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.

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