A nonstandard term for WELD INTERFACE. 


    Metal in a fusion weld consisting of that portion of the base metal and filler metal melted during welding. See MIXED ZONE and UNMIXED ZONE.

    Weld metal is an admixture of melted base metal and deposited filler metal, if filler is used. Typical weld metals are rapidly solidified and have a fine- grain dendritic microstructure. In most arc welding processes filler metal is added. Some welds are com- posed of only remelted base metal; for example, electron beam and resistance welds are made without filler metal.

    Microstructure-The microstructure of weld metal is considerably different from that of the base metal of similar composition. The difference in microstructure is not related to chemical compositions, but to different thermal and mechanical histories of the base metal and the weld metal.

    The structure of the base metal is a result of a hot rolling operation and multiple recrystallization of the hot-worked metal. In contrast, the weld metal has a solidified or cast structure and has not been mechanically deformed. This structure and its attendant mechanical properties are the direct result of the sequence of events that occur as the weld metal solidifies. These events include reaction of the weld metal with the gases in the vicinity of the weld and with non-metallic liquid phases (slag or flux) during welding, and also reactions that took place in the weld after solidification.

    Solidification- The unmelted portions of grains in the heat-affected zone at the solid-liquid interface serve as nucleation sites for weld metal solidification. Metals grow more rapidly in certain crystallographic directions. Therefore, favorably oriented grains grow for substantial distances, while the growth in others that are less favorably oriented  is blocked by faster growing grains. As a result, weld metal often exhibits a macrostructure, described as columnar, in which the grains are relatively long and parallel to the direction of heat flow. This structure is the natural result of the influence of favorable crystal orientation on the competitive nature of solidification grain growth. Weld metal solidification of most commercial metals involves microsegregation of alloying and residual elements. This action is associated with, and in large measure, responsible for the formation of dendrites. A dendrite is a structural feature which reflects the complex shape taken by the liquid-solid interface during solidification.

    Strengthening Mechanisms- Practical methods for strengthening weld metal are fewer than for base metal. For example, weld metal is not usually cold- worked. However, there are four mechanisms for strengthening weld metal, and where applicable, mechanisms are additive:

    (1) Solidification grain structure

    (2) Solid solution strengthening

    (3) Transformation hardening

    (4) Precipitation hardening

    The first mechanism is common to all welds, and the second is applicable to any alloy type, but the third and fourth apply to only specific groups of alloys. See MIXED ZONE and UNMIXED ZONE. 


    The area of weld metal as measured on the cross section of a weld. 


    That portion of the weld area consisting of weld metal.


    A single progression of welding along a joint. The result of a pass is a weld bead or layer. 


    The order in which the weld passes are made. See also LONVITUDINAL



    A nonstandard term for JOINT PENETRATION and ROOT PENETRATION.


    The time required to complete one cycle of a resistance welding operation. In pulsation welding, the weld period includes the “cool time” intervals. 


    The localized volume of molten metal in a weld prior to its solidijkation as weld metal. 


    A nonstandard term for WELD POOL. 


    A function of an adaptive control that determines changes in the shape of the weld pool or the weld metal during welding, and directs the welding machine to take appropriate action. See also JOINT RECOGNITION and JOINT TRACKING. 


    Weld metal in excess of the quantity required to fill a joint. See also FACE REINFORCEMENT and ROOT REINFORCEMENT. 


    The points, shown in a cross section, at which the weld metal extends furthest into a joint and intersects the base metal. See Figure W-6. 


    A gauge that measures the size of a weld, the amount of convexity and the amount of reinforcement.

    In Figure W-7, (A), (B), and (C) illustrate how the weld size gauge is used to determine the various dimensions of a weld.

    (1) To determine the size of a fillet weld, place the gauge against the toe of the shortest leg of the fillet and slide the pointer out until it touches the structure. Read “Fillet Weld Leg Length” on the face of the gauge. See Figure W-7(A).

    (2)To determine the size of a concave fillet weld, place the gauge against the structure and slide the pointer out until it touches the face of the fillet weld. Read “Concavity” on the face of the gauge. See Figure W-7(B).

    (3) To determine the reinforcement of a butt weld, place the gauge so that the reinforcement will come between the legs of the gauge and slide the pointer out until it touches the face of the weld. The reinforcement is indicated on the face of the gauge. See Figure W-7(C). 


    A graphical character connected to the welding symbol indicating the type of weld. See WELDING SYMBOL. 


    Additional material that extends beyond either end of the joint, on which the weld is started or terminated.  See also RUNOFF WELD TAB and STARTING WELD TAB. 


    The junction of the weld face and the base metal.


    The capacity of material to be welded under the imposed fabrication conditions into a specific, suitably designed structure and to pel3cor-m satisfactorily in the intended service. 


    Art created through the use of a welding process. Welding is a highly adaptable and versatile medium for the artist or sculptor. Many different materials and areas of creativity are possible. Artwork can be created by joining material to build an object, or by removing material from larger pieces to achieve a desired effect. Many sculptors use a combination of the two techniques, using both arc and oxyfuel gas welding and cutting.

    The use of welding techniques in modern sculpture has developed gradually. Until recently, artists used age-old methods of casting to create three-dimensional metal figures.

    Pablo Picasso was one of the first artists to experiment with welding. Through the ages, the development of sculpture has essentially been a concern with mass, space and volume, leaving linear expression to the draftsman or painter. However, during the 1930s two very distinct movements with strongly opposed philosophies were creating the new ideas that would liberate sculpture from the restrictions of the foundry. One group, the Surrealists, commanded the most immediate attention with their attempts to suggest the activities of the subconscious mind. The second group, the Constructives, achieved the most far-reaching technical influence with their concern for the formal arrangement of planes expressed through modern industrial materials. Both of these schools of thought had numerous and talented practitioners, and these basic approaches continue to influence welded sculpture.

    In the past, much of the welded sculpture had been produced with the oxyacetylene torch. Currently, the well-equipped sculptor probably has a small SMAW or GMAW outfit in his studio for creating artwork from materials such as aluminum and stainless steel, as well as the mild steels. 


    One who performs manual or semiautomatic welding.  


    Written verification that a welder has produced welds meeting a prescribed standard of welder performance.  See also CERTIFlED WELDER.


    The demonstration of a welder’s ability to produce welds meeting prescribed standards.  Welder, welding operator, and tack welder qualification tests determine the ability of the persons tested to produce acceptably sound welds with the process, materials, and procedure called for in the tests. Qualification tests are not intended to be used as a guide for welding during actual construction, but rather to assess whether an individual has a required minimum level of skill to produce sound welds. The tests cannot foretell how an individual will perform on a particular production weld. For this reason, complete reliance should not be placed on qualification testing of welders. The quality of production welds should be determined during and following completion of actual welding.

    Various codes, specifications, and governing rules generally prescribe similar, though frequently somewhat different, methods for qualifying welders, welding operators, and tack welders. The applicable code or specification should be consulted for specific details and requirements. See QUALIFICATION AND TESTING. 


    The act of registering a welder certification or a photostatic copy of the welder certification. 


    A joining process that produces coalescence of materials by heating them to the welding temperature, with or without the application of pressure or by the application of pressure alone, and with or without the use of filler metal.  


    A controlled electrical discharge between the electrode and the workpiece that is formed and sustained by the establishment of a gaseous conductive medium, called an “arc plasma.”