Showing papers on "Welding published in 1993"

Welding, brazing, and soldering

Abstract: Volume 6 is the most comprehensive reference book ever produced on the major joining technologies and their applications to engineered materials. With over 500 illustrations and 400 tables, this book includes practical advice on consumable selection and procedure development, as well as joining fundamentals. Find the Answers in Four Major Sections: Fundamentals of Joining--addresses fundamental principles including basic chemistry, physics, and metallurgical concepts. Joining Processes--provides details on all major joining processes, including process parameters, advantages and limitations, applications, equipment, and health and safety. Materials Selection for Joined Assemblies--describes how to optimize materials selection for particular applications. Consumable Selection, Procedure Development, and Practice Considerations--serves as a guide to practices for joining specific materials, based on comprehensive, up-to-date information and data on all principal materials types and joining processes. Additional topics include: joint evaluation and quality control, modelling of joining processes, underwater welding, space welding, cryogenic welding, joining of composites and plastics, intelligent automation for joining technology, corrosion of weldments, thermal spray coating, cutting processes, health and safety, and welding terms and definitions. Portions of this Volume have been updated in and are replaced by ASM Handbook, Volume 6A: Welding Fundamentals and Processes .

Welded radially expandable endoprosthesis and the like

Abstract: Radially expandable endoprostheses or stents are provided, as well as their method of manufacture. These stents include a plurality of adjacent generally circumferential sections that are substantially axially positioned with respect to each other. Included are generally circumferentially disposed expandable segments that impart circumferential and radial expandability to the stents. The terminal portions of the end circumferential sections are welded directly to a portion of a generally adjacent circumferential section, and the welding preferably is carried out within an inert gas environment in a manner that minimizes crack formation at the weld locations.

Analysis of metal transfer in gas metal arc welding

Abstract: Droplet sizes produced in GMAW are predicted using both the static force balance theory and the pinch instability theory as a function of welding current, and the results are compared with experimental measurements The causes for the deviation of predicted droplet size from measured size are discussed with suggestions for modification of the theories in order to more accurately model metal transfer in GMAW The mechanism of repelled metal transfer is also discussed The transition of metal transfer mode has been considered as a critical phenomenon which changes dramatically over a narrow range of welding current

Joining of advanced materials

Abstract: Introduction to joining mechanical fastening mechanical fasteners and joining methods adhesive bonding process welding as a process the metallurgy of welding brazing soldering other joining processes joining of metals alloys and intermetallics joining of ceramics and of glasses joining of polymers joining composite materials joining dissimilar material combinations.

Welding steels without hydrogen cracking

Abstract: Defining the problem Guidance on safe welding procedures by graphical methods Selecting values for graphical presentation Welding procedures for different steel types Removing hydrogen during welding and heat treatment Appendix A: Typical hydrogen levels Appendix B: Techniques of hydrogen measurement Glossary: Trade names used in the text.

Prediction of Residual Stresses in Butt Welded Plates Using Inherent Strains

Abstract: The source of residual stresses in the vicinity of a weld may be expressed in terms of inherent strains. The characteristics of the inherent strain distributions in butt welds are investigated. It is found that the patterns vary little with changes in the welding conditions and sizes of the welded plates. With some assumptions, simple formulas are derived for the distribution and magnitude of inherent strain in a butt weld. A method of predicting the residual stress in a butt-welded plate using the characteristics of inherent strain distributions is presented. The validity of the method is confirmed by thermal elasto-plastic analysis using the finite element method (FEM).

Heat conduction losses in laser cutting of metals

Abstract: Using the model of a cylinder-type heat source, the power loss owing to heat conduction in laser cutting and welding of metals is calculated analytically. The case of laser cutting is described by taking into account the influence of the generated cutting kerf using numerical calculations. Both the analytical and the numerical solution for the power loss deposited into the material are well described by approximative formulae. The theoretically predicted power loss into the cut workpiece is confirmed by measurements of the temperature rise within the metal sheet in laser cutting experiments.

A study of arc force, pool depression and weld penetration during gas tungsten arc welding

Abstract: Weld pool depression, arc force, weld penetration, and their interrelations have been studied as a function of welding current. Pool depression and welding arc force have been measured simultaneously using a recently developed technique. The authors found quadratic dependence of arc force on current, confirming similar findings in previous studies. Pool depression is essentially zero below a threshold level of current (200 A in this experiment) and then increases quadratically with current. A perfectly linear relation between arc force and pool depression was found in the current range from 200 to 350 A, with pool depression onset at about 0.35 g force (0.34 [center dot] 10[sup [minus]2]N). The total surface tension and gravitational forces were calculated, from the measured surface topography, and found to be about five times that required to balance the arc force at 300 A. Thus electromagnetic and hydrodynamic forces must be taken into account to explain the measured levels of pool depression. The relation between weld penetration and pool depression for different welding currents has been established. Three distinct regimes of weld penetration on weld current were found.

Weld modeling and control using artificial neural networks

Abstract: Artificial neural networks were evaluated for monitoring and control of the variable polarity plasma arc welding (VPPAW) process. Three areas of welding application were investigated: weld process modeling, weld process control, and weld bead profile analysis for quality control. Experiments and analysis confirm that artificial neural networks are powerful tools for analysis, modeling, and control applications. They are particularly attractive in view of their capabilities to process nonlinear and noisy data, learn from actual welding data, and execute at relatively high speed. It is shown that neural networks are capable of modeling parameters of the VPPAW process to on the order of 10% accuracy or better. The same was observed when neural networks were used to select welding equipment parameters and the resulting bead geometries were estimated. These performance figures suggest that a VPPA welding control system can be implemented based on neural network models and control mechanisms. >

The kinetics of composite particle formation during mechanical alloying

Abstract: The kinetics of composite particle formation during attritor milling of insoluble binary elemental powders have been examined The effects of processing conditions (ie, mill power, temperature, and charge ratio) on these kinetics were studied Particle size distributions and fractions of elemental and composite particles were determined as functions of milling time and processing conditions This allowed the deduction of phenomenological rate constants describing the propensity for fracture and welding during processing For the mill-operating conditions investigated, the number of particles in the mill generally decreased with milling time, indicating a greater tendency for particle welding than fracture Moreover, a bimodal size distribution is often obtained as a result of preferential welding Copper and chromium 'alloy' primarily by encapsulation of Cr particles within Cu This form of alloying also occurs in Cu-Nb alloys processed at low mill power and/or for short milling times For other conditions, however, Cu-Nb alloys develop a lamellar morphology characteristic of mechanically alloyed two-phase ductile metals Increasing mill power or charge (ball-to-powder weight) ratio (CR) increases the rate of composite particle formation

New explosive welding technique to weld

Abstract: Various aluminum alloys and stainless steel were explosively welded using a thin stainless steel intermediate plate inserted between the aluminum alloy driver and stainless steel base plates. At first, the velocity change of the driver plate with flying distance is calculated using finite- difference analysis. Since the kinetic energy lost by collision affects the amount of the fused layer generated at the interface between the aluminum alloy and stainless steel, the use of a thin stainless steel intermediate plate is effective for decreasing the energy dissipated by the collision. The interfacial zone at the welded interface is composed of a fine eutectic structure of aluminum and Fe4Al13, and the explosive welding process of this metal combination proceeds mainly by intensive deformation of the aluminum alloy. The weldable region for various aluminum alloys is decided by the change in collision velocity and kinetic energy lost by collision, and the weldable region is decreased with the increase in the strength of the aluminum alloy.

Automobile framing system

Abstract: A framing system and framing device for assembling and welding a body-in-white utilizes completely separate framing and welding operations, which are typically intermixed in conventional framing systems. The framing device is a unitary frame structure within which an underbody, side frames and other body components can each be supported and accurately positioned with respect to each other prior to the welding operation. The framing device includes a cart which serves as the base and main support for the framing device, and an upper body support member. Using an appropriate number of clamping devices, the net positions of the body components which constitute the body-in-white are properly established and maintained, such that gate fixtures are unnecessary during the welding operation. The structure of the framing device provides considerable access to the body-in-white supported within the interior of the framing device, such that a greater number of welding guns can be used during the welding operation. As a result, essentially all of the welds necessary to achieve and maintain the rigidity and geometry of the body-in-white can be formed during a single welding operation.

Capped electric lamp

Abstract: A cap electric lamp of the type used in optical systems, for example, or as a vehicle headlamp, includes a glass lamp vessel with a first and a second neck-shaped portion in mutually opposing arrangement with seals through which current supply conductors extend to an electric element arranged in the lamp vessel. A metal sleeve is provided having a longitudinal slot around the first neck-shaped portion holding the lamp vessel with a clamping fit. This sleeve has a welding zone and a first and second clamping zone, each of which has a loop in the shape of an open hair pin. The clamping zones have respective, mutually opposing welding lugs which are interconnected by a welded joint so as to close the sleeve. A metal fixing member is provided with tongues which are welded to the sleeve in a welding zone of the sleeve. A lamp cap of insulating material is connected to the lamp vessel in which the fixing member is fixed and which has contact members to which the current supply conductors are connected. The welding zone is provided with mutually opposing closing tags alongside the longitudinal slot.

Weld pool oscillation during GTA welding of mild steel

Abstract: In this paper the results are reported of a study dealing with the oscillation behavior of weld pools in the case of GTA bead-on-plate welding of mild steel, Fe 360. During welding, the weld pool was brought into oscillation by applying short current pulses, and the oscillation frequency and amplitude were measured by monitoring the arc voltage. It was found that the oscillation of the partially penetrated weld pool is dominated by one of two different oscillation modes (Mode 1 and Mode 2) depending on the welding conditions, whereas the oscillation of the fully penetrated weld pool is characterized by a third oscillation mode (Mode 3). It is possible to maintain partially penetrated weld pool oscillation in Mode 1 by choosing appropriate welding conditions. Under these conditions, an abrupt decrease in oscillation frequency occurs when the weld pool transfers from partial penetration to full penetration. Thus, weld penetration can be in-process controlled by monitoring the oscillation frequency during welding.

Manual arc welding speed pacer

Abstract: An apparatus and method for pacing the application of a manual weld along the weld line generates beeps or light flashes at a rate which can be correlated by the welder with markings along the weld line. As each beep or flash is perceived, the welder should reach the next marking. Spacing between the markings determines the desired rate at which the weld is being applied. Alternatively, sequentially lightable areas are distributed along the weld line and sequentially lit a desired rate. The welder chases the sequence along the weld line to achieve the optimum rate of welding.

Experimental study of laser‐induced plasma in welding conditions with continuous CO2 laser

Abstract: Laser‐induced plasmas obtained during a welding process have been studied Spectroscopic diagnostics and an integrating sphere collecting the reflected CO2 light are the principal diagnostics used in order to determine the spatial variations of the microscopic parameters such as electron density and temperature, and the energy absorption during this process For several experimental processing conditions of shielding gases, the main perturbing effects such as absorption and refraction of the CO2 laser radiation are quantified Several possibilities for reducing these perturbing effects are then discussed

Electrical contact resistance under high loads and elevated temperatures

Abstract: This research is focused on characterizing electrical contact resistance involved in resistance spot welding of thin sheet steels. It is part of a larger study in which a mathematical simulation of the welding process is being developed. A special test fixture has been fabricated that allows contact resistance at the electrode-to-sheet interface and the sheet-to-sheet interface to be measured under typical welding pressures (e.g., 14 ksi) and from room temperature to elevated temperatures. Bare and galvanized mild and HSLA steels have been considered. The nature of the contact resistance is discussed, and experimental findings are presented

Retainer ring for welding wire container disclosure

Abstract: A retainer ring for a container of low twist welding wire which container includes a cylindrical outer wall, a lower partition and an upper opening through which the welding wire is drawn from a hollow, cylindrical spool of welding wire formed from a multitude of convolutions of wire in layers provided in the container wherein the retainer ring comprises a generally flat outer portion with an outer periphery fitting into the outer wall of the container, minimally contacting the wire surface, and comprising a number of projecting lobe portions whereby the outer periphery of the ring contains alternate areas first being closer to and then being farther from the outer walls of the container when the retainer ring is resting upon the hollow spool of welding wire in the container and an inner bell mouthed portion extending upwardly and defining an innermost wire extraction opening with a diameter substantially smaller than the spool of wire in the container.

Calculation of weld metal composition change in high-power conduction mode carbon dioxide laser-welded stainless steels

Abstract: The use of high-power density laser beam for welding of many important alloys often leads to appreciable changes in the composition and properties of the weld metal. The main difficulties in the estimation of laser-induced vaporization rates and the resulting composition changes are the determination of the vapor condensation rates and the incorporation of the effect of the welding plasma in suppressing vaporization rates. In this article, a model is presented to predict the weld metal composition change during laser welding. The velocity and temperature fields in the weld pool are simulated through numerical solution of the Navier-Stokes equation and the equation of conservation of energy. The computed temperature fields are coupled with ve-locity distribution functions of the vapor molecules and the equations of conservation of mass, momentum, and the translational kinetic energy in the gas phase for the calculation of the evap-oration and the condensation rates. Results of carefully controlled physical modeling experi-ments are utilized to include the effect of plasma on the metal vaporization rate. The predicted area of cross section and the rates of vaporization are then used to compute the resulting com-position change. The calculated vaporization rates and the weld metal composition change for the welding of high-manganese 201 stainless steels are found to be in fair agreement with the corresponding experimental results.

Mechanical properties of laser welds of titanium in dentistry by pulsed Nd:YAG laser apparatus

Abstract: The use of titanium in dentistry is increasing, and an adequate method of joining titanium units of restorations is needed. This study examined the welding of titanium with a normal pulse Nd:YAG laser. Laser welding of titanium was effective when performed in an argon atmosphere. ANOVA for the three-point bending test showed a correlation between the bending strength of a weld, the atmosphere under which the irradiation is performed, and the intensity of the irradiation.

Welding management apparatus

Abstract: A welding machine apparatus for use with a tube production machine (10). A workpiece (1) fed from a roll of metal strip is formed in a tubular formation having side surfaces (1b, 1c) opposite to each other. An upsetting pressure is applied to joint the opposite side surfaces (1b, 1c) of the workpiece (1) at a jointing point (1a). A high frequency power is supplied to the workpiece (1) to weld the opposite side surfaces (1b, 1c) at the jointing point so as to produce a metal tube member. The welding management apparatus comprises a camera (40) positioned to have a visual field (VF) including the jointing point (1a) for producing a video signal (S1) indicative of an image including an area luminous with a pre-arc produced in the visual field (VF). An image processor (50) converts the video signal (S1) into a luminance distribution pattern. An inference unit (60) is provided for inferring a defective welding condition based upon the luminance distribution pattern. The inference unit (60) includes an alarm unit (66) for producing an alarm when a defective welding condition is inferred.

Resistance welding monitor

Abstract: A welding voltage output from a power source of a resistance welder is derived on the basis of a welding current and an interelectrode voltage, and diameter of a nugget which is formed in a sheetlike work to be welded is estimated on the basis of the welding current, the welding voltage, data of material constant and a thickness of the sheetlike work, subsequently, the estimated diameter of nugget is composed with a target diameter of nugget, and thereby quality of the resistance welding is determined.

Analysis of heat conduction in deep penetration welding with a time-modulated laser beam

Abstract: The heat conduction model of a cylinder-type source in laser keyhole welding is extended to a time-modulated laser beam with a prescribed energy flux density instead of a prescribed temperature at the wall of the cylinder. A new non-dimensional parameter Omega = omega r02/ kappa ( omega denotes the frequency of the time-modulated laser beam, r0 the focus radius and kappa the thermal diffusivity of the metal) is found, characterizing the behaviour of the system. The resulting temperature oscillations mainly affect the weld seam, whereas the heat-affected zone is not influenced. The time behaviour of the surface temperature of the keyhole is calculated. The study is also applied to a laser beam modulated as a pulse train.

Investigation of the effect of welding parameters on weld quality of plasma arc keyhole welding of structural steels

Abstract: In the present investigation, the individual and interactive effects of the main welding parameters on weld quality of plasma arc keyhole welding of conventional structural steel, high strength microalloyed steel and strong formable microalloyed steel have been examined using welding of butt joints with a square groove in various welding positions, and welding of joint roots with a single-V-groove and the root face in the flat position. The most important welding parameters are welding current, welding speed and welding gases, especially plasma gas flow rate. Welding parameter combinations producing the best quality welds are presented. It is shown that it is possible to achieve defect-free high-quality welds with good strength and toughness properties, but the allowable range of variation of welding parameters, especially for the highest weld quality, is narrow. An argonhydrogen mixture for the plasma gas together with argon as shielding and backing gases give the best results with respect to weld quality.

Method of making a vacuum-tight seal between a ceramic and a metal part, sealed structure, and discharge lamp having the seal

Abstract: A vacuum-tight seal, particularly for an arc tube or discharge vessel for a metal halide or sodium high-pressure discharge lamp, is made by forming the arc tube of transparent ceramic, typically Al2 O3, having two open ends, into which connecting plugs (3), with central openings, are sealed. Open metal tubes (4) fitting into the openings of the plugs (3) are then vacuum-tightly sintered therein. An electrode system (5, 10, 10'), forming a subassembly with a current supply lead or lead-through (6, 11, 14, 15, 20, 24) is provided, having an outer diameter fitting into the metal tube. After mounting one of the electrode systems and lead-through into the metal tube (4), and welding the lead-through to the metal tube, the vessel can be evacuated through the still open tube (4) at the other end, supplied with suitable fill substances and an ignition gas, such as argon or xenon, and the second electrode system then introduced, and welded, for example by a laser, to the outer end of the other metal tube (4). The arrangement permits use of molybdenum tubes, molybdenum lead-throughs, in Al2 O3 ceramic, in spite of different thermal coefficients of expansion. Preferably, the metal tube extends beyond the end face of the vessel and/or sealing plug (3), to permit free access during the welding step and reduce heat transfer into the interior of the arc tube or discharge vessel (1).

The science and practice of welding

Abstract: The Science and Practice of Welding, now in its tenth edition and published in two volumes, is an introduction to the theory and practice of welding processes and their applications. Volume I, Welding Science and Technology, explains the basics principles of physics, chemistry and metallurgy as applied to welding. The section electrical principles includes a simple description of the silicone diode and resistor, the production and use of square wave, and one-knob stepless control of welding current. There is a comprehensive section on non-destructive testing (NDR) and destructive testing of welds and crack tip opening displacement testing. The text has been brought completely up to date and now includes a new chapter devoted to the inverter power unit. Duplex stainless steel has been included in the list of material described.