Not sure if this is fixable, but it'd be nice if you unlock it alongside the Double Steel Furnace since that's what you need to craft it. Currently, it unlocks with Steel Processing - meaning you just have a useless recipe until you get the mod's research, which is a bit annoying.

Taking a look the furnace recipes unlock when they should.

The Double Iron recipe they use is actually unlocked from the very start of the game.
When i have some free time I could probably get this to unlock with the Double Steel Furnace

I've just do a PR to update for 2.1 and have included the change for the double iron recipe at the same time.