Colour of inox steel surface upon heating

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SUMMARY

Heating inox steel in the presence of air results in a color change of the metal surface due to the formation of oxide layers. At specific temperatures, the surface exhibits a yellow color, which transitions to red and then blue as the temperature increases. The key factor influencing these colors is the thickness of the oxide layers, which affects light scattering and interference. This phenomenon is not influenced by the angle of observation, indicating a consistent interference effect.

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  • Understanding of oxide layer formation on metals
  • Knowledge of light scattering and interference principles
  • Familiarity with temperature effects on material properties
  • Basic metallurgy concepts related to inox steel
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Metallurgists, materials scientists, engineers, and anyone interested in the thermal properties and surface treatments of inox steel.

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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?
 
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lightarrow said:
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
 
Astronuc said:
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?
 

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