Showing papers on "Heat-affected zone published in 1975"

Mechanism of solid state pressure welding

Abstract: The mechanism of pressure welding in polycrystalline aluminum, copper, silver and gold was investigated. The role of the oxide fi lm was studied and it was found that no metal to oxide bonding contributes to the strength of the weld. From scanning electron microscope observations a two-stage model has been suggested which could explain the dif ferent behavior of the metals studied. The first stage of welding involves the formation of overlapped oxidefree metallic areas; this is controlled by: (a) difference on a microscale of the local plastic strain occurring on matching opposite faces of the weld interface, (b) relative hardness of the metal and its oxide fi lm, and (c) mechanical properties of the oxide. The second stage involves: (a) plastic flow of the metal to the overlapped areas; the stress at which this can take place is influenced by the stacking fault energy of the metal, and (b) some relative shear displacement at the points where metal cleaned of oxide comes into contact; this is influenced by surface roughness. The different weldability of different metals is attributed to differences in stacking fault energy, hardness ratio and plastic properties of the oxide. The weld strength calculated theoretically on the basis of measured The authors are associated with the Inorganic Materials Research Division. Lawrence Berkeley Laboratory and the Department of Materials Science and Engineering, College of Engineering, respectively, at the University of California, Berkeley, California 94720. welded area was in agreement with measured fracture strength. It was concluded that the strength attained after a given deformation is determined by the fractional welded area at that deformation.

Short-circuit arc welding with constant beads

Abstract: In short circuit arc welding there are many parameters which influence the automatically controlled welding procedure, but which frequently may affect the quality of the weld. In some circumstances the welding bead which is formed does not flow in to the molten pool of the workpiece, but disintegrates into many small drops around the weld owing to an excessive short-circuit current. The invention proposes methods and arrangements in which certain parameters, such as arc time and a short-circuit current delay time are controlled or maintained constant, so that always a constant bead size is assured owing to a constant power, after which said bead of constant size is first partly introduced into the molten pool and subsequently the short-circuit current for separation is applied.

Clamping of film-like material for radiant energy welding

Abstract: Sheets of film-like material such as thermoplastic sheets, coated paper, or metallic foil may be clamped together for radiant energy welding by directing jets of gas against the outer surfaces of two opposed sheets to press or clamp the sheets firmly into contact with each other; and, then by irradiating the contact area to heat the material to its welding temperature, the sheets will be fused together.

Thermoplastics welding method

Abstract: A welding method for joining self-supporting structures made of thermoplastics by assembling said structures to form an area of mutual overlap, generating heat in said area to produce a welding zone having an elevated temperature and containing said thermoplastics in an at least plastic state for mutual coalescence of said structures in said area; an expanding agent is provided in the welding zone to generate a gas pressure therein for promoting coalescence of the weld. The invention is particularly suitable for welding tubes and other pipeline elements, such as fittings or sleeves, of thermoplastics and produces a tumescent weld which fills any macroscopic voids while including a plurality of minute closed cell voids.

Arc welding method and arc welding apparatus

Abstract: This invention provides arc welding methods and arc welding apparatus which weld materials by giving a plastic deformation of definite curvature to wire itself in a process before supplying the wire to a welding nozzle, restoring the wire delivered from the welding nozzle to the plastic deformation of definite curvature, delivering rotatively the end of the wire in a definite period from a delivery hole of the welding nozzle in butt welding of thick board, especially narrow gap welding.

Electron beam welding technique for joining two workpieces together

Abstract: In the preparation of plane or curved workpieces for welding together by means of an electron beam and wherein the weld takes the form of a full penetration joint, fusion lips are provided at the place where the lower welding bead forms. In the case where the workpieces are constituted by rotationally symmetrical thick-walled hollow bodies such as rotor discs for construction of turbo-machines which upon welding together form a closed cavity, the fusion lips have an annular configuration and are located at the inner radial contour of the welding interface. The workpieces are also provided with an arrangement for centering the lips and a metal foil is inserted between the lips to improve the toughness of the weld material, the foil having a carbon content lower than that of the parent metal of the workpieces.

Method and apparatus for shortcircuiting arc welding

Abstract: A method and apparatus for controlling the welding current in shortcircuit transfer arc welding including a method and control apparatus for maintaining the effective value of the welding current during arcing period at a predetermined value. Maintenance of the effective value of welding current during arcing period is necessary to keep the size of a fusion zone and the depth of penetration constant throughout welding operation.

Cored wire junction

Abstract: Ductile junction of metal-sheathed composite wire, such as flux-cored welding wire for use in automatic arc welding machines, is provided by process comprising resistance upset welding

Methods of welding corner joints

Abstract: A method of welding corner joints by means of a multiple electrode submerged-arc welding and adapted to be utilized for the manufacture of a hollow square steel pillar and the like structural frameworks is disclosed. The method of welding is effected under the following three conditions: 1. The distance between first and second electrodes is 30 to 80 mm, 2. The current flowing through the second electrode is 60 to 85% of the current flowing through the first electrode, and 3. The welding heat input H is given by H ≦ 24d.t KJoule/cm where t is a thickness of a steel flange plate in cm and d is a required penetration depth in cm, whereby a weld bead is completed by a single pass of welding.

Analysis of Thermal Stresses and Metal Movement During Welding—Part II: Comparison of Experimental Data and Analytical Results

Abstract: This is the second part of a study of thermal stresses and metal movement during welding. Part I described the finite-element analysis of two-dimensional thermal stresses and metal movement during bead-on-plate and butt welding. Part II presents results of experiments on bead-on-plate and butt welds in 6061-T6 aluminum alloy. Measurements were made of changes of temperature, thermal strains, and metal movement during welding. The paper then compares experimental data with analytical results. Good agreements were obtained between experimental and analytical results.

High temperature welding backup strip

Abstract: The tendency of molten weld metal to burn through a supported refractory welding backup material is greatly reduced by incorporating a woven carbon fiber cloth between the refractory and the support. A preferred product is a pressure-sensitive adhesive tape construction incorporating the carbon-fiber cloth in the backing; surprisingly, the carbon does not embrittle the weld.

Method for electron-beam welding of dissimilar metals

Abstract: A method whereby defect-free welds can be produced in joining metallic members of dissimilar materials by electron-beam welding. The method consists in inserting one of the metallic members in openings formed in a metallic plate of the same material as the other metallic member and welding one metallic member to the metallic plate by providing a weld metal, providing by overlay welding on the weld metal a padding metal of a material substantially similar to that of the other metallic member but lower in oxygen content, effecting machining of the outer surface of the padding metal to form a faying surface, and joining by electron beam welding the faying surface of the padding metal to a faying surface formed on the other metallic member whereby the faying surfaces can be rigidly welded.

Method for specifying hot isostatic pressure welding parameters

Abstract: A procedure for graphically presenting the minimum pressure and temperature required for hot isostatic pressure welding of metals and alloys is described. The use of one such graph for specifying weld parameters is demonstrated and is found to be reasonably accurate. (auth)

Delivery of welding flux in a method of submerged arc strip cladding of metallic work pieces

Abstract: A method and apparatus is disclosed for feeding welding flux to both the leading and trailing sides of the strip electrode used in a submerged arc strip cladding process. In order to prevent distortion of the bead shape the pressure due to the weight of the flux burden is controlled to be less in the region of the molten metal and slag pools lying directly behind the welding arc. The flux burden is caused to increase from a first depth directly behind the strip to a maximum depth at the trailing edge of the weld crater region where the quantity of liquid metal and liquid slag is a minimum.

Butt welding process and apparatus for effecting same

Abstract: Disclosure is made of a butt welding process, whereby butt ends of articles to be welded together are placed one opposite the other in a chamber containing a shielding medium. The butt ends are then heated until a layer of molten metal is formed on their surfaces, and upset in order to effect their plastic deformation and produce a weld joint. According to the invention, the heating and flashing-off of the butt ends are effected by a low-pressure arc uniformly distributed over the entire butt end surfaces of the articles being welded. The proposed method is effected through the use of an apparatus which, apart from a welding transformer whose secondary winding terminals are connected to articles being welded, comprises, in accordance with the invention, an auxiliary transformer that serves to initiate a low-pressure arc, or, successively, a glow discharge and a low-pressure arc between the butt ends of the articles being welded, as well as to stabilize said low-pressure arc, the secondary winding terminals of the auxiliary transformer being connected to the articles being welded via a valve-type breaker intended for controlling the low-pressure arc. The proposed process and apparatus for effecting this process make it possible to weld articles with different cross-sectional configurations, while making use of small deformations of articles in order to produce a weld joint. The process and apparatus of the present invention also account for a stable welding process.

Method of multiple gas shielded arc welding

Abstract: of the Disclosure In a method of multiple electrode gas shielded arc welding wherein a plurality of electrodes are arranged along the welding seam line of a piece of metal to be welded and the continuous gas shielded arc welding of the piece is accomplished simultaneously by the electrodes, the chemical. composition of the electrode wire of the electrode or electrode group for depositing a proceeding layer or layers is selected to differ from that of the electrode wire of another electrode or electrode group for depositing a subsequent layer or layers, whereby the chemical composition of the weld metal made by the preceed-ing welding operation is brought near to that of the weld metal made by the following welding operation and thus the uniform properties are ensured for the welding metals at the respective positions in the weld zone.

Method of vertical welding of aluminum and aluminum alloys

Abstract: A method of vertical welding of aluminum and aluminum alloys comprising welding Al or an Al alloy while oscillating in a welding groove an electrode in a closed pattern corresponding substantially to the groove shape, wherein the welding is conducted by using a welding current higher by 10 to 150 A than the base welding current at least during the course of oscillation of the electrode along the groove face of one of the materials to be welded while the electrode is pursuing courses of oscillation along both groove faces of the materials to be welded.

Automatic arc welding process using a consumable nozzle

Abstract: An automatic arc welding process for welding in a substantially horizontal direction, includes the steps of placing a longitudinal consumable nozzle along the joint line within the weld groove, the nozzle being coated with an insulating material disposed therearound and having a hollow core portion, and continuously feeding a wire through the hollow core portion.

Backing flux for one side arc welding

Abstract: PURPOSE:To provide the subject flux wherein an aqueous dextrin solution which has been prepared in a specific viscosity is mixed and added in the flux thereby to apply the solution on the flux uniformly, and further applying a suitable quantity of calcium stearate on the surface thereof thereby to make it possible to carry out effective welding.

Method for welding through paint

Abstract: Relates to a method of and apparatus for electric welding through insulation coatings, such as paint, on metallic surfaces by directing a vapor jet of paint solvent upon a selected area of a painted metal surface to first soften and then vaporblast the softened paint away from the area to expose a bare spot of the metal surface for welding Then, before the softened paint reflows back over the bare spot as a result of the discontinuance of the vapor jet, quickly bringing a metal part into welding range of the bare spot and welding the two metal parts together Following the welding operation, the softened paint coating reflows over the exposed welded juncture and hardens to form a protective film thereover

Diffusion welding of bearing bushes in steel parts - using difference in thermal expansion to generate pressure during heating

Abstract: In a process for joining a hollow bush, made of non-ferrous metal, to the bore of an iron or steel part, the bush is inserted and a high-strength supporting core is then inserted in the bush, the core material having a higher m.pt. than the material of the bush and preventing the bush from shrinking. The assembly is then heated for diffusion welding of the parts. A low m.pt. metal may be placed between the parts opt. with another metal forming an alloy with the low m.pt. metal, the alloy having the same or similar structure as >=1 of the parts being joined, and a groove may be provided for the additional metal(s); heating for welding may be in a moderate vacuum or in inert gas. Used e.g. for diffusion welding of a bearing bush in a steel housing or cylinder-drum for axial- or radial-piston engines. A flaw-less metallurgical bond is obtd. and no special device is required for applying press., which is generated by the difference in thermal expansion of parts being welded.

Investigations on laser-welding

Abstract: A welding method has been developed that makes use of fundamental mode laser pulses. These pulses show single-mode relaxation oscillations with a high peak power first spike causing breakdown of the material surface. The laser emission following the first spike can be adapted to the welding requirements and the material properties. Metallurgical problems of intermixing of dissimilar materials in the weld puddle have been investigated with an electron beam microprobe analysis. In the case of materials which normally show bad weldability uniform welds with maximum strength could be achieved by local addition of welding agents to the weld puddle. The lap weld of a stainless-steel spring with a nickel-iron baseplate has been performed with Nb as welding agent.