Showing papers on "Gas metal arc welding published in 1985"

Welding apparatus method for depositing wear surfacing material and a substrate having a weld bead thereon

Abstract: The welding method may be used to lay down weld beads on metallic substrates with a narrow width of 0.125 inch and less. The process employs a plasma transferred arc and pulses the current delivered to the arc such that a wave form having at least a main amplitude and a lower auxiliary amplitude is provided. The powdered metal which is delivered is laid down in a series of overlapping weld deposits which solidify very rapidly and produce a fine grain structure.

Method and apparatus for welding thin metal sheets

Abstract: There is described a method for welding thin metal sheets (A, B) by the localized heating of limited juxtaposed zones of the metal sheets to be welded to cause their fusion and to form spot welds (S). In each weld zone, the metal sheets (A, B) are heated and fused along a closed line so that each weld spot (S) has a substantially annular configuration in cross section in a plane parallel to the metal sheets. This welding may be achieved for example with the use of a laser (2) produced by a laser source (1), or by electrical resistance welding with a pair of opposed electrodes (6, 7) the ends whereof which are intended to grip the metal sheets (A, B) are suitably shaped.

Gas metal arc welding process

Abstract: The gas metal arc welding process of the present invention extends the axial spray metal transfer range with a non rotating arc from 10 to 25 Ibs/hr using an electrode wire diameter between .035 to .052 inches. The process is carried out by maintaining an electrode extension of between 3/4 to 1 1/4 inches with a three component shielding gas mixture consisting essentially of argon and oxygen in combination with carbon dioxide or carbon monoxide in a volume proportion of oxygen 1-2%, carbon dioxide 8-15%, balance argon. The arc voltage is maintained in a range of between 29 and 40 volts.

Method of welding nitrogen-containing alloys

Abstract: A method for improving the weld strength, structure and crevice corrosion resistance of nitrogen-containing alloy weldments by adding nitrogen to the inert gas used for shielding during the welding operation.

Time resolved optical spectra from MIG welding arc ignitions

Abstract: Optical radiation from MIG (GMAW) welding arc ignitions has been measured with a rapid scan spectrometer. The time resolved spectral measurements reveal a substantial overshoot of ultraviolet radiation during the ignition phase of a 200 A aluminum arc. Calculations which follow the ACGIH guidelines show that, at a welding current of 300 A, the unprotected eye at a distance of 0.5 m may suffer a “flash” after the reception of radiation from only one ignition.

Process and apparatus for partially or fully mechanised inert gas (protective gas) joint welding

Abstract: The invention starts from the known WIG or plasma welding process using an inert gas, with weld (filler) material being supplied as a welding rod (wire). According to the invention, the welding rod is introduced into the torch in such a way that it is located in the arc between the end of the non-consumable electrode and the workpiece and accordingly passes in an electroless dripping manner into the arc. Accordingly, the torch is equipped with a welding rod feed, by means of which the rod can be introduced into the nozzle channel of the torch and accordingly into the arc.

EXPOSURE OF WELDERS TO FUMES, Cr, Ni, Cu AND GASES IN DUTCH INDUSTRIES

Abstract: The exposure of welders in Dutch industries to total particulate, chromium, nickel and copper fume during the welding of unalloyed, stainless and high alloyed steels has been investigated. The exposure to the gases NO2, NO and ozone is also discussed. The results are presented in tables and graphs. The correlation between the arc-time factor and the welding fume concentration in the breathing zone appeared to be bad MMA-welding fumes of stainless steel contain mainly soluble hexavalent chromium. During MIG and TIG welding the fumes contain chromium which was insoluble in water and not hexavalent. The nickel was insoluble in water in all three processes. In comparison with the Dutch occupational health standards, it appears that the dust exposure is often higher than the limit value of 5 mg m3 in M MA and gas-shielded arc welding. The exposure to chromium is usually higher than the standard of 0.05 mg m 3 lor hexavalent chromium and the standard o[0.5 mg m-3 lor total chromium in MMA welding of stainless steel, and the exposure to copper fumes during welding of copper is usually higher than the standard of 02 mg m3. Among the gaseous contaminants NO2, NO and ozone, only ozone with MIG welding of aluminum gives concentrations in the breathing-zone exceeding the standat'd of 0.2 mg m3(0.1 ppm).

Sus 304 mig溶接金属中の酸素と破壊靱性に関する研究

Abstract: In the gas shield arc welding with SUS304 austenitic stainless steel base metal and, JISY308L type electrod, the effect of the welding condition on the oxygen content and microstructure of weld metal has been investigated. Next, the effect of the oxygen on the mechanical properties, mainly on the fracture toughness, were studied. The main results are summarized as follows;1) The oxygen content of weld metal is increased with dicreasing the welding current (from 200A to 400A) and with increasing the arc voltage (from 20V to 30V). At the constant welding atmosphere, there is a linear correlation between the oxygen content and a parameter of A/V which is established by the authors, where A is welding current and V is arc voltage. The oxygen content decreases with increasing the parametre A/V.2) The most of the oxygen exists in the γ region as the spherical oxide of Mn-Silicate. The number of oxide per unit volumu is related to the welding heat input. The number decreases with increasing the heat input.3) Charpy impact values and Jin values decrease with increasing the oxide volume fraction.4) The relationship between Charpy impact value and oxide volume fraction is represented by linear line on the log-log cordinate. At the constant oxide voulme fraction, the distribution (number and size) of oxide has little effect to Charpy impact value.

Effect of helium gas on arc characteristic in gas tungsten arc welding.

Abstract: Effects of helium gas on the maximum arc pressure and on the critical travel speed to melt a base metal were investigated in GTA welding.Results were obtained as follows;(1) The critical speed in helium (He) gas arc is much higher than in argon (Ar) gas arc. Heat input per bead length at the critical speed in He gas arc is lower than in Ar gas arc. This fact is understood because distribution of a heat source in He gas arc is more concentrative than in Ar gas arc.(2) Electrode geometry is effective on the critical speed and especially the critical speed has a maximum value at a vertex angle of 45°, when a diameter of electrode is held constant.(3) The pressure in He gas arc is much lower than in Ar gas arc and is not sensitive to electrode geometry. This fact is understood because a spreading angle of arc current in a front of an electrode tip in He gas arc is smaller than in Ar gas arc.(4) When He gas is mixed into Ar shielding gas, generally the pressure decreases, but the critical speed is held constant. This fact shows that mixed He gas has a great influence on arc phenomena in a front of electrode tip, but it has little influence on an arc column.(5) When a few litter per minute of He gas is added to an upper part of an electrode tip through a nozzle in Ar shielding gas, the pressure effectively decreases to the degree of the pressure measured in He shielding gas.

Shielded arc welding using auxiliary voltage

Abstract: Shielded arc welding apparatus advances a consumable electrode towards a workpiece; applies a welding voltage between the electrode and the workpiece; and applies an auxiliary voltage between the electrode and the workpiece, whereby the auxiliary voltage initiates an arc between the electrode and the workpiece before the electrode engages the workpiece.

Multiple electrode submerged arc welding method

Abstract: PURPOSE: To facilitate a bead formation under the effect of gravity that a high speed welding is difficult due to the increase in the input by adequately setting the welding current and wire extension according to the wire diameter and by obtaining the stabilized state available for submerged arc welding. CONSTITUTION: The first electrode is connected to the power source 4a having DC constant voltage characteristic and the second and third electrodes to the welding electrode 4b having AC dropping characteristic respectively by feeding at high speed with a feeding roller 3 the fine diameter wire 1 of about 1.0W1.6mm. The wire 1 then receives the feed of the input which is from the welding power source with keeping the prescribed intervals 6 by the electrode tip 5 for twin wire. For the while the distance 7 between electrodes is kept in 10W50mm. The second and third electrodes are then connected to the dropping characteristic of the AC welding power source. The submerged arc welding is performed under the high speed low heat input welding conditions by setting the welding current at 250W500d 2 A and the wire extension of the wire 1 in 15W40d with said constitution. COPYRIGHT: (C)1986,JPO&Japio

Cast iron welding electrodes

Abstract: Metal filler compositions based on manganese and nickel for the welding of cast iron are disclosed. The filler composition preferably contains about 15 to 50% manganese and 15 to 35% nickel. The filler compositions may be incorporated into a welding rod for Shielded Metal Arc (SMA) or into the welding wire for Gas Metal Arc (GMA) welding or added as metal powders in Flux Cored Arc (FCA) or submerged Arc (SA) welding. The compositions are particularly useful for welding gray and ductile (nodular) cast irons.

Control of fusion characteristics in pulsed current mig welding. part 2 - simple model of fusion characteristics

Abstract: In this second part of their paper, the Authors develop a simple conduction-based theoretical model to describe aspects of the results presented in Part 1 , with particular emphasis on dilution behaviour. The model is combined with calorimetric heat transfer measurements in order to investigate the finding that only a small fraction of the total process power is required to melt observed plate fusion-zone areas. A dual heat source' fusion model is suggested in which plate melting is largely in response to direct arc heating, providing a means of optimising plate dilution and so reducing the risk of fusion defects. These and other aspects of the problem are considered in some detail; apart from the choice of mean current and welding speed, only limited opportunities appear to exist for manipulating the plate fusion characteristics; dilution may be maximised by increasing arc cathode heating, use of preheat, and by choice of wire size and/or pulse structure.

Resistance electroslag (RES) surfacing

Abstract: RES-surfacing is an abbreviation of resistance electroslag surfacing. The ElectroSlag Welding (ESW) process is wellknown for the welding of heavy-walled materials. During the past few years, a RES-surfacing system has been developed, in which a strip electrode is used in an ESW process. This is a development of the submerged arc welding (SAW) surfacing process using strip electrodes, which has been used in industry for many years. The basic difference between the SAW- and RES-surfacing processes is in the way of obtaining penetration in the base metal, and in fusion of the strip electrode and flux. In the SAW process, the required heat is derived from an electric arc; in the RES-process, it is obtained by resistance heating (i.e., the Joule effect) as a result of current flowing through a shallow molten pool of electrically conductive slag. To satisfy the basic differences in the processes, specific combinations of strip electrodes and fluxes have been developed. The welding equipment used for RES-surfacing is basically the same as for SAW-surfacing, except for minor modifications of the welding head due to heat radiation from the visible molten slag pool, and the use of additional equipment for magnetic control of the molten pool. resultmore » of the magnetic control of the molten pool.« less

Corrosion and corrosion-fatigue behavior of IN625 Weld Surfaced 3.25 Nickel Steel

Abstract: The corrosion and corrosion-fatigue behaviors of INCONEL 625 weld metal surfaced onto 3.25 pct nickel steel using the gas metal arc welding-pulsed arc process are presented. General, crevice, and bent-beam stress corrosion studies were performed. Completely reversed bending corrosion-fatigue and corrosion fatigue crack growth behaviors were also evaluated. The sea water corrosion resistance of the surface weld metal was equivalent to wrought base metal at levels of iron up to 9 pct, provided the molybdenum concentration was greater than 8 pct. Stress relief heat treatment did not degrade corrosion resistance properties. The corrosion fatigue strength of the surface weld metal at 108 cycles was found to be 103.4 MPa (15 ksi) which is lower than values reported for multiple pass INCONEL 625 welds, but is significantly higher than the corrosion fatigue strength of 3.25 nickel steel. Fatigue crack growth rates for the surface weld metal were found to be higher than the wrought INCONEL 625 base metal and the steel. Stress relief heat treatment does not alter corrosion fatigue crack growth rates of the clad 1N-625 surface weld metal.

Welding procedure of steel material with high quality, high toughness and high efficiency

Abstract: PURPOSE:To execute welding with high quality, high toughness and high efficiency by combining laser tack welding and submerged arc welding to execute said welding. CONSTITUTION:An open pipe 7 after UO working is moved toward an arrow 14 by a pipe mover 10 of a tack welding machine. On the other hand, laser light 8 to be used for laser welding is bent to a perpendicular direction by a mirror right above the weld point and is condensed by a lens so as to be irradiated onto the target weld point. The focus of the condensed light is so adjusted as to be positioned lower than the top point in the butt part of the pipe 7 in order to obtain deep penetration at a high speed. The weld point is shielded by the inert gas ejected from a welding torch in the direction coaxial with the beam. Since the laser welding is used for tack welding in the above-mentioned way, the stubbing and humping defects at the beginning and terminal ends of welding are thoroughly eliminated. The high-speed welding and penetration depth equal to or higher than by an MIG welding method are obtd. with the small molten area.

Nitrogen absorption into stainless steel weld metal under welding atmosphere of high pressure —nitrogen absorption into weld metal under welding atmosphere of high pressure (part 2)—

Abstract: 20Cr-10Ni stainless steel was welded in N2 and N2-Ar atmospheres at 1-30 atm pressures. Effects of welding conditions and the nitrogen partial pressure on the nitrogen content of stainless steel weld metal were systematically studied. The results are summarized as follows:(1) In the nitrogen welding atmosphere, the nitrogen content of the weld metal decreased with increasing the welding current and increasing the travel speed, and with decreasing the arc voltage.(2) In the nitrogen welding atmosphere, the nitrogen content of the weld metal increased with the nitrogen pressure, but the nitrogen absorption of the weld metal does not obey the Sieverts' law.(3) In N2-Ar welding atmosphere, the nitrogen content of the weld metal was lower in high atmospheric pressure than in low pressure at the same nitrogen partial pressure.(4) Using thermodynamic data obtained by equilibrium study, the nitrogen absorption into the stainless steel weld metal in the nitrogen atmosphere of high pressure was discussed.(5) All stainless steel weld metals had no porosity.

Automatic overhead welding method

Abstract: PURPOSE:To perform overhead welding with higher stability and efficiency by synchronizing the current control of MAG welding with a composite core wire with weaving so that the arc length is extended to melt the groove wedge while the current is large and that the arc length is reduced to accelerate solidification while the current is small. CONSTITUTION:Welding current is synchronized with weaving and is impulsively controlled at a low frequency in the stage of welding automatically a groove in an overhead position by an MAG welding method using a composite wire having 1.2-1.6mm. diameter and using a gaseous mixture composed of Ar and CO2 as a shielding gas. The arc length is maintained long to melt widely both corners of the groove while the current is large in this stage and the arc length is maintained short to narrow the heating range by the arc and to accelerate solidification from the periphery of a molten pool while the current is small. The penetration in the corner parts of the groove is thus made thorough and the flat bead optimum for the overhead position is assured. The automatic continuous welding of the long-sized joint in the overhead position is thereby made possible and the efficiency and stability of welding are improved.

Flux cored wire for welding

Abstract: PURPOSE: To obtain a weld zone having high strength without welding defects such as high-temp cracking and to make possible sure and easy welding by using a flux contg CaO and incorporating a metallic Al component into either or both of the flux and base material for a wire CONSTITUTION: The flux 3 is prepd by adding and mixing adequately CaO powder or Al (alloy) powder together with the CaO powder to and with a flux consisting of an ordinary compsn The flux 3 cored wire 1 for welding is constituted by filling the flux 3 into a hollow wire 2 The wire 2 consists of an Fe, Ni, Co or other alloy to be used for ordinary welding and in the case of incorporating Al therein, the Al is incorporated into a molten pool by way of a droplet and reacts with CaO thereby deoxidizing and desulfurizing powerfully the molten metal The weld zone which obviates the generation of the high temp cracking, etc and has the high strength is obtd and the sure and easy welding is made possible by the above-mentioned constitution COPYRIGHT: (C)1986,JPO&Japio

Multielectrode high speed submerged arc welding method

Abstract: PURPOSE: To prevent the generation of an undercut and to enable the high speeding by forming the wire diameter of the first electrode in one piece with the specified diameter and those of the final and immediately before electrode in two pieces with the specified diameter and by specifying the range of the using current. CONSTITUTION: One piece of larger diameter wire more than 2.4mmϕ is used for the welding wire 1, 2 to be used by the first electrode 7-1 and second electrode 7-2. The final electrode 7-4 and immediately before electrode 7-3 thereof are composed of two pieces of welding wires in 1.0W1.6mmϕ. The electrodes are arranged so that the arc of each electrode becomes an independent welding arc inside the same molten pool 11. The welding is performed with the using current range as 300W1,000A as well. The sound bead quality having the necessary penetration is obtd. with preventing the generation of undercuts in high speed welding. COPYRIGHT: (C)1987,JPO&Japio

Narrow gap welding with the hot wire GTA process

Abstract: Narrow gap welding offers the promise of dramatically improved weld completion rates and reduced heat input for welding of butt joints in materials of 10 mm (0.4 in.) section thickness and larger. Techniques for successful welding of narrow gap joint preparations have been discussed in the literature for approximately twenty years, with the majority of these based on the consumable electrode processes. Gas tungsten arc welding with cold wire filler addition has been shown to be capable of narrow gap welding although limited deposition rate capability has not made this a competitive alternative. The GTAW process offers the advantages of superior penetration control for one-sided welding of butt joints, as well as the potential for reducing incomplete fusion defects. The addition of hot wire filler metal to the gas tungsten arc provides an attractive alternative that combines high deposition rate capability and independent control of heat input.

Welding device for inert-gas welding, with observation of the welding spot by a fibre-optic waveguide

Abstract: The invention relates to a welding device, in particular for automatic arc welding under inert gas, consisting of a welding torch and an inert-gas feed connected to it. In order to optically scan the welding spot or the arc during the welding operation, an optical scanning system is connected to the inert-gas feed. The scanning system has a fibre-optic waveguide (quartz fibre, quartz-fibre bundle and the like) which produces the optical transmission to an emission spectrometer, by means of which the radiation emitted from the welding spot is determined spectroscopically, it being possible to control the welding operation for exact weld scanning by means of an electronic analysing system allocated to the emission spectrometer. According to the invention, the fibre-optic waveguide is arranged at the inert-gas feed in such a way that the path of rays from the welding spot to the fibre-optic waveguide leads through the inert-gas stream. In this way, the path of rays is kept free of fume and dirt particles and the like to a very large extent during the welding operation.