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.