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Re: [Phys-L] Blue color heated steel

Roberto,The standard reason given  for example at Wikipedia the progressive accumulation of a thin translucent surface oxide layer  on carbon steel when reheated after quenching in an oxidising atmosphere. This provides  color by interferometric means.
A moment's consideration will suggest however, that a layer of increasing thickness provides light reinforcement at progressively lower frequencies , rather than blue representing a spring temper requiring a higher temperature andpresumably thicker oxide layer. The answer may lie in the growth of microcrystalline structure of a particular kind with heat, but I did not quickly find a sensible reference.

On Monday, October 4, 2021, 09:26:11 AM CDT, M R Carabajal via Phys-l <> wrote:


I would greatly appreciate a bibliographic indication on the subject of
heating steel. I have not been able to find a clear explanation of the
reason for the blue color, that steel presents when heated to about 600
Kelvin. That is, to substantiate the deviations of the blackbody heating

Thanks very much for your attention.


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