Ferrotitanium is a ferroalloy, an alloy of iron an titanium with between 10-20..45-75 % titanium and sometimes a small amount of carbon. It is used in steelmaking as a cleansing agent for iron and steel; the titanium is highly reactive with sulfur, carbon, oxygen, and nitrogen, forming insoluble compounds and sequestering them in slag, and is therefore used for deoxidizing, and sometimes for desulfurization and denitrification. In steelmaking the addition of titanium yields metal with finer grain structure.