| W | Chemical symbol for Tungsten, from wolfram. |
| Water Quenching | A quench in which water is the quenching medium. The major disadvantage of water quenching is its poor efficiency at the beginning or hot stage of the quenching process. |
| Welding | The process of joining together two pieces of metal so that bonding accompanied by appreciable interatomic penetration takes place at their original boundary surfaces. The boundaries more or less disappear at the weld, and integrating crystals develop across them. Welding is carried out by the use of heat or pressure or both and with or without added metal. There are many types of welding including Metal Arc, Atomic Hydrogen, Submerged Arc, Resistance Butt, Flash, Spot, Stitch, Stud and Projection. |
| Whiskers | Thin hair-like growths on metal that are barely visible to the naked eye, they are stronger than the metals from which they are formed, probably because they are free from defects. |
| White Annealing | A heat treatment process carried out on pickled steel with the objective of eliminating the hydrogen that has entered the steel during the pickling operation and thus removing any tendency to hydrogen embrittlement. |
| White Layer | Compound layer that forms as a result of the nitriding process. |
| Widmanstatten Structure | A microstructure resulting when steels are cooled at a critical rate from extremely high temperatures. It consists of ferrite and pearlite and has a cross-hatched appearance due to the ferrite having formed along certain crystallographic planes. |
| Wolfram | The alternative name for tungsten. |
| Woody Fracture | A fracture that is fibrous or woody in appearance due to the elongation of the individual grains. This may be accentuated by the presence of slag or by a banded structure. It is grey and dull and is characteristic of ductile but non-homogeneous material such as wrought iron. |
| Work Hardening | The increase in hardness and strength produced by cold plastic deformation or mechanical working. |
| Working Zone | That portion of the enclosed volume of a piece of thermal processing equipment occupied by parts or raw material during the soaking portion of a thermal treatment. It is usually, but not always, a high percentage of the total enclosed volume. It may include more than one control zone. |
| Wrought Iron | A commercial iron that has little use today and has been replaced by mild steel. It was commonly produced by the puddling process. The temperatures employed in its production are too low to render it fluid, it is heated until it forms a pasty mass then it is squeezed or forged. The process does not lend itself to removal of impurities so it contains an appreciable quantity of slag. It will not respond to any heat treatment designed to increase the hardness or strength. |
