Low-alloy low-hydrogen types.

These are kinds of steel where one or more alloying elements are intentionally added to improve their characteristics to improve their mechanical strength, corrosion and abrasion resistance and that also contain small amounts of manganese, silicon, sulphur and phosphorus.

They are hardenable or self-hardening. The main elements are Mn, Cr and Mo. Those alloying elements influence the hardenability of steel. Because of that, the equivalent carbon must be added.