I have a piece of railroad rail that I may use for making a little homemade anvil (just a fun project with scrap materials such as that rail and 4140 bars). That rail is a light gauge rail, maybe from a tram line or a factory railroad, I am not sure.
To weld on a 4140 bar, I suppose, it is best to flatten the rail's top.
Since it may be work hardened (I suppose I could check that with a regular file), I suppose that it would be wise to anneal it, by, say, putting it in a decent wood fire and then, once it gets hot, into sand such as that on my kids' playground.
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