Showing papers on "Heat-affected zone published in 1978"

Methods and apparatus for cutting and welding

Abstract: Methods and apparatuses for cutting, welding, drilling or surface treating a workpiece are described. A laser beam is directed towards a workpiece and an arc is struck between an electrode and the heat affected zone created by the laser beam in the workpiece.

Low Temperature Sensitization of Welded Type 304 Stainless Steel

Abstract: It has been shown that the sensitization of Type 304 stainless steel occurs at temperatures well below the normal isothermal temperature range for sensitization. A prerequisite for this low temperature sensitization (LTS) is the presence of chromium carbide nuclei along grain boundaries. This paper shows that the thermal exposure during welding can nucleate the grain boundary carbides necessary for subsequent LTS. Quantitative transmission electron microscopy studies show that no new carbides nucleate during an LTS heat treatment at 400 C. However, carbides that were nucleated at the time of welding grow during the LTS heat treatment. These findings are consistent with the proposed nucleation and growth LTS model. Using an accelerated test for intergranular stress corrosion cracking (IGSCC) in high temperature, high purity, 8 ppm oxygen water, it has been found that the rate of LTS in a Type 304 stainless steel weld heat affected zone obeys an Arrhenius temperature dependence which predicts that ...

Apparatus and method for sensing welding point in automatic welding apparatus

Abstract: An automatic welding apparatus comprises a welding torch including an electrode and a fixture for fixing a workpiece, and a relative positional relation of the welding torch and the workpiece fixture is controlled such that the electrode of the welding torch is moved to trace the welding line of the workpiece, whereby automatic welding is achieved. The automatic welding apparatus further comprises a switch for selectively connecting the electrode of the welding torch to a welding power supply or a detecting power supply, and a sensor for sensing a current or a voltage between the electrode and the workpiece when the electrode is switched to the detecting power supply, whereby the relative positional relation between the welding torch and the workpiece is detected in response to the output of the sensor, and thus a welding point or a welding line is sensed. In the case where the automatic welding apparatus is a wire extension type, adapted to successively feed the electrode in accordance with the progress of welding, a collet chuck for clamping the electrode to the welding torch is provided for fixing the length of the electrode from the welding torch on the occasion of the sensing mode.

Apparatus for connecting metallic parts by means of arc fusion welding

Abstract: An apparatus for connecting metallic parts, and metallic parts so produced, by means of arc fusion welding by producing a low volume welding seam (narrow gap welding), wherein the workpiece parts to be joined and forming a narrow gap are initially welded at their butt joint by means of, for instance, electron-beam welding, plasma-arc welding, laser-beam welding or argon arc-welding to produce a base seam with or without filler material, and thereafter the workpiece flanks forming the narrow gap are united by alternately depositing weld beads at first one and the other workpiece flank by submerged-arc welding

Multiple electrode submerged arc welding method

Abstract: A submerged arc welding method and more specifically, a multiple electrode welding method is disclosed wherein welding is performed by arranging electrodes in such a manner that the distance becomes at least 300 mm between a first molten pool formed by multilayer welding or by a single or plural electrodes preceding along the weld line and a subsequent molten pool formed by a single subsequent electrode or plural subsequent electrodes, as well as a submerged arc welding method which is characterized in that there is formed a slag having the components listed below on the weld metal formed by an electrode or a preceding electrode forming a preceding layer, and welding is carried out as such, without removing the slag, using an electrode or a subsequent electrode forming a subsequent layer; TiO 2 : 20-65% by weight (up to 60% by weight, based on the total TiO 2 amount, of which may be substituted by ZrO 2 ); CaF 2 : 9.6-40% by weight, and Al 2 O 3 : 10-56% by weight.

Method for preventing cracks below seams during plating and welding

Abstract: A method for preventing the development of cracks below seams during the plating and welding of material by employing a heat source for producing local heating of the regions of the material adjacent the welding zone.

Narrow weld-groove welding process and apparatus therefor

Abstract: A narrow weld-groove welding process, in which a bare welding wire is fed into a weld groove defined between the opposed surfaces of two pieces of metals for producing a metal arc therein for welding. In this process, a welding wire is subjected to a plastic deformation of a wave form, before being fed into a nozzle hole provided in a contact tip, and then the wire is fed into a nozzle hole, while maintaining elasticity tending to cause waving, whereby the tip of a welding wire being fed through a nozzle exit is automatically waved between the opposed surfaces of metals to be joined, with the tip of wire being alternately faced in the opposite directions, in response to the weaving motion thereof, with the feeding of the welding wire and progress of welding. In addition, the apparatus for use in a narrow weld-groove welding process is also disclosed.

High Power Laser Welding - 1978

Abstract: Current high power laser welding technology is reviewed. The nature of the beam-material interaction, the influence of laser, process and material parameters on welding response and the unique characteristics of the process are discussed. Examples are given of representative laser welding performance in ferrous and nonferrous alloys and selected illustrations are presented of weld mechanical properties. A relationship is noted for the dependence of maximum single-pass laser weld penetration on power and a range of laser welding applicability is delineated. Laser welding efficiency is identified and process advantages and disadvantages are compared. The potential for future utilization of lasers in welding is discussed.

Method of cold welding using ion beam technology

Abstract: A method for cold welding metal joints. In order to remove the contamination layer on the surface of the metal, an ion beam generator is used in a vacuum environment. A gas, such as xenon or argon, is ionized and accelerated toward the metal surface. The beam of gas effectively sputters away the surface oxides and contamination layer so that clean underlying metal is exposed in the area to be welded. The use of this method allows cold welding with minimal deformation. Both similar and dissimilar metals can be cold welded with this method.

Welding process for production of a steel pipe

Abstract: Disclosed herein is an improvement of a welding process for welding a steel pipe, wherein a gas metal arc welding is performed to form the first welding layer and a submerged arc welding is performed to form the last welding layer. According to the conventional gas metal arc welding process, i.e. the MIG or CO2 welding processes, the combined use of a high welding current and a welding wire having a small diameter is known to bring about the rotation of the welding arc and the formation of an undercut along the toe of the weld metal. The purpose of the present invention is to weld a steel pipe having either a large thickness or an excellent ductility at a temperature of less than -40° C., or both. According to the present invention, the combined use of a high welding current and a wire having a small diameter is possible, by employing a gas mixture containing an inert gas as a major part thereof and CO2 as an additional part thereof as a shielding gas. In addition, by adequately selecting the wire extension, the gas metal arc welding is improved to provide the features of: deep and round penetration; stable arc formation with stiffness of the arc, and; high metal deposition rate.

Method of arc welding with reverse side cooling for obtaining highly tough large-diameter welded steel pipes

Abstract: An arc welding method for manufacture of a welded steel pipe wherein the edges of a steel plate bent into a pipe shape are welded together on one side for forming a pipe and then the seam line of the thus formed pipe is welded by a second welding operation at the side opposite to the side where the first welding was performed. During such second welding, the weld is cooled forcedly from the side where the first welding was performed. Such forced cooling compensates for any physical effects accompanying the welding and imparts elevated toughness to both the weld metal and the heat affected zone.

Method and apparatus for controlling welding operations during resistance welding

Abstract: A method of, and apparatus for, respectively controlling the start of welding and the termination of welding during continuous resistance welding with the aid of an alternating-current at a roll-welding machine, wherein at least at one measuring station or location arranged ahead or upstream of the welding station or location and the workpiece to be welded passing through the measuring station there is determined the position as a function of time of the leading end as well as the trailing end of the workpiece to be welded with respect to the frequency and the phase of the welding current. By means of a computer processing the determined value there is accommodated to one another the speed of the workpiece to be welded and the frequency and phase of the welding current in such a manner that the first welding spot and the last welding spot are applied at an adjustable spacing from the leading end and the trailing end, respectively, of the workpiece to be welded.

Method for welding bodies made of very hard or greatly refined armored steel, respectively, and structures made according to this method

Abstract: A method for welding bodies made of very hard or highly refined armor steel, particularly objects to be armored against the penetration of projectiles, flying bodies, splinters or the like, wherein armor steel bodies arranged in juxtaposition with a gap therebetween are provided, in the region of the root of the joint, with preferably one bar each, and/or a filler body of, in particular, an unalloyed steel is arranged in the joint so as to cover the joint gap. The armor steel bodies are welded together without preheating with a suitable ferritic welding material, of like base, under a protective gas atmosphere and after cooling of the weld seam from the welding heat to not less than 100° C., the weld seam is heated locally and progressively without any holding period to at least 450° C. and subsequently, without maintaining a certain ambient temperature and/or period of time, the weld seam is cooled to ambient temperature in air. Alternatively, a like-base layer of armor is locally applied onto a wall of armor steel from a suitable ferritic welding material in that the welding area, which has been cooled from the welding heat to no less than 100° C., is heated locally and progressively without any holding period to at least 450° C., and subsequently the weld region is cooled in air without maintaining a certain time period and only the last (uppermost) welded layer of the weld region is again locally reheated, before being cooled from the welding heat to below 100° C., at least 450° C. without holding period and subsequently again cooled in air to ambient temperature without maintaining a cetain time period and or temperature.

Buildup welding of inclined surfaces

Abstract: A method of building up lines or layers of metal on a region of a workpiece, especially a region which terminates at the top of a vertical surface of the workpiece, by fusion arc welding, comprises: building up a barrier along at least one edge of the region, and this is along the top of the vertical surface when one exists, by welding with a low-power arc and then building up the remainder of the region against the barrier by welding with a much higher power arc, which is preferably of the submerged-arc type.

Reduction of arc blow in multi-electrode welding

Abstract: A method and apparatus for reducing "arc blow" in multi-electrode welding of a metallic workpiece Arc blow is produced by interaction between the magnetic fields produced by the closely spaced arcs and electrodes, and takes the form of the end arcs being attracted inwardly towards the others This reduces the welding efficiency and the maximum welding speed The invention reduces or eliminates the arc blow by providing shunts made of magnetically permeable material close to the arc-producing ends of the electrodes at the two ends of the row of electrodes This reduces the concentration of magnetic flux in these regions and reduces the deviation of the end arcs The invention can be applied wherever multi-electrode welding is used, but is especially useful when the workpiece is made of aluminum as arc blow is a particular problem with this metal

Submerged arc welding process

Abstract: Submerged arc welding process for 3.5% Ni steel which can provide a welded portion having a satisfactory impact resistance at low temperatures such as below minus 100° C. In the process, use is made of a flux having a basicity as defined by a formula (CaO+MgO/SiO 2 ) in weight percentages of between 1.5 and 3. The weld metal is deposited in a plurality of superimposed welded layers, each having a thickness less than 7 mm so that the weld metal in an underlying layer is thermally affected by an adjacent overlying layer whereby recrystallization is effected in substantial thickness of the underlying layer to provide a fine crystalline structure.

Energy beam welding with filler material

Abstract: In automatic energy beam welding, as electron beam welding, of workpiece edges which form a gap of varying width along the weld line, the amount of filler material needed for making up for the volume of the gap is determined by probing the size of the solidified weld bead at a surface of the workpiece and the rate of supply of filler material to the welding zone is controlled on the basis of the result of such determination such that the size is maintained between predetermined limits.

Method for electroslag welding of metals

Abstract: A method for electroslag welding of metals whose density is less than thatf welding fluxes, is provided. The method is based on floating-up of drops of molten metal of the edges being welded and of the electrode in a slag whose density exceeds that of the metal. The floating-up metal drops form a metal bath on the surface of the slag bath, and crystallization of the metal bath produces a weld. In the course of welding, the electrode metal is fed into the slag bath in the upward direction, while the electrode metal melts and the weld is built up in the downward direction.

Method and device for welding in a thermally ionized gas

Abstract: A plasma-MIG welding system in which the power for establishing the MIG-arc is supplied to the consumable electrode at a point downstream of the non-consumable electrode.

Method and device for welding protected metal parts

Abstract: A method and apparatus for welding or brazing of sheetmetal or plate covered with a temperature degradable protective coat, such as zinc or plastic. A cooling saddle supplied with liquid nitrogen is arranged on the side of the plate opposite that adjacent the welding torch. During the formation of the weld, gaseous nitrogen escapes through holes in the saddle to cool the protective coat and keep it from melting or volatilizing.

Inconel welding method of dissimilar material joint

Abstract: PURPOSE: To improve the strength of weld zone and welding efficiency by controlling the temperature of weld pass through water cooling at the time of Inconel welding the dissimilar material joints of austenite base stainless steel and ferrite steel. CONSTITUTION: A weld torch nozzle 1 and electrode 3 are disposed in the joint part and an Inconel welding material 6 is welded by generating arc between the joint part and electrode while blowing Ar gas 2. At this time, cooling water 9 is sprayed through the water injection holes 8 of a water supply pipe 7 disposed on the side opposite from the torch nozzle in the entire stage or part of the stage of the welding work to water cool the weld zone and weld side end part of the austenite base stainless steel 4. Thereby, the thermal stress affecting the low alloy steel material 5 such as of Cr-Mo steel or other may be eliminated and cracking and degradation of material quality may be prevented. COPYRIGHT: (C)1980,JPO&Japio

Welding method using a break away flux dam

Abstract: The invention relates to an improvement in a method of welding a first workpiece to a second workpiece which comprises utilizing the flux dam composition on each side of a weld groove to define a dam and electrical welding along the weld groove while adding flux thereto to maintain a slag blanket over a pool of molten weld metal in the groove.

Oscillating arc welding

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.

Detecting susceptibility to intergranular corrosion of stainless steel weld heat affected zones

Abstract: A Scanning Reference Electrode Technique (SRET) has been developed to study intergranular corrosion of austenitic stainless steels. The potential variations produced in the electrolyte due to the intergranular corrosion of the sensitized grain boundaries have been measured by scanning a microtip reference electrode across a weld and heat affected zones. The development of a test based on the SRET for determining the degree of sensitization of stainless steels has been explored. The technique is particularly useful in determining the degree of sensitization and the location of the sensitized grain boundaries adjacent to welds. The effect of material and welding variables on the location and degree of sensitization has been studied. The results have been compared with conventional tests for detecting susceptibility to intergranular corrosion.

Welding method for forming thick walled steel pipe

Abstract: PURPOSE: to obtain high quality weld zone excellent in the low temperature toughness at high efficiency, by employing the thin wire with the high current at welding the thick walled steel pipe, by preparing the mixed gas atmosphere from the inert gas added with CO 2 , and by giving a fast fine oscillation to the arc. CONSTITUTION: At welding work for forming the thick walled steel pipe, by first executing the MIG welding for the root layer and then by executing the SAW welding for obtaining the flush weld as the final layer; the mixed shielding gas atmosphere is prepared by adding CO 2 to the main mass of the inert gas, and the thin welding wire of diameter 0.8W2.4mm is employed. The distance l(mm) between the feeding tip and the groove bottom is set at l>10d+5, and the welding current I is set against the wire diameter (d) at the range, 500d≥I≥500d-150. Furthermore, a fast oscillation of frequency 3W30 cycle/sec and amplitude 1W15mm is given to the arc. Hereby, the arc is generated in the state of being throttled to thin and stiffened, the resistance against the magnetic blowout is improved, the directivity of the arc in the direction of wire extension is improved, and the smooth appearance of beads is obtained. COPYRIGHT: (C)1980,JPO&Japio

Stud welding with fluid shield

Abstract: Method and apparatus are provided for welding studs to a work surface wherein a substantially smut free surface is produced adjacent the weld. Apparatus is provided for depositing a thin coating of liquid in spray form onto the work surface adjacent the area whereon the stud is to be welded, prior to the welding operation. Contaminates formed in suspension in the liquid during the welding operation are removed by removal of the liquid suspension which is accomplished in a simple and inexpensive manner.

Gas metal arc welding apparatus for repairing misaligned tube holes

Abstract: A welding apparatus including a nozzle assembly having a contact extension and a contact tip for guiding a consumable welding wire into a tube hole. The consumable welding wire is guided into the tube hole and an electric current is passed to the wire to produce an arc between the tip of the wire and the sidewall of the tube hole, melting the wire and supplying filler weld to the hole. The nozzle assembly has a gas nozzle; and, during the welding process, an inert gas is delivered into the tube hole through the gas nozzle.

Apparatus for monitoring and controlling a welding phenomenon in an electric resistance welding

Abstract: An apparatus for monitoring and controlling a welding phenomenon in an electric resistance welding process, which comprises a welding characteristics measuring instrument for carrying out digital measurement of at least one of high frequency welding characteristics, a welding phenomenon monitor circuit for detecting variations in the welding characteristics, and a welding phenomenon controller circuit for automatically adjusting a parameter of a welding power source or other welding conditions, wherein the welding characteristics include an oscillating frequency and an oscillating period of a high frequency used for the welding, and a phase difference between a high frequency voltage and a current. Changes in the welding characteristics occur in correspondence with the occurrence of periodic fluctuations in the shape of the high frequency welding current circuit formed in the material to be welded during high frequency electric resistance welding process.

Automatic tig welding method of pipe and pipe plate

Abstract: PURPOSE: To achieve the improvement in the toughness of weld heat affected zone and welding efficiency by welding a pipe and pipe plate while cooling the same by the pressure air or the like from the circumference of a welding torch at the time of subjecting the pipe and pipe plate to TIG arc welding. CONSTITUTION: The pipe 1 and pipe plate 3 belonging to a chemical apparatus such as methanol converter or the like are seal welded in a three o'clock welding posture. A welding torch 5 is made in double construction and pressure air, pressure carbonic acid gas or the like is jet out near the weld zone from the circumferential hole at the end of the outer nozzle 11 thereof, whereby the weld zone is cooled. Arc is generated between the welding torch 5 and the corner part of the end faces of the pipe 1 and pipe plate 2 and automatic welding is performed while the wedling torch 5 is being rotated along the circumferential direction of the pipe. According to this method, sound beads 9 are formed without becoming dropping beads. In addition, the weld heat effected zone 10 is suppressed of particle coarsening and the toughness is considerbly improved. Since the quantity of heat input may be increased, the considerably improvement in welding performance may be achieved as well. COPYRIGHT: (C)1980,JPO&Japio