Showing papers on "Filler metal published in 1976"

Vacuum brazing of aluminum: Auger studies of wetting and flow characteristics

Abstract: Fluxless vacuum brazing has become a commercially feasible process for the high‐volume, low‐cost production of aluminum heat exchangers. With an Al–Si–Mg filler metal, excellent joint quality is obtained without requiring the use of a flux. A limited understanding of the wetting and flow characteristics of the filler alloy and the role of the magnesium promoter in the vacuum process, however, have hampered efforts to optimize control of the vacuum process. Auger electron spectroscopy and vaporization methods have been used in studying the mechanism of brazing to elucidate the characteristics of the oxide film barrier and magnesium promoter. With these methods it is possible to follow the distinctive variations in surface composition and magnesium vaporization rate that occur in the braze sheet as a function of its temperature. The mechanistic details of the wetting and flow processes in this commercially important material are delineated in the results.

Inert gas welding

Abstract: Welding apparatus for inert gas shielded arc welding comprising a welding gun for holding and controlling a non-consumable electrode and including means for supplying inert gas to the welding arc region by way of a gas cup surrounding but spaced from such an electrode when positioned in the gun, the welding gun being further provided with an extended gas shielding wall arrangement protruding a substantial distance beyond the gas cup and capable, either by itself or in combination with a narrow gap weld preparation, of substantially enclosing an electrode in the gun, except for its tip, when the electrode is protruding for a similar distance beyond the gas cup.

Laser Welding of Dissimilar Metals: Titanium to Nickel Metallurgical study shows why Ti to Ni joints were un­ successful by laser welding

Abstract: Laser welding is sometimes used to weld dissimilar metals when other methods prove unsat isfactory. A number of such cases have been reported in the literature and are listed in Table 1. However, the welding of these pairs of metals was usually done in response to a specific engineering need, and very little has been reported on the relationship between the welding variables, the propert ies of the weldment , and metallurgical structure. No systematic studies of laser welding of dissimilar metals have apparent ly been attempted yet. The present investigation was initiated with the intent of metal lurgical ly character iz ing d issimilar metal welds.

Wrought filler metal for welding highly-castable, oxidation resistant, nickel-containing alloys

Abstract: An alloy particularly directed to use as a wrought filler metal and contains certain percentages of chromium, iron, boron, molybdenum, nickel and optionally carbon, manganese and silicon.

Overhead submerged arc welding process

Abstract: The present disclosure relates to an overhead submerged arc welding process wherein a flux for the submerged arc welding is supplied from the underside of the welding line while at the same time a consumable electrode is supplied from the underside of the welding line, the process being characterized by maintaining the interrelationship between a flux supply cylinder and the plates to be welded such that the length from the under surfaces of the plates to be welded to the upper end of the open flux supply cylinder and the diameter D of the opening at the end of the flux supply cylinder is represented by the formula 2≦D/I≦15.

Low hydrogen welding electrodes

Abstract: An improved welding electrode for producing weld metal having low amounts of hydrogen therein so that hydrogen-assisted cracking in the weld zone is minimized. This is especially beneficial for welding high strength steels having tensile strengths of about 70,000 psi and above. The electrode has a filler wire core and a flux covering of predetermined constituents and low moisture levels such as below about 0.6 percent. The flux is bound together with a binder of hydrolyzed organic silicate (silica) which makes no substantial contribution to the moisture level of the covering and which also makes the covering resistant to hygroscopic moisture pickup before the electrode is used for welding. Thus, this binder minimizes the amount of hydrogen from any moisture in the covering which may be introduced into the weld metal during welding. Additionally, the flux covering contains a source of barium or cesium in an amount effective to reduce the slag/metal reaction temperature during welding. By so reducing this temperature, the amount of hydrogen actually introduced into the weld metal from the electrode covering and binder is minimized. This reduction of the slag/metal reaction temperature during welding has been found to have the additional advantage of reducing the amount of oxygen in the weld metal. This provides increased impact properties for the weld metal.

Apparatus for welding articles of thermoplasts

Abstract: The apparatus for welding articles of thermoplasts using additional welding material is provided with a special melting device for the welding material. The melting device comprises a guide channel for the supply and preheating of the welding material, which channel merges into a melting channel of diminishing cross section closed at one end. The melting channel is provided with lateral bores which discharge into a melting chamber of low height in communication with a collecting zone for the plasticized welding material, which collecting zone is connected with the outlet opening of the welding shoe.

Direct brazing of ceramics, graphite, and refractory metals

Abstract: ORNL has been instrumental in the development of brazing filler metals for joining ceramics, graphite, and refractory metals for application at temperatures above 1000$sup 0$C. The philosophy and techniques employed in the development of these alloys are presented. A number of compositions are discussed that have been satisfactorily used to braze ceramics, graphite, and refractory metals without a prior surface treatment. One alloy, Ti--25 percent Cr--21 percent V, has wet and flowed on aluminum oxide and graphite. Further, it has been utilized in making brazes between different combinations of the three subject materials. The excellent flowability of this alloy and alloys from the Ti--Zr--Ge system is evidenced by the presence of filler metal in the minute pores of the graphite and ceramics. (auth)

Development of Automatic Underwater Welding With Local Cavity Formation Method

Abstract: This paper describes the development of automatic underwater welding system based on an unique localized dry environment by a fluid curtain. With only the welding machine submerged, the system is operated by remote control in the ocean in connection with materials supply and supervision of works, thus considerably reducing its reliance on diving and underwater operations. In this process, a stabilized gaseous zone can be created only around the welding spot just underneath the welding torch by inclined water jet stream from the outer circumference of the double nozzle. Then various gas shielded arc welding methods such as TIG, MIG and CO2 arc welding are performed in the dry environment. As the initial plan, a submersible automatic welding machine has been produced, and the trial test of this system has been successfully performed on objects submerged in a large cistern while supervising and controlling their welding conditions by TV monitoring from outside the cistern. Welding results have proved excellent, being not much different from those undertaken in an ordinary environment on land.

Method for welding lead wires together

Abstract: A method for welding lead wires together by twisting into a strand a plurality of lead wires of electrical parts or the like, producing an arc between the strand and a carbon electrode, thereby melting and welding the strand by the heat from the arc to obtain a weld of high quality.

Development of explosive welding procedures to fabricate channeled nozzle structures

Abstract: Research was conducted to demonstrate the feasibility of fabricating a large contoured structure with complex internal channeling by explosive welding procedures. Structures or nozzles of this nature for wind tunnel applications were designed. Such nozzles vary widely in their complexity. However, in their simplest form, they consist of a grooved base section to which a cover sheet is attached to form a series of internal cooling passages. The cover sheet attachment can be accomplished in various ways: fusion welding, brazing, and diffusion welding. The cover sheet has also been electroformed in place. Of these fabrication methods, brazing has proved most successful in producing nozzles with complex contoured surfaces and a multiplicity of internal channels.

Some improvements in self-shielded flux cored electrodes for arc welding

Abstract: A fundamental study has been conducted in Japan on reducing the atmospheric gas content of self-shielded flux-cored arc-welding electrodes, in order to improve the impact toughness of the weld metal. The effect of various factors on arc and gas abosrbing phenomena has been elucidated and the quality of commercial electrodes improved. Making the electrode cross-section more complex and the size as fine as possible succeeded in minimizing the gas content and improving the quality of the weld metal. In commercial electrodes, reducing tha A1 content to improve weld-metal toughness was achieved by adopting a constant potential dc power source. In addition, reducing the welding fumes and using surface treatment without hydrogen-forming materials have greatly improved the usability of the electrodes.

Fundamental Studies on Electron Beam Welding of Heat-resistant Superalloys for Nuclear Plants (Report I) : Effect of Welding Conditions on Some Characteristics of Weld Bead

Abstract: The effect of the welding conditions on the characteristics of the weld geometry and the weld defects was made clear, concerning the heat-resistant superalloys for nuclear plants. Obtained conclusion may be summarized as follows: the weld defects were R-porosity and microcrack, S/sub p/ and ..delta..A/sub b/ are considered to be the important criteria for the evaluation of the susceptibility to the R-porosity; superalloys could be evaluated in the sensitivity to the microcrack in terms of the critical heat input to avoid microcrack q/sub cr/. This q/sub cr/ is considered to be one of the proper criteria for evaluating the superalloys in the susceptibility to the microcrack, and most microcracks were apt to occur when h/sub c/h/sub N/ came near to 1.0. These microcracks came to occur easily with the increase of d/sub B.N//d/sub B/.

Method of automatic or semi-automatic welding with gases

Abstract: The invention relates to an improved method of automatic or semi-automatic welding with gas, or brazing, effected by using a coil of fillet wire brought to the welding point by continuously passing through the center of a gas flame, (oxy-acetylene, oxygen-propane for example) which melts the wire and heats the work part, said improvement comprising the application of an electrical voltage between a member mounted on the forward-movement path of the fillet wire and the work part under treatment, so as to cause the passage therein of a heating current. The electrical voltage is preferably applied either between the welding torch nozzle or the forward-movement rollers and the part treated.

Flux-Metal-Arc Welding

Abstract: Metal-arc welding is a process that employs electricity to generate heat by means of an arc between the workpiece and the welding electrode.

Welding At Kennedy Space Center

Abstract: Welding plays a major role in the design, manufac­ ture, and construction of the ground support equip­ ment at the Kennedy Space Center. Three applications of welding are described, i.e., an example of the structural welding of a girder in a mobile launcher (presently designated mobile launcher platform), an example of the repair welding of crawler/transporter shoes, and an example of the welding of the liquid hydrogen and liquid oxygen storage spheres and vacuum jacketed piping in the propel 1 ants system. This welding technology was developed during the Apollo and earlier programs. It is now being ap­ plied to the Space Shuttle. KSC WELDING SPECIFICATIONS AND PROCESSES The welding of GSE, at the Kennedy Space Center is specified in the design phase to meet certain en­ gineering requirements. These requirements are sti­ pulated in welding specifications generated in the Design Engineering Directorate of the Kennedy Space Center. A list of Kennedy Space Center (KSC) Weld­ ing Specifications is given in Table 1. Gas tungsten-arc welding is the process most used on the critical piping of the major systems on the launch sites at the Kennedy Space Center. GTAW is used in welding the 36% nickel and stainless steel piping in vacuum jacketed lines in the propellants system. It is used to weld the aluminum alloy piping in the environmental control system. G1AW is used also in welding the high pressure piping in the pneu­ matic system. The gas metal arc welding process was used in weld­ ing the vessels for liquid hydrogen and liquid oxy­ gen storage in the propellants system. The shielded metal-arc welding process (SMAW) and the submerged arc welding process (SAW) were used extensively on the heavy structural sections of the mobile launcher and the transporter/crawler. The welding processes now used at the Kennedy Space Center are: • Shield metal-arc welding (SMAW) • Gas tungsten-arc welding (GTAW) • Submerged arc welding (SAW) • Induction brazing (IB) • Torch brazing (TB) WELDING MOBILE LAUNCHER GIRDERS One typical application of structural welding is the welding of the girders in mobile launchers. There are several large girders in the base of a mobile launcher. One centrally located girder, (G-14), Figure 1, is described as typical. The girder is 135 feet long and 25 feet high. The web is constructed of steel plate 1% inches thick. The top and bottom flanges are constructed of steel plate six inches thick. The base metals used in the construction of the gird­ er conform to ASTM A 36 Specification for Structural Steel and ASTM A 441 Specification for High Strength Low Alloy Structural Manganese Vanadium Steel. The weld filler metal used for manual shielded metal arc welding was AWS A 5.1 Class E7018. The filler metal and flux combined in submerged arc welding were Grade SAW-2 of the American Institute of Steel Construction. The girder was prefabricated at the contractor's plant in six parts, consisting of two identical end sections and four inner sections. These were mas­ sive parts, each weighing approximately 40 tons. The six prefabricated parts of the girder were shipped to Kennedy Space Center where the field erection was performed at the mobile launcher (ML) parking site adjacent to the Vehicle Assembly Building (VAB). As this was to be the permanent parking site for the mobile launchers, it was cover­ ed with a level, hard top, asphalt surface. The geometry for the control of the erection of the mobile launchers was laid out on the asphalt surface of the parking site. The locations and dimensions of the cribbing and blocking needed for their con­ struction were established on this layout. The G-14 girder was assembled on the ML parking site in the following manner: 1. Initially, the four inner sections of the girder were fitted together on blocking sufficiently heavy to hold the dead weight and to facilitate maintain­ ing the camber. They were braced in the vertical position with steel guy cables. The welds splicing together the four inner sections were made in the sequence 1, 2, 3 shown in Figure 2. This sequence minimized distortion and maintained the beam camber within the 9/16 inch tolerance for the complete gird­ er. Camber was checked by periodic rod readings. 2. After the four inner sections were welded to-