Old steel

Teisani · 11th June 2023, 09:12 AM

Quote:

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.

Triarii · 12th June 2023, 10:57 AM

Not my field but air is used (drawn in for Bessamer process steel or processed air used for more modern steelmaking) and that will contain minute traces of radionucliedes.

This is a reason that sunken pre WW2 era ships are especially attractive, apart from the obvious scrap value. Known as 'low background steel'. Parts of the scuttled WW1 German fleet at Scapa Flow has been used for this.

It's useful for tools that need to sense minute traces of radioactive material and for MRI scanners.

Jim McDougall · 12th June 2023, 01:32 PM

This is all fascinating, however I think the original premise here had to do with 'all' ? post WWII steel having minute presence of radioactivity due to circulating radioactive material from testing of A bombs.

The suggestion was that this radioactivity remained airborne and would be absorbed in the processing of steel so by testing sword blades it could be determined if they were indeed antique or modern reproduction.

It is understandable that radioactivity is naturally present not only obviously in uranium or certain other minerals in degree, but here the idea remains that contamination could come from trace radiation in the air.

12th June 2023, 10:57 AM	#2
Triarii Member Join Date: Oct 2021 Location: Bristol Posts: 122	Not my field but air is used (drawn in for Bessamer process steel or processed air used for more modern steelmaking) and that will contain minute traces of radionucliedes. This is a reason that sunken pre WW2 era ships are especially attractive, apart from the obvious scrap value. Known as 'low background steel'. Parts of the scuttled WW1 German fleet at Scapa Flow has been used for this. It's useful for tools that need to sense minute traces of radioactive material and for MRI scanners.

12th June 2023, 01:32 PM	#3
Jim McDougall Arms Historian Join Date: Dec 2004 Location: Route 66 Posts: 10,281	This is all fascinating, however I think the original premise here had to do with 'all' ? post WWII steel having minute presence of radioactivity due to circulating radioactive material from testing of A bombs. The suggestion was that this radioactivity remained airborne and would be absorbed in the processing of steel so by testing sword blades it could be determined if they were indeed antique or modern reproduction. It is understandable that radioactivity is naturally present not only obviously in uranium or certain other minerals in degree, but here the idea remains that contamination could come from trace radiation in the air.