Red heat
From Wikipedia, the free encyclopedia
For other uses, see Red Heat (disambiguation).
The practice of using colours to determine the temperature of a piece of (usually) ferrous metal comes from blacksmithing. Long before thermometers were widely available it was necessary to know what state the metal was in for heat treating it and the only way to do this was to heat it up to a colour which was known to be best for the work.
The colours which can be observed in steel are:[1]
| Colour | Temperature [°C] |
|---|---|
| Black red (when viewed in dull light) | 426 to 593 |
| Very dark red | 593 to 704 |
| Dark red | 704 to 814 |
| Cherry red (lower critical point) | 815 to 870 (critical point depends on carbon content of steel) |
| Light cherry red | 871 to 981 |
| Orange | 981 to 1092 |
| Yellow | 1093 to 1258 |
| Yellow white | 1259 to 1314 |
| White | 1315+ |
See also
References
This article is issued from Wikipedia. The text is available under the Creative Commons Attribution/Share Alike; additional terms may apply for the media files.