Forging Tool Steel

Working with Tool Steel

When forging a high carbon or tool steel it is important to know the specific requirements of each type of steel.
Following the information supplied by the mill or steel distributor should help reduce problems.

1) Plan your forging process carefully to minimize the number of heats required. Each time that you heat the steel you lose a bit of carbon and decrease the usefulness of the steel.
2) Most tool steels must be allowed be heated slowly to the forging heat. This slow climb in temperature is generally referred to as “soaking”. In the Forgemaster TM forge soaking is easily accomplished. Bring the forge up to a strong heat (run the forge at 10-12 psi for about 5 minutes), place the tool steel into the heating chamber and heat the steel for about 30-40 seconds. Shut the forge off and leave the door closed, allowing the steel to soak up the heat of the forge without the added oxidation of the forge blast. When the steel becomes the same color as the heated forge re-ignite the forge and raise the steel to forging temperatures (usually between 1850 and 2000 degrees F).
3) Always forge the steel within the recommended heat range. Never forge tool steel at a heat below orange. Never heat tool steel above a bright lemon. Forging above or below the proper heat range may stress the steel and render it unusable.
4) Many tool steels require a “normalizing” following forging. Normalizing means that you bring the steel back to the forging temperature, and allow it to cool slowly at room temperature. NOTE:Air hardening steels cannot be normalized in this manner.

Carbon Steel Guide for Blacksmithing

AISI #Carbon contentTypical ApplicationsForging Heat RangeHeat Treating Method
O-1.90Taps, punches, dies1850-1950 F. Stop at 1500. Normalize.Oil quench
A-21.00Trimming Dies, Shear Blades, Punch Plates2000-2050 F. Stop at 1700 F. Normalize.Oil quench
D-21.55Blanking Dies, Bushings, Shear Blades, Burnishing Tools1950-2050 F. Stop at 1700 F. Do not Normalize.Oil quench
S-1.50Heading Dies, Hot forming dies, Chisels2000-2100 F. Stop at 1660 F. Normalize.Oil quench preferred, but larger sections may be water quenched
S-3.40-.50Chain link, Riveting, Caulking dies, Heading dies, Stone points, Trip Hammer Anvils1700-1900 F. Stop at 1500 F. NormalizeOil quench
S-7.45-.55Bending Dies, Hot Heading tools, Rivet Sets and Busters, PunchesPreheat 1200-1300 F. Raise to 2000-2050 F. Stop at 1700 F. Do Not Normalize.Air quench
4140.36-.50Jigs, molds, fixtures, holding blocksPreheat 1200-1300 F. Raise to 1850-2050 F. Stop at 1500 F. Normalize.Oil quench
6150.43-.48Gears, Shafts, Spindles1950-2250 F. Stop at 1800 F. Normalize.Oil quench