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The OnlineMetals Guide to Tool Steel
The term Tool Steel is a generic description of steel which has been developed specifically for tooling applications. Generally speaking, Tool Steels are known for their distinctive toughness, resistance to abrasion, their ability to hold a cutting edge, and/or their resistance to deformation at elevated temperatures (red-hardness). Some of the operations that tool steels are used in include Drawing, Blanking, Mold Inserts, Stamping, Metal Slitting, Forming and Embossing, although they are not limited to just those areas.
Tool Steels are produced in the annealed condition for ease of machining. After machining, the steel is heat-treated and quenched depending upon the type of steel being used. The heat treating and quenching operations increase the toughness and strength of the material.
There are three classes of tool steel generally available in the market today - cold work, hot work, and high speed steel:
- Cold Work steels have high strength, hardenability, impact toughness, and wear resistance. As the name would imply, they are used in environments with lower operating temperatures, typically at 400° or less. The materials that we carry that fall into the Cold Work category are O1, A2, D2, S7 and W1.
- Hot work steels have many of the same properties of cold working steels, with the added advantage that that those properties are retained at elevated operating temperatures where the tool literally becomes red-hot.
- High speed steels have all of the properties listed above, but retain those properties in operating areas where the temperatures exceed 1000° F.
Tolerances of Tool Steel
Drill Rod Tolerances
| Diameter |
Diameter Tolerance |
Straightness |
Length Tolerance |
| .124” and less |
+/- .0003” |
.005” |
+1/8”, -.0” |
| .499“ to .125” |
+/- .0005” |
.005” |
+1/8”, -.0” |
| 3.000” to .500” |
+/- .0010” |
.005” |
+1/8”, -.0” |
Ground Flat Stock Tolerance
| Thickness |
Width |
Length 18” |
Length 36" |
Squareness Edge |
Squareness End |
| +/-.001” |
+.000/.005 |
+.125/.250” |
+.250/.500” |
.003”/in. |
.004” /in. |
Oversize Flat Stock Tolerance
| Thickness |
Width |
Length 18” |
Length 36" |
Squareness Edge |
Squareness End |
| +.010/.015” |
+.000/.005 |
+.125/.250” |
+.250/.500” |
.003”/in. |
.004” /in. |
Square Bar Tolerances
| Ground Stock |
Oversized |
Length 18” |
Length 36" |
Squareness Edge |
Squareness End |
| +/-.001” |
+.010/.015” |
+.125/.250” |
+.250/.500” |
.003” per inch |
.004” per inch |
The basic properties of the tool steel carried by OnlineMetals.com are listed below:
| W-1 Tool Steel |
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Heat treat temperature |
1450-1600 F |
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Quench |
Water or Brine |
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Hardness as shipped
After Heat Treating
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Rockwell 91b
Rockwell 56c
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Applications |
Blacksmith tools
Cold Chisels
Hand punches
Cold Forming Tools
Knives
Scissors and Shears
Razors
Woodworking Chisels |
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Disadvantages |
Water hardening tool steels tend to experience significant distortion during the quench operation. In addition, the hardening operation applies only to the outer "case" of the material, rather than being "through-hardened". |
| O-1 Tool Steel |
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Heat treat temperature |
1450-1600 F |
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Quench |
Oil |
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Hardness as shipped
After Heat Treating
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Rockwell 88-95b
Rockwell 62c-64c
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Applications |
Taps
Reamers
Knurling Tools
Shear Blades
Drills
Coining Dies
Trimming Dies |
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Disadvantages |
Oil hardening tool steels tend to experience less distortion during the quench operation, but they do still show distortion from the original size. The hardening operation is more thorough than with water hardening steels, but not as thorough as the air-hardening grades. |
| A-2 Tool Steel |
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Heat treat temperature |
1700-1900 F |
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Quench |
Air |
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Hardness as shipped
After Heat Treating
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Rockwell 94-99b
Rockwell 59c-62c
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Applications |
A2 can be used in the same applications as both O1 and W1, but the heat-treated air-hardening steels have deeper hardenability and there is less movement or distortion during heat treatment. |
| S-7 Tool Steel |
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Heat treat temperature |
1725-1750 F |
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Quench |
Air or Oil |
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Hardness as shipped
After Heat Treating
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Rockwell 90-97b
Rockwell 55c-57c
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Applications |
S7 is good for general tooling and molding applications. It possesses high toughness and shock resistance. |
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Disadvantages |
While S7 is very tough compared to other tool steels, it doesn't have hardness comparable to the other tool steels. |
| D-2 Tool Steel |
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Heat treat temperature |
1600-1650 F |
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Quench |
Air or Oil |
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Hardness as shipped
After Heat Treating
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Rockwell 97-102b
Rockwell 60c-62c
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Applications |
D2 has high wear resistance, good toughness, and low distortion. It is often chosen when long tool life is required. |
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