A state of being bent or twisted out of true, or out of alignment. The amount of warp that occurs during welding of sheet and plate material depends on the amount of heat that spreads away from the weld and through the parent metal. Some warping occurs when welding heat relieves strains left in the metal after rolling. Warping can be reduced by using jigs, chill bars, and plates to absorb excess heat. The backstep weld sequence also helps reduce warps. See EXPANSION and CONTRACTION; SHEET METAL WELDING, PREHEAT, and BACKSTEP SEQUENCE.


    Melting the surplus metal on the outer surface of a weld to obtain an esthetically pleasing weld and to ensure complete fusion. 


    Water jet cutting, also called hydrodynamic machining, severs metals and other materials using a high-velocity water jet. The jet is formed by forcing water through a 0.1 to 0.6 mm (0.004 to 0.024 in.) diameter orifice in a man-made sapphire under high pressure (207 to 414 MPa[30 000to 60 000 psi]). Jet velocities range from 520 to 914 m/s (1700 to 3000 ft/s). At these speeds and pressures the water erodes many materials rapidly, acting like a saw blade. The water stream, with a flow rate of 0.4 to 19 Umin (0.1 to 5 gal/min), is usually manipulated by a robot or gantry system, but small workpieces may be guided manually past a stationary water jet.

    Metals and other hard materials are cut by adding an abrasive in powder form to the water stream. With this method, called hydroabrasive machining or abrasive jet machining, the abrasive particles (often gamet) are accelerated by the water and accomplish most of the cutting. Higher flow rates of water are required to accelerate the abrasive particles.

    Materials are cut cleanly, without ragged edges (unless the traverse speed is too high), without heat, and generally faster than on a band saw. A narrow, 0.8 to 2.5 mm (0.030 to 0.100 in.), smooth kerf is produced. There is no problem of thermal delamination, or deformation, when water jet cutting is properly applied.

    The wide application range and lack of beat are the major advantages of water jet cutting.

    Water jet and abrasive water jet systems compete with such processes as band saws, the reciprocating knife, flame cutting, plasma, and laser cutting. They can handle materials that are damaged by heat from thermal processes, or materials that gum up mechanical cutting tools. In some cases, they can cost effectively replace three operations: rough-cutting, milling, and deburring of contoured shapesl. The wide range of materials which may be cut appears in Table W-1.


    The forcing of exhaust air and fumes from a spray booth through water so that the vented air is free of thermal sprayed particles or fumes. 

  • WATT

    A unit of electric power equal to voltage multiplied by amperage. One horsepower is equal to 746 watts. Named for J. Watt, a Scottish engineer, a watt is a unit of power consumption that standardizes and allows comparison between different rates of consumption. 


    A unit of work or energy equivalent to the power of one watt operating for one hour. 


    An instrument that records watt-hours of power consumption. 


    An automatic soldering process where workpieces pass through a wave of molten solder. See DIP SOLDERING. 

  • WAX PATTERN, Thermite Welding

    Wax molded around the workpieces to the form desired for the completed weld. 


    A type of weld bead made with transverse oscillation.  


    A technique of depositing weld metal in which the electrode sweeps back and forth across the joint in a serni-circular motion. Weaving increases the width of the deposit, decreases overlap and assists slag formation. Sometimes called wash welding. See WEAVE BEAD. 

  • WELD

    A localized coalescence of metals or nonmetals produced either by heating the materials 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 material.


    A line through the length of the weld, perpendicular to and at the geometric center of its cross section. 


    A weld resulting from a pass. See STRINGER BEAD and WEAVE BEAD. 


    A resistance spot welding process variation in which the spot weld strength is augmented by adhesive at the faying surfaces. 


    A joining method that combines resistance welding with brazing.  


    In stainless steel, a condition of lowered resistance to corrosion caused by carbide precipitation.  When stainless steel that has not been stabilized with titanium or another stabilizing element is heated to a temperature ranging between 500 and 900°C (930 and 1650°F), which occurs during welding, chromium carbide precipitates along the grain boundaries, reducing the corrosion resistance at these locations. The corrosion does not occur in the weld itself but in the heat-affected zone adjacent to the weld. This loss of corroion resistance can be eliminated by heat treating. The welded part should be heated to 1100°C (2010°F) and quenched in water. 


    A crack located in the weld metal or heat-affected zone. 


    In spot and projection welding, a delay in the weld process that ensures the proper sequence of mechanical functions in relation to electrical functions. 


    The exposed surface of a weld on the side from which welding was done. See Figure W-3. 


    A device designed for measuring the shape and size of welds.  


    A channel in the surface of a workpiece or an opening between two joint members that provides space to contain a weld.  


    The interface between weld metal and base metal in a fusion weld, between base metals in a solid-state weld without filler metal, or between filler metal and base metal in a solid-state weld with filler metal. 

  • WELD INTERVAL, Resistance Welding

    The total of all heat and cool times, and upslope time, used in making one multiple-impulse weld. See Figure I-1. See also WELD TIME. 


    Misalignment of the joint members. See Figure W-4.