Showing papers on "Heat-affected zone published in 1980"

Metallurgy of Welding

Abstract: The effect of surface forces on the bonding of materials. Solid-phase welding and adhesive joining. Soldering and brazing. The joining of ceramics: microjoining. Fusion welding: processes. Fusion welding: mass and heat flow. Metallurgical effects of the weld thermal cycle. Carbon and ferritic alloy steels. Austenitic and high-alloy steels. Non-ferrous metals. The behaviour of welds in service.

Arc augmented laser processing of materials

Abstract: It has recently been found that an electric arc can be added to the interaction between a laser beam and a material surface in such a way that in welding and cutting it produces an effect similar to that from a more powerful laser. The experimental results are discussed together with an analysis of the process mechanism. In particular it appears that the arc strikes the work piece at the same interaction zone as the laser, and in so doing undergoes a contraction in width to near the same size as the laser beam. It also seems probable that some of the arc energy penetrates the laser generated keyhole. So far the experimental results have shown that arc augmentation of the laser by some 2 kW of arc power in the work piece can be achieved without unduly spoiling the high quality of the cut or weld that would be made by a laser alone of similar total power.

Composite wire for gas shielded arc welding

Abstract: PURPOSE: To execute vertical up welding with high efficiency and to obtain the composite wire which has the good migratability of droplets and decreases the amt. of the spatters to be generated by specifying the grain size constitution, incorporating TiO 2 at a specific ratio into the wire and incorporating specific components at specific ratios therein. CONSTITUTION: A flux is filled in the sheath made of a steel. The grain size constitution is so specified that the particles having the grain size exceeding 149μ are incorporated into the wire at 10wt.% and the particles having 44μ grain size or below at ≤30wt.%. The TiO 2 is incorporated into the wire at 3.5W7.0wt.% of the total weight of the wire. Further, contains 0.4W1.0wt.% ZrO 2 , 0.1W1.0wt.% Al 2 O 3 , 0.3W1.0wt.% Si, 1.2W3.2wt.% Mn, 0.1W0.6wt.% Al, 0.03W0.3wt.% total of 1 or 2 kinds of Na, K:Na, K, and 0.01W0.2wt.% F. The vertical up welding is thereby executed with high efficiency and the amt. of the spatters to be generated is decreased; in addition, the working efficiency of welding is improved. COPYRIGHT: (C)1989,JPO&Japio

Liquation cracking during the welding of austenitic stainless steels and nickel alloys

Abstract: Liquation cracking can occur during fabrication by welding in either the heat affected zone in the parent material, or in previously deposited weld metal during a subsequent run. It results from localized melting at grain or other boundaries, combined with the thermal strains associated with welding. This review paper opens with brief descriptions of the classification, identification and mechanisms of liquation cracking. Following an outline of the material classes and circumstances in which it is most likely to occur, compositional influences in austenitic stainless steels and nickel alloys are considered in more detail. It is emphasized that although residual elements such as S, P or B may have an important role in causing or enhancing liquation effects, much liquation cracking is associated with intentional minor alloying additions, such as Nb. The influence of deliberate alloying additions, and compositional balance, in limiting the influence of residuals will be considered. In conclusion the detection, significance and avoidance of liquation cracking are discussed briefly.

Resistance welding sequence cycle control

Abstract: A method and apparatus are shown for controlling the cycle of a resistance welding device by providing compensation for variations in the effective weld area and the primary input electric power variations through a composite correction applied to the length of the squeeze time cycle portion prior to the weld cycle portion when weld current is activated. Compensation is made for secondary weld current variations by altering the length of the hold cycle, during which electrode contact is maintained with the work subsequent to the weld cycle portion, to change the amount of heat quenched from the weld zone. Further by sensing the condition wherein either the electrical input or the motive power that drives the movable electrode is beyond correctable limits, the welding cycle is aborted when suitable quality welds cannot be made.

Welding powder feed device

Abstract: A combination for feeding welding powder from a welding tractor for arc welding over a vertical to horizontal curved surface includes a pivotable powder vessel and a mechanism for maintaining the vessel in a vertical position.

Method for manufacturing high strength rail of excellent weldability

Abstract: A method for manufacturing high strength rail having excellent weldability comprises subjecting a steel rail of specific composition to specific heat treatment conditions at the surface layer portion of the head thereof, to impart high strength to the rail and to assure that the welded portion as well as the welded heat affected zone are free from deterioration caused by the welding process. The heat treatment conditions include a cooling rate which is substantially equivalent to that in a conventional welding process so as to impart high tensile strength to the treated portion of the rail.

Vertical plate welding using double bevel joint

Abstract: A method is provided of vertical gas metal-arc two-sided welding of thick plate in a single welding pass on each surface of the plate. The method includes providing a first weld groove on one surface of the plate into which a weld bead is deposited in a single pass. Thereafter, a second weld groove is formed on the opposite surface of the plates by removing base plate material along the joining line to a depth extending at least to the first weld bead penetrating from the welding pass in the first weld groove. The plates are further joined together by depositing a weld bead in a single pass along the second welding groove. The welding is provided by impressing a direct electric current of from 290 to 420 amperes between an electrode and the plates shielded primarily by argon gas. A metal article and a welded joint are also provided.

Weldability and hot cracking in thorium-doped iridium alloys.

Abstract: Modified iridium alloys containing ≥ 100ppm Th were found to be very susceptible to cracking during gas tungsten-arc and electron-beam welding. However, the electron-beam welding process showed greater promise of success in welding these alloys, in particular Ir–0·3W doped with 200ppm Th and 50ppm Al. The weld ability of this particular alloy was extremely sensitive to the welding parameters, such as beam-focus condition and welding speed, and the resulting fusion-zone structure. At low speeds successful electron-beam welds were made over a narrow range of beam-focus conditions. However, at high speeds successful welds can be made over an extended range of focus conditions. The fusion-zone grain structure is also a strong function of welding speed and focus condition. Weld-metal cracking was found to be caused by the combined effects of heat-affected-zone liquation cracking and solidification cracking. Scanning electron microscopic analysis of the fractured surface revealed patches of low-melting...

Non-consumable electrode arc welding method

Abstract: PURPOSE: To obtain weld beads of uniform depth of penetration and a broad sectional shape by applying alternating magnetic fields to the arc generated from a nonconsumable electrode of which the sectional shape near the leading end part is approximately a rectangular shape, thereby oscillating the arc in the long side direction of the electrode section and controlling the shape of the weld beads. CONSTITUTION: In the sectional shape near the leading end part of a nonconsumable electrode 2, the direction approximately perpendicular to the weld line direction is made the long side of a rectangular shape section, and the width thereof is formed approximately equal to the diameter (d) of the circular section of the electrode. The long side end part thereof is beveled as shown by a symbol (r), to make the arc easy to oscillate. The weld line direction X-Y is made the short side of the rectangular section and the width thereof is set at (t). Next, alternating magnetic fields are applied from a magnetic controller 7 to the electrode 2 of this shape in the arrow 8 direction, thereby oscillating the arc in the arrow A-B direction. Since this welding method controls the arc smoothly by the slight change in the magnetic fields while maintaining the arc constant, the depth of penetration in both end parts of beads is positively assured. COPYRIGHT: (C)1982,JPO&Japio

Gas tungsten arc welding torch and welding process

Abstract: A gas tungsten arc welding torch having an elongated gas nozzle (18) with an oblong cross section designed for deep groove, narrow gap welding is coupled to a main torch body (16). A gas passage is formed along the welding electrode (10), which includes a detachable end section (42) which captures and supports a replaceable gas lens (30) disposed within the gas passage of the nozzle. The nozzle (18) is sealably mounted (38) to the main torch body and readily detachable for easy replacement during the welding process in which successively wider nozzles (18) are used as the gap to be welded becomes wider with successive weld passes.

Thick welded steel pipe of large diameter and production thereof

Abstract: Circular pipe of large diameter progressively formed of flat stock, the pipe having a single longitudinal seam is seam-welded by preparing welding grooves such that the inner groove is smaller in size and angle than the outer groove, sequentially carrying out submerged arc welding on the inner welding groove, and large current MIG welding to then first layer of the outer welding edge and a submerged arc welding to a second layer thereof.

Mig arc welding method

Abstract: This disclosure relates to MIG welding. In order to obtain an instantaneous short circuit type of metal transfer in the process using only a pure inert gas shield a small amount of rare earth elements is added to the weld wire. The amount of rare earth added is between 0.02%-0.03% by weight of the wire.

Control of welding energy flux density

Abstract: An electrical resistance spot welding system and method is disclosed. The system has adjustable output power circuitry for applying electrical heating energy to a weld site by way of weld tips, in accordance with a welding operation. An energy monitor senses instantaneous accumulated energy applied during the welding operation, and terminates the operation when an adjustable predetermined total energy has been applied. Other circuitry monitors applied welding voltage, and derives therefrom a signal which is a function of the energy density per unit area applied at the weld site. Circuitry responds to the energy density sensing to control the energy monitor and the power circuitry to govern the total energy applied in the welding operation. As weld energy flux density decreases, such as happens when weld tips spread or "mushroom", total applied energy is increased, compensating for weld tip changes, thereby holding the amount of applied energy per unit of weld site area relatively constant from one welding operation to another.

Liquid cooling for a welding torch

Abstract: During operation of a welding torch (10), electrode wire (17) travels through a contact tip assembly (14) directly into a weld area. The torch (10) is exposed to elevated temperatures which can cause damage from weld spatter and increased deterioration of the assembly (14). In the welding torch (10), a liquid is delivered onto an expansion element (44) and gasifies owing primarily to the elevated welding temperatures at the expansion element (44). The result is to cool the assembly (14) and substantially overcome the problems of temperature. In a nozzle (18) equipped torch (10), the nozzle (18) directs a portion of the gasified liquid to the welding area for shielding the welding operation.

Horizontal electro-slag welding process for surfacing

Abstract: Surfacing is conducted with horizontal electro-slag welding by using a strip electrode, and by applying a magnetic field, having component perpendicular to a base metal, to a molten metal and slag pool to control the flow of the molten pool.

Welding Characteristics of Ag-W Contacts Under High-Current Conditions

Abstract: The welding characteristics of Ag-W (65 weight percent W) have been evaluated In a weld-test apparatus at 1000 A, 2000 A, and 3000 A. Two experiments are discussed: a) comparison of the welding characteristics of two different samples of Ag-W contacts and b) changes In the surface structure of the Ag-W contacts and the effect of these changes on the contacts' welding characteristics. It is shown that, in new contacts, the Ag content at the surface Is relatively high (about 5O percent by volume). As the contacts continue to operate at these high currents the Ag Is gradually ejected from both the contact surface and also from the contact's subsurface. This leaves a brittle W-rich surface on top of a weak porous W matrix. The Ag-W contacts are shown to exhibit n higher probability of welding and they also form stronger welds during the first few operations of the weld-test apparatus than they do Inter In the experiments. Indeed, any difference between contact samples is shown to occur during the first 50 operations of the weld-test apparatus.

A study on weld repair through half bead method

Abstract: ASME Boiler and Pressure Vessel Code specifies the half bead method for carbon steel or low alloy steel weld repairs in case post weld heat treatment (SR) is impractical. A study was made to identify the appropriate procedure for the half bead method applied to repairs for forged low alloy steel (JIS G3212 SFVV 2). As the most recommendable practice, the conclusion suggests that the upper portion of the 1st layer welded by 2.6 mm diameter electrodes is ground off leaving the remainder approximately 2.0--2.5 mm thick from the groove surface prior to the 2nd layer deposition. Parts repaired by the described half bead method were tested in terms of tension, bend, hardness, metallogrphy, V-notch Charpy impact, fracture toughness, fatigue crack initiation and fatigue crack growth rate. These various properties of the rapair parts are comparable to those of repairs with the conventional SR, and particularly the method is found to be significantly effective in avoiding the degradation in toughness of the heat affected zone.

Composite wire for stainless steel welding

Abstract: A composite wire containing a flux for use in gas-shielded arc welding of stainless steels which contains, in the flux, the following inorganic components with respect to the total weight of the wire: 0.1 to 10% by weight of an anhydrous silicate, and 0.01 to 0.75% of a metallic oxide having a melting point of no more than 888° C.

Welding of fins to tubing

Abstract: A method of manufacturing a solar panel element comprising a metal sheet or sheets secured to fluid-tight tubing substantially continuously along its length by metal which has been heated and cooled, e.g. weld metal, in which the tubing and the metal sheet or sheets are held in contact while they are heated to welding temperature, either forge welding or melting temperature. In the preferred methods, the heating is accomplished by high frequency, electric currents using a proximity conductor. Also, in the preferred methods, the tubing is formed with longitudinal lips as the heating is carried out, and the lips are secured together by welding them together simultaneously with the welding of the sheet or sheets to the tubing.

Arc welding process.

Abstract: An arc welding process for welding a circumferential surface of a fixed pipe etc. by shielding a work part with a shield gas is provided. It is welded by a flat arc formed in a flat sectional view by simultaneously ejecting a gas from nozzles (19) to the arc formed between a welding torch (10) and a product for welding by placing a pair of the gas nozzle (19) for ejecting the gas at the end of the welding torch (10).

All position tig welding method

Abstract: PURPOSE: To increase the maintaining performance of the molten pool and to improve the working efficiency in all position welding, by supplying the pulse current which is synchronized in phase with the medium frequency DC pulse current of welding current, to the filler wire. CONSTITUTION: The DC welding current which is pulse controlled to several tens to several hundred Hz in frequency, is supplied from pulse power source 7 to electrode 8 of welding torch 3, and the welding arc is generated. Pulse power source 9 is controlled by phase controller 10 simultaneously with the starting of welding, and the pulse current generated from pulse power source 9 is supplied to filler wire 5 after it is controlled in synchronizing phase with the pulse waveform of DC welding current. Then the end of filler wire 5 is inserted into the molten pool as it is melted rapidly by passing it through the high temperature plasma gas flow of welding arc column from the backside of proceeding direction A of torch 3 and thus the welding is proceeded. Moreover, when a bias current is added to current Ib which is supplied to filler wire 5, the molten pool can be maintained more effectively. COPYRIGHT: (C)1981,JPO&Japio

Plastics welding system - with electric current passing through conductive plastic wire with metal powder admixture

Abstract: Thermoplastic materials can be welded together by laying into the seam a plastic wire which has been made conductive by an admixture of metal chips or metal powder. The electric current flowing in it when a voltage is applied to its ends causes the plastic material to melt and to fuse together. d.c or a.c. of any frequency can be applied. the same effect can be achieved by metallising the surface of an intended weld so that a current can flow. When either of these systems is applied to dielectric welding, a cocn. of the electric field lines to the seam is attained. Systems saves energy by locally concentrated heating leads to faster welding rates and is easy to apply.

The correlation of microstructure and stress corrosion fracture of HY-130 steel weldments

Abstract: Microstructure is among the most important factors known to affect the stress corrosion cracking (SCC) susceptibility of medium and high strength steels. Multipass welding can produce various microstructures in the weld and heat affected zone on quite a fine scale, so that intimately mixed fracture modes are observed on SCC specimens of such welds. Performance of these welds mirrors the different SCC susceptibilities of the different microstructures. Detailed metallographic observations have been carried out to demonstrate the correlation between the microstructural features and SCC fracture of HY-130 steel weldments. It is shown that the refined microstructures were most resistant to SCC and the accompanying fracture mode was microvoid coalescence. Those microstructures giving rise to the more brittle fracture modes and thus less resistant to SCC were associated with the columnar/coarse equiaxed grain structures of untempered (or slightly tempered) martensite and/or bainite. These results were used as the basis for suggested welding practice to improve the SCC resistance of HY-130 and other medium strength steel weldments.

Welding of a textile material and method of welding such a material

Abstract: This welding of lap material presents welding areas of which the mass exceeds 80% of the mass of corresponding areas of the lap and of which the shearing resistance is higher than 10% of the tensile strength of the laps and the peeling resistance is higher than 5% of that strength. The ultrasonic welding process comprises the transmission of ultrasounds to the material parts to be welded via a heat insulating material, particularly a sheet material such as a paper sheet interposed between an anvil, respectively a welding sonotrode and a textile material. This process is applicable to all textile materials having more than 50% of thermoplastic fiber material.

Manufacture of composite wire for welding

Abstract: PURPOSE:To obtain a composite wire for welding that makes the packed flux difficult to absorb moisture by joining the butted metal outer cover containing welding flex length-wise and continuously by a laser. CONSTITUTION:Laser light 5 is irradiated lengthwise and continuously on the butted part 3 of a metal outer cover 1 containing flux 2. As the result, the butted part 3 is joined partially or wholly in the direction of thickness to form a laser joint 4.

Apparatus for gas-shielded arc welding

Abstract: An apparatus for gas-shielded arc welding comprises a mechanism (1) for guiding and feeding an electrode to a welding zone (3), a nozzle (4) for feeding a protective gas medium to the welding zone (3) and a TV transmission camera (6) for realtime monitoring of the welding process. A cover plate (8) made of an optically transparent material is provided at the end (7) of the gas nozzle (4) which is remote from the welding zone (3), and a lens (9) of the TV camera (6) is installed above the cover plate (8) coaxially therewith. The distance ("a") from the cover plate (8) to the lens (9) is selected in such a manner that the zone (3) of sharpness of the lens is located beyond the edge (11) of the gas nozzle (4) which is adjacent to the welding zone (10) and extends over the components of the welding process. An apparatus for gas-shielded arc welding is designed preferably for welding thick plate materials, for example, pressure vessel casings.

Electron-beam welding

Abstract: An electron-beam welding system for use in welding large masses of magnetic metals such as steel. Abutting segments of metal masses such as adjacent plates are welded by electron-beam welding. Two electron-beam welding units are used. One unit is used from one side of the plates to preheat the joint to a temperature to the transformation melting temperature. This preheating eliminates the magnetic field in the heating area. Subsequent electron-beam welding from the other side of the plates, while still hot, creates a welded joint in which the electron-beams are unaffected by magnetic fields within the plates.

Structure improving heat treatment method of welding heat affected zone of low alloy steel

Abstract: PURPOSE:To prevent occurrence of reheat crack or notch creep crack or the like while in use, by applying a special heat treatment to the coarse grain structure region in the heat affected zone formed in the boundary vicinity surface layer part of weld joint of low alloy steel structure to turn the structure to fine grains. CONSTITUTION:Members 1, 1 made of low alloy steel such as Cr-Mo steel are welded together to form a weld joint 2. At this time, welding heat affected zones 3, 3 are formed on both sides thereof. These heat affected zones 3 are heated to high temperatures to produce coarse grain region, which may result in reheat crack or notch creep crack when put in use in operation. In order to prevent occurrence of such defects, a high frequency coil 4 is applied to each welding heat affected zone 3, and the surface layer of the heat affected zone 3 is heated to a temperature slightly higher than the austeniting temperature Ac3 by high frequency induction heating. Then, letting stand to cool, the coarse grain region in the welding heat affected zone 3 remaining in the vicinity of weld joint 2 is improved to fine grain structure, so that occurrence of defects such as reheat crack due to stress-relieving annealing and plant operation may be prevented.