At a complete guess I would go for 24 tpi and bi metal, but I am reading 14 to 18tpi. What in all of your's experience has been best for cutting high carbon steel on a horizontal bandsaw? Thanks.
It firstly depends on the thickness. Atleast 3 teeth in the metal.
HSS cobalt blades will give the best life.
The smaller bandsaws dont like low TPI blades as the bend radius is too sharp, they can still cut thick stuff with higher TPI blades but its not ideal. Low TPI blades will snap if the bends too sharp.
High carbon generally machines and cuts nicer but is it hardened? Even so, it will likely cut ok.