Showing papers on "Shielding gas published in 1983"

Gas metal arc welding method

Abstract: A gas-metal-arc welding method is provided for high speed, high melting rate, substantially spatter-free, all-position welding. The method is particularly useful for out-of-position welding, that is, to produce vertical, inclined and overhead welds. A consumable wire electrode is held within and fed through the tubular contact tip of a continuous feed type welding gun having a tubular nozzle surrounding and extending beyond the tip. A shielding gas, formed of unique ratios of a minor proportion of a carbon dioxide and oxygen mixture combined with a major proportion of an argon and helium mixture, is flowed in a substantially longitudinally laminar pattern between the nozzle and contact tip and along the electrode extension from the tip. The contact tip is cooled, and sufficiently high power electrical current is passed through the contact tip and electrode extension to produce the arc and to melt the end of the electrode into molten drops for short-circuiting (e.g., low current) or for spray (e.g., higher current) transfer of the drops to the weld deposit. The electrode extension is pre-heated by maintaining a long electrode extension or stick-out beyond the contact tip end, with a substantial portion of the extension recessed within the nozzle.

The Metallurgy of Underwater Welding

Abstract: Wet and dry welding processes are surveyed in terms of compositional changes, cooling programme and weld joint performance. Introduction of hydrogen and oxygen in wet welding may lead to porosity and slag inclusions. High cooling rates, mainly controlled by convection, may cause cracking. Significant improvements can be achieved by local protection of the site of welding. Effects of pressure predominates in dry welding, leading to increased absorption of hydrogen, oxygen and carbon and to reduced contents of silicon and manganese in MMA welding. The increased impurity level limits the application of hyperbaric MMA welding to about 300m depth. Inert-gas protected processes are shown to be much less affected by pressure. Examples of performance and methods of predicting the chemistry and properties are given.

Spectroscopic measurement of hydrogen contamination in weld arc plasmas

Abstract: The introduction of hydrogen into metals during welding is known to cause hydrogen assisted cracking and embrittlement in certain situations. It has been shown that the weld metal hydrogen content is directly related to hydrogen concentration in the weld arc plasma. In this paper we describe a simple spectroscopic technique for measuring the arc plasma hydrogen concentration in real time when an argon shield gas is used. This technique is based on the fact that the intensity ratio of the hydrogen Balmer Alpha emission line at 6563 A and an argon emission line at 6965 A was observed to be an approximately linear function of hydrogen concentration in the weld arc plasma. This technique was experimentally verified under a variety of welding conditions for gas metal arc welding and found to have an error of less than 10% when measuring hydrogen concentrations in the arc plasma as low as 0.25% by volume. This method of hydrogen measurement is also applicable when welding with shield gases not containing argon so long as a suitable ratioing line is available.

The Influence of Nitrogen from Welding on Stainless Steel Weld Metal Microstructures Soluble nitrogen is found to exert a major influence—particularly on the quantity and distribution of weld metal delta ferrite

Abstract: Small amounts of nitrogen were injected into Type 304L austenitic stainless steel weld metal. This was accomplished by using an argon-nitroge n shielding gas mixture on autogenous gas tungsten arc welds. Weld metal nitrogen as a function of nitrogen shielding gas content and applied pressure was exam­ ined. Nitrogen shielding gas contents below 5% were found to have a major effect on the weld metal microstructure. The base metal nitrogen did not influence the nitro­ gen solubility reaction and solidification behavior during welding. For Type 304L austenitic stainless steel, a nitrogen coeffi­ cient was determined for the nickel equivalent expression.

Welding apparatus with monitor means

Abstract: A welding apparatus with monitor means including a welding torch having an electrode located in the vicinity of its forward end and supported at its rearward portion by a welding head for rotational movement about its longitudinal axis and back-and-forth reciprocatory movement along the longitudinal axis. The welding torch further includes an electric conductor covered at its outer periphery with an insulator and formed with a gas sump in the vicinity of the electrode. The electric conductor has defined therein a gas supply passageway for supplying gas shield gas, a bore for allowing an image guide and a light guide to extend therethrough, and a bore for allowing a fluid to flow therethrough to cool the electric conductor. The image guide and light guide have their forward ends located in the gas sump, so that they can command a view of outside through guide openings serving concurrently as gas ejecting ports for ejecting the shield gas therethrough. A filter is located at the other end of the image guide, and an industrial television camera and a television receiver are mounted for converting optical images formed on the filter to television pictures to enable monitoring of welding operations to be effected.

Flexible trailing shield for welding reactive metals

Abstract: A flexible trailing shield for providing nonreactive gas shielding to arc lding operations comprises a housing formed of interlocking transverse segments adapted to flexibly cover weld surfaces having varying configurations. The housing has a torch entrance port for slidably receiving a welding torch, a conduit for receiving gas into the housing, a foraminous material to uniformly distribute the gas within the housing, and a pervious structure through which the gas is dispersed over the weld surface.

Welding Under Water and in the Splash Zone — a Review

Abstract: The author reviews the parameters controlling underwater welding especially arc welding with covered electrodes, MIG, TIG and with cored wire. It describes wet welding and hyperbaric welding, with the use of nitrogen and noble gases for shielding and in the welding chamber. The specific problems of underwater welding are described in detail: hardness of the HAZ, cold cracking by hydrogen, method of calculating the thermal input, consequences of pressure on fusion characteristics.

Narrow gap welding torch

Abstract: A narrow gap welding torch using a twisted wire center electrode. The torch has water-cooled gas bars and a water-cooled center. The gas bar delivers shielding gas to the weld site at a flow of about 100 cu.ft./hr. The water-cooled gas bars and center bars prevent splatter from adhering to the torch and permit the torch to operate at lower shielding gas flows. The water-cooled torch is also thin to enable gaps of narrower width to be welded which requires less weld material to be laid down and which permits welds to be accomplished more quickly and efficiently.

Method for welding very low carbon steel

Abstract: A method for arc welding a very low carbon steel containing 0005-006% C characterized by employing a welding material with nickel together with high carbon so as to form weld metal containing nickel Solidification cracking on the thus welded metal can be prevented

Gas shielded arc welding torch with consumable electrode wire

Abstract: A gas shielded arc welding torch is described which uses a consumable electrode wire. A cylindrical support member carries a guide tube for guiding the electrode wire through the torch. An electrical contact member is pivotably mounted at the end of the torch and includes a bore through which the wire passes. A spring biases the contact member into constant engagement with the electrode wire. A gas nozzle is mounted on the cylindrical support member and is movable with the contact member to provide a uniform, constant-dimensioned shielding gas passage around the contact member regardless of the movement thereof.

Laser welding device

Abstract: PURPOSE:To protect a condenser lens and to shield stably a welding part with gas by providing a nozzle which discharges high-velocity gas in the form of a film across the optical axis of the condenser lens and a nozzle which discharges low-velocity shielding gas near the focusing point of a laser beam. CONSTITUTION:A lens protecting nozzle 21 which discharges lens protecting gas such as air, nitrogen or the like for protecting a condenser lens 5 against spatter in the form of a film across the optical axis of the lens from a nozzle hole 21a is attached to the top end of a working head body 1. The nozzle hole 21a of said nozzle 21 is made into approximately a sectorial shape in, for example, the plane shape thereof and is so formed that the lens protecting gas covers the entire surface of the lens 5. A nozzle 22 for supplying shielding gas such as gaseous Ar at a relatively low flow rate is coupled and fixed to the body 1 by means of a coupling member 23 near the focusing point 4a of a laser beam 4.

Method and device for narrow groove welding

Abstract: PURPOSE:To form sound weld zones having no lack of penetration by supplying two pieces of insulated wires to a groove, and feeding electricity in such a way as to change the sizes of the arcs generated in the respective wires alternately. CONSTITUTION:In narrow groove welding by consumable electrode arc welding, tips 12a, 12b mounted to a torch 10 are inserted in the groove of base materials 16, wires 14a, 14b are supplied as consumable electrodes, and electricity is fed to the electrodes under ejection of a shielding gas 28 from a shielding nozzle 26, whereby the base materials are welded. The tips 12a, 12b are mounted via an insulator 24, hence the wires 14a, 14b are insulated as well. The sizes of arcs 18, 18 are changed alternately by feeding pulse currents in such a way that while one of the arcs has the peak current or peak voltage the other has the base current or base voltage, whereby the lack of penetration is prevented and a molten pool 20 of good shapes is formed.

Torch for arc welding

Abstract: PURPOSE:To improve working efficiency by an automatic welding machine in an arc welding torch using a welding wire as a consumable electrode by forming a contact chip to have a successively larger diameter near the root part thereof so that a spatter is dropped downward without being stuck to the root of the contact chip. CONSTITUTION:An arc welding torch has a contact chip 3, the outside circumference of which is covered by a gas nozzle 6 and therefore the spatter from a horizontal direction hardly enters the contact chip but the spatter scattering in a vertical direction jumps into the contact chip. An inclination of a suitable angle is consequently provided to the screwing part at the root of the chip 3 to force the spatter to drop opposite from the intruding direction without depositing in the spacing between the nozzle 6 and the chip 3, by which the drop of the spatter is accelerated and the turbulence in the shielding gas is prevented.

Shielding gas for electric arc welding

Abstract: A shielding gas for use in electric arc welding is disclosed. The gas comprises a mixture of helium, argon, 1.75% to 2.25% carbon dioxide and 0.25% to 1.0% oxygen (by volume). Use of the gas enables slag-free welds which accept readily paint applied by an electrostatic deposition process.

Device for passing gas into two pipes to be joined by welding, especially pipes of small diameter

Abstract: 1. A device for application of shielding gas to the area adjacent a joint between two tubes to be welded, in particular tubes of small diameter (1, 2), with a body (6, 19) of fine pored material which can be introduced to the portion of the joint where shielding gas shall be applied, a gas supply means (10, 11) which can be connected to that body and with supports sealing the interior of the tube, characterized in that the body (6, 19) is held between two disks (3, 4) which are continuously fitted at their circumference with lamellar brush means (7, 8), the lamellar brush means being fastened to segmental elements (22, 23) which are displaceably mounted in radial direction in the disks (3, 4).

Process for manufacturing welded ferritic-austenitic crnimo steel structures

Abstract: 1. A method of preparing welded articles, which are intercrystalline-corrosion resistant without subsequent heat treatment, from a ferritic/austenitic Cr-N-Mo steel alloy, consisting in percentage by weight of max. 0.06% C max. 0.80% Si 4.0 to 6.0% Mn 23.5 to 28.0% Cr 3.5 to 5.5% Ni 1.0 to 3.0% Mo 0.35 to 0.60% N remainder Fe and unavoidable impurities, which are welded by means of a ferritic/austenitic additive material, characterized in that for welding purposes a material which differs from the main material and which has : max. 0.06% C max. 1.0% Si 4.0 to 6.5% Mn 23.5 to 28.0% Cr 6.5 to 8.5% Ni 1.0 to 3.0% Mo 0.30 to 0.50% N remainder Fe and unavoidable impurities, is used as an additive material in the form of a wire or strip electrode welded under a shielding gas or with a fluxing agent covering, a filler wire which supplies this compound as a pure welding material, or a sheathed rod electrode of this type.

Joining method of aluminum-titanium by arc welding

Abstract: PURPOSE:To obtain a defectless joint part by combining specifically a welding power source, heat source, shielding gas and welding rod or electrode wire so that only the Al base metal side and welding rod are melted and that the Ti base metal side is hardly melted. CONSTITUTION:An arc 5 is generated between an electrode 6 of a torch 7 and base metals 1, 2 for the butt parts of the base metal 1 consisting of an Al alloy and the base metal 2 consisting of Ti. The TIG arc by a DC power source of a straight polarity or AC power source AC as a welding power source P or the MIG arc by a DC power source of a reversel polarity is used as a heat source for the arc 5. Al or the alloy thereof, phosphor copper solder or silver alloy contg. >=20% (by weight) Al is used as the welding rod or electrode wire. Gaseous Ar 8 is used as the shielding gas. The weld metal 3 formed in the joint parts between the base metals 1 and 2 has the compsn. in which the Al base metal 1 and the welding rod 4 are mixed.

Tig arc and mig arc composite welding method

Abstract: PURPOSE:To form an excellent bead by a stable arc, by directing a preceding MIG arc welding torch and a following TIG arc welding torch to the same part of a weld line, and providing a magnetic field to its composite arc. CONSTITUTION:Along a weld line of a base material 1, a MIG arc welding torch 2 is preceded, and a TIG welding torch 3 is followed. The torch 2 executes arc welding by a welding wire 4 by flowing a shielding gas from a flow path 8, and the torch 3 executes arc welding by a tungsten electrode 7 by flowing shielding gas from the flow path 8. The electrodes of the torches 2, 3 are directed to the almost same part on the base material 1, and a magnetic field is provided to a generated composite arc 10 by permanent magnets 11, 12, and against repulsion of the MIG arc and the TIG arc, the MIG arc is mainly corrected in the feed direction of the wire 4 by a magnetic field. In this way, an excellent bead 13 is obtained.

Rotary arc-welding apparatus

Abstract: A rotary arc-welding apparatus which comprises: a rotatable nozzle having in its interior thereof a passage for directing a consumable welding electrode eccentrically from the center axis of the nozzle toward a groove formed between objects of welding; a consumable welding electrode feeding mechanism for continuously directing the consumable welding electrode toward the groove through the nozzle; a welding current feeding mechanism for feeding a welding current to the nozzle, which comprises a current receiving plate fixed to the top end of the nozzle, a brush having on the upper surface thereof a current feeding plate, the brush and the current receiving plate having a flat contact interface therebetween, a plurality of rods for stationarily holding the brush and the current feeding plate, and a plurality of springs for applying a pressure onto the contact interface between the brush and the current receiving plate; a nozzle rotating mechanism for rotating the nozzle about the center axis thereof at a high speed to cause a circular movement of an arc from the tip of the consumable welding electrode corresponding to the eccentricity thereof; and a shielding gas feeding mechanism for feeding a shielding gas toward the arc and a weld zone.

A real time approach to quality control in welding

Abstract: The U.S. Army Construction Engineering Research Laboratory has, in conjunction with Illinois University, developed a digital system, the Weld Quality Monitor , for monitoring welding process variables and providing continuous video or printed output; it can also provide adaptive feedback control of welding variables, maintaining them within preset limits. The Authors describe a WQM subsystem for observing, by an opto-electronic method, the weld arc from a suitable distance and noting variations in its composition; a fibre-optic bundle is used to collect light emitted by the welding arc in the 3000-12,000 angstrom range. The research has indicated the feasibility of opto-electronic monitoring methods for detecting, as the weld is being made, three common welding problems: the presence of hydrogen, loss of shielding gas, and voids in flux-cored wire. The high sensitivity of the opto-electronic spectrograph, and its broad wavelength range, suggest that these are only a few of its possible uses. The laboratory equipment that was used in this development work is expensive and unsuitable for an industrial environment, but further work is being done to reduce costs and make the equipment less sensitive to a shop atmosphere.

Ni-containing wire for mig arc welding of low temperature use steel

Abstract: PURPOSE:To obtain high toughness by adding a specific amt. of a rare earth element, Al and B to a titled wire and using pure gaseous argon as a shielding gas thereby decreasing the content of oxygen in the weld metal and forming the finer structure. CONSTITUTION:A rare earth element is added at 0.02-0.30wt% to a titled wire to stabilize an arc and Al is added thereto at 0.010-0.080wt% and B at 0.0004- 0.0015wt% to form the finer structure. The wire for pure gaseous argon shielded MIG arc welding for low temp. use steel contains, by weight %, <=0.05% C, 0.1- 0.60% Si, 0.4-1.5% Mn, 2-6% Ni and 0.05-0.25% Mo as the other components and consists of the balance Fe and unavoidable impurities.

Rotary arc welding device

Abstract: PURPOSE:To obtain a rotary arc welding device which executes electrification exactly and is capable of welding a groove smoothly, by providing a power receiving plate and a power feeding plate on the upper part of a rotary nozzle, and pressing a carbon brush of the power feeding plate against the power receiving plate by an elastic body fit-inserted to a guide rod or the like. CONSTITUTION:A power receiving plate 11 having a wire insert-through hole, and a power feeding plate 13 stuck to the upper face of a carbon brush 12 are fixed to the upper part of a rotary nozzle 3 rotated by a motor 2. The carbon brush 12 of the power feeding plate 13 is pressed against the power receiving plate 11 by installing a wire inlet 4 to a supporting arm 19 extended out from the device body and fit-inserting an elastic body 16 of a spring, etc. to a guide rod 15 vertically provided on the supporting arm 19. A welding wire 8 is fed to the rotary nozzle 3 through the wire inlet 4 by a wire feeding device 7. A shielding gas nozzle 6 is provided on both sides of the rotary nozzle 3, and is opened toward the tip of the nozzle 3. According to this mechanism, even in case when the groove is narrow, the nozzle tip can be contained in the groove.

Process Variables and Properties of Wet Underwater Gas Metal Arc Laboratory and Sea Welds of Medium Strength Steels

Abstract: Wet underwater GMA welding by assistance of a gas cavity stabilizing water jet was investigated with respect to critical gas flow for the reduction of diffusible hydrogen and to the effect of multilayer technique on CVN toughness. Diffusible hydrogen contents as low as 2–4 Nml/100gFe can be achieved, depending on gas flow and jet conditions. In butt welding of St E 36 increasing the number of stringer beads leads to CVN toughnesses at −20 °C of up to 50–70 J in the weld metal using a Mn-Ni flux cored filler wire. Too small stringer beads yet encounter the danger of hydrogen assisted cold cracking.

Underwater Dry TIG Welding Using Wire Brush Nozzle

Abstract: In an underwater dry welding in a deep water, mixed gas of helium and oxygen is used as the environmental atmospheric gas and to reduce the fume and the spatter, the most suitable welding method is TIG welding. However the helium gas as the shielding gas has such drawbacks as tungsten electrode is eroded seriously and arc-starting is difficult in high pressure, while argon gas is superior to helium gas in the said characteristic but argon is about twice as narcostic as nitrogen, thus a special wire brush nozzle which consist of dual nozzle was developed: Argon was flowed out from a inner nozzle and the gas was inhaled by a vacuum pump from a circular gap between the inner nozzle and the outer nozzle having wire brush which prevented to leak the argon to the environmental atmosphere. With this nozzle as the result that inhalation ratio is selected 2.0 under the current of 200A, satisfactory welds could be obtained even in a water depth of 200m and welding could be done comparatively in long time under the condition that the shielding gas and the fume did not leak to the environmental atmosphere.

Cr-mo-welding wire heat resistant steel

Abstract: PURPOSE:To provide sufficient strength and toughness by using steel contg. specific amts. of C, Si, Mn, Cu, Mo, etc. for a welding wire which uses a gaseou mixture of Ar and a specific amt. range of CO2 as a shielding gas. CONSTITUTION:A Cr-Mo welding drive for heat resistant steel which uses a gaseous mixture of Ar and 10-25% CO2 as a shielding gas is made of the following compsn.: The wire consists, by weight %, of 0.04-0.095 C, <0.5 Si, 0.4- 0.9 Mn, <0.3 Cu, 2.2-2.6 Cr, 0.9-1.2 Mo, <0.04 V, <0.05 Nb, <0.01 Sn+Sb+ As, <0.01 P, <0.01 S, and the balance Fe. In some cases, <0.006 B is added to said compsn.

Detector for weld line

Abstract: PURPOSE:To detect a weld line easily without degrading workability by detecting the rate of displacement from the weld line by the detection signal from a magnetic field sensor which detects the leaking magnetic field generated by welding current. CONSTITUTION:A magnetic field detector 32 is oscillated at a specified amplitude in a y-axis direction with respect to a shielding gas nozzle 30 of a torch by a freely rotatable coupler 33. When a torch 30 is advanced in the direction of the straight line connecting the center of the amplitude and the nozzle 30 and if the center of the amplitude advances on the same weld line together with a wire electrode 31, the detection signal for the leaking magnetic field from the detector 32 is the pulse signal of a specified interval. When the electrode 31, hence the detector 32 deviate from the weld line 7 on advancing of the torch 30, the interval of the pulse signal changes. If the width of the deviation exceeds the amplitude of the detector 32, the pulse signal is no more produced.

Build-up welding method

Abstract: A build-up welding method for the inner surfaces of chemical reaction containers has the step of preferentially padding a welding metal layer of an austenite series stainless steel of special composition with a delta ferrite phase, as an intermediate layer prior to the build-up welding of a surface layer of stainless steel or nickel alloy over a base material of carbon steel or low alloy steel, so as to prevent exfoliation or cracking in the boundary between the build-up welding metal and the base material. As can be seen from Figs. 1, 2, the composition contains a ratio (Creq/Nieq) of nickel equivalent to chromium equivalent of at least 1.85 to prevent exfoliation or cracking, and less than 26% chromium equivalent and less than 20% delta ferrite phase thereby, in particular, preventing bending ductility. This method is adapted for lining the inner surfaces of a chemical reaction container, such as a petroleum refining desulfurizing reactor, which is used under high temperatures and in a high-pressure hydrogen environment.