Showing papers on "Shielding gas published in 1989"

Weld pool development during GTA and laser beam welding of Type 304 stainless steel; Part I - theoretical analysis

Abstract: A computational and experimental study was carried out to quantitatively understand the influence of the heat flow and the fluid flow in the transient development of the weld pool during gas tungsten arc (GTA) and laser beam welding of Type 304 stainless steel. Stationary gas tungsten arc and laser beam welds were made on two heats of Type 304 austenitic stainless steels containing 90 ppm sulfur and 240 ppm sulfur. A transient heat transfer model was utilized to simulate the heat flow and fluid flow in the weld pool. In this paper, the results of the heat flow and fluid flow analysis are presented.

Modular welding gun

Abstract: Disclosed is a welding gun which includes a mounting block, a motor mounted to the welding block and a barrel through which welding wire is fed by drive rollers turned by the motor. There is a passageway through the welding block which has a valve therein for controlling the flow of a shielding gas through the passageway and through the barrel. A speed control mechanism device is mounted within a removable casing that encloses the block, motor, and speed control mechanism. The speed control includes a knob which is turned by the welder and includes a tactile response element that better enables the welder to determine the correct setting for the desired speed of the wire even though wearing a glove.

Emission spectroscopy of plasma during laser welding of AISI 201 stainless steel

Abstract: The rates of vaporization of alloying elements from the weld pool were related to the emission spectra of the plasma during pulsed laser welding of AISI 201 stainless steel under various welding conditions. The temperature distribution in the plasma was determined from the spectra obtained from various locations in the plasma plume. The extent of ionization of the plasma was calculated from the electron temperatures To understand the role of surface active elements, emission spectra and the vaporization rate of iron that resulted from the welding of ultrapure iron samples were compared with those from the welding of oxidized samples or samples that were doped with sulfur or oxygen.

Control unit for welding apparatus having offset and tracking control features

Abstract: Disclosed is a control unit for welding apparatus which feeds wire in the presence of a shielding gas to a workpiece at different rates with different heat inputs in accordance with the wire feed rate. The control unit is designed so that through a single control element the workman may adjust the wire feed rate and simultaneously and automatically adjust the heat input. When different wire types are employed in different welding processes, adjustments in the control unit are provided that allow the workman to reset the relationship between the wire feed rate and heat input in accordance with the type of wire being used. A hot-start feature is provided so that more power is applied for a predetermined manually adjusted time period during start-up.

Metal Transfer in Gas Metal Arc Welding: Droplet Rate A study of droplet rates for various transfer modes verifies optimum operating parameters

Abstract: This study reports the changes in droplet-trans fer mode and rate during gas metal arc welding as the voltage is varied at a series of current levels. The droplet-transfer rate was found to be maximum (approximately 100 s_1) for the voltage/current combi­ nations that are normally suggested by the electrode manufacturers and are con­ sidered optimum in the judgment of experienced welders. At voltages above or below the TV-wide optimum range, the transfer rate decreased by about 10 s_1 per V in the vicinity of the optimum condition. Furthermore, statistical analysis of the arc current and voltage data showed that during operation outside the optimum range, the welding arc was unstable and the current output was very irregular with varying cycle time between each droplet transfer. At the maximum droplet-transfer rate, the droplet-transfer cycle time was very consistent and revealed a narrow rate range, which correlated with the high stability and lower spatter at these optimum operating conditions. The possibility of using the concept of maximum droplet-transfer rate range with minimum rate fluctuation and corresponding arc current-voltage signals as a means of short-circuiting welding process control and automation is being considered. At voltages below the optimum range, high-speed video recording confirmed that the short- circuiting transfer was very unstable and the arc reignited explosively. Above the optimum voltage, the arc became longer and the droplets became visibly larger, with mixed globular and short-circuiting transfer. The droplets, however, were no longer directed uniformly to the weld pool, resulting in increased spatter. arc (FCA), submerged arc (SA) and gas tungsten arc (GTA) welding. With the exception of GTA welding, all these pro­ cesses require a consumable electrode, which has the dual function of carrying the current that heats the weld pool and providing filler metal to complete the weld joint. This dual function has long been a topic of research. Spraragen and Lengyel (Ref. 1) reviewed the basic princi­ ples of an electric arc and summarized the development of the field of welding arc physics. In particular, they concluded that in the area of liquid metal transfer from the electrode to the weld pool, the electromagnetic pinch force, gravity, shielding gas drag force and surface ten­ sion are the major forces that act on the electrode tip. Using high-speed cinemat­ ographic techniques, Muller, Greene, and Rothschild (Ref. 2) found that large spher­ ical liquid-metal droplets in a GMA arc decreased in size with increasing current. As the electrode feed rate was continu­ ously increased, however, a sudden decrease in droplet size occurred at what was termed the transition current. In addition, they determined that with inert gas shielding, the droplet composition remained constant during the metal trans­ fer. Lesnewich (Refs. 3-5) investigated the physics of arc welding using SMA and CMA welding. Particularly, he studied the effects of welding process parameters such as current, voltage, electrode polar-

Spectroscopic Study Of Laser-Induced Plasma In The Welding Process Of Steel And Aluminium

Abstract: Results of spectral diagnostics of the plasma produced by intense laser radiation during the welding process of steel and aluminium with CO2 lasers are presented. The experiments were carried out in an intensity range I = 106 ÷ 107 W/cm and with He, N2, Co2, Ar as shielding gases. The electron plasma temperature T and density n were measured under various processing and shielding gas conditions.It is shown that the time-averaged plasma temperature correlates with the welding results such as e.g. a welding depth obtained by varation of the welding speed and process gas. In this way it is demonstrated that spectral characteristics of the plasma can be used in the monitoring of the plasma and in the optimalization of the welding process. Furthermore, it is shown that spectroscopic results help to explain the influence of the process gas. Examples of cooling, heating and shielding effects caused by process gases are shown and discussed in view of the efficiency of the welding process.

The Effect of the Surface Oxides Produced during Welding on the Corrosion Resistance of Stainless Steels

Abstract: AISI type 304L (UNS 30403) and 316L (UNS 31603) stainless steels were heat treated under controlled conditions to produce surface oxides similar to those formed during welding. The oxides ...

Spray mode gas metal arc welding process

Abstract: A spray mode gas metal arc welding process employing a shielding gas mixture consisting essentially of (A) 3 to 8 volume percent carbon dioxide, (B) 30 to 40 volume percent argon and (C) the balance helium

Fe-MnおよびFe-Si-Mn溶接金属の酸素吸収について

Abstract: Pure iron plates were welded using Fe-Mn and Fe-Si-Mn alloy electrode wires in a controlled arc atmosphere. The effects of manganese and silicon-manganese on the oxygen contents and non-metallic inclusions in the weld metals were investigated under various welding conditions in Ar-O2 and Ar-CO2 welding atmospheres. The oxygen contents of the Fe-Mn and Fe-Si-Mn weld metals increase with an increasing the partial pressure of oxidizing gases and decrease with an increasing manganese and silicon-manganese contents in the weld metals. The oxygen contents of the weld metals welded in Ar-CO2 are lower than those in Ar-O2. The oxygen contents of the Fe-Si-Mn weld metals significantly decrease comparing with those of the Fe-Si and Fe-Mn weld metals. The nonmetallic inclusions in the Fe-Mn and Fe-Si-Mn weld metals increase with an increasing oxygen contents of the weld metals. The nonmetallic inclusions in the Fe-Mn weld metals are oxide of manganese-oxide accompanying with iron-oxide. The nonmetallic inclusions in the Fe-Si-Mn weld metals are oxide composed of silica, manganese-oxide and iron-oxide. Behavior of the oxygen absorption into the Fe-Mn and Fe-Si-Mn weld metals is discussed using thermodynamic data.

Plasma Absorption Effects In Welding With CO 2 Lasers

Abstract: The laser-induced plasma which is essential for the laser welding process absorbs a fractional part of the beam power above the workpiece as well as inside the "keyhole". The absorption above the surface of the workpiece always reduces the welding efficiency. It is demonstrated at which processing parameters this absorption takes place and how it can be reduced by shielding gases. Inside the keyhole, different absorption mechanisms could take place. 1st: Fresnel-absorption at the keyhole walls is the substantial absorption mechanism. In this case the direction of the beam polarization shows a strong effect on the welding result. The absorption length of the laser induced plasma Labs is well above the welding depth d (Labs >> d) 2nd: Plasma absorption inside the keyhole takes place. In this case, the welding depth is a function of the plasma absorption length. These absorption mechanisms are described and examples are shown.

Effect of additional elements on oxygen absorption by steel weld metal during arc welding. (Part II). Oxygen absorption by Fe-Mn and Fe-Si-Mn weld metal.

Abstract: Pure iron plates were welded using Fe-Mn and Fe-Si-Mn alloy electrode wires in a controlled arc atmosphere. The effects of manganese and silicon-manganese on the oxygen contents and non-metallic inclusions in the weld metals were investigated under various welding conditions in Ar-O2 and Ar-CO2 welding atmospheres. The oxygen contents of the Fe-Mn and Fe-Si-Mn weld metals increase with an increasing the partial pressure of oxidizing gases and decrease with an increasing manganese and silicon-manganese contents in the weld metals. The oxygen contents of the weld metals welded in Ar-CO2 are lower than those in Ar-O2. The oxygen contents of the Fe-Si-Mn weld metals significantly decrease comparing with those of the Fe-Si and Fe-Mn weld metals. The nonmetallic inclusions in the Fe-Mn and Fe-Si-Mn weld metals increase with an increasing oxygen contents of the weld metals. The nonmetallic inclusions in the Fe-Mn weld metals are oxide of manganese-oxide accompanying with iron-oxide. The nonmetallic inclusions in the Fe-Si-Mn weld metals are oxide composed of silica, manganese-oxide and iron-oxide. Behavior of the oxygen absorption into the Fe-Mn and Fe-Si-Mn weld metals is discussed using thermodynamic data.

Laser welding method

Abstract: PURPOSE:To enable good welding without using the welding equipment of a large capacity by executing laser welding by generating the magnetic line of force whose magnetic flux density becomes smaller according to departing to the track from the projection point of the laser light and whose track is in the same direction as the laser light. CONSTITUTION:When a voltage is impressed on a electromagnetic coil 5 by the DC power source 6 for exciting, the magnetic line of force is generated around the coil 5. The welding joint part of the bodies 3, 4 to be welded is irradiated with laser light L in this state. The irradiation part of the laser light in welding joint parts 3a, 4a is melted and the Ar of an argon gas as the shielding gas of shielding this part is ionized. A generated plasma P is closed in a melting part 7 by the direction of a magnetic line of force, the energy of the laser light L is absorbed to the plasma P, the melting of the melting part 7 is promoted and no laser light L is passed through the gap between the bodies 3, 4 to be welded.

The Influence And Role Of Helium And Nitrogen As Shielding Gases In 2KW CO2 Laser Welding Of Austenitic Stainless Steels : Physical, Geometrical And Technological Characterization

Abstract: Laser welding processes require nozzles with a " large " outlet in order both to avoid turbulent gas flow which can cause removal of the melt and to ensure an adequate protection of the melt against atmospheric oxidation. The gas can be supplied in a variety of ways but in this work the coaxial gas-laser beam geometry was used. CO2, He and N2 have been tested as covering gases with flows between 30+100 Nl/min. It has been observed that, once the gas and the steel have been set, the penetration depth and the width of the melted zone are, in the majority of cases, virtually constant when the flow rate increases from 30 to 100 Nl/min.

Effect of the composition of flux and welding wire on the properties of deposited metal of 05N4MYu type

Abstract: (1989). Effect of the composition of flux and welding wire on the properties of deposited metal of 05N4MYu type. Welding International: Vol. 3, No. 2, pp. 109-111.

Gas metal arc welding method

Abstract: PURPOSE: To perform welding at high speed by inclining a welding power source below specific V at specific A and making Ar + CO 2 or CO 2 gas to shielding gas. CONSTITUTION: When the welding power source with an inclination below 1V at 100A is used, since an external characteristic (current-voltage characteristic) of the welding power source is flat, the arc length is always fixed easily and an arc is stabilized and as a result, welding at high speed is performed even by using the inexpensive shielding gas: Ar + CO 2 or CO 2 gas. COPYRIGHT: (C)1991,JPO&Japio

Welding method for al alloy

Abstract: PURPOSE:To improve a welding quality by generating an arc by feeding a shielding gas between the zone to be welded of an A alloy and the electrode of an anode side and executing welding by projecting a laser beam. CONSTITUTION:A tungsten electrode 20 is arranged inside a nozzle 18 for the Al alloys 2a, 2b composing ths part 3 to be welded and the head 4 for laser welding is set up at the upper part of the part to be welded. First, an arc 29 is generated between an anode side electrode 20 and the welding part 3 with feeding an inert gas to the nozzle 18 inside. In this case, the positive ionized particle of a gas evaporates an Al oxidized film by decomposing it. The part 3 to be welded is then melted by a laser light beam under an inert gas environment to form a welding bead. The heat of the arc 29 is added and deep welding is executed after the evaporation of the Al oxidized film, so the welding quality is improved.

High current density welding method and flux-cored wire

Abstract: PURPOSE: To obtain a welded zone having excellent bead external appearance and penetration shape by using a flux-cored wire with gaseous carbon dioxide as shielding gas to perform welding with high current density having more than a specified value. CONSTITUTION: Even if either of pure Ar or mixed gas of every kind is used as shielding gas, the penetration shape of a bead shape is formed in a finger shape. Only when CO 2 is used, the stable circular penetration is obtained with ≥300A/mm current density. Further, the flux 3-cored wire for high current density gas shielded arc welding consisting of, by wire weight ratio, 1.5-7.5wt.% TiO 2 , 0.3-1.5% SiO 2 , 1.5-6.0% deoxidizer and ≤10.0% oxidizer (including TiO 2 and SiO 2 ) is used. When the flux-cored wire is then used, welding with high deposition excellent in arc stability and welding workability can be performed and further, the welded zone having the excellent bead external appearance and penetration shape is obtained. By this method, highly efficient welding and labor saving can be realized. COPYRIGHT: (C)1991,JPO&Japio

Mechanism for selecting shielding gas of gas shielded arc welding

Abstract: PURPOSE: To obtain plural shielding gases by one equipment by receiving the supply of gases from different gas supply sources of ≥ two kinds and mixing the gases at a specified mixing ratio by a gas mixer to supply the gases to a welding torch CONSTITUTION: The gas mixer 4 receives the supply of the gases from the respective gas supply sources 1, 2 and 3 according to the specified mixing ratio by instructions of a worker and mixes the necessary shielding gases and supplies these gases to the welding torch 22 through a shielding gas supply pipe 5 By this method, the plural shielding gases are obtained by one equipment and optimum welding can be performed COPYRIGHT: (C)1991,JPO&Japio

Hot wire welding method

Abstract: PURPOSE:To improve welding efficiency and quality by applying a high-frequency current to a filler wire of consumable electrode type or nonconsumable electrode type arc welding from a high-frequency power source for the filler wire to prevent arc deflection, arc instability and spatters. CONSTITUTION:An arc column 5 is generated between a nonconsumable electrode 2 and base metal 1 by a current supplied from a main welding power source 4. At this time, shielding gas is supplied to the periphery of the arc column 5 from a shielding nozzle 6. On the other hand, the current supplied from the high-frequency power source 11a for the filler wire 9 is applied to the filler wire 9 via a wire guide 10 and the filler wire 9 supplied from a wire reel 7 is fed to the inside of the arc column 5 by feed rollers 8 and welding is proceeded. Since the filler wire current and the welding main current at this time are the high-frequency current and DC respectively, even if eletromagnetic force acts between the current carried to the filler wire 9 and the current carried to the arc column 5, its change is fast, so the arc column 5 is not deflected following it and in addition, the arc instability and the occurrence of spatters are prevented.

Variable shielding box for welding

Abstract: PURPOSE:To complete back shielding by following the weld line of a curved face by refractably linking the shielding box body divided into the front and back, fitting it liftably to the upper part of a welding torch and providing a shielding gas pipe at the inner part of the shielding box body and a roller at the lower part. CONSTITUTION:A shielding gas is fed to a torch as well as an electric power is fed to a tungsten electrode 18 and when a shielding box 20 is moved along the weld line inside a curved face with feeding a shielding gas to shielding gas pipes 10, 11, the respective shielding box front and back parts 6, 7 execute a refraction motion centering around a pin 9 with the respective roller 16, 17 of each shielding boxes 6, 7 coming into contact with the base metal surface and are deformed by following the curved face. Therefore even in case of a tungsten electrode 18 being welded by repeating the vertical movement inside a groove shielding boxes 12, 13 keep a fixed gap at all times with the base metal, a shielding effect is obtd. and stabilized arc welding can be executed.

Device for cleaning a gas outlet nozzle of a welding gun by means of a jet of pressurised gas, and welding gun fitted with such a device

Abstract: Device for cleaning a gas outlet nozzle of a welding gun by means of a jet of pressurised gas and welding gun fitted with such a device. The device is intended for providing a powerful flush of pressurised gas coming from a reservoir in the shielding-gas pipe of the tubular tip 2 of a welding gun and in the outlet nozzle 1 mounted on the end of the tip, in order to free this nozzle of adhering spatter (projections) resulting from the welding carried out with a metal wire serving as electrode. This wire arrives, in continuous movement, via an axial channel made in a contact piece 5 mounted on the end of the tip 2 in the outlet nozzle 1. A valve 10, connected to a pressurised-gas pipe 12, serves to control the gas flush in the outlet nozzle 1 of the gun. The valve 10, preferably a diaphragm valve, is mounted on the body 7 of the welding gun; a pressurised-gas accumulator 13 is preferably connected to the pressurised-gas pipe 12 near the inlet of the valve 10. Application to arc welding guns operating with a consumable electrode constituted by a wire, with shielding gas.

High current density welding method

Abstract: PURPOSE: To obtain stable droplet transferability and a satisfactory penetration shape by using a steel wire with specific electric resistivity containing the spe cific quantity of C and having a specific value of X shown by the expression and specific mixed gas as shielding gas and performing welding with specific welding current density. CONSTITUTION: The steel wire with 25-65μΩcm electric resistivity containing 0.010-0.040% (weight) S and having the K value of 20-40 shown by the following expression is used. Further, the mixed gas consisting of ≤20% (CO 2 +2×O 2 ) with one or both 2-20% (vol.%) CO 2 and 1-10% O 2 and the balance Ar substan tially is used as the shielding gas and welding is performed with ≥300A/mm 2 welding current density. The expression: K=505.S(%)+0.41.ρ(μΩcm) is formulat ed. By this method, the stable rotating transfer is carried out and high current density welding having the satisfactory penetration shape and excellent porosity resistance with little quantity of generation of spatter is made possible. COPYRIGHT: (C)1991,JPO&Japio

Gas shielded nozzle

Abstract: PURPOSE:To prevent scattered materials such as spatters from reaching above a welding electrode with overhead welding by forming gas shielded nozzles of double structure consisting of an outside nozzle and an inside nozzle with a fine diameter and providing an insulating member and a shielding member on these. CONSTITUTION:The welding electrode 1 is passed through the heat resistant insulating member 5 and inserted into the heat resistant inside nozzle 3. The inside diameter of an opening 3a of the inside nozzle 3 is formed fine extremely to an extent of the rotating diameter where the electrode 1 rotates revolvingly and the penetrating rate of the scattered materials such as spatters is reduced and its upper part is shielded by packing 6. In addition, the outside nozzle 4 of the same quality as the inside nozzle 3 is fitted integrally to its lower half part and a partition 7 having a pore 7a for the gas flow is provided thereto. By such constitution, shielding gas is supplied to a weld zone via gas nozzles 3b and 4b, gas supply ports 3c and 4c and openings 3a and 4a. By this method, at the time of performing overhead welding, the scattered materials such as spatters can be surely prevented from reaching above the welding electrode.

Fitting method for radiation fin of cylindrical body

Abstract: PURPOSE:To stabilize welding and to improve the quality of a weld zone by arranging a shield plate at the opposite side to the beam projecting side of a fin in case of the laser beam welding of a radiation fin to a cylindrical body. CONSTITUTION:Welding is executed by a laser beam radiation gun by inserting fixtures 4a, 4b into a cylindrical body 1 and holding a radiation fin 2 on the cylindrical body 1 by a presser bar 5. In this case, the shield plate 6 whose tip part is bent is arranged at the opposite side to the beam radiation side and fixed to the presser bar 5 via an annular seat 8 and a volt 8. In case of the laser beam emitted from a beam radiation gun 3 welding the fin 2, a shielding gas is filled up in the space A formed by the shielding plate, the cylindrical body 1, fin 2 and presser bar 5 by passing through the key hole of a welding point and released in an optimum amt. from a discharging port B. Due to the shielding gas surely sealing a weld zone the laser beam welding is stabilized and the quality of the weld zone is improved.

Properties of Hyperbaric Flux Cored Arc Welds: Weld Metal Chemistry

Abstract: A literature review on the factors affecting weld metal chemistry on hyperbaric flux cored arc welds has been carried out. The following aspects have been considered: shielding gas flow, shielding gas activity and oxidation/deoxidation reactions. It has been shown that the available knowledge allows an adequate selection of conditions leading to acceptable weld metal chemistry in hyperbaric FCAW.

Aspects of oxidation/deoxidation reactions of weld metals deposited under hyperbaric conditions

Abstract: The main objective of this work is to provide means which could assist the forecast of oxygen contents in the weld metal deposited under hyperbaric conditions, with different CO2 contents in the shielding gas and a specific filler metal carbon level. Hence, some of the experimental results obtained from the manual hyperbaric welding research programme at GKSS have been evaluated using existing empirical/theoretical treatments on carbon and oxygen absorption from CO2 containing shields.

High deposition rate submerged arc welding

Abstract: In this paper the authors discuss four developments in submerged arc welding which are of significance for high deposition rates. These developments include the use of microalloyed wires which enhance weld root toughness, the process of metal powder additions, improved consumables for higher strength steels and increasing productivity in pipe welding.

Arc welding torch

Abstract: PURPOSE:To reduce expenses of shielding gas used and to simplify cooling by providing a first gas passage to surround the periphery of a wire holding body concentrically and a second gas passage which is arranged to the outside of the first gas passage and covered. CONSTITUTION:A path 11 is provided to the holding body 1 to supply flux to the first gas passage 7 and mix it into gas supplied from a path 9. A path 12 is provided to the holding body 1 to supply waterdrops to the second gas passage 8 and mix these into gas supplied from a path 10. The shielding gas 17 is kept at a value higher than the outside air pressure and carbon dioxide gas 19 displays an effect of an air curtain and the shielding gas 17 covers a molten pool 15 to be protected in an inert state. Immediately after minute particles 18 of the flux are carried to the shielding gas, these particles are attached to the work surface to be welded and cover an arc 13 and the molten pool 15, hence these are mixed in molten metal and a welding state can be kept optimum.