Showing papers on "Shielded metal arc welding published in 1988"

Welding Metallurgy of Stainless Steels

Abstract: Contents: Significance of Constitution Diagrams for the Understanding of Welding Phenomena * Metallurgical Processes During Solidification and Cooling in Stainless Steel Weld Metal * Metallurgical Phenomena in Secondary Crystallization of Stainless Steels and Weld Metals * Precipitation Phenomena in Stainless Steel and Weld Metals * Hot Cracking Resistance During the Welding of Austenitic Stainless Steels * Welding Metallurgy of Ferritic Stainless Chromium Steels with Carbon Contents Below 0.15 per cent * Welding Metallurgy of Low Carbon Chromium-Nickel Martensitic Stainless Steels (Soft Martensitic Steels) * Welding Metallurgy of Duplex Austenitic-Ferritic Stainless Steels * Welding Metallurgy of Austenitic Stainless Steels * General Instructions for the Welding and Post-Weld Surface Treatments of Fabrications and Welded Components Made from Austenitic Stainless Steel * Welding Metallurgy of Heat Resisting Steels * Welding Metallurgy of Austenitic-Ferritic Dissimilar Joints * Appendix: Abbreviations and Short Designations * References * Author Index * Subject Index.

Ac tig welding apparatus using hot wire

Abstract: An unconsumable electrode such as tungsten is opposingly arranged with a base metal to be welded. An AC arc welding power supply is connected between the base metal and the unconsumable electrode. A filler wire such as of aluminum is fed by a wire feeder toward an arc-generated part between the base metal and the unconsumable electrode. Also included is a wire-heating power supply for producing a pulsed current. The wire heating power supply heats the filler wire by supplying thereto a pulsed current in accordance with a sync signal from the AC arc welding power supply or a detection signal of an arc current i A or an arc voltage of the AC arc power supply. The filler wire is thus heated by being supplied with a heating current i W in pulse form while the unconsumable electrode is kept negative by an AC arc formed between the unconsumable electrode and the base metal. During the period when the unconsumable electrode is kept positive by the AC arc, the filler wire is not supplied with any current or is heated by being supplied only with a sufficiently small current not to cause any substantial magnetic flow. Accordingly, even if a large current flows through the wire, arc interruptions can be eliminated, thereby improving the welding process of aluminum by using an AC TIG arc.

Resistance welding of galvanized steel

Abstract: A coating for improved resistance welding of galvanized steel parts or sheets comprises a binder, and a metal phosphide pigment, preferably a ferrophosphorus pigment, having a particle size of from about 0.1 to about 30 microns. The pigment can also include up to about 40% by weight of an additional metal such as tin, aluminum or lead, which can be combined with the metal phosphide in pigment form or deposited onto the surface of the particles. The coating can be applied to either the faying or non-faying surfaces of the galvanized steel, or to the resistance welding electrode, and may be removed, if desired, after the welding operation. The advantages of the present invention include a significant reduction in welding current and an increase in the weldability lobe width, a restoration of the dynamic resistance beta peak, and an increase in electrode life.

Constant arc voltage gas metal arc welding process

Abstract: A gas metal arc welding process employing a shielding gas mixture consisting essentially of (A) 2 to 12 volume percent carbon dioxide, (B) 20 to 45 volume percent helium and (C) the balance argon.

Optimisation of the plasma arc welding process

Abstract: Plasma arc processing of metals and alloys - cutting, welding, overlaying and spraying - is highly efficient and there is a wide area of applications for the process, primarily due to the advantages of a constricted arc as opposed to an open one. As a result of an investigation of the technological characteristics of a plasma welding arc and the heat and mass transport in the weld pool during welding, the role of the plasma-forming constricting orifice was shown to be of decisive importance for weld quality. The procedure for calculating optimum conditions for plasma arc welding was developed, enabling the sphere of applications for the process to be extended. Parameters that increase the reliability of the process are discussed.

Effect of delta ferrite content on the corrosion resistance of type 316 clad metals

Abstract: Austenitic claddings of type 316 were obtained by SMAW (Shielded Metal Arc Welding) and SAW (Submerged Arc Welding) processes, using type 316 L electrodes on low carbon boiler steel (SA 515 Gr 60) with type 309 L as a barrier layer deposited by the SAW process. Welding heat input was changed in order to obtain different ferrite contents in the cladding. The clad samples were post-weld heat treated at 650°C for 50 and 200 h. The top layer of the cladding was removed and the specimens were then subjected to intergranular corrosion tests (ASTM A-262-75, practices A, B, C and E, viz. 10% oxalic acid electrolytic etch; ferric sulfate −50% sulfuric acid; 65% nitric acid and copper-copper sulfate −16% sulfuric acid tests) and controlled potential etching test. The study indicated that the ferrite content of the cladding decreases with increasing current. Ferrite transformed after PWHT (post weld heat treatment) was relatively more in claddings obtained with low heat input and containing high ferrite content in the as-clad condition. PWHT led to brittle fracture of high ferrite claddings (above 10 FN). The corrosion attack of ferrite was found to depend on environment. 65% nitric acid attacked ferrite preferentially, whereas in acid-ferric sulfate, ferrite was intact and austenite was attacked. No sample exhibited susceptibility to intergranular corrosion in the as-clad or PWHT conditions in the copper-copper sulfate −16% acid test. However, PWHT specimens with low ferrite contents (3.55 FN) exhibited grain boundary precipitation at the interface of two adjacent layers. In general, ferrite was found to be beneficial in controlling corrosion rates of clad metals after PWHT. Heat input, within the range studied, did not affect the corrosion rates significantly.

Process for terminating closed through-hole plasma arc welding

Abstract: To terminate welding, the mean energy of the arc is first reduced to obtain plugging of the hole, then this energy is briefly increased before again being decreased. Application to plasma arc welding of carbon steels.

One-side welding method for stainless clad steel plate

Abstract: PURPOSE: To efficiently perform one-side welding by filling metal powder with specific composition in a groove and welding carbon steel plates to each other by using submerged arc welding material for stainless steel and welding the groove surface side constituted of stainless steel plates with the same kind of metal material. CONSTITUTION: Stainless clad 1 steel plates formed by cladding the stainless steel plates S on the surfaces of the carbon steel plates C are subjected to one-side welding from the stainless steel plate S clad side. In this case, the metal powder consisting of, by weight, 50W70% Cr, 20W30% Ni and the balance Fe with impurities is filled in the groove. The submerged arc welding material for the stainless steel is then used to weld the carbon steel plates to each other and an austenitic metallic structure containing 3W15% ferrite is obtained. The groove surface side constituted of the clad stainless steel plates is then welded by using the same kind of welding metal material. By this method, weld metal excellent in the corrosion resistance and the impact resistant performance is obtained. COPYRIGHT: (C)1989,JPO&Japio

High speed welding of 0.5mm thickness alloy sheets using pulsed TIG welding

Abstract: (1988). High speed welding of 0.5mm thickness alloy sheets using pulsed TIG welding. Welding International: Vol. 2, No. 7, pp. 602-608.

Estimation of contact tip-workpiece distance in gas shielded metal arc welding

Abstract: (1988). Estimation of contact tip-workpiece distance in gas shielded metal arc welding. Welding International: Vol. 2, No. 6, pp. 522-528.

Method and device for underwater electrical welding

Abstract: Method of underwater arc welding comprising the steps of placing a welding electrode nearby a parent material to be welded, immerged in water; generating a high frequency voltage between the electrode and the parent material for starting a striking arc and supplying a high frequency current to said electrode, after said striking arc has been initiated; generating a welding voltage for producing a weld at the parent material and; simultaneously sustaining the high frequency current, superimposed to the welding current, for stabilizing said welding arc during the time duration of the underwater arc welding.

Effect of nitrogen on weld metal toughness in self-shielded flux-cored arc welding

Abstract: Self-shielded flux-cored welds were made with varying electrode extension to investigate the effects of atmospheric nitrogen on mechanical properties. It was concluded that formation of aluminium nitrides seriously degrades weld metal toughness at long electrode extensions.

Welding method and welding wire for galvanized steel sheet

Abstract: PURPOSE:To suppress the frequent generation of pits and blowholes and to improve bead shapes as well as to decrease the generation of spatters by producing the welding wire of a steel having a specific alloy compsn. CONSTITUTION:The welding wire produced by using the steel contg., <=0.15% C, <=0.50% Si, <=1.50% Mn, and 0.002-0.10% Bi, and consisting of the balance Fe or the steel further contg. 0.005-0.10% Ti in addition to the above-mentioned wire. This welding method for galvanized steel sheets executes welding by using Ar contg. <=50% CO2 as a shielding gas and executing MAG welding or pulse MAG welding.

Method for overhead submerged arc welding and apparatus to implement the same

Abstract: The invention relates to technology and equipment for arc welding. A method of overhead submerged arc welding consists in that flux at the wing site is pressure-fed to the joint being welded from below at different pressures along the joint being welded, a consumable electrode (3) is fed through the flux (3) from below and an arc is struck. A weldpool is formed thereat with a layer of liquid slag. The joint is welded by feeding the flux (A) on the section (A) before the arc relative to the weld being formed under a constant pressure, needed to provide conditions for pressuring the weldpool, and on the section of the arc burning and the weldpool location pressure is exercised through a layer of flux and a layer of liquid slag, the bulk of the flux being pressure-fed to the zone of the weldpool formation and the pressure gradually built up in a manner that its maximum value is distributed along the boundary of the section of the beginning of the weld solidification and maintained constant all along the boundary of solidification. Then solidification is effected and the weld is formed. There is also proposed an apparatus to implement the method. The invention may be used for welding longitudinal and circumferential rotatable joints.

Metallophysical processes in the welding of copper and copper alloys - welding methods

Abstract: After a description of the basic features of gas, manual arc and gas-shielded arc welding of copper materials, the welding of, in particular, copper, copper-zinc, copper-tin, copper-nickel and copper-nickel-zinc alloys as well as copper-tin-zinc casting alloys and low-alloyed copper materials is discussed. Weld joints between copper or copper alloys and other materials are also dealt with. Inert-gas tungsten-arc (TIG) welding and inert-gas metal-arc (MIG) welding have tended to replace gas and manual arc welding for copper and its alloys. Of the resistance welding methods, spot welding, resistance butt welding and flash welding are most important. Plasma, electron beam, laser beam, friction and ultrasonic welding are also used for special tasks.

Spot welding of hot-dipped galvanised steel sheet

Abstract: The use of zinc-coated steel sheets in industries has increased rapidly. Spot welding of galvanized steel sheets, however, has been a problem from the beginning. That is poor electrode life due to high welding current.An attempt has been made in this program to improve weld quality deterioration in the spot welding of galvanized steel sheets. Aluminum oxide powder is interposed at the interface between two galvanized steel sheets to be welded, having an aim to increase contact resistance at faying surface.Tests have indicated that the powder addition is much effective to reduce weld time requirements and consequently, for improving tip life and welding performance.

Reinforcing welding method for constructed pipe weld defect part

Abstract: PURPOSE: To make it possible to perform main welding without difficulty and to obtain a reinforced weld zone with fine quality by pretreating a weld defect part to be reinforced by arc heat, etc., in advance. CONSTITUTION: In the case the groovelike defect part 4 exists in the welded zone 3 interior side 1B of constructed pipes 1 and 2, since oils and fats, rust 5, etc., stick and accumulate in the defect part 4, pretreating welding is performed in advance by gas-arc welding equipment to perform main welding. In pretreating welding, the arc heat is generated under conditions with little quantity of deposition and a stuck deposit 5 in the defect part 4 is burnt and molten. Welding including a pretreated weld zone 6 is performed by the first pass of next main welding and the pretreated weld zone 6 is remolten and integrated with main welding and the stable welding quality is maintained. COPYRIGHT: (C)1990,JPO&Japio

Metal gas reactions in gas-shielded arc welding

Abstract: Mixed gas-shielded arc welding is becoming more and more popular. The influences of the gas components on arc and material transfer are known to a considerable extent. There is as yet no general quantitative description of the chemical behaviour of the gases dependent on the composition of the gas shield in arc welding. A contribution to this subject is made here.

Effect of reinforcement shape factor on stress intensity factor at the tip of micro-crack in the toe.

Abstract: This paper deals with the effect of reinforcement shape factor on the stress intensity factor (KI) at the tip of a nonpropagating crack at the toe by using a Boundary element method. As micro-cracks exist in the welded joint, the fatigue strength of welded joint is determined by the propagating condition of nonpropagating cracks.The following conclusions were derived from the numerical results of KI and the investigation of the shape of reinforcement made by shielded metal arc welding and CO2 gas welding; (1) The micro-crack does not affect KI; (2) The toe radius considerably influences KI; (3) The reinforcement angle affects KI; (4) The height and width of reinforcement do not affect KI.

Investigation on the phenomena of high speed one-side welding of thin sheet paying attention to arc force.

Abstract: Paying special attention to the arc force, the welding phenomenon of high speed one-side welding of thin sheet was investigated.In high speed and high current one-side welding method, the arc force becomes very strong. The solid surface is produced at the front part of the molten pool by this strong arc force and others. But the high speed one-side welding of thin sheet is possible using high current TIG and plasma arc welding method because the strong arc force effects to this solid surface. However, in the case of these welding, the face bead becomes undercut bead.In spite of high welding current, the arc force holding forward torch angle keeps lower level. So this method is more effective for high speed one-side welding. Especially, using the knife-edge electrode with forward torch angle, these tendency becomes more effective.