The oil itself must be preheated to work effectively. Cold oil is more viscous and may cool the metal too slowly or unevenly. Heat Treating Knives : 7 Steps - Instructables
For oil quenching a knife blade, the steel must typically be heated to its , which generally falls between 1,400°F and 1,650°F depending on the specific alloy. A common practical method is to heat the blade until it becomes non-magnetic and then continue heating it for a brief period—often just a few shades brighter in color—to ensure it has fully transitioned to the austenite phase before rapidly plunging it into the oil. Heating the Steel (Austenitizing) The oil itself must be preheated to work effectively
: Many blacksmiths look for an even dull cherry red to bright orange color. A common practical method is to heat the