Hello all, As I collect Kingdom of Italy coins, I have encountered the problem that surrounds the 1939 and 1940 stainless steel coins. Standard Catalog of World Coins divide the coins into 'magnetic' and 'non-magnetic' - and the difference in the alloy is in Nickel content. So called 'magnetic' grade does not contain Nickel, but the 'non-magnetic' alloy contains app. 8% Nickel. Ok, sounds fairly easy at the moment. But then I found out that in reality we have (I used regular ferromagnet): 1) strongly magnetic coins - if you place a magnet within few centimeters of the coin, the coin will 'jump' to the magnet. 2) weakly magnetic coins - the 'jump' effect is not there, but you're most likely able to lift the coin from the table with a magnet. 3) partly magnetic coins - the magnetic effect occurs only some part of the coin, I found that some larger 2 lire coins are non-magnetic in the centre, however, weakly magnetic at the edges. 4) non-magnetic coins - no magnetic effect, what so ever. This lead me to think about this matter and I suddenly realized, that there is a possibility that we cannot separate different alloys by using simply magnets!! For example an austenitic stainless steel, which would be non-magnetic in normal state - this can be transformed into magnetic phase, if the piece of steel is formed (striking with coin dies!!!). Also, since Nickel itself is one of the ferromagnetic metals, this also lead me to think that using simply a magnet would not give accurate results. Just to test my suspicions, I have been thinking about XRF analysis, if I can get hold of some handheld unit at my work... Thoughts anyone? -JJ-
Sorry JJH, i have only found myself in the situation of needing to test by magnet once - and that was on a French Indo-China coin. I only had the one coin, and it was non-magnetic, so i wasnt able to test the results as you did. Seeing the results of your tests, i can see the implications. Although it could be the different strngths of the magnetic attraction is nothing mroe then a poor mixing of the metals./
Nickel is strongly magnetic but combined with iron the resultant is often not magetic. It's a complicated world. You can do a lot of things with steel and it will still be magnetic but you can't add much nickel. Even nickel tends to not be magnetic unless it's nearly pure. Bad mixing of the metals can easily result in the things you mention. The 2L is much more interesting and one is left to believe striking the metal caused it to be magnetic. Planchets have the rim raised up in the upsetting mill so there is more metalo to form the rim. Most coins will experience more striking pressure around the periphery than elsewhere despite the fact that this is where poor metal fill first appears. It's the coin between the design elements that recieve this additional pressure and the fact is evidenced by the fact that die wear normally first shows up around the periphery (and design elements). Interestiong post. Thanks for the info.
According to the catalog I use, the "austenitic" type was made using planchets with varying nickel content in the alloy ("Niox"), and is thus weakly magnetic (to a varying extent). The "ferritic" type is made from chrome steel without nickel ("Acmonital") which is strongly magnetic. However, none of the two types is absolutely "non-magnetic", it seems. Christian
