Showing papers on "Heat-affected zone published in 1977"

Welding Process Technology

Abstract: Preface 1. Properties and classification of welding processes 2. The welding arc 3. Flux-shielded arc welding 4. Gas-shielded arc welding 5. Unshielded and short-time arc welding 6. Resistance welding 7. Thermochemical welding 8. Radiant-energy welding 9. Solid-phase welding 10. The selection of welding processes 11. Automatic welding 12. Economic considerations Index.

Melting Phenomena in Solid State Welding Processes

Abstract: Different aluminum and copper alloys with a well defined microstructure are joined by ultra­ sonic, explosion and friction welding. Transmission electron microscopy is used to study the microstructure with­ in the bonding area of the welded joints. From the change in microstruc­ ture, as compared to the material in its original state, conclusions are drawn on the bonding mechanism of these welding processes. In ultrasonic welding, bonding occurs predominantly by a short time melting of a narrow surface layer (less than 1 fim thick) followed by rapid cooling. In explosion welding, melting phenomena are not only found in the well known melt pockets of wavy interfaces; even plane interfaces of similar alloy welds show evidence of melting within a 0.5 to 4 /am thick zone. During the friction welding of two dissimilar aluminum alloys used in this investigation, the temperature exceeds the melting point only within isolated areas along the interface up to 15 fim in size.

Automatic pipe welding apparatus and method

Abstract: A TIG pipe welding method which employs two sets of machine guide surfaces on the pipe ends. First radially inner guide surfaces cooperate with a sensor coupled to the welding torch to continuously monitor the arc gap between the welding electrode and the weld puddle as the welding electrode moves around the circumference of the pipe. The second set of radially outer surfaces cooperate with a welding carriage to guide the carriage and welding modules around the pipe joint. The carriage is constructed to provide a sealed welding chamber surrounding the electrode. An additional flow of shielding gas is provided around the torch electrode of a TIG or hot wire TIG welding module to augment the normal gas shield. The augmented shield provides a gas flow in opposition to pressurized air flowing through the welding chamber to prevent exposure of the weld nugget to the pressurized air flow being maintained in the welding chamber while permitting the pressure forces to be transmitted through this shield to the weld nugget, creating a "puddle pushing" effect. The transfer of forces through the gas shield, while preventing contaminating air from entering the weld zone itself, provides a positive force for pushing the molten weld puddle through the joint to the interior surfaces of the joined pipe ends. The pressurized air further flows outwardly between the seals of the welding carriage and the pipe surfaces to create an air cushion between the pipes and the carriage. An internal weld backup and pipe alignment ring is also provided.

Prior austenite grain growth in heat-affected zone of a O.5Cr-Mo-V steel

Abstract: A weld thermal-simulation technique has been used to produce prior austenite grain sizes similar to those observed in the heat-affected zones (HAZs) of O.5Cr-Mo-V welds. Grain-size measurements have been used to develop an Arrhenius equation for grain growth in artificial HAZs. This equation is in reasonable agreement with an ‘impurity drag’ theory for grain growth. In applying the equation to weld HAZs it was found that the steep thermal gradients present resulted in a ‘thermal pinning’ effect which inhibited growth. A final expression has been obtained which describes prior austenite grain growth in manual metal arc weld HAZs in 0.5 Cr-Mo- V steel as a function of heat input. The practical implications of this equation are discussed in terms of grain-size control in the HAZ during welding and these indicate that finegrained HAZs can be produced by low heat inputs and a suitable weld-bead overlap technique. In principle, the approach described

Method of arc-welding

Abstract: In underwater arc welding in a chamber filled with gas a consumable flux cored arc welding wire is fed to a welding torch and an arc is struck between the wire and the work to be welded so as to effect transfer of weld metal from the wire to the work. The arc welding wire contains at least one strong deoxidizer selected from the group consisting of magnesium, aluminium, zirconium, titanium, barium, lithium and calcium. A shielding gas is fed to the torch and emerges therefrom as an annular curtain of gas which shields the arc. The shielding gas also helps stabilize the arc from the effects of underwater pressure. The shielding gas comprises at least one oxygen-containing gas selected from oxygen and carbon dioxide.

Diagram for the prediction of weld heat-affected zone microstructure

Abstract: The performance of welded joints, both during fabrication and operation, can depend critically upon the microstructure ofthe heat-affected zone, which, in a steel of given composition, is a function of the welding procedure andjoint geometry. The selection of suitable welding conditions which avoid the formation of crack-sensitive structures is clearly desirable. Standard heat-flow equations have been used in conjunction with continuous cooling transformation diagrams, determined using a weld simulation and dilatometric technique, to predict as-welded heat-affected zone microstructures for a wide range ofwelding conditions. A novel microstructure-welding diagram is described in which the variation in heat-affected zone microstructure as a function of process heat input, joint thickness, and preheat temperature is presented in a readily comprehensible form. A 0.5Cr-Mo-V steam-pipe composition is used as a detailed example, but the method is, in principle, applicable to a wide range ofsteel composi...

Method and apparatus for tig welding

Abstract: A method for TIG welding by using a plurality of nonconsumable electrodes extending frm the tip of a TIG welding torch and one filler wire fed through a space between the electrodes, each electrode being independently supplied with power. A molten pool is formed by melting both the base metal to be welded and the filler wire by means of arcs generated between respective electrodes and the base metal. Melting of the base metal is mainly controlled by the arc produced by one of the plurality of electrodes while melting of the filler wire is mainly controlled by the arc generated by the other electrode.

Welding apparatus with shifting magnetic field

Abstract: The present invention relates to a welding process and apparatus. More particularly, the invention relates to a welding process and apparatus for performing welding in various positions characterized in that a shifting magnetic field is generated in the vicinity of a molten metal pool to induce an eddy current in the molten metal pool, whereby an electromagnetic driving force is caused to act on the molten metal pool to control the shape of the molten metal pool, and welding is carried out while controlling the shape of the molten metal pool in this manner. According to the welding process and apparatus of the present invention, the welding efficiency can be enhanced irrespective of any welding positions.

Automatic hot filler wire welding method and apparatus

Abstract: OF THE DISCLOSURE In an application to welding generally cylindrical members along a designated circumferential weld seam, the method and apparatus of this invention simultaneously pro-duce substantially identical welds at a plurality of spaced weld zones along the weld seam symmetrically situated about an axis bisecting the axis of revolution of the member by automatically controlling and establishing a substantially identical ratio of heat input to volume of deposited metal along the weld seam at each of the weld zones at any given point in time. Identical welds are achieved by automati-cally, programmably, controlling the power employed to preheat the filler material at each welding location as a function of the corresponding filler material feed speed and the respective feed speed and power imparted to each weld zone as a programmed function of the speed of the weld zone along the seam and the respective feed speed and welding power corresponding to each of the other weld zones along the seam.

Method of arc welding under water

Abstract: In a method of arc welding under water or at superatmospheric pressure (or both) the weld is made in a chamber containing a gaseous atmosphere. The weld metal is deposited from flux-cored welding wire whose core contains strong deoxidant(s) such as aluminium, magnesium, titanium, zirconium, lithium and calcium. A shielding gas containing a selected proportion of oxygen or oxygen-containing gas but consisting mainly of an inert gas such as argon or helium is employed to surround the arc. The shielding gas is constituted by the atmosphere in the chamber.

Method of welding laminated sheed metals

Abstract: PURPOSE:To accomplish welding of two assemblies of laminated sheet metals together in a proper fusion width by preventing the peeling of sheet metals and the development of defective welding through irradiation of electron beam or the like along a weld line, with clamping of press plates having a given thickness, made of the material identical to the metals so arragned on the surface of the metal assemblies or placed in contact therewith.

Method of connecting metallic parts by means of arc fusion welding

Abstract: A method of connecting metallic parts, and metallic parts so produced, by means of arc fusion welding by producing a low volume welding seam (narrow gap welding), wherein the workpiece parts to be jointed and forming a narrow gap are initially welded at their butt joint by means of, for instance, electron-beam welding, plasma-arc welding, laser-beam welding or argon arc-welding to produce a base seam with or without filler material, and thereafter the workpiece flanks forming the narrow gap are united by alternately depositing weld beads at first one and the other workpiece flank by submerged-arc welding.

A review of minor element effects on the welding arc and weld penetration

Abstract: A critical review of all the available literature pertaining to welding arc and weld penetration has been undertaken The review revealed several studies which indicate that the intentional or unintentional addition of small amounts of halides to the base material significantly improves weld penetration The presence of oxygen in the weld materials has been reported to have both positive and negative effects on the depth and shape of the weld Various other elements present in the base material have been alluded to as a means of changing the penetration characteristics of the GTAW process In particular, aluminum addition to the arc or excessive aluminum in the base material has been observed to produce a flared arc at the anode surface In many cases these changes are accompanied by variations in the arc voltage which, if properly interpreted can act as a warning signal for potential problems The general conclusion of all the published reports stress the need for additional systematic study and further research into this problem area in order to understand the causes and effects that have been noted experimentally An attempt has therefore been made to provide some beginning and rationale for understanding how the properties of minor elements can affect the factors which influence weld penetration In particular, the factors discussed relate to changes in the work function of both the anode and cathode surfaces, the arc voltage and arc configuration, in addition to surface tension effects of the weld puddle and arc stability In order to provide much-needed additional experimental data to this problem area, a spectroscopic analysis of a typical GTAW arc was undertaken and a simple test initiated to determine the "penetration" qualities of various heats of EN 82 filler material The results and conclusions of these studies are reviewed

Electron beam welding of carbide inserts

Abstract: Carbide inserts in earth boring drilling tools are attached to the tool base metal by means of one or more spike welds formed by electron beam welding. The spike weld is formed at an angle through the metal surrounding the base of the insert and into the side of the insert near its inserted end.

Narrow weld-groove welding process

Abstract: A narrow weld-groove welding process, in which a bare welding wire is fed into a weld groove defined between the opposed surfaces of two pieces of metals for producing a metal arc therein for welding. In this process, a welding wire is subjected to a plastic deformation of a wave form, before being fed into a nozzle hole provided in a contact tip, and then the wire is fed into a nozzle hole, while maintaining elasticity tending to cause waving, whereby the tip of a welding wire being fed through a nozzle exit is automatically weaved between the opposed surfaces of metals to be joined, with the tip of wire being alternately faced in the opposite directions, in response to the weaving motion thereof, with the feeding of the welding wire and progress of welding. In addition, the apparatus for use in a narrow weld-groove welding process is also disclosed.

Weld heat-affected zone liquation cracking and hot ductility in high-strength ferritic steels

Abstract: In this paper, the authors examine the correlation between hot-ductility test data obtained in simulated weld thermal cycles and weld heat-affected zone (HAZ) liquation cracking in ferritic, low-alloy steels of the En 24, SAE 4130, and ASTM A387B types. The work covered steels containing various levels of carbon, sulphur, and phosphorus whose cracking susceptibility had already been quantitatively assessed. It was shown -that hot-ductility testing under the conditions of thermal simulation reproduced the metallurgical processes occurring in the real weld HAZ and was, therefore, a valid method of investigation. Furthermore, it was demonstrated that the severity of cracking in these steels could be related quantitatively to the zero ductility range (ZDR) measured during cooling, provided that the peak temperature was equivalent to or higher than the nil strength temperature. Since the ZDR and weld-cracking susceptibility were affected in a similar way by the elements carbon, sulphur, and phosphorus,...

Composite piston for high performance engines - has thermal cracking preventing welding ring on piston cavity edge

Abstract: The composite piston for an internal combustion engine has upper and lower part. The upper part has cavity for combustion chambers, and is used in high performance engines. The upper edge of the piston top face cavity is especially protected against thermal cracking. A ring of high temperature resistant material is welded on the edge (20) of the combustion chamber cavity in the piston. This ring is welded without use of filler metal by electron beam welding on the piston upper part (12) or by friction welding. A conical seat between the ring (16) and the piston upper part (12) is provided for welding. A tubular component can be welded by friction welding and excess material is removed by machining.

Method and apparatus for control of method parameters in energy beam welding

Abstract: A method and an apparatus for the control of the filler material supply rate in energy beam welding as electron beam welding is disclosed. The width or cross-sectional area of a gap defined by opposed faces of two workpiece parts to be joined is measured by radiation, preferably X-ray radiation, and the rate with which filler material is supplied into a welding zone produced by the energy beam is controlled in proportion to the result of the measurement. The measurement may be made in advance of the welding zone and the control is then delayed by a period of time, which the welding zone takes to arrive at the position of the gap, where the measurement was made.

Preliminarily treating method for diffusion welding of stainless steel, aluminum or aluminum alloy

Abstract: PURPOSE: To enable the effective diffusion welding, by electrolyzing in the electrolytic solution using the welding material consisting of stainless steel or Al(alloy) as the anode, removing the oxide and nitride coating on the surface and then immediately plating a specified metal respectively using the welding material as the cathode. COPYRIGHT: (C)1978,JPO&Japio

Method for producing an electrical contact element

Abstract: A contact element is produced by sonically welding one or more contact pieces onto a carrier, an intermediate layer, for example of aluminium foil, being interposed between the contact piece and the carrier prior to such welding in order to assist in the welding of the contact pieces made of material which would otherwise be difficult to weld. Typical frequencies of sonic welding lie in the range between 20 kHz and 50 Hz.

Automatic arc welding method for high efficiency multielectrodes of low temperature high toughness steel

Abstract: PURPOSE: To weld the thick steel plate, having a superior low temperature toughness, with a high efficiency, by forming the root pass bead with HIG welding using the wire, restricted C, P, S by multielectrodes automatic welding and carrying out submerged arc welding by heat input quantity of the wire, having a specific composition. COPYRIGHT: (C)1978,JPO&Japio

Method for longitudinally seam-welding pipe-blank for welded steel pipe from the inside along a groove

Abstract: In longitudinally seam-welding a pipe-blank for welded steel pipe from the inside along a groove by the reverse-polarity GMA welding process comprising using direct electric current supplied to a consumable electrode through a cable as the welding current with said consumable electrode as the anode, the direction of said direct electric current for welding flowing through said cable introduced into said pipe-blank is set in the same direction as that of welding, thereby preventing occurrence of a magnetic arc blow of the welding arc from said consumable electrode toward the upstream side of the welding direction, ie, in the opposite direction to that of welding

Welding manganese steel

Abstract: Sections of cast manganese steel, or manganese steel to be interfaced to another steel, are joined by electroslag welding. Metallurgical limitations, operating parameters and physical attributes of the guide tube are imposed to retard embrittlement of the base metal and weld metal as well, to prevent tearing, to assure satisfactory ductility, and to preserve the integrity of the austenitic manganese steel in the weld metal.

Method of making an electrical contact element

Abstract: The contact element is produced by sonic or ultrasonic welding one or more contact pieces onto a carrier, an intermediate layer in the form of a grinding powder being interposed between the contact piece and the carrier prior to such welding in order to assist in the welding of contact pieces made of material which would otherwise be difficult to weld.

Apparatus and method for inert gas arc welding

Abstract: An arc welding torch terminates in a gas cup open at one end through which an electrode projects. Inert gas is introduced under pressure at the other end of the gas cup and flows past and through a gas diffuser disposed in said gas cup. The diffuser is spaced from the inner wall of the gas cup, and a portion of the gas flows axially parallel to the central axis of the gas cup. The diffuser has a set of passageways to form and direct columns of gas in an outward direction, and another set of passageways to form and direct columns of gas in an inward direction. The diffuser is axially and angularly adjustable to vary the pattern of gas discharge with relation to the arc and to control the contour of the weld bead. BACKGROUND OF THE INVENTION The present invention relates to inert-gas arc welding, and more particularly, to a method and apparatus for applying a shielding gas in the welding operation. In the conventional arc welding processes, such as either the TIG (tungsten inert-gas type) or the MIG (consumable inert gas type), the heat generated by the electrical arc is utilized to reduce the metal material to be joined to a molten state to effect fusion between the parts to be joined. Most metals in a molten state will react with atmospheric gases, usually resulting in an unstable arc and a poor weld. In one known process for stabilizing the arc, when welding aluminum plate or the like, a shielding gas, which is normally argon or helium, is utilized to surround the arc and exclude atmospheric gases from the weld area and prevent oxidation of the molten metal which will ultimately form the weld. In addition, the gas provides a low resistance path for the arc and the gas ions provide a cleaning action by bombardment of the metal surfaces to be welded. Various problems have existed in the application and utilization of the shielding gas. For example, optimum cleaning action was not achieved. Weld bead contours were not as controllable as desired. A very close torch cup to work distance had to be maintained to prevent disruption of the gas pattern by external forces. Moreover, the efficiency of the gas consumption was less than desired. In addition, when welding in vertical position, the weld metal flow and solidification patterns were less than optimum. An example of a plasma generating torch is shown in U.S. Pat. No. 3,604,889 but in such patent the gas, instead of being directed in columns, is cone-shaped and is concentrated into a stream which penetrates the arc externally of the torch. Moreover, there is not axial or angular adjustment of the stream. SUMMARY OF THE INVENTION A gas cup substantially closed at one end and open at the other has an electrode disposed therein. An inert gas entrance means is disposed remote from the open end. A diffuser in accordance with the present invention is mounted to direct the gas in a predetermined manner relative to the arc and the pieces to be welded, in accordance with the present invention. The diffuser is adapted to form and direct columns of the inert gas in an outwardly flaring direction from the central axis of the electrode and to form and direct other columns of the inert gas towards the longitudinal central axis of the electrode. The diffuser also coacts with the body of the torch to form a cylindrical column of gas which surrounds the directed columns of gas to provide a protective shield for the directed columns. The diffuser is adjustable axially and/or angularly with reference to the electrode, whereby the gas columns may be varied for the most efficient operation. By the foregoing arrangement, improved cleaning patterns provided by the cleaning action of gas ions bombarding the metal surface has been achieved, and improved weld bead contours have been obtained. The torch cup to work distance is not as critical, and the disruption of the gas pattern by external forces is reduced. The gas consumption for a given torch nozzle size and set of welding parameters has also been reduced by the improved utilization of the gas to provide optimum effect. Moreover, improved weld metal flow and solidification patterns have been obtained when welding in the vertical position.

Welding method for manufacture of thick walled steel pipe

Abstract: PURPOSE: To improve the low-temperature toughness of the weld zone in the thick walled steel pipe, by finishing the surface layer of the weld zone according to the submerged arc welding, after carrying out the MIG welding on the groove face, prepared into a specified shape, by supplying a large welding current to the thin wire and by giving a vibration to this thin wire. COPYRIGHT: (C)1978,JPO&Japio

Process for welding glass so that metallic elements pass through the weld bead

Abstract: A process for welding two glass members together to form a weld bead through which connecting wires extend. The glass members are first brought into intimate contact with metal parts which can be heated by a high frequency current. The glass members are held close to one another with the wires disposed in the space between them, and the glass is then melted until it welds by heating the metal parts with the aid of high-frequency heating coil windings surrounding the metal parts.

Welding method for ferritic stainless steel

Abstract: PURPOSE: To weld ferritic stainless steel efficiently to produce weld joint of excellent mechanical property by utilization of metallurgical reaction of CO 2 and molten metal through mixing CO 2 of specific quantity with inactive shield gas for nonconsumable electrode type arc welding machine. COPYRIGHT: (C)1978,JPO&Japio