O-6 is an oil-hardening, graphitic tool steel with outstanding resistance to metal-to-metal sliding wear and galling. The steel contains a uniform dispersion of graphite particles which impart excellent machinability and non-seizing characteristics. The graphite particles make the steel self-lubricating in dry environments, and help to retain oil in lubricated environments.
Analysis:
| C | CO | CR | MN | MO | NI | P | S | SI | V | W | 
| 1.25 - 1.55 | 
  | 0.30 Max. | 0.30 - 1.10 | 0.20 - 0.30 | 
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  | 0.55 - 1.50 | 
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  Size Availability:
Flats • Hollowbar • Metric • Non-Standard • Rounds • Squares • StandardApplications:
| Arbors | Blanking Dies | Bushings | 
| Forming Dies | Forming Rolls | Gauges | 
| Jigs | Machine Parts | Perforating Dies | 
| Piercing Dies | Punches | Spindles | 
| Taps | Trimming Dies | Wear Plates | 
Designations:
ASTM A681-US
FED QQ-T-570-US
SAE J437-US
SAE J438-US
UNS T31506-US
AISI O6 Tool Steel-US
| Treatment | Temperature Range | Cooling/Quenching | Notes | 
| Forging | 1900-2000° F | In air. | Heat slowly to maximum temperature. Do not work below approximately 1500° F. Normalizing is recommended. | 
| Annealing | 1550-1600° F | Cool slowly at a rate of 25° F per hour to 1000° F. | 
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| Stress Relieving | 
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  | Stress relieve after rough machining | 
| Preheating | 1200-1250° F | 
  | Preheat time in furnace is ¾ Hr. per inch of thickness. | 
| Hardening | 1400-1450° F | In warm oil. | A neutral or slightly oxidizing atmosphere is desirable. Temper immediately after hardening. Allow to cool to 125-150° F before tempering. | 
| Tempering | 
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  | Temper for 1 Hr. per inch of thickness with a minimum of 2 Hrs. Recommended temperature is 300-750° F. |