*Always consult your Heat Treater*
      *Information Provided is General*


O-6 is an oil hardening, non-deforming type tool steel for use on tool and die applications requiring good resistance to wear and abrasion. Uniformly distributed graphite particles in O-6 provide it with remarkable machinability. Since graphite pockets retain lubricant, O-6 tool steel is of particular advantage for tools requiring non-seizing properties. O-6 especially is suitable for dies and punches in drawing, forming and shaping operations, which take advantage of its outstanding self-lubricating characteristics.

Heat slowly to 1450 – 1500°F, soak at temperature until thoroughly and uniformly heated, then quench into warm oil. Pieces ½ inch in thickness and smaller should be austenitized at 1450°F, pieces ½ to 2 inches in thickness at 1475°F and pieces over 2 inches at 1500°F. Remove pieces from quenching oil for tempering immediately after reaching 125 – 150°F to avoid stress cracking. Best results are obtained by austenitizing in controlled atmosphere or vacuum furnaces or neutral salt baths.

O-6 should be tempered immediately after the quench is completed. Most tools and other parts are tempered at 300-400° F for maximum hardness response although the temperature might vary for some special applications. Actual hardness obtained will depend on section size since it affects the quenching rate in hardening.

Hardening happens between 1450 – 1500°F.

O-6 is an oversized material.


  • + .015 up to .040 on thickness

  • + .080 up to .125 on width


  • Up to 1″ + .007 up to .0181

  • 1” up to 6″ + .015 up to .0406

  • 6” and up + .0625 up to .250

 Hardening Temp.:    145 through 1500°F

 Quench Medium:     Oil

 Tempering Range:    300 through 400°F

 Typical Hardness Level:    59 to 61 R/C

 Preheat Forging Temp.:    1400 through 1500°F

 Forging Temp:    1900 through 1950°F

 Anneal Temp.:     1450°F

 Anneal Cooling Method:     Furnace cool at 10 – 15°F per hr. max. to 1000°F or less, then air cool

Anneal Hardness:   229 BHN

 O-6 Material in Stock

 Color Code:    GREEN

 Flat Dimensions

  • 7/8″ x 3 1/2″ up to 1 1/2″ x 1 1/2″

  • Non-standard sizes, quoted upon request

 Round Dimensions

  • 1/2″ up to 10″

  • Non-standard sizes quoted upon request.

 O-6 Typical Analysis









 · Slight variations from typical analysis shown may occur in order to  maintain the desired graphitizing potential.