Approximate Temperature of Steel by Colour

Colour of Metal Degrees C Degrees F
Feint Straw 200 390
Very Faint Yellow 210 410
Light Yellow 220 430
Pale Straw Yellow 230 445
Golden Yellow/Dark Straw 240 465
Dark Yellow Brown 250 480
Brown Yellow/Purple 260 500
Brown Purple 270 520
Dark Purple 285 545
Full Blue 290 555
Dark Blue 300 570
Very Dark Blue 315 600
Greyish Blue 330 625
Dark Grey 427 800
Black Red/Red-grey 537 1000
Brown Red 600 1110
Blood Red 650 1200
Dark Cherry Red 715 1320
Medium Cherry Red 770 1420
Full Cherry Red 815 1500
Bright Orange Red 843 1550
Light Red 875 1610
Orange 930 1705
Orange Yellow 990 1815
Dark yellow 1050 1920
Bright Yellow 1093 2000
Light Yellow 1100 2010
White 1200 2190
Beginning to sparkle 1400 2550
Melting N/A 1500 2730

 

Steel exhibits different colours depending on temperature.
Temperatures below 800°F (427°C) produce oxidation colours.
Temperatures above 800°F (427°C) produce incandescent colours

As the steel is heated, an oxide layer forms on the surface; its thickness (and thus the interference colour as light is reflected) is a function of temperature. These colours may be used in determining the temperature of the steel, when for example tempering tool steel.

The melting point of mild steel (0.1%~0.2% Carbon) is approximately 1500°C (2730°F), and a bit higher for the various alloy steels. The MP of these steels depends on the composition and quantity of the alloying metal.