Search Results for weld bead size

This article describes the characterization of welds as a sequence of procedures, where each procedure is concerned with a finer scale of detail. The first level of characterization involves information that may be obtained by direct visual inspection and measurement of the weld. The article discusses nondestructive evaluation of welds by encompassing techniques that are used to characterize the locations and structure of internal and surface defects, including radiography, ultrasonic testing, and liquid penetrant inspection. It reviews the macrostructural characterization of a sectioned weld, including features such as number of passes; weld bead size, shape, and homogeneity; and the orientation of beads in a multipass weld. The article provides examples that describe how welds are characterized according to the procedures.

Gas-metal arc welding (GMAW) is an arc welding process that joins metals together by heating them with an electric arc that is established between a consumable electrode (wire) and a workpiece. This article discusses the advantages and limitations, operating principle, metal transfer mechanisms, and process variables of the GMAW process. The process variables include welding current, polarity, arc voltage, travel speed, electrode extension, electrode orientation, and electrode diameter. The major components of the basic equipment for a typical GMAW installation are discussed. The article also describes two consumable elements, such as electrode and shielding gas, of the GMAW process. It concludes with information on the safety aspects.

Submerged arc welding (SAW) is suited for applications involving long, continuous welds. This article describes the operating principle, application, advantages, limitations, power source, equipment, and fluxes in SAW. It reviews three different types of electrodes manufactured for SAW: solid, cored, and strip. The article highlights the factors to be considered for controlling the welding process, including fit-up of work, travel speed, and flux depth. It also evaluates the defects that occur in SAW: lack of fusion, slag entrapment, solidification cracking, and hydrogen cracking. Finally, the article provides information on the safety measures to be followed in this process.

This article provides an overview of the types of weld discontinuities that are characteristic of specialized welding processes. These welding processes include electron-beam welding, plasma arc welding, electroslag welding, friction welding, resistance welding, and diffusion welding. The article also describes the common inspection methods used to detect these discontinuities.

This article provides a review of metallographic procedures and techniques for analyzing the microstructure of fusion welded joints. It discusses sample preparation, the use of backing plates, and common sectioning methods. It identifies the various types of defects that can occur in arc welded metals, organizing them according to the sectioning method by which they are observed. It describes the relationship between weld bead morphology and sectioning direction and its effect on measurement error. The article examines micrographs from stainless steel, aluminum, and titanium alloy joints, highlighting important details such as solidification and solid-state transformation structures and what they reveal about the welding process. Besides arc welding, it also discusses laser and electron beam welding methods, resistance and spot welding, and the welding of dissimilar metals.

The shielding gas used in an arc welding process has a significant influence on the overall performance of the welding system. These gases are argon, helium, oxygen, hydrogen, nitrogen, and carbon dioxide. This article discusses the shielding gas selection criteria for plasma arc welding, gas metal arc welding, and flux cored arc welding. It describes the basic properties of shielding gases, namely, dissociation, recombination, reactivity potential, oxidation potential, and gas purity. The article also provides information on the influence of the shielding gas on weld mechanical properties and self-shielded flux cored arc welding.

The shielding gas used in a welding process has a significant influence on the overall performance of the welding system. This article discusses the basic properties of a shielding gas in terms of ionization potential, thermal conductivity, dissociation and recombination, reactivity/oxidation potential, surface tension, gas purity, and gas density. It describes the characteristics of the components of a shielding gas blend. The article discusses the selection of shielding gas for gas-metal arc welding (GMAW), gas-tungsten arc welding (GTAW), and plasma arc welding (PAW), as well as the influence of shielding gas on weld mechanical properties. It concludes with a discussion on flux-cored arc welding.

Nickel alloys can be joined reliably by all types of welding processes or methods, with the exception of forge welding and oxyacetylene welding. This article discusses the heat treatment of nickel alloys and tabulates nominal compositions of selected weldable wrought nickel and nickel alloys. It provides information on gas-tungsten arc welding, gas-metal arc welding, plasma arc welding, shielded metal arc welding, and submerged arc welding for welding nickel alloys. The article reviews the defects encountered in the arc welding of nickel alloys, including porosity, cracking, and stress-corrosion cracking. It provides information on the factors that influence the choice of filler metal and welding process of nickel alloys.

This article provides information on heat and mass transfer from the arc to the base metal in the gas-metal arc welding (GMAW) process. It discusses the development of welding procedures and the general operation of the process. The issues described in this article include the: total heat transferred to the base metal; partitioning of heat transfer between the arc and the molten electrode droplets; transfer modes of the droplets; role of the arc in droplet transfer; and simple model for welding procedure development based on an understanding of heat and mass transfer to the base metal.

Hybrid laser arc welding (HLAW) is a metal joining process that combines laser beam welding (LBW) and arc welding in the same weld pool. This article provides a discussion on the major process variables for two modes of operation of HLAW, namely, stabilization mode and penetration mode. The major process variables for either mode of operation include three sets of welding parameters: the variables for the independent LBW and gas metal arc welding processes and welding variables that are specific to the HLAW process. The article discusses the advantages, limitations, and applications of the HLAW and describes the major components and consumables used for HLAW. The components include the laser source, gas metal arc welding source, hybrid welding head, and motion system. The article also describes the typical sources of defects and safety concerns of HLAW.

Heat and mass transfer in arc welding is normally studied from the standpoint of the weld pool and heat-affected zone. This article examines the heat and mass transfer from the arc to the base metal during the gas metal arc welding process. It also provides information on the selecting parameters for the development of welding procedures.

Shielded metal arc welding (SMAW), commonly called stick or covered electrode welding, is a manual welding process whereby an arc is generated between a flux-covered consumable electrode and a workpiece. This article discusses the advantages and limitations and applications of the SMAW process and describes the equipment used. It provides information on various coated electrodes used in the SMAW process, including mild and low-alloy steel-covered electrodes, stainless steel covered electrodes, and nickel and copper alloys covered electrodes. It reviews weld schedules and procedures, as well as the variations of the SMAW process. The article concludes with information on the special applications of the SMAW process and safety considerations.

This article discusses the metallurgical aspects of underwater welds. It describes the microstructural development, which mainly includes three types of ferrite associated with low carbon steel weld metal: grain-boundary ferrite, sideplate ferrite, and acicular ferrite. The article explains the factors that affect heat-affected zone (HAZ) cracking. These include hydrogen from the weld pool, microstructures that develop in the HAZ, and stress levels that develop in the weld joint. The article describes the welding practices that can reduce residual stresses. It explains the effect of water pressure on the formation of porosity in underwater gravity welding. The article concludes with a discussion on the practical applications of underwater welding.

This article briefly reviews the general causes of weldment failures, which may arise from rejection after inspection or failure to pass mechanical testing as well as loss of function in service. It focuses on the general discontinuities observed in welds, and shows how some imperfections may be tolerable and how the other may be root-cause defects in service failures. The article explains the effects of joint design on weldment integrity. It outlines the origins of failure associated with the inherent discontinuity of welds and the imperfections that might be introduced from arc welding processes. The article also describes failure origins in other welding processes, such as electroslag welds, electrogas welds, flash welds, upset butt welds, flash welds, electron and laser beam weld, and high-frequency induction welds.

Submerged arc welding (SAW) is an arc welding process in which the arc is concealed by a blanket of granular and fusible flux. This article provides a schematic illustration of a typical setup for automatic SAW and discusses the advantages and limitations and the process applications of SAW. The article discusses flux classification relative to production method, relative to effect on alloy content of weld deposit, and relative to basicity index. It describes the procedural variations and the effect of weld current, weld voltage, electrical stickout, travel speed, and flux layer depth on weld bead characteristics. The article concludes with information on weld defects, such as lack of fusion, slag entrapment, solidification cracking, hydrogen cracking, or porosity.

This article is a compilation of definitions for terms related to welding fundamentals and all welding processes. The processes include arc and resistance welding, friction stir welding, laser beam welding, explosive welding, and ultrasonic welding.

Cast iron can be described as an alloy of predominantly iron, carbon, and silicon. This article discusses the classification of cast irons, such as gray cast iron, white cast iron, malleable cast iron, ductile cast iron, and compacted graphite iron. It reviews the various special techniques, such as groove face grooving, studding, joint design modifications, and peening, for improving the strength of a weld or its fitness for service. The article discusses the need for postweld heat treatment that depends on the condition of the casting, possible distortion during subsequent machining, the desired finish of the machined surfaces, and prior heat treatment. It describes various welding process for welding cast irons, including oxyfuel welding, braze welding, shielded metal arc welding, gas metal arc welding, and gas-tungsten arc welding.

This article discusses the operation principles, advantages, limitations, process parameters, consumables or electrodes, the equipment used, process variations, and safety considerations of gas metal arc welding (GMAW). It reviews the important variables of the GMAW process that affect weld penetration, bead shape, arc stability, productivity, and overall weld quality. These include welding consumables, equipment settings, and gun manipulation. The major components of a GMAW installation such as a welding gun, shielding gas supply, electrode feed unit, power source, and associated controls are discussed.