Showing papers on "Cold welding published in 1970"

The cohesion of previously fractured Fcc metals in ultrahigh vacuum

Abstract: The cohesion of clean surfaces of the fcc metals Ag, Al, Cu, and Ni was investigated using the technique of cold welding specimens previously fractured in an ultrahigh vacuum The cohesive strength of the weld increased with compressive load, all data falling on a single curve with slight positive curvature when the cohesive strength and compression load were normalized through the initial fracture strength of each metal The cohesion coefficients ranged from 062 to 115 and were in accord with those obtained using more elaborate techniques of surface preparation and testing It is proposed that the essentially constant cohesion coefficient obtained for all the unalloyed fcc metals resides in the fact that the area of contact produced by a given compressive load is inversely proportional to the fracture stress of the metal and the cohesive strength is directly proportional to this fracture stress A lowered cohesion coefficient was observed for copper specimens which had recrystallized in the vicinity of the interface either during the cold welding or as the result of a subsequent heat treatment

Methods of making heat exchangers

Abstract: A method of making a heat exchanger of the kind consisting of a stack of sheet metal pressings in face to face relation, adjacent pairs of pressings providing between them alternately channels for flow of coolant and spaces for flow of air, in which method the pressings are joined together by cold welding operations.

Welding of explosive-plated metal sheets

Abstract: The present disclosure relates to a process and arrangement of elements for welding explosive-clad metal sheets which substantially eliminate the formation of cracks when the weld is exposed to mechanical stresses.

Welding of wires to each other

Abstract: The invention relates to an improved means and process for welding wires and, more particularly, for welding lead wires to the ends of the magnet wire in small wire coils. The invention also embraces an improved welding torch using a small-orificed burner tip and providing a sheath of shielding inert gas around the welding flame. Improved fixture means is likewise provided for tensioning and holding the wires in intimate contact while welding or fusing. The fixturing includes a means holding one wire in tension and coiling the other thereabout. The torch is moved up to the wrapped wires to effect the weld by fusing the wires at a temperature such that the insulation first vaporizes, obviating the need for initial removal of the insulation by other means or methods. The fixture includes rotatable means to bring the two ends of the coil wire into position for making welds to the leads.

Welding by electron bombardment

Abstract: Electron beam welding apparatus wherein means are provided for welding a joint sealed by a sheet of foil and thereafter depositing a plastic product on the weld head to prevent contamination.

Resistance welding coated sheeting

Abstract: Welding current is fed, at least for one of the coated sheets, indirectly to the point to be welded by means of the sheet surface in order that an external layer remains intact and a contact established between the surfaces which have been uncovered for welding. Annular or linear edges and depressions are formed at the welding point in the sheet or on the intermediate welding pieces with the aid of stamps and/or cutting. Overcomes drawbacks encountered with conventional prior art welding machines where the outer layers of the welded sheets are destroyed by uncovering or by the fusion caused by the electrodes. Use: welding metal sheeting or elements coated with synthetic material, varnish or some other substance, such as steel, chrome-nickel steel, aluminium (anodised) or other metals.

Cold welding machine

Abstract: A cold welding machine which includes a special transformer adapted to carry out two functions, one of which is the upsetting of metal pieces to be bonded, and the other of which is the releasing of stress or strain caused by the pressure applied to the metal pieces by the hammering member, the strain being released by the electric current in the secondary winding of the special transformer.

Method and apparatus for electron beam welding

Abstract: This invention relates to a method of welding low carbon steel using an electron beam. The portion of the workpiece being welded is located in an evacuated welding zone and a deoxidizing metal backup member is disposed in spaced relation to the joint to be welded. During welding, the electron beam vaporizes a portion of the deoxidizing metal and the release of the metal vapor aids in increasing the soundness of the weld.

PROCESS DEVELOPMENT FOR DIFFUSION WELDING Ti--6Al--4V ALLOY.

Abstract: A low pressure diffusion welding technique for joining Ti-6A1-4V alloy is described. Diffusion welding experiments were carried out in an argon atmosphere under dead-weight compressive loading. Process parameters of time, temperature, pressure and surface finish were determined. Diffusion welded joints were evaluated by mechanical property testing, metallographic examination, and nondestructive testing methods. Excellent weld quality was obtained at 1800° F with a pressure of 60 psi and a time of 180 min. The optimum surface finish was 15 RHR or better. With these process parameters, joint efficiencies of 100% were obtained. The fatigue properties of the diffusion welded joints approached those of the base metal. NDT methods used were X-ray and ultrasonic A and C scan techniques. Satisfactory NDT results were obtained by both the ultrasonic A and C scan methods. Introduction The diffusion welding process offers the potential for improving properties and reducing weight of structural elements such as reinforced panel assemblies. In addition, metalworking costs for producing certain types of forgings could be reduced by diffusion welded built-up laminate structures as forging substitutes. The pressure required to produce intimate contact during the early stages of diffusion welding of titanium can be high (above 1,000 psi) or low (below 1,000 psi). Several investigators'-' have shown that Ti-6A1-4V alloy can be diffusion welded at high pressures (1,000-2,500 psi) and low temperatures (1200-1600° F ) . Such parameters offer high potential for joining multi-layered structures. However, for joining elements such as reinforced panel assemblies, the tooling required for high pressure difR. J. REHDER and D. T. LOVELL are Research Engineers, Aerospace Group, The Boeing Company, Seattle, Wash, Paper presented at the AWS 50th Annual Meeting held in Philadelphia, Pa., during April 28-May 2. 1969. fusion welding would be extensive and costly. Therefore, diffusion welding at the lowest possible pressure and at temperatures just below and above the beta transus was evaluated in this program. The beta transus for Ti6A1-4V is approximately 1825° F. Diffusion aids have been successfully used to produce joint properties superior to those of conventional brazing methods. In the joining of dissimilar metal tubes, (stainless steel to aluminum), the use of a diffusion aid in the form of silver plating on the faying surfaces produced an excellent joint and avoided detrimental stainless steel-aluminum concentration gradients. However, because of metallurgical and corrosion problems associated with diffusion aid concentration gradients, it was decided not to use a diffusion aid in this program. Low pressure diffusion welding is a relatively new process. A development effort was required to determine its most optimum weld cycle. Primary interest was placed on developing a capability to low pressure diffusion weld both thin sections and built-up laminate production parts, such as those shown in Fig. 1. The T-stiffened panel in Fig. 1A required two longitudinal welds connecting the thin center section to the horizontal panel and the T-cap strip. The bell crank forging replacement of Fig. IB was built up by laminating seven pre-machined parts together by diffusion welding. The program was conducted in two major phases. In the first phase, a study was conducted to establish an optimum range of w?ld cycle parameters, i.e., time, temn~-ature, pressure, and surface finish. The times considered ranged from 60 to 180 minutes. Temperatures of 1700, 1800, and 1900° F, were chosen in order to obtain results below and above the beta transus (1825° F) of the alloy. The diffusion weldirg pressures evaluated ranged from 15 to 75 psi. The surface conditions investigated included finishes of 15 to 60 RHR as well as chemically milled surfaces. In the second phase, the quality of diffusion welds produced with the developed parameters was evaluated by mechanical testing and nondestructive quality control techniques. Mechanical testing dealt with the determination of diffusion weld joint tensile and fatigue properties. Nondestructive testing (NDT) techniques were used to evaluate their effectiveness of detecting artificial discontinuities such as voids, contamination, and lack of joint fit-up. Experimental Procedures

Cold welded semiconductor package having integral cold welding oil

Abstract: A hermetically sealed enclosure for a semiconductor device and method for making same which includes providing a tubular ceramic housing with a circumferential integral cold welding die on one end face thereof. A cold weldable layer is bonded to the one end face of the housing, with a portion of the layer overlying the die. A first cover member is cold welded to the layer over the die to provide a hermetic seal at the die end and a first electrical and thermal contact. A second cover member hermetically encloses the end opposite the integral die and provides an electrical and thermal contact at the opposite end of the housing.

Explosives for welding

Abstract: Welding is a process for joining metals by local coalescence or union across an interface. The essential conditions for any form of welding are that the two surfaces prior to welding should be absolutely clean and uncontaminated, and that these surfaces should be brought into contact.

Cold welded-ceramic semiconductor package

Abstract: A hermetically sealed enclosure for a semiconductor device and a method and apparatus for making same is disclosed. A tubular ceramic housing is provided with an integral die on one end. A cold weldable layer is brazed on the integral die. A first cover member is brazed onto the other end providing a hermetic seal there. A second cover member is cold welded to the layer hermetically sealing the one end. The cold welding apparatus includes a pressure equalizing assembly having a pair of spaced resiliently coupled elements with facing hemispherical recesses. One of the elements slides on a bearing ball nested within the recesses to equalize the compressive forces of the cold welding around the end of the housing.

Silica-clay tooling material for welding and brazing operations

Abstract: A heat-resistant salt-free ceramic material especially suitable for use as a tooling mandrel for assemblies to be welded or brazed where the temperature of the entire mandrel is not raised above approximately 600 DEG F., and where the temperature adjacent to the mandrel is highly localized and of short duration. The invention material is thus especially suitable for electron beam welding, percussive arc welding, and induction brazing where heating is confined to a small portion of the article to be brazed. The material readily disintegrates or slakes when impinged with jets of hot water following the welding or brazing operation.