Colour of inox steel surface upon heating

[lightarrow]

If you heat inox steel in presence of air, up to a specific temperature, you get a yellow colour of the metal surface; increasing the temperature it becomes red; still increasing, blue.
Is it due to the formation of oxide layers of different thickness? Which effect is responsible of the colour?

[Astronuc]

If you heat inox steel in presence of air, up to a specific temperature, you get a yellow colour of the metal surface; increasing the temperature it becomes red; still increasing, blue.
Is it due to the formation of oxide layers of different thickness? Which effect is responsible of the colour? Thickness (number of layers) of the oxide is the key factor. Different thicknesses produce different scattering or interference.

http://www.bssa.org.uk/topics.php?article=140

http://www.tpub.com/steelworker1/11.htm

[lightarrow]

Thickness (number of layers) of the oxide is the key factor. Different thicknesses produce different scattering or interference.

http://www.bssa.org.uk/topics.php?article=140

http://www.tpub.com/steelworker1/11.htm

Thank you Astronuc.

If the interference is responsible of the phenomenon, why the colour doesn't change with the angle of observation?