As for the high silicon content, isn't it possible that the artifact had been contaminated by the sand at the bottom of the pond, which has aggregated with it? You mentioned that the scan was surface scan only.
I had the same thought, but apparently not. We have a 1975 breakdown (see below) of the elements in Gull Pond (referred to by its topographic map name Goose Pond).
Interestingly, there is no naturally-occurring:
• Silicon
• Vanadium
• Titanium
• Tin
• Phosphorpus
Alll of which were detected in the XRF scans of the artifact. The titanium (like the cobalt and lead) is probably from the paint. The silicon and vanadium are apparently part of the alloy. The little bit of copper could be from a tiny pocket of sediment. There shouldn't be any phosphorous in alloyed steel so it's probably an impurity. Ditto for the trace of tin.
If I’m right, the base metal is steel alloyed with manganese, molybdenum, chromium, silicon, zinc, and vanadium. That’s a complex, very high-quality “special steel’”.
I couldn't find any mention of L2R among French forges in 1918... But if Levasseur uses it in 1929, it's because it's an established standard, and probably a widespread one.
Agreed.
The 'R' reference could be the metal treatment. Perhaps a reference to the French term 'recuit' which is a heat-tratment of the laminated steel (beteween 500 and 800 °C) to restore his original mécanical properties.
That would make sense.