Showing papers on "Heat-affected zone published in 1979"

High Temperature Electrochemical Studies of the Stress Corrosion of Type 304 Stainless Steel

Abstract: Stress corrosion studies have been conducted with Type 304 stainless steel using a variety of electrochemical techniques at elevated temperatures. The object of these studies was to determ...

Method and apparatus for arc welding of metal plates from one side only

Abstract: An apparatus for arc welding of a pair of spaced steel plates from one side only using a grooved back-up plate which gives a good weld bead shape on the under side, gives high linear welding speeds, and avoids contamination of the deposited weld metal by the metal from the back-up plate. A pair of consumable electrodes connected in electrical series between the output terminals of the power source and with one connected by an independent connection to the workpiece are advanced into the weld gap on lines of movement which intersect at a point above the lower surfaces of the plates so that an arc is maintained between the electrodes spaced from the base of the back-up plate groove. A separately energized electrode trails the first two electrodes and deposits a weld bead on the first deposited weld metal while it is still hot.

Method of ensuring the maintenance of constant quality of spot welds

Abstract: A method of improving the reproducibility of the welds in an electric spot welding machine comprises prior to the initiation of a welding operation passing a preheating current of lower magnitude than the welding current through the parts to be welded. When either the total electrical workpiece resistance of the parts to be welded has fallen below a given limit or when its rate of decrease is slower than a predetermined limit the changeover from preheating current to welding current is effected.

Cored type welding electrode

Abstract: A cored type welding electrode which enables good penetration, has an improved range of welding voltages, produces low smoke and provides a weld deposit having good impact properties. The flux contains larger than normal quantities of basic oxides, controlled maximum amounts of acidic or amphoteric oxides and deoxidizers, and a very carefully controlled maximum and minimum amount of combined fluorine in the form of a fluoride.

Method of resistance welding

Abstract: An improved method for resistance welding two metallic articles, made of dissimilar metals which form brittle intermetallic compounds when melted together A first one of the metallic articles is provided with a tapered, flat-topped projection which is pressed against the other metallic article The first article preferably is composed of the metal most difficult to melt, as determined by the four parameters of melting point, electrical resistance, heat conductivity and specific heat The projection is formed with a predetermined relation between height, top width, and angle of taper such that a preselected extremely high welding current passed for a very short time will establish a maximum temperature near the top of the projection sufficient to melt the contacting surfaces of the two metallic articles and a temperature gradient such that an intermediate portion of the projection becomes markedly plastic while the adjacent base portion of the projection remains undeformable under extremely high welding pressure Impurities and intermetallic compounds in the molten metal at the top of the projection are squeezed out to the periphery of the surfaces to be welded, and the weld joint is made between plastic but unmelted metal of the projection and the other article

Process and apparatus for exhausting fumes produced by arc welding

Abstract: During arc welding, optical radiation emitted from an arc is detected by means of a photoelectric device, and an electric detection signal from the photoelectric device is used for controlling the travel of a suction hood along a weld line so that the weld fumes may be exhausted through the suction hood and to insure that the weld metal zone is always covered by the suction hood.

Arc welding cupro nickel parts

Abstract: A weld and process for making same and usable in the arc-welding of cupro-nickel (ASME P.34) parts particularly pipe ends using a flux-coated stick electrode, characterized in that an "open V" butt weld is employed with a root face having a mean width greater than 1/16 inch (1.5 mm) and not greater than 1/8 inch (3.2 mm) and a root gap from 2 to 3 mm. The process is further characterized in that the welding is carried out solely from the open side of the V without employing additional inert gas shielding, backing material or subsequent welding at the reverse face.

Efficiency of tungsten-inert-gas arcs in very-high-speed welding

Abstract: Previous work with high-speed tungsten-inert-gas (t.i.g.) arcs has shown the need for experiments to determine their melting performance. To achieve this, a new apparatus has been built in which the workpiece is of substantial thickness, rather than the earlier tests which used thin shims as the workpiece. The apparatus also has a calorimetric capability, which allows the magnitude of the total heat input to be determined. Data describing the variation of the weld penetration, width and cross-section over a wide range of arcing conditions (current, speed, tip angle, arc gap) have been determined. Additionally, interesting observations have been made concerning the changing distribution of heat input under certain arcing conditions.

Fundamental mechanisms of penetration in GTA welding

Abstract: Continued study of arc properties using emission spectroscopy coupled with computer simulation of the heat flow in welds has led to an understanding of the phenomena that control weld fusion zone shape. It was found that the liquid metal flow patterns in the weld pool are of prime importance and that arc current density characteristics and base metal properties have only indirect influence. The mode of interaction between the arc and weld pool flow is presented in qualitative terms.

Filler metal for a -zn-mg alloy

Abstract: PURPOSE:To provide the titled filler metal consisting of a prescribed percentage of Mg and the balance Al and impurities and giving weld metal with low weld crack sensitivity in the welding of an Al-Zn-Mg alloy. CONSTITUTION:This filler metal for an Al-Zn-Mg alloy consists of 6-9wt% Mg and the balance Al and inevitable impurities such as Fe and Si. By adding 0.05- 1.0wt% Mn and/or 0.01-0.3wt% Cr to the metal, the mechanical properties of the metal are improved and the stress corrosion crack resistance can be enhanced. When base metal made of Al-Zn-Mg alloy is welded with this filler metal, the crack rate can be lowered considerably in comparison with a commercially available welding wire.

Arc welding apparatus with oscillating electrode

Abstract: A welding process, such as a GMA welding process, employs a consumable electrode with the consumable electrode being oscillated back and forth over the surface of an object to which welding material is to be applied or across the gap between two pieces of metal to be welded together. At the ends of the swings of the consumable electrode an impact force is applied to the consumable electrode to interrupt its movement, thereby causing molten metal at the end of the consumable electrode from which the arc is struck to be impelled therefrom.

Method of welding corrugated metallic materials

Abstract: In an automatic arc welding method for welding metallic materials having a vertically curved weld line, a change in the arc voltage is compared with a arc length setting voltage and the resulting difference signal is used to control the vertical position of a welding torch and hold the same at a predetermined distance from the materials to be welded, while on the other hand in response to a signal generated from an obliquity detector made integral with the torch, the torch is controlled at an angle corresponding to the oblique angle of the materials to be welded and at the same time the welding speed is controlled at a constant value in response to a signal corresponding to the torch angle.

Process for welding cast iron

Abstract: 1. In a process for welding cast iron with welding alloys of nickel-iron compositions, the improvement being applying one or two interlayers on the joint faces of the cast articles to be welded together, and producing the actual joint weld with welding alloys selected form the group consisting of chrome-steel, chrom-nickel-steel, nickel-chrome and nickel-copper compositions.

Method of welding utilizing both consumable and non-consumable electrodes

Abstract: A method of welding utilizing consumable and non-consumable electrodes blanketed with inert gas to weld with a minimal amount or no preheating.

Laser welding of steels for power plant

Abstract: Many welding applications in CEGB power plant involve components with wall thicknesses in the range 2–10 mm. Therefore, an investigation into the feasibility of laser welding types 316, 310 and DUCOL W30 steels in 6 mm thick plate has been made, the materials being typical of those used in CEGB power plant. The welds were made using the high power, transverse flow, CO2 laser based at UKAEA Culham Laboratory. The laser welding process used has been compared with TIG (tungsten inert gas), plasma and electron beam using capital cost, power requirement, ease of handling and distortion in workpieces as the criteria for comparison. Possible applications of laser welding to power plant manufacture are discussed.

Characteristics of high frequency pulsed dc tig welding process

Abstract: As a result of the improved efficiency and quality of the high frequency pulsed DC TIG welding process, much attention has been given to this system. In this paper the effect of pulsed frequency and peak current on arc stiffness and the possibility of increased speed of welding is discussed using low currents. A double switching system makes it possible to obtain higher peak currents at higher pulsed frequencies. Experimental results show that the arc pressure at the arc center is an indication of arc stiffness which increases with increasing pulse frequency and appears to be constant with a pulse frequency more than 5 KHz. Under constant average welding conditions arc pressure is almost proportional to pulse peak current. With a constant width of the weld, the depth of penetration increases with increasing pulse peak current for a constant average welding current. Compared with the penetration of DC TIG process the influence of arc length for the pulsed TIG process is decreased. In the DC TIG process at high speed of travel both fluctuation and discontinuous motion of the anode spot often occurs especially for low welding currents. In the pulsed TIG process, however, with improved arc stiffness fluctuation is reduced and welds can be made with low currents at higher speeds. If the torch is inclined forward the tendency for undercutting along the edge of the bead is reduced permitting even higher speed welding conditions.

Narrow groove arc welding method

Abstract: PURPOSE: To perform the high-performance and stable narrow groove arc welding by performing welding while letting the wire inserted into the narrow groove between base metals revolve at a high speed in one direction at more than the specified speed. CONSTITUTION: A nozzle 5 is inserted into a narrow groove 2 and while shielding gas is blown into the groove 2, the welding is done by letting the nozzle 5 revolve in one direction at a high speed of 2Hz or more by a motor 12. As a result of this, the arc of a wide width is given by the wire 3 mounted to the nozzle 5 end with a deviation thereto and the welding is done without causing the lack of penetration at the corner part by widening the width of the molten pool. Since the nozzle 5 revolves at a high speed, the spray migrating characteristic of globules and melting speed are improved by centrifugal force, the arc is stabilized, magnetic blow is prevented and high-performance welding is done. COPYRIGHT: (C)1980,JPO&Japio

Laser welding of an electron gun

Abstract: A method of assembling an electron gun, which method permits welding of a number of welding points to be effected simply, in a short period of time and without causing mechanical distortion in welded parts and comprises the steps of; causing relative movement of electron gun parts to be welded together and the axes of a laser beam for welding and a light beam for positioning a welding point, these axes being in a predetermined positional relation to each other; causing the light beam for positioning to be incident on a part to be welded; detecting reflected light obtained when the light beam for positioning is reflected by a portion of the aformentioned part to be welded corresponding to a welding point; stopping the aforementioned relative movement according to the detection of the aforementioned reflected light; and exposing the aforementioned welding point to the laser beam for welding according to the detection of the reflected light so as to effect welding of parts to each other.

Machining welding or surface treating using laser beam - with heating augmented by arc struck to zone of beam incidence

Abstract: Workpiece is treated by directing a laser beam onto it, and striking an arc from an electrode the zone heated by the beam. Pref. the heated zone extends through the workpiece and the arc is struck to the surface opposite to the beam; or arcs may be struck to both the beam-incident and opposite surfaces. The incident zone may be moved relative to the workpiece. The workpiece may be surface alloyed by applying a suitable material prior to heating as above with scanning of the whole surface, or the process may be used for cutting drilling or welding with one or more gas jets directed as the heated zone to disperse the generated vapour plume. The gas may be reactive. The use of supplementary arc heating, possibly aided by exothermic reactions involving the gas jet, provides greater thermal energy input to the workpiece than can be achieved by increasing the laser power. Machining is thereby accelerated and weld penetration improved.

Noncoated electrode wire for arc welding

Abstract: PURPOSE:To obtain a noncoated electrode wire being able to avoid any chance for defect welding such as slag enfolding and/or inferior penetration, by filling the powdered flux made of essential elements such as BaF2, iron oxide, Al, Mg and Mn in a metallic sheath at a predetermined ratio to a quantity of the wire. CONSTITUTION:The powdered flux made of essential elements such as 31-75% BaF2, 2-25% iron oxide, 3-15% Al, 3-15% Mg and 0.5-10% Mn is prepared. Next, the required noncoated electrode wire is manufactured by filling the flux in a metallic sheath made of mild steel etc. at a ratio of 15-30% to a total quantity of the wire. If such electrode wire is used for the arc welding, the welding work efficiency at vertical position should be remarkably improved and higher welding current is also applicable.

Prevention of sensitization of welded-heat affected zones in structures primarily made from austenitic stainless steel

Abstract: A process for joining together parent parts made from wrought austenitic stainless steel without sensitization of the parent material, and the product produced by this process Each wrought workpiece has welded thereto an appendage made from cast (not wrought) austenitic stainless steel which is equal to or better in corrosion resistance and mechanical properties, and is compatible with the solution heat treatment requirements of the parent austenitic stainless steels The resulting workpiece is solution heat treated at in-process stages of manufacture to dissolve the carbides which have been formed in the heat affected zone created by the welding operation Then two of said workpieces are welded together at the abutment of the appendages, there being no formation of precipitated carbides in the parent material, because the heat affected zone does not extend into the wrought parent material, but instead is restricted to the appendage which by definition is not sensitizable

Welding method of austenitic stainless steel

Abstract: PURPOSE: To prevent the degradation in corrosion resistance in weld heat affected zone in welding of austenitic stainless steel, by suppressing the deposition of Cr carbide in the weld heat affected zone by water cooling. CONSTITUTION: Austenitic stainless steel 1 is welded by the weld metal 2 produced by the welding arc from a welding wire 3 to which welding current is led from a power supply tip 9, in a shielding gas 4 such as Ar or Ar+CO 2 . In this case, the double torches are used and the water flow of high velocities is discharged from 6 of the trumpetlike nozzles 5, 6 provided at their end, whereby the weld zone of high temperatures is quickly cooled. Further, a cavity forming gas is discharged from the nozzle 5 to the inner side of the abovementioned water flow to form a stable gas phase area. The weld zone is quickly cooled by the water jet of high velocities discharged from the nozzle 6, whereby the deposition of the Cr carbide which degrades corrosion resistance is prevented. COPYRIGHT: (C)1981,JPO&Japio

Steel wire for ar-co2 gas shielded arc welding and welding method

Abstract: PURPOSE:To stabilize the transfer condition of arc and globules at the short circuit transfer welding and improve bead shapes by such things as addition of a suitable amount of S in particular into the welding wire, limitation of Ti and Al to slight amounts and limitation of the remaining of Ca on the wire surface to a slight amount. CONSTITUTION:In the finish wire drawing process after plating of the Ar-CO2 shielded arc welding wire composed of the wire composition comprising C; 0.2% or less, Si; 0.51-1.20%, Mn; 0.8-2.5%, S; 0.016-0.060%, Ti; 0.03% or less, Al; 0.02% or less, N; 0.010% or less, Ca; the total amount of the wire composition and surface pickup is 0.0050% or less and the rest substantially Fe, seed oil is used as a lubricant and the seed oil is let to remain at 0.001-0.05wt% on the wire surface. By this wire composition, the weld bead width is made wider, the deviation in the aiming of the weld line may be covered and the weld metal of superior weld shape and high toughness may be obtained.

Influence of heat-affected-zone refinement on high-temperature crack growth in thick-section O·5Cr–O·5Mo–O·25V steel weldments

Abstract: Crack-growth tests have been made at 565°C on thick-section butt welds produced to assess the effect of manual metal arc process parameters on heat-affected-zone (HAZ) refinement in O·5Cr–0·5Mo–0·25 V steel. It was confirmed that the increased degree of HAZ refinement achieved by weld-procedure control resulted in improved resistance to crack propagation. It was also possible to relate instantaneous rates of crack growth to the local microstructures in the HAZ at the tip of the crack by potential-drop measurements andpost-test metallography. The behaviour of a weld subject to post-weld renormalizing and tempering, as an alternative means of achieving microstructural refinement, was also examined. In this case it wasfound that crack initiation was delayed and the overall growth rate reduced relative to the welded and tempered structures. However, crack growth was accompanied by low displacements, similar to those for an as-welded untempered specimen. These were attributed to the concentration of st...

Frictional pressure welding method

Abstract: PURPOSE: To reduce the power cost in comparison with the conventional method to make efficient frictional pressure welding possible, by gradually extending the molten junction part to the set size after a pair of metal bodies are brought into contact with each other partially and pressure and relative rotating movement are given to them to form a half-fused part. CONSTITUTION: In frictional pressure welding of a pair of metal bodies 1 and 2, the junction end of metal body 2 is formed into truncated cone 5, and the tip of contact part as partial contact part 6 is opposite to contact face 7 of the other metal 1 in parallel, and metal 1 is fixed, and set rotating movement in the arrow direction is given to metal 2, and pressure as shwon by the arrow is applied to metal 2. Partial contact parts of metal bodies 1 and 2 are made into a half-fused state due to frictional heat, and this half-fused part is extended gradually into full-fused junction face 4 and is finally subjected to a pressure welding junction by set pressure welding pressure in the axial direction. By this method, metals can be joined with a little input, and inputted heat per the contact face is small, so that the process can be shortened and the work efficiency can be improved. COPYRIGHT: (C)1981,JPO&Japio

Non-marring spot weld tip

Abstract: To prevent buckling and indentation of a panel being spot welded, a welding tip including an electrode of large load bearing and heat conducting surface is used to spread the load and also efficiently cool the workpiece. The large area electrode is a water cooled copper disk of large mass connected to a support arm by a coil spring. An electrical contactor on the support arm releasably engages the electrode to supply welding current thereto when welding pressure is applied to the workpiece by the welding gun. When the pressure is removed, the coil spring separates the electrode from the contactor.

Electrode method for welding thin steel sheets

Abstract: An electrode method for welding thin steel sheets using the MIG and/or MAG welding process is made from a copper-manganese alloy with 3-35% Mn, 0-15% Ni, 0.02-0.7% Si and the remainder copper.