Warpage: Deformation other than contraction that develops in a casting between solidification and room temperature; also, distortion occurring
during annealing, stress relieving and high-temperature service.
Wash: A casting defect resulting from erosion of sand by metal flowing over the mold or corded surfaces. They appear as rough spots and excess
metal on the casting surface. Also called cuts.
Washburn Core: A thin core which constricts the riser at the point of attachment to the casting. The thin core heats quickly and promotes feeding of the casting. Riser removal cost is minimized.
Water Test: To subject a casting to water pressure in such a manner that any porous areas will show leakage.
Water Glass: Sodium silicate, a viscous liquid which when mixed with powdered fireclay forms a refractory cement; used in CO., Molding.
Wax Pattern: 1. A precise duplicate, allowing for shrinkage, of the casting and required gates, usually formed by pouring or injecting molten wax into a die or mold, 2. wax molded around the parts to be welded by a thermit welding process.
Weld Bead: The built-up portion of a fusion weld, formed either from the filler metal or from the melting of the parent metal.
Welding: A process used to join metals by the application of heat. Fusion welding, which includes gas, arc and resistance welding, requires that the parent metals be melted. This distinguishes fusion welding from brazing. In pressure welding joining is accomplished by the use of heat and pressure without melting. The parts that are being pressure welded are pressed together and heated simultaneously, so that recrystallization occurs across the interface.
Welding, Arc: Welding accomplished by using an electric arc that can be formed between a metal or carbon electrode and the metal being welded; between two separate electrodes, as in atomic hydrogen welding or between the two separate pieces being welded, as in flash welding.
Welding, Autogenous: Method of uniting two pieces of metal by melting their edges together without solder or any added welding metal, as by the thermite process which employs a medium of finely divided aluminum powder and oxide or iron by which a temperature of some 5400 F (2982.2 C) is obtained.
Welding, Electrode: A metal or alloy in rod or wire form used in electric arc welding to maintain the arc and at the same time supply molten metal or alloy at the point where the weld is to be accomplished.
Welding Flash: Skin exposed too long to the ultraviolet rays of welding or melting arcs will burn as in a sunburn. Though temporary blindness can result, it is not permanent, as is popularly believed.
Welding, Shielded-Arc: Electric-arc welding in which the molten weld metal is protected from the atmosphere. An inert gaseous atmosphere, or flux-coated electrode may be employed.
Welding Stress: That stress resulting from localized heating and cooling of metal during welding.
Wet Scrubber (Gas Washer): In air pollution control, a liquid (usually water) spray device for collecting pollutants in escaping foundry gases.
Widmannstatten Structure: Platelike structure seen in grains of steel in the course of transformation of a solid solution.
Wild Steel: Steel which has not been completely deoxidized and reacts violently after casting due to liberation of gases on cooling.