As far as I know RPatel, you need to buy some books. A 10th edition of the UNS handbook and one of the good spec cross index.
Of course, nothing beats owning the ASTM specs that you are working with.
I recall that ASTM A848 is for pure magnet iron. I don't have a copy since I don't use it any more. There is a UNS for commercially pure iron, K00095. Thisi s basically 99.5% with Cu being the major impurity. There are also a number of steels with special magetic properties, K00600, K00800, K01000 (the number is the carbon level with K00600 = 0.06 max C). I don't know of any ASTM specs that ref these UNS values.
I am trying to recall, but I think that Armco A was 99.5%, as the C goes down you get high O2 and such. There are vacuum melted irons out there that are 99.95%.
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Corrosion, every where, all the time.
Manage it or it will manage you.