Showing papers on "Electric resistance welding published in 1990"

Effects of welding flux additions on 4340 steel weld metal composition

Abstract: The effects of CaF2, CaO and FeO additions on weld metal chemistry were evaluated for the manganese — silicate flux system. Comparisons were made between AISI 4340 steel and lowcarbon steel welds to understand the weld metal chemistry. The results show that the elemental transfer from the slag to the weld metal and vice versa cannot be consistently explained using thermodynamic data; e.g., the carbon/oxygen partition is apparently controlled by a CO reaction in the 1010 steel welds, but the AISI 1020 and 4340 steel welds show constant carbon contents despite increasing oxygen levels. In addition, data are reported as a resource for future analytical and comparative purposes. Introduction Submerged arc welding of high integrity can be achieved through proper selection of the wire and flux combination for the specific base metal and welding parameters. Small amounts of alloying elements such as nickel, chromium and molybdenum are added to steels to increase strength, hardness or toughness, as is the case with AISI 4340 steel. Generally, welding low-alloy steels requires more careful control of procedures and selection of consumables than welding the carbon steels. Moreover, the oxygen potential of the flux influences the loss or gain of alloying elements during welding, the weld-deposit oxygen content, and the type, size and distribution of oxide inclusions in the solidified weld metal. The effective application of the submerged arc welding process for joining high-strength, low-alloy steels depends heavily upon understanding the behavior of the flux. Understanding the elemental P. A. BURCK and D. L. OLSON are with the Center for Welding and joining Research, Colorado School of Mines, Golden, Colo. J £ INDACOCHEA is with the University of Illinois at Chicago, Chicago, III. transfer mechanisms between the flux and the weld metal can be attained by studying the influence of each chemical additive on the flux behavior. To determine the many slag/weld metal chemical reactions occurring simultaneously during welding, a state of thermodynamic equilibrium has been assumed to be attained. The basis for this assumption is that the high temperatures and high surface-to-volume ratio associated with the welding process counteract the short time available for a reaction to be completed (Ref. 1). Chai and Eagar (Ref. 2) reported that the very short times and the large thermal gradients involved in the process prevent overall slag-metal equilibrium from being reached. They also reported that an understanding of kinetics, in combination with the thermodynamic limits of the process, would be necessary to determine the final weld metal composition. Blander and Olson (Ref. 3) also discussed the influence of kinetics, the role of interfacial reaction, and the degree to which equilibrium is approached. This paper is a part of the systematic investigation undertaken by the Colorado School of Mines (Refs. 3-7) to better understand the behavior of different flux additions to the manganese-silicate and lime-silicate flux systems. The influence of FeO, CaO and CaF2 additions to a manganese-silicate flux on AISI 4340 steel weld metal chemistry is reported here. In addiKEY W O R D S Welding Flux Effects Flux Additions 4340 Steel Weld Metal Weld Composition Submerged Arc Fluxes 1020 Steel Weld Metal Ca2/CaO/FeO Addition Mn-Silicate Fluxes SAW Flux Systems tion, a comparison of the effects of CaF2 and FeO additions to a manganese-silicate flux on welds on AIS11020 and 4340 steels was made in an effort to understand the effect of alloying elements on weld metal chemistry. The results presented in this paper should be a useful database for future analytical modeling and comparisons. Materials and Procedure Single pass, bead-on-plate welds were made using the submerged arc welding process on AIS11010,1020 and 4340 steel base plates. The dimensions of the plates were 73 X 203 X 13 mm (2.9 X 8 X 0.5 in.). The welding wires used were AWS Type E70S-3 for welds produced on AISI 1010 and 1020 steels, and Type EM12K for AISI 4340 steel welds. Compositions of the base plates and welding wires are given in Table 1. The submerged arc welding process was performed using direct current, electrode positive. The welding parameters were maintained constant at 30 V, a travel speed of 8 mm/s (19 in./min), and the wire speed was varied to give 500 A. All welds were made with a heat input of 1.9 kj /mm (48 kj/in.). Three different flux systems were used in this investigation: Si02"MnO-FeO, Si02" MnO-CaO and Si02-MnO-CaF2. The fluxes were prepared using reagent grade chemical powders. The flux compositions were reported as wt-% MnO because M n 0 2 decomposes to form MnO during the melting operation used to produce the fused flux. The iron ion in the fused flux was determined to be in the Fe + state and is reported as wt-% FeO (Ref. 10). The reagent-grade powders were weighed and mixed prior to induction melting. The powders were then placed in a graphite crucible for the melting operation. All fluxes were brought to 1773 K. The crucible was then removed from the furnace and the flux poured onto a stainless steel plate to solidify. After cooling, the fused fluxes were crushed and sized. Fluxes sized 14 to 100 mesh were used for WELDING RESEARCH SUPPLEMENT 1115-s

Computerized radiographic sensing and control of an arc welding process

Abstract: This paper summarizes an effort in which real-time radiography was implemented for on-line arc welding process study and control. X-ray penetrating radiation was used for volume observation in the welding pool and the heat-affected zone during the weld process. The advantages of such a technique are online detection and monitoring of defect formation in the weld and capability to study metal fusion and filler metal/base metal interaction and metal transfer in the welding pool. This technique may also be used for postservice, real-time remote testing of weld quality.

Process and connection component using an electrical resistor for the welding of plastic elements

Abstract: The invention relates to the welding of components made of heat-fusing plastic, using an electrical heating resistor arranged in the thickness of a connection component. According to the invention, the resistor is a thin electrically conductive layer advantageously formed on a supporting film made of heat-fusing plastic and capable of causing the tearing of the layer at a specific temperature corresponding to the welding temperature of the components. The invention is used particularly for the thermal welding of polyethylene pipes used in the gas industry.

Method of automatically welding rails

Abstract: In a method of automatically welding rails, welding of bottom portions of the rails is carried out as root pass welding of a first layer according to CO2 gas shielded arc weld technique, and as continuous multilayer welding of layers above the first layer according to CO2 gas shielded arc weld technique without discontinuing the welding of a second layer and upper layers. In welding of ankle portions (R2) of the rails, a flux is rapidly added to promptly shift to electroslag weld. Then, welding is conducted to head surfaces (R5) of the rails by continuing electroslag weld technique. This automatic welding method enables high efficiency field welding of rails, obviating the need for any complicated switching operation of the electric power source and use of several kinds of welding materials.

Connection component for together plastic elements by thermal welding

Abstract: The invention relates to a connection component equipped with an electrical resistor for the welding of elements made of heat-fusing plastic. According to the invention, the resistor takes the form of a single wire coated with an electrically insulating layer and having points of intersection, the coating layer fusing at a temperature between the fusion temperature of the components to be joined together and their temperature of thermal damage, so that short-circuits are generated on the wire and so that the stopping of the supply of current to the latter is commanded. The invention is used particularly for the thermal welding of polyethylene pipes used in the gas industry.

Closure development for high-level nuclear waste containers for the tuff repository; Phase 1, Final report

Abstract: This report summarizes Phase 1 activities for closure development of the high-level nuclear waste package task for the tuff repository. Work was conducted under U.S. Department of Energy (DOE) Contract 9172105, administered through the Lawrence Livermore National Laboratory (LLNL), as part of the Yucca Mountain Project (YMP), funded through the DOE Office of Civilian Radioactive Waste Management (OCRWM). The goal of this phase was to select five closure processes for further evaluation in later phases of the program. A decision tree methodology was utilized to perform an objective evaluation of 15 potential closure processes. Information was gathered via a literature survey, industrial contacts, and discussions with project team members, other experts in the field, and the LLNL waste package task staff. The five processes selected were friction welding, electron beam welding, laser beam welding, gas tungsten arc welding, and plasma arc welding. These are felt to represent the best combination of weldment material properties and process performance in a remote, radioactive environment. Conceptual designs have been generated for these processes to illustrate how they would be implemented in practice. Homopolar resistance welding was included in the Phase 1 analysis, and developments in this process will be monitored via literature in Phases 2 and 3. Work was conducted in accordance with the YMP Quality Assurance Program. 223 refs., 20 figs., 9 tabs.

Inverter type resistance welding machine

Abstract: There is described an inverter type resistance welding machine comprising one rectifier, one inverter connected in series to the rectifier, and a plurality of welding current elements connected in series between a plurality of welding transformers and an output of one inverter. It is possible to reduce the space of installation of the resistance welding machine and cost involved in the installation thereof and reduce a weld time.

Resistance welding apparatus

Abstract: Apparatus for welding longitudinal seams in can bodies includes upper and lower electrode wheels mounted on arms, a transducer for detecting vertical displacement of the upper wheel, a pair of pick-ups for detecting the rotational positions of the wheels, and a single processing circuit. The transducer output is divided into a set of traces, each corresponding to a single wheel rotation. The traces are averaged to produce a representation of the wheel profile. Each wheel profile is subtracted from the transducer output to produce a good indication of weld thickness. Alternatively, the transducer output is divided into a series of traces, each of which represents the vertical displacement of the upper wheel while welding a single can body. These are averaged to provide a good indication of weld thickness. The wheels have surface irregularities and each is inevitably mounted with some degree of eccentricity. Unwanted transducer output components due to these irregularities and eccentricities are removed.

Method and apparatus of submerged arc welding with electrodes in tandem

Abstract: A method and apparatus for submerged arc welding using five-electrodes having direct current (DC) connected to one electrode and alternating current (AC) connected to the other four electrodes. The electrodes are aligned in a row with predetermined angles to the direction of the weld. Alternating current is supplied to the electrodes so that a 90° phase difference is applied to adjacent electrodes and a 180° phase difference is applied between alternating electrodes. With such power application and the electrical connections of the electrodes, the welding process has a more stable weld puddle that suppresses welding defects at higher speeds than previously achievable.

Simultaneous in-process control of heat-affected zone and cooling rate during arc welding

Abstract: The problem of process control welding involves not only regulation of weld bead geometry, but also thermally induced changes such as distortion, residual stresses and metallurgical transformations near the weld. This paper addresses the last of these, and poses it as a feedback control problem. The objective is transformed to one of controlling the surface temperature field in-process, and using temperature feedback to implement such a scheme. A control model of the process is presented, and a parameter adaptive controller is designed to ensure consistent control system performance. A series of numerical simulations and experiments using GMA welding is presented that confirms the model and illustrates the desired properties of the controller. With this system, the heat-affected zone and cooling rate (through their correlates in surface temperature-time relationships) can be regulated independent of each other, and gross disturbances to the temperature field rejected totally in the steady-state. In addition, dynamic performance of the control system is illustrated, and the limits imposed by current hardware are discussed.

Electrode for resistance welding surface-treated sheets of steel and method of manufacturing such electrodes

Abstract: The invention concerns an electrode for the resistance welding of sheets of surface-treated steel. A thin disk of high melting-point metal is permanently attached to the electrode's shaft or cap at the contact surface. The grain of the high melting-point metal is oriented at an angle to the axis of the electrode and the rolled-out material has a flattened grain.

Pulsed arc welding machine

Abstract: In a pulse arc welding machine which is adapted to feed at a constant speed a welding wire as a waste electrode to turn the molten lump of the wire tip end into a spray state with a pulse current so as to effect a welding operation, the risetime and falltime of the pulse current influence the bead outer appearance, the gas shielding property and welding function and are varied independently of the other parameters controlled by the machine in accordance with the material quality of the welding wire, the wire diameter, and the wire feeding speed.

Method and apparatus for electrically heat welding thermoplastic fittings

Abstract: An improved method and apparatus for electrically heat welding a thermoplastic fitting having an electric resistance heating element disposed therein. A controlled quantity of electric power is supplied to the heating element during the welding process to insure the making of a high quality weld. After the size of heating element and fitting are determined, a substantially constant voltage level electric power is supplied to the heating element of the fitting. When it is determined that the welding process is proceeding abnormally, the supply of electric power is terminated unless the abnormality is that the current level is too high. In that case, instead of terminating the welding process, the voltage of the electric power is reduced to that which results in current levels substantially equal to predetermined current levels for the size of heating element and fitting being welded which often results in a good weld being obtained even where the heating element is partially shorted out. Also, fires and other problems which have heretofore resulted due to such short circuits are prevented.

Method for joining different metals

Abstract: PURPOSE: To widen the range of joining conditions under which the joining of different metals can be surely executed and to make it possible the joining between a stainless steel plate and Al plate being the above-mentioned different metals can be executed simultaneously, and further to increase the strength of a joint part because the melt of the welded thin metallic material removes the surface contaminating layer of the different metals. CONSTITUTION: Resistance welding is executed by inserting the thin metallic material 4 consisting of the Al system having the m. p. lower than the m. p. of Al between the Al sheet 3 and the Al surface of a clad material 1 and specifying the weld time at the time of the above-mentioned resistance welding to ≤10ms at the time of joining the different metals by crimping the clad material 1 consisting of two kinds of the different metals between the stainless steel plate 2 and the Al sheet 3 which are these different metals in such a manner that respectively the same kinds of the metals come into contact with each other and subjecting these materials to the resistance welding. COPYRIGHT: (C)1992,JPO&Japio

Lap resistance welding method of aluminum material and steel material

Abstract: PURPOSE: To prevent the deterioration, etc., of a welded joint at the time of lap resistance welding of Al materials and steel materials by executing two-step energization of first passing the current conformed to the weld heat input of the steel material, then passing the current conformed with the weld heat input of the Al material. CONSTITUTION: Clad materials 3 of the Al material 5 and the steel material 4 are interposed and superposed between the Al material 2 and the steel material 1 in such a manner that the same kinds of the metals face each other. These materials are thereafter inserted between resistance spot welding electrodes 6 and are subjected to the two-step energization. The steel materials 1, 4 are first melted and joined to each other and in the next step the Al materials 2, 5 are melted and joined to each other. Namely, the energization system to take the weld heat input of the steel materials and the Al materials into consideration is adopted and, therefore, expulsion and surface flash, crack, discoloration, deterioration of the welded joint, etc., are effectively prevented. COPYRIGHT: (C)1992,JPO&Japio

Resistance welding electrode coated with ceramic layer

Abstract: An outer surface of a resistance welding electrode tip is coated with a layer of an electrically conductive ceramic material. A preferred layer contains tungsten disulfide applied by chemical vapor deposition.

Pulsed arc welding equipment

Abstract: The welding equipment according to the present invention divides the pulsed electric current fed to a base metal in the course of a welding process into a plural number of pulse groups, performing instantaneous control over the base electric current period and the base electric current value applied to each of the pulse intervals of the individual pulses within such a group of pulsed electric currents and to each of the groups of pulsed electric currents, the pulse peak value and pulse width of each pulse, and such instantaneous control over a short circuit period and an arc period in the course of performance of the short circuiting transfer arc welding process, in accordance with the detected arc length, in such a manner that an ideal target arc length is thereby achieved. The welding equipment is capable of achieving the separation and transfer of molten globules to the base metal with regularity and also reducing the fluctuations in the short circuit period and the arc period in the short circuiting transfer arc welding process, offering the advantage that the equipment can control the growth and separation of molten globules without being affected by the phenomenon of magnetic arc blow of the arc and can achieve improvements on the quality of weldments even if fluctuations should occur in the shape of welded joints and in the position of the earthing point in operation with the actual arc.

TIG and Plasma Welding: Process Techniques, Recommended Practices and Applications

Abstract: Process fundamentals Applying the TIG process Mechanised Orbital tube welding Tube to template welding Micro-TIG welding Hot wire TIG welding Narrow gap TIG welding Process fundamentals: Applying the plasma process The future.

Pressure applying device for resistance welding

Abstract: Pressure applying device for resistance welding which includes a pair of two gun arms having an electrode tip at two opposed ends of the arms, a flexible supporting means connecting said two arms, an actuator provided between said two arms, and a link mechanism connecting said two arms to define movement of the electrode tip According to this invention, the operation of said actuator to pull the gun arm allows the electrode tips in the open position as well as the supporting means accumulating resilience And, the reverse operation of said actuator can provide an elastic force by said flexible supporting means acting on the pieces between the electrodes, in addition to the welding pressure by the actuator

Occupational asthma due to spot-welding.

Abstract: A case of occupational asthma from fumes due to spot-welding is described. The hazards from resistance welding have been considered minimal as compared to other types of welding. This paper illustrates the possible hazards of occupational asthma among welders including those doing spot-welding. It also illustrates the difficulties encountered in identifying the specific causative agent in such cases.

Thermal Cycle and Microstructure of Heat Affected Zone (HAZ) of Flash Butt Welded Mn-Cr-Mo Dual Phase Steel

Abstract: Flash butt welding of 3.7 mm thick Mn-Cr-Mo dual phase steel is carried out at different final jaw distances, where various post weld cooling systems such as the normal machine cooling, forced air cooling and water spray cooling are used. The energy input during welding such as the current and voltage are kept constant. The intention of this investigation is limited to study the influence of various weld thermal cycle on the behaviour of phase transformation at weld centre and different regions of HAZ. Under different conditions of welding the weld thermal cycle is analysed and the behaviour of phase transformation at different regions of the weldment is determined with the help of welding CCT diagram. A detail microstructural study is carried out under optical and scanning electron microscopes. A special attention is paid to study the behaviour of tempered martensite region of HAZ, which is identified earlier as the weakest region of HAZ, under different welding conditions. The weakening of tempered martensite region is estimated by measuring its microhardness under different conditions of welding.

Welding machine for plastic components - moves them to heated blade and then butt welds them together using feed system which moves them very precisely

Abstract: A layout for welding successive plastic components has a control system and at least one device to guide and feed the components during the welding process, this device has an electromagnetic drive and stepped motor. ADVANTAGE - The layout is efficient and convenient. In partic. its feed system is efficient.

Wet welding electrode evaluation for ship repair

Abstract: An evaluation of submerged arc welding (SMAW) electrodes shows that wet welding is a viable process for underwater repair and maintenance of ships.

Method and apparatus for resistance welding wherein the electrode axis is included with respect to the electrode forcing axis

Abstract: A method and apparatus for resistance welding in which, while both or one of the electrode center axes of a pair of opposing electrodes is inclined with respect to the electrode forcing axis, the electrode tip of the electrode is intermittently pivoted about the electrode center axis for welding. The contact between the electrode tip and workpiece is moved at a preset number of welds to define a next contact surface on the face of the electrode tip, and thus the number of welds (electrode tip life) is considerably improved.

Solid electrolytic capacitor

Abstract: PURPOSE:To completely remove a danger of improper sealing due to cavity of solder caused by expansion of inner air at the time of sealing by placing a capacitor element on a metal stem having the first lead welded to a metal plate and the second lead to be glass-sealed via the hole of the plate, covering it with a metal cap, and sealing by resistance welding. CONSTITUTION:An oxide film, manganese dioxide, a carbon layer, silver paste are sequentially formed on an anode made of a valve operating metal such as tantalum, etc., and a capacitor element 11 is formed. The element 11 is secured to a metal stem 15 having the first lead (outer cathode) 12 welded to a circular metal plate, and the second lead (outer anode lead) 14 glass-sealed via the hole of the plate via conductive adhesive or solder 16. Thereafter, after the anode lead 17 of the element 11 is welded to the lead 14, it is covered with a metal cap 18, the stem 15 and the outer periphery of the cap 18 are eventually sealed by resistance welding to obtain a solid electrolytic capacitor filled in a metal case.

Resistance welding electrode having an angled nose and process of fabrication thereof

Abstract: Resistance welding electrodes and processes of using and of fabricating the same are provided. The electrodes have a base portion and an integral nose portion projecting therefrom, with the nose portion terminating in a welding tip face. The nose portion tapers inwardly between said base portion and said welding tip face with a concave profile taper such as a frustum of a vortical surface. The electrodes used may be made up of a conventional copper material having copper combined with one or more metals selected from the group consisting of chromium, zirconium, cadmium, cobalt, nickel, beryllium, tungsten, aluminum, tungsten carbide, iron, and molybdenum; or, may be made of essentially pure copper. The electrodes may be used in a welding process, which provides for a generally linear increase in current stepping with reduced or eliminated conditioning of the electrodes. The welding tip face has a convex curvature which may range between about a two inch and a eight inch radius of curvature, and which preferably has a radius of curvature of about four inches. Both male and female electrodes may be used with cooling recesses in the electrodes as well as an offset nose portion. The diameter of the welding tip face may be about equal to the length of the nose portion. The nose portion may be angled with respect to the base, and additionally may be offset. Fibrous grain structure may be formed which is at a non-normal angle with respect to the welding tip face to reduce cracking.

Fluid filter and method of manufacture

Abstract: In a process for the manufacture of a filter for liquid or gaseous media, especially for exhaust gases of combustions engines, the filter is formed from one or several filter plates out of a mesh, network, reticulation or fabric of metal wires. The filter body of a plurality of layers or plies of wires is brought between the electrodes of a resistance welding unit and subsequently a resistance welding is performed for partial connection of the wires to one another by spot welding.

Spot welding method and apparatus having weld electrode lock-up

Abstract: A method and apparatus for single-sided resistance spot welding that prevents excessive weld indentation. A first flat part and a tubular part are clamped between welding electrodes with a predetermined welding force. A welding current is applied to the electrodes to heat the parts where the spot weld is made. One of the electrodes is locked from movement as welding current is applied to prevent that electrode from indenting into the heated weld zone.