Tool Steel O1

Grade Summary: O1 Tool Steel is a general purpose oil-hardening tool and die steel. Normal care in heat treatment gives good results in hardening and produces small dimensional changes. O1 has good abrasion resistance and sufficient toughness for a wide variety of tool and die applications. When properly annealed, O1 has a machinability rating of 90 when compared to a 1% Carbon Steel rated at 100. When oil quenched from the proper hardening temperature, this grade can be expected to expand approximately .0015 in. per in. Note: Distortion (bending, bowing and twisting) and part geometry can add to the variations in movement of a part being hardened.

Thermal Cycling: In order to avoid decarburization, this grade should be annealed and/or hardened in a controlled neutral atmosphere, vacuum, or neutral salt furnace.

1. Anneal: Heat slowly to 1450° F, soak thoroughly. Cool 25° F per hour to 900° F. Air cool to room temperature. Approximate annealed hardness, 221 Maximum Brinell.

2. Stress Relief of Unhardened Material: Heat slowly to 1250° F. Soak for two hours per inch of thickness at heat. Slow cool (furnace cool if possible) to room temperature.

3. Hardening:

  • Preheat: Heat to 1200° F, and hold at this temperature until thoroughly soaked.
  • Hardening: Heat to 1475° to 1500° F. Soak at heat for 30 minutes per inch of thickness.
  • Quench: Oil quench to 150° to 200° F. Temper immediately.
  • Temper: Normally oil hardening steels need to be single tempered only. However, double tempering may sometimes be preferred. Soak at heat for 2 hours per inch of thickness for each temper. Air cool to room temperature between tempers. The normal tempering range for this grade is 300o to 450° F.

1” diameter specimens, oil quenched from 1475° F.

4. Stress Relief Temper: A stress relief temper for hardened material is strongly recommended after significant grinding, or welding, or EDM. Select a temperature that is 25° or 50° F lower than the last tempering temperature used.

Typical Applications: See – Tool Steel Selector Guide (Above)

Available products: Round Bar, Drill Rod and Ground Flat Bar.

Typical Chemical Analysis: * C – .90 *Mn – 1.20 *W – .50 *Si – .25 *Cr – .50 *V – .20

* Chemical Analysis will vary.

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