This handy little book I have found to be very useful.
It may not be a blacksmith book but I think it is a lot of help to anyone working with steel.
In its is imformation for threads, hole fits, harderning & tempering steel, properties for different types of steel.
EMI Supply : Engineers Black Book - USA Edition - The engineers quick reference manual [EBB-USA] - $29.99
This is a link for some more imformation. Imformation in it is easy to find.