I think you will find that it is impossible to cast a file texture surface in steel. Files are cut to that form; actually it is a cutting and deforming process.
It is possible that you could get what you are asking for by a powder metallurgy process which can provide very fine detail but your volumes would need to be very high and the upfront cost for the sintering dies might be very high assuming it is possible to do that size of part.
If you have to have actual file teeth in hard steel so they can cut like a file I think the file cutting process will be needed. If you just need a textured surface I expect the best approach could be looking at some form of knurling process either hot or cold.
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