| Analysis | Applications | Heat Treating | Tolerances | Speedy Metals items |
O1 tool steel is a low alloy cold work tool steel that must be oil-quenched in heat treatment. O1 contains small amounts of manganese, tungsten, and chromium, giving O1 adequate toughness for normal tool & die uses. O1 has deep hardening properties with fine grain structure with unusual toughness. O1 has good response to heat treatment with small dimensional changes. Sizes over approximately 2 inches thick or round may exhibit a lower hardness in the interior. O1 tool steel is available in standard de-carb free rounds, flats and squares, as well as the largest size selection in ground flat stock and drill rod of all the tool steel grades.
| Carbon (C) | Manganese (Mn) | Silicon (Si) | Chromium (Cr) | Tungsten (W) | Vanadium (V) | Phosphorus (P) Max | Sulfur (S) Max |
| 0.95 | 1.2 | 0.4 | 0.5 | 0.5 | 0.2 | 0.03 | 0.03 |
A.I.S.I. O1 conforms to ASTM A681, DIN 1.2510, SAE J437, J438
Typical applications for O1 tool steel are blanking, forming, and trim dies, gages, slitting cutters, punches, bolster dies, knock-out pins, thread roll dies, bending dies, plastic mold dies, shims, cams, machine ways, stamps, machine parts, jigs, cutter templates, swaging dies, etc.
FORGING
Heating for forging must be done slowly and uniformly. Soak through at 1800°-1900°F and reheat as often as necessary, stopping work when the temperature drops below 1600°F. After forging, cool slowly in lime, mica, dry ashes or furnace. O-1 should always be annealed after forging.
ANNEALING
Heat slowly to 1400°-1450°F, hold until entire mass is heated through, and cool slowly in the furnace (40F per hour) to about 1000°F, after which cooling rate may be increased. Suitable precautions must be taken to prevent excessive carburization or decarburization.
STRESS RELIEVING
When desirable to relieve the strains of machining, heat slowly to 1050°-1250°F, allow to equalize, and then cool in still air (Strain Relieving).
PREHEAT PRIOR TO HARDENING
Warm slightly before charging into the preheat furnace, which should be operating at about 1100°-1200°F.
HARDENING
After thorough preheating, transfer to the hardening furnace, operating from 1450°-1500°F, depending on the size of the part.
QUENCHING
Quench in warm oil and allow to cool in the oil until a temperature of 125°-150°F has been reached, or to where the part can be held in the bare hand, and temper immediately.
TEMPERING
O1 is generally tempered in the range of 300°-600°F. Tempering temperatures and resulting Rockwell C hardness, based on a 1 inch round samples oil quenched from 1475°F and tempered for 2 hours, are as follows:
| Tempering Temperature F | Rockwell C |
| 300 | 65 |
| 350 | 63 |
| 400 | 62.5 |
| 450 | 61 |
| 500 | 60 |
| 600 | 57 |
O1 de-carb free rounds are produced .015-.035 oversize. O1 de-carb free flats and squares are produced .015-.035 oversize on thickness, and widths are milled or cut oversize sufficiently to clean to nominal size.
O1 ground flat stock, produced in standard 18" and 36" lengths, is available in standard precision ground (+/-.001" on thickness, +.005/-.000" on width), and oversize ground (+.010/+.015 on thickness and width).
O1 drill rod (36" long standard length and 144" available) tolerances on diameter are as follows:
.124" rd and less (+/-.0003")
.125" to .499" rd (+/- .0005")
.500 to 2" rd (+/-.001")