Colour Temperatures
The colour of a piece of steel may be used as a guide to it's temperature. These are particulalrly useful when hardening or tempering steel.
| Colour | °C |
| Pale yellow | 221 |
| Straw | 230 |
| Golden yellow | 243 |
| Brown | 254 |
| Brown to purple | 266 |
| Purple | 277 |
| Bright blue | 288 |
| Blue | 293 |
| Dark blue | 316 |
| Just visible red | 500 to 600 |
| Dull cherry red | 700 to 750 |
| Cherry red | 750 to 825 |
| Bright cherry red | 825 to 875 |
| Brightest red | 900 to 950 |
| Orange | 950 to 1000 |
| Light orange | 1000 to 1050 |
| Lemon | 1100 to 1200 |
| White | 1200 to 1300 |
See also: Colour, Heat Treatment, Temper, Temper Colours, Temperature.
Subjects: Mechanical Engineering