Showing papers on "Shielded metal arc welding published in 1973"

Adaptive control for arc welding

Abstract: A semiconductor electronic chopper precisely controls the current to a welding arc in response to arc length as represented by arc voltage. The actual arc current is compared with a reference current to generate a switching signal which adaptively controls electronic switches in order to meet arc requirements. For manual welding with covered electrodes (SMAW), frequently referred to as ''''stick welding,'''' a slope control potentiometer is used to vary the value of the reference current when the arc length (voltage) deviates from a preset normal operating length (voltage). This creates a family of volt-ampere characteristic curves all passing through the preset voltage and current operating point. A digging characteristic is obtained by increasing the reference current rapidly when the arc voltage (length) goes below a preset value. An intermittent spray transfer welding process, particularly applicable to continuous wire feed electrode systems, is created by maintaining the welding current at a high constant value until the electrode wire burns back to a maximum desired length (voltage) and then automatically reducing the current to a low constant value until the electrode is advanced sufficiently to shorten the arc and signal the system to change to a high current, etc.

Method for welding iron steel and nonferrous alloy

Abstract: In welding iron, steel, and nonferrous alloys, the wire feed is changed periodically and in synchronism with periodic changes of the electric welding current to establish a previously defined relation between the welding current value and the arc length. The welding current is varied between one producing a spray transfer arc and a current just maintaining the arc.

Grain refinement control in tig arc welding

Abstract: A method for controlling grain size and weld puddle agitation in a tungsten electrode inert gas welding system to produce fine, even grain size and distribution is disclosed In the method the frequency of DC welding voltage pulses supplied to the welding electrode is varied over a preselected frequency range and the arc gas voltage is monitored At some frequency in the preselected range the arc gas voltage will pass through a maximum By maintaining the operating frequency of the system at this value, maximum weld puddle agitation and fine grain structure are produced

Electrode for vertical-up open arc welding using molding shoes

Abstract: A cored-type welding electrode for vertical-up welding using molding shoes to hold the molten metal in position, using an open arc which does not require an externally-supplied shielding gas and which permits very high linear welding speeds. The core materials include a metal fluosilicate capable of breaking down in the heat of the arc to produce: a gas in sufficient volume to shield the arc from the atmosphere and a slag forming ingredient; and, other slag forming ingredients including the metal oxides and the alkali metal fluorides in a critical volume such that the total slag forming ingredients do not exceed six percent of the total electrode weight and the oxides are present in quantities at least greater than the fluorides. The self-shielded electrode further permits the use of active deoxidizers in quantities of under 0.5 percent.

Tungsten inert gas arc striking device

Abstract: A tungsten inert gas arc striking device for welding stainless steels and nonferrous metals, e.g., aluminum is provided, in which when striking an arc or restriking the arc, the charge stored in a capacitor is momentarily discharged through a discharge switch and a coupling coil to produce a kick voltage and this kick voltage is then superimposed on a welding current to effect the arc striking or restriking. Thus, welds of high quality can be produced and the occurrence of radio interferences can also be eliminated.

Vertical welding of heavy aluminum alloy plates

Abstract: A system for welding large aluminum alloy plates in a single vertical pass by the gas metal-arc (GMA) process wherein the technique comprises spacing square butt edges of the plates about three-fourths inch to form the welding gap; oscillating between defined dwell limits a welding electrode across the gap at comparatively high rate to deposit thin layers of weld metal, and confining the weld metal by dams having facing surfaces of molded high-density electrographitic material machined to high finish respectively. The dams together with the welding head are moved vertically upward at a smooth, uniform rate to preclude any objectionable jerking movement of the facing surfaces.

Submerged arc welding process for very low-temperature steel and welded product

Abstract: A submerged arc welding process forming a welded steel joint consisting of said steel pieces joined by weld metal having superior impact resistance at low temperatures, said weld metal consisting essentially of up to 0.1% carbon, less than 0.4% silicon, between 1.2% and 1.7% manganese, between 0.08% and 0.5% molybdenum, between 0.02% and 0.05% titanium, between 0.0012% and 0.004% boron, up to 4% nickel, and less than 0.045% oxygen. The process utilizes specified low-temperature steel base metal which is to be welded; specified welding electrodes; and a flux.

Welding method and materials

Abstract: Methods and materials for submerged arc welding for obtaining a high toughness welded metal containing titanium and boron by using a flux cored wire composed of a steel sheath and a core containing titanium and boron with the addition of a metal fluoride.

Welding of copper and iron

Abstract: A method for welding copper or a copper base alloy and iron or an iron base alloy characterized in that an element for enhancing the mutual miscibility of copper and iron and an element for refining the crystal grains of the weld metal is added to weld metal in a total amount of 1 to 25 percent by weight based on the weld metal, thereby preventing the welded portion from crack formation and segregation.

Creep properties of a type 308 stainless steel pressure vessel weld with controlled residual elements

Abstract: A SMA Type 308 stainless steel pressure vessel test weld with the CRE (controlled residual elements) boron (0.007 percent), titanium (0.06 percent), and phosphorus (0.04 percent) has been tested in creep between 482 and 650$sup 0$C. Improved ductility compared with that of standard welds in tests lasting several thousands of hours is observed. Systematic variations of creep properties through the weld are due to thermal and mechanical cycling during the welding process. Anisotropic deformation related to local substructure and preferred crystallographic orientation occurs. Creep strengths are acceptable by present design rules. (auth)

Electrode and flux combination for submerged arc welding

Abstract: In order to apply the submerged arc method of welding to a medium-carbon, Ni-Cr-Mo-V steel, and obtain a weld deposit which can be heat treated to provide a yield strength of 160-180 ksi along with a reduction in area of at least 25 percent and an impact resistance of at least 15 ft/lbs. at -40*F, an electrode wire having no more than 0.04 percent of silicon is utilized with a neutral welding flux having a residual percentage of manganese and from 1.5-3.0 percent of silicon to insure the proper deoxidation of the molten electrode. The flux also includes about 0.30 percent carbon for replacing that portion thereof lost from the electrode wire during the formation of the weld deposit.

Method of welding metals under water

Abstract: The underwater welding of metal surfaces using a plasma arc, wherein the plasma arc, plasma gas and weld part are sealed with a layer of water glass.

Weld rod containing manganese

Abstract: A cored wire welding electrode for welding cast iron having an outer sheath made of nickel or a nickel-iron alloy and a powedered core composition containing copresent metallic magnesium and graphite and slag-forming ingredients along with special amounts of manganese. The electrode is particularly useful for open arc welding wherein a high strength weld deposit is required.

Process of welding a high tension steel

Abstract: A process of welding a high tension steel comprising welding said high tension steel by the Metal-arc-Inert-Gas welding method with an electrode by which a metastable austenitic steel weld metal is obtained and, thereafter, subjecting said welded high tension steel to (1) a sub-zero cooling to transform the austenitic steel into martensitic steel and (2) an aging treatment at a temperature and for a period of time sufficient to improve the tensile strength and yield strength of the product.

Plasma Arc Welding for Thick Plate (Report 1)

Abstract: This study was conducted as a preliminary research for further development of some plasma arc welding methods for thick plate above 10 mm.The large plasma torch and the control equipment designed to be proof against up to 1000 A with straight polarity connection have been fabricated especially for this study in our laboratory. With the ues of these equipments a series of experiments was carried out on the arc characteristics, welding conditions and welding sound.Conclusions obtained are summarized as follows:1) Thermal efficiency of plasma arc is in range of 53-60% and its heat losses to cathode, nozzle, shield cover and the other parts are 2, 20, 9-11 and 7-11% respectively at 500 A arc current.2) The Va-I (arc voltage vs. arc current), Va-Qp (arc voltage vs. plasma gas flow rate), and Va-la (arc voltage vs. arc length) characteristics of plasma arc at 300-500 A have been obtained as linear relationships whose slopes are in range of 0.02-0.05 V/A, 0.4-0.6 V/l/min and 0.4-0.6 V/mm respectively.3) The optimum welding conditions for plasma arc welding of 6, 8 and 10 mm thick mild steel plates have been evaluated in connection with welding speed, welding current, and arc constricting wall length of nozzle.4) In plasma arc welding of 16 mm thick mild steel plates, weld beads were produced as burn through or incomplete penetration beads. When the plates were backed up with copper plates, unstable plasma arc and sometimes series arcing occured and resulted in a defective bead.5) The frequency characteristic evaluation of plasma arc welding sound reveals that welding sound consists of mainly 300 Hz frequency as fundamental tone and its higher harmonics due to current pulsating (300 Hz frequency) in full wave rectification, and also that frequency characteristic is subject to the influence of welding condition mainly in above 2kHz frequency range.

Method of submerged arc welding of high tension steel workpieces

Abstract: Submerged arc welding of high tension steel workpieces by using bonded flux capable of generating at least 7 percent by weight of carbon dioxide gas during welding operation and producing slag with a basicity B L of not smaller than 1.0, in conjunction with a welding wire capable of providing alloying elements to weld metal, so as to produce weld metal having a high toughness and a high crack-resistivity.

Study of gas tungsten arc welding procedures for tantalum alloy T-111 (Ta-8 W-2Hf) plate

Abstract: Methods of eliminating or reducing underbread cracking in multipass GTA welds in thick T-111 plate were studied. Single V butt welds prepared using experimental filler metal compositions and standard weld procedures resulted in only moderate success in reducing underbread cracking. Subsequent procedural changes incorporating manual welding, slower weld speeds, and three or fewer fill passes resulted in crack-free single V welds only when the filler metal was free of hafnium. The double V joint design with successive fill passes on opposite sides of the joint produced excellent welds. The quality of each weld was determined metallographically since the cracking, when present, was very slight and undetectable using standard NDT techniques. Tensile and bend tests were performed on selected weldments. The inherent filler metal strength and the joint geometry determined the strength of the weldment. Hardness and electron beam microprobe traverses were made on selected specimens with the result that significant filler metal-base metal dilution as well as hafnium segregation was detected. A tentative explanation of T-111 plate underbread cracking is presented based on the intrinsic effects of hafnium in the weldment.

Weld additive for electric-arc deposit welding

Abstract: A welding additive for incorporation into electric-arc welding rod, e.g. of the coated or core type, contains chromium carbide with superstoichiometric quantities of carbon in the lattice of the chromium carbide to ensure a carbon content of 15 to 25 percent by weight. Preferably the additive is a low-melting hypereuctectoid of Cr3 C2 and elemental carbon. The additive improves the wear resistance and frictional characteristics of a deposit weld by imparting to its characteristics which have hitherto been associated only with high-carbon deposites of autogenous welding.

Composite metal thermostatic element

Abstract: A method for welding alloys of high manganese content to avoid the development of weld flash is shown to comprise the steps of resistance welding the manganese alloy under conditions of temperature and pressure which are adequate for forcibly expelling manganese oxide from the surface of the alloy. The resistance welding is performed while a thin layer of tin is disposed at the weld location, the tin being melted but remaining fluid without significant vaporization thereof at the welding temperature for restraining expelled manganese oxide at the extremities of the weld location to prevent the formation of weld flash.

Studies on the underwater CO2 arc Welding method with a curtain nozzle

Abstract: CO2 arc welding which is employed in the wet underwater welding has the following advantages.(1) The process is simple to operate.(2) In the safety aspects, the lower open voltage characteristics of arc welder is particulary helpful to avoid electric shock.(3) Welds can be made in all positions.But, in conventional wet underwater CO2 arc welding, nozzle-base metal distance was not more than 4 mm, therefore the welding operation was very difficult.We studied the following system that was called curtain water type underwater CO2 arc welding aimed to improve this problem. In the dual flow system which we used, curtain water was introduced from the outer nozzle. By this system we could take nozzle-base metal distance about two times longer than that for conventional shielding system. As the results of radiographic examination, no difficulty was found to obtain the welds without blowholes. At the first step to develop this process, we report experimental results of down hand position butt welding for mild steel.

Resistance welding - a sheet metal fishplate perpendicularly to a metal plate without welding marks

Abstract: One strip of sheet metal, e.g. a fishplate, is perpendicularly welded onto another metal plate by shaping the welding lips of the fishplate at slightly less than 45 degrees so that they are in linear contact with the other plate and constitute selected points for current passage. The lower welding electrode may be a copper alloy plate which pref. covers the whole of the welding area of the other plate, while the upper welding electrode presses only the welding lips against the welding area.

Effect of the thermal cycle in welding on the structure and phase composition of the heat-affected zone in maraging steel

Abstract: 1. The increase of grain size during welding depends on the cooling rate and on the time the metal remains at temperatures above the α→γ transformation temperature. 2. Cooling from α→γ transformation temperatures at a low rate leads to an increase in the amount of retained austenite and some reduction of hardness in the heat-affected zone.

Furnace plant for the drying or baking of coated arc welding rods

Abstract: A tunnel furnace plant for the drying or baking of coated arc welding rods in which the welding rods are suspended freely from straight carriers extending transversely to the direction of advancement through the furnace, each of said carriers carrying a row of welding rods. The plant also includes automatic equipment for fitting the welding rods to the carriers.