Showing papers on "Heat-affected zone published in 1985"

Image processing welding control method

Abstract: An image processing welding control method comprises detection of isothermal pattern of a weld zone in the welding state through photographing the weld zone by an infrared camera; calculation of the area of the region defined by the isothermal line detected; comparison of the area with a standard area which is obtained in advance; control of welding heat input such that the area will be substantially the same as the standard area whereby a suitable welding heat is input the welding portion; detection of an asymmetric extent of said isothermal pattern; and controlling the torch position such that the asymmetric extent will be within a predetermined value, so that the torch will be strictly aligned with the welding groove center. This method enables two kinds of welding control methods, torch position control and welding heat input control, based on the same image information.

Welding apparatus method for depositing wear surfacing material and a substrate having a weld bead thereon

Abstract: The welding method may be used to lay down weld beads on metallic substrates with a narrow width of 0.125 inch and less. The process employs a plasma transferred arc and pulses the current delivered to the arc such that a wave form having at least a main amplitude and a lower auxiliary amplitude is provided. The powdered metal which is delivered is laid down in a series of overlapping weld deposits which solidify very rapidly and produce a fine grain structure.

Feasibility Study of the Welding of Sic

Abstract: In a brief study of the feasibility of welding sintered alpha-SiC, solid-state welding and brazing were investigated Joint quality was determined solely by microstructural examination Hot-pressure welding was shown to be feasible at 1950 C Diffusion welding and brazing were also successful under hot isostatic pressure at 1950 C when boride, carbide, and silicide interlayers were used Furnace brazing was accomplished at 1750 C when a TiSi2 interlayer was introduced

Ultrasonic spot welding tip assembly and method for using the same

Abstract: An ultrasonic welding tip assembly and associated method of use are described. The welding tips of the assembly may be conical with the cone height A and base width B having a ratio of A/B=1.2 or frusto-conical with a ratio of 0.76 in preferred embodiments. The welding tips are supported on anvils. In the welding process, the tips are only partially inserted into the material being welded so that the anvils remain spaced from the material. This space provides a reservoir into which molten material may flow away from the regions of the welding tips.

Apparatus and method for edge welding sheet metal

Abstract: A laser welding apparatus and process is provided for edge welding sheets of metal to one another. The laser welding apparatus includes aligners to advance the edges to be welded into the laser beam. The apparatus includes first and second laser welders. The first laser welder is operative to eliminate the edge discontinuities and to effect an initial attachment of the edges to one another. The second laser welder provides a larger and stronger weld bead. The process includes first aligning the edges, second removing discontinuities therefrom and third laser welding the edges. The discontinuities preferably are removed by a laser apparatus with a rotating lens.

Method of welding metal matrix composites

Abstract: A welding method forms a fiber reinforced weld in a fiber metal matrix composite. Novel weld rods or consumable electrodes for introducing the fibers to the molten weld pool are disclosed. Reinforcing fibers are added to a molten weld pool that is initially substantially free of fibers. The fibers strengthen the weld. The concentration of the fiber should be controlled so that the viscosity of the pool remains suitable for welding.

Shielding apparatus for metal processing operations

Abstract: The invention provides a generic shield that can be used in welding, surfacing and cladding operations. These operations can be performed with either high power density processes such as lasers and out of vacuum electron means or arc assisted processes and plasma welding and/or cladding systems. The shield physically isolates the shielded region from the surrounding area by providing a zone of inert gas over the work area. As a result, the shield is functionally made to resemble a chamber which moves over the substrate.

Weld nut welding apparatus

Abstract: A weld nut welding apparatus includes upper and lower electrodes. A weld nut and a plate material which are to be welded together are clamped between the upper and lower electrodes, and a welding current is supplied to the weld nut and the plate material via these electrodes, whereby the weld nut is welded to the plate material. A groove is formed in that surface of the weld nut which abuts against the plate material, while a punch is provided inside the lower electrode, and the punch is moved toward the upper electrode after the welding operation, whereby it is possible for the plate material to be formed with a bore which corresponds to the groove. This bore is punched in the plate material only at a required welding position and at the same time as the welding operation. It is therefore possible to overcome the disadvantage that it would otherwise be necessary for a bore to be previously formed in the plate material. Thus, even if there is a change in the number of weld nuts which are to be secured to the plate material or the nut mounting positions on the plate material, it is possible for bores to be punched in the plate material at appropriate positions thereon, provided that nut welding positions alone are determined.

Arc welding adaptive process control system

Abstract: A robotic arc welding system has an integrated vision sensor to image and analyze the weld scene in real time. The most effective weld puddle geometry discriminants for use in an adaptive feedback control, to assure full penetration welds, are weld puddle area and maximum width. The adaptive control system determines a puddle geometry error and a correction to nominal welding current to change the heat input to the weld pool, regulating a combination of puddle area and width, or only puddle area under some welding conditions, to control weld quality during the welding process. Arc voltage is modulated to reflect changes in welding current and maintain constant arc length.

Alloy powder for building up of powder

Abstract: PURPOSE: To improve the shape of weld beads and to prevent the generation of blowholes by specifying the oxygen and nitrogen contents of Ni-base alloy powder to be used for build-up welding of powder. CONSTITUTION: The Ni-base alloy powder for build-up welding of powder has a spherical shape of ≤1.5 ratio between the major and minor axes and is adjusted to 0.01W0.50wt% oxygen content and ≤0.30wt% nitrogen content. The excellent feeding property of the powder in the build-up welding stage is thus obtd. and the generation of troubles such as the disconnection of molten metal and ununiform width of beads is obviated. The welding to the good bead shape without generating the blowholes in the build-up metal is thus executed. COPYRIGHT: (C)1987,JPO&Japio

Deformations and Stresses in Butt-Welding of Large Plates With Special Reference to the Mechanical Material Properties

Abstract: Simulation of automatic butt-welding of large plates was investigated. Two different steels were considered. The plates were tack-welded before the butt-welding. The simulation includes the tack-welding, the butt-welding and the cooling to room temperature. The simulations should lead to an understanding of the mechanics behind the change in gap width in front of the moving arc, which is of importance in automatic welding production. The residual stresses due to the butt-welding were also studied. The magnitude and the distribution of the residual stresses are important in design of welded structures. The change in gap width in front of the moving arc and the residual stresses depend on the material in the plates, the restraints of the plates, the size of the plates and the welding parameters. The most important welding parameters are the arc energy per unit length of the weld and the welding speed. The change in gap width depends also on the tack-welding procedure.

Ultrasonic monitoring and control during arc fusion welding

Abstract: Ultrasonic examinations were first shown to be capable of detecting weld pools in 1978 using simple N.D.T. techniques and manual metallic arc welding. Further work, using submerged arc welding, demonstrated that the best technique was to employ shear waves operated from the upper plate surface. A control alogarithm relating beam path length to welding current was identified and used to control penetration depths to within 1mm of desired depth. Utilising ultrasonic beam spread has been shown also to monitor the seam immediately in front of the weld pool. Seam tracking simultaneously with penetration control is therefore possible from one piece of apparatus.

Method and apparatus for welding thin metal sheets

Abstract: There is described a method for welding thin metal sheets (A, B) by the localized heating of limited juxtaposed zones of the metal sheets to be welded to cause their fusion and to form spot welds (S). In each weld zone, the metal sheets (A, B) are heated and fused along a closed line so that each weld spot (S) has a substantially annular configuration in cross section in a plane parallel to the metal sheets. This welding may be achieved for example with the use of a laser (2) produced by a laser source (1), or by electrical resistance welding with a pair of opposed electrodes (6, 7) the ends whereof which are intended to grip the metal sheets (A, B) are suitably shaped.

Deep penetration laser welding of sheet metal

Abstract: A sheet metal welding process is described in which limited zones of contact of metal sheets (A, B) are heated locally by a power laser so as to cause fusion in the manner of spot or seam welds (P, C). Such spot or seam welds are achieved by deep penetration welding of juxtaposed metal sheets joined by a plurality of welding spots or seams, these may be spaced apart such that the sheet metal portions between the spots or seams can deform in an elastic-plastic manner under stress.

Welding torch with dual gas shielding

Abstract: A welding torch is shown with a dual shield gas flow for preventing flux buildup on the weld area for welds in confined spaces. The torch has a wire conduit for receiving an advancing supply of welding wire. The wire conduit has a curved end portion for guiding the welding wire toward the weld area and has an opening through which the welding wire extends for welding. A primary gas conduit directs the flow of primary shield gas and has an open, gas dispensing end adjacent the wire conduit opening. A secondary shield gas source located rearward of the gas dispensing end directs the flow of secondary shield gas in the direction of the weld area. The secondary shield gas flow is arranged to surround the primary gas flow in the direction of the weld. The orientation of the primary gas exiting the primary gas conduit induces the flow of secondary gas to change direction to provide additional gas shielding for the weld area.

Distribution of Toughness in HAZ of Multi-Pass Welded High Strength Steel : Study on Distribution of Microstructure and Toughness in Multi-Pass Weld HAZ (Report 2)

Abstract: The characteristic of toughness in weld heat affected zone (HAZ) of multi-pass welded high strength steel was investigated in this study. In multi-pass HAZ, some kinds of microstructure are distributed and toughness can be affected by this microstructure distribution. Therefore, in this report, the distribution of microstructure in HAZ of multi-pass welded 60 kgf/mm2 class high strength steel was investigated.The main results obtained were as follows.(1) It was confirmed that HAZ was heated above the reverse transformation temperature once, twice or three times by weld thermal cycles. But it was found that the microstructure in HAZ could be almost simulated by single or double thermal cycles.(2) Peak temperature of weld thermal cycle could be divided into three regions according to its effect on microstructure. That is, (I) α-γ dual phase region, (II) low hardenability region and (III) hardenability recovered region.(3) Microstructure was relatively uniform in the outer and the intermediate part of HAZ. But, in the inner part (that is, near the fusion line), three kinds of microstructures were ditsributed.

Simulation of Tack Welding Procedures in Butt Joint Welding of Plates

Abstract: In butt joint welding of plates, the change in root opening in front of the welding arc is of great importance. In order to automate the welding process, one must know how the change in root opening is affected by welding variables and plate configuration. The most important welding variables are the welding speed and the arc energy per unit length of the weld. The configuration is dependent on the material of the plates, their size, their restraints and the tack welding procedure. In this paper, the influence of the tack welding procedure on the change in root opening was inves­ tigated. This change during the first part of welding depends on the order in which the tack welds are made. It is also affected by the starting position of the welding arc. These effects were studied in seven theoretical analyses —three cases where the tack welding procedures differed and four cases where the tem­ perature fields at the beginning of the butt joint welding differed. In two of the cases, theoretical results were compared with experiments. In the theoretical anal­ yses, the finite element method was used. It was found that the change in root opening during the first part of welding is strongly dependent on the tack welding procedure.

Method of controlling multi-layer welding

Abstract: In the multi-layer welding of a joint of two pieces of metal to be welded by arc welding, the proper number of passes and the desired tracing positions of a welding torch for each layer are automatically established during the welding of the preceding layer. The welding torch is subjected to a Y-axis control so as to maintain constant the arc voltage or current during the welding and simultaneously the torch is caused to weave in the direction of an X-axis within the groove. The tracing of the groove by the torch is accomplished by controlling the weaving turning positions of the torch in accordance with the X-axis and Y-axis direction displacement data of the torch and the torch displacements in the X-axis direction are compared with a predetermined value thereby determining the proper number of passes to be made in the welding of the next layer.

Method of welding nitrogen-containing alloys

Abstract: A method for improving the weld strength, structure and crevice corrosion resistance of nitrogen-containing alloy weldments by adding nitrogen to the inert gas used for shielding during the welding operation.

Process and apparatus for partially or fully mechanised inert gas (protective gas) joint welding

Abstract: The invention starts from the known WIG or plasma welding process using an inert gas, with weld (filler) material being supplied as a welding rod (wire). According to the invention, the welding rod is introduced into the torch in such a way that it is located in the arc between the end of the non-consumable electrode and the workpiece and accordingly passes in an electroless dripping manner into the arc. Accordingly, the torch is equipped with a welding rod feed, by means of which the rod can be introduced into the nozzle channel of the torch and accordingly into the arc.

Effects of transformation plasticity on welding residual-stress fields in thin-walled pipes and thin plates

Abstract: Stress accumulation during cooling after single–pass butt welding is numerically studied for a pipe and a plate made of a microalloyed fine–grain C–Mn steel. The finite–element method is applied. Transformation plasticity is modelled by use of low yield stress values in the weld metal and in the heat affected zone during the final phase transformation. It is found that the stress changes induced in the pipe during the final phase transformation will partly remain at room temperature because of the low circumferential restraint during the final cooling. In the plate, however, the residual–stress field is governed mainly by the strong stress increase occurring after the final phase transformation. Stress changes induced in the plate before that event are thus hardly noticeable in the residual field.MST/25

Welding and weldability of nickel-iron aluminides

Abstract: An important area in the development of any commercial alloy is the ease with which it may be joined or welded. A study was undertaken to investigate the weldability of the borondoped (500 ppm by weight) ductile aluminides by gas tungsten arc (GTA) and electron beam (EB) welding processes. Autogenous GTA welding of boroncontaining nickel-iron aluminides produced severe cracking within the weld metal and the heat-affected zone (HAZ). The hot cracking appears to be related to complex phase changes that the material undergoes at elevated temperatures in the HAZ and also during the liquid-tosolid transformation in the fusion zone. A series of EB welds with welding speeds ranging from 13 to 64 mm/s (30 to 150 ipm) with varying beam focus conditions gave successful complete joint penetration welds only in a narrow range of speeds and focus conditions. The cracks were predominantly intergranular in the HAZ and interdendritic in the fusion zone presumably associated with the presence of NiAl (..beta..') phase along the grain boundaries and interdendritic regions. Transmission electron microscopy (TEM) revealed tetragonal distortions of the ordered B2 (NiAl type) phase with a martensitic appearance. Microprobe analysis revealed extensive solute redistribution in the fusion zone and the HAZ asmore » a result of the weld thermal cycle.« less

Sus 304 mig溶接金属中の酸素と破壊靱性に関する研究

Abstract: In the gas shield arc welding with SUS304 austenitic stainless steel base metal and, JISY308L type electrod, the effect of the welding condition on the oxygen content and microstructure of weld metal has been investigated. Next, the effect of the oxygen on the mechanical properties, mainly on the fracture toughness, were studied. The main results are summarized as follows;1) The oxygen content of weld metal is increased with dicreasing the welding current (from 200A to 400A) and with increasing the arc voltage (from 20V to 30V). At the constant welding atmosphere, there is a linear correlation between the oxygen content and a parameter of A/V which is established by the authors, where A is welding current and V is arc voltage. The oxygen content decreases with increasing the parametre A/V.2) The most of the oxygen exists in the γ region as the spherical oxide of Mn-Silicate. The number of oxide per unit volumu is related to the welding heat input. The number decreases with increasing the heat input.3) Charpy impact values and Jin values decrease with increasing the oxide volume fraction.4) The relationship between Charpy impact value and oxide volume fraction is represented by linear line on the log-log cordinate. At the constant oxide voulme fraction, the distribution (number and size) of oxide has little effect to Charpy impact value.

Method of laser-welding sheet metal protected by low-temperature vaporizing materials

Abstract: Method of laser welding sheet metal protected using low-vaporizing-temperature materials, whereby, before being subjected to a laser welding beam along a weld area (11), two metal sheets (1, 2) are placed on top of each other in such a manner that at least one layer (4) of the said protecting material is located between the sheets (1, 2) at the weld area (11) and communicates externally in essentially direct manner.

Shielded arc welding using auxiliary voltage

Abstract: Shielded arc welding apparatus advances a consumable electrode towards a workpiece; applies a welding voltage between the electrode and the workpiece; and applies an auxiliary voltage between the electrode and the workpiece, whereby the auxiliary voltage initiates an arc between the electrode and the workpiece before the electrode engages the workpiece.