Old steel

[Teisani]

Originally Posted by Raf

2. My understanding is that radiation in steel is introduced in the manufacturing process , either as a consequence of the process itself or contamination from other sources. Steel cannot acquire radiation through being exposed to sources of radiation, accept under exceptional circumstances like being at the epicentre of an atomic bomb blast.

Iron and its alloys, in the molten state, do have a higher solubility for gases like oxygen, hydrogen, nitrogen than in solid state. Hidrogen is actually a big problem for high-strength steels which are susceptible to hydrogen-embrittlement. But the actual amounts entrapped are very small. See here an example in weld seams: https://www.youtube.com/watch?v=bv9ApdzalHM

Of course, other elements prezent in the atmosphere can theoretically be dissolved in the steel, while molten, maybe even radioactive isotopes resulting from man's nuclear activities. But the amounts would be extremely small (I would think much less than 0.001% by mass).

If the radioactivity levels are high enough to be detected, and the isotopes haven't all decayed yet, then I really don't see a problem with this method of dating steels, provided that some old steels were not made from iron ore rich in radioactive isotopes that would give false readings.