of fused flux particles which tend to form a sheet in front of the welding arc which, if permitted to form would block the flux feed into the welding arc on the leading side. The slag breaker thus serves to prohibit formation of such a sheet and thereby permits uniform flow of flux to insure complete submergence of the arc in the flux material thus minimizing the chance of the arc flashing through the flux burden and resulting in defects in the deposited cladding material.

Vertical arc welding with consumable electrode wire - using intermittent arc to produce a series of overlapping spot welds

Abstract: Prodn. of vertical welded seams with endless wire electrodes and esp. fillet welds, in which the welding gun is moved either stepwise or continuously along the seam while the arc is operated at a low, partial power or switched intermittently on and off so that a seam is produced consisting of individual overlapping spot welds, and the welding of the next spot only occurs when the molten pool of the preceding spot has cooled sufficiently so that there is no danger of falling drops from the previously molten material. Welding is pref. carried out upwards with an and off times of 0.7-2.5 seconds, the same time intervals pref. being used in both cases, and with the welding gun oscillating transversely with amplitude 40% of the half the seam width and at 2.5-8 Hz. Used for vertical welding, e.g. in shipbuilding. Thin seams can be obtd. without difficulty, e.g. only 3-6mm on plates 10-25mm thick.

Transport circuit for welding powder in submerged arc welding - in which powder sucked off seam is directly re-used

Abstract: In submerged arc welding of the bores of tubes, esp. large dia. tubes, the used welding powder is sucked up from a point behind the welding zone and fed into a container located above the welding zone; the powder then being fed in controlled amts from the container to a point in front of the welding zone. A separate inlet is pref. provided for adding new powder to the used powder, and the pref. appts. consists of a container with an outlet for the powder and a suction pipe contg. an injector, plus an air outlet connected to a suction device and the inlet for new powder.

Spot-welding using spring-loaded electrodes - which rotate under pressure so surface impurities on workpieces are removed

Abstract: Device for the welding together of metal parts, the surfaces of which are coated with oxides and/or other impurities, e.g. rust, scale and/or oil, directly reduces the electrical vol. resistance between the welding electrodes and the metal parts being welded together. The welding electrodes rotate when subjected to the welding pressure. Pref. the electrodes are mounted in threaded bushes so they rotate under pressure and remove the unwanted surface layer(s), pref. using a thread with a coarse pitch, location stops, and a pressure which is a function of the angle of rotation using either a constant or increasing pressure. Used for single- and/or multi- spot welding. The simple device cleans the surfaces of the metal parts and also the electrodes, so the required welding voltage is reduced and electrode life increased.

Theoretical model of the submerged arc welding process

Abstract: Expressions for the direct current and melting rate of wire electrodes in the submerged arc welding process are derived via the principles of irreversible thermodynamics. The melting rate of the consumable wire electrode under quasi steady state conditions consists of eight contributions: 1) Peltier heating effect, 2) Arc heating effect, 3) Contact resistance effect, 4) Radiation heat transfer effect, 5) Joule heating effect, 6) Heat conduction effect, 7) Melting rate effect of electrolyte flux, 8) Melting rate effect of the sublayer zone. Application of the general theoretical melting rate to a limiting case of practical interest reveals good agreement between theoretical predictions and experimental results. The affect of polarity reversal on melting rate is explained in terms of thermionic emission phenomena.

Fracture Toughness of Welded Joints of 9% Ni Steel for the Tank of LNG Carriers

Abstract: The basic premise of the MOSS-Rosenberg LNG containment system and other spherical LNG tank system is “leak-before-failure”. In other words, the design concept applied to this type of pressure vessel is basically “fail-safe”.Therefore, to evaluate the structural safety of the spherical LNG tank, it is neccesary to obtain the fracture toughness of the tank shell plate and the welded joints, quantitatively. Considering the strength of brittle fracture initiation of 9% Ni steel LNG tank, the fracture toughness in the heat affected zone is the most important problem.Accordingly, the authors carried out the tension test with wide center-notched plate test specimens, notched in the heat affected zone of submerged arc welding with heat input values of about 1050 KJ/cm, in order to evaluate the fracture toughness of welded joints of 9% Ni steel.The following conclusions were obtained.(1) It is reasonable to calculate the critical crack length, using the experimental results obtained from the standard size specimens (about 400 mm wide) on the basis of Linear Elastic Fracture Mechanics.(2) For the butt-welded joints produced with the most practical heat input values of about 1040 KJ/cm, the lowest Kc values at the cryogenic temperature of LNG, -62°C, will be 775500 kg, √mm/mm2, and the critical crack length for brittle fracture initiation of 9% Ni steel LNG tank is satisfactorily long.