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S7 Tool Steel

 What is S7 Tool Steel?

S7 tool steel is a shock-resistant grade containing high impact properties. Its charpy (a test that measures the impact strength) is over 200 ft-lb. at 400°F temper. As an air-hardening grade, S7 is stable for heat treatment, and its combination of high machinability and dimensional stability makes it ideal for a variety of different tool and die work.

Carbon

0.50

Chromium

3.25

Molybdenum

1.40

Silicon

0.25

Manganese

0.70

 

What Is S7 Tool Steel Used For?

S7 is recommended for applications that require a high level of shock resistance, medium hot-work properties and/or ease of machining. This grade is well suited for a range of hot-shock and cold-shock applications, including rivet sets, chisels, punches moil points, hot headers and gripper dies. Short-run dies used in cold-forming, blanking and bending also use S7.

Heat Treatment

This is the process of heating metal to an elevated temperature to obtain change in properties of metallurgical structure. The heat treatment for S7 is as follows:

Forging

Annealing

Preheating

Hardening

Tempering

1800-2100°F

1500-1600°F

 

1725-1850°F

400-1150°F

 

How do you Temper S7 Tool Steel?

Temper S7 for 1 ½ - 2 hours for each inch of greatest cross-section. Base your tempering temperature on the end use of the metal: 400°F for cold-working and similar applications, and 900°-1000°F for hot-work applications. Tempering at temperatures less than 400°F is not recommended.

What is the Hardness of S7 Tool Steel?

Hardness tests determine the various properties of a specific metal, which includes its resistance to wear, toughness, and formability. Two widely used tests are Rockwell C and Brinell. Rockwell C is measured in the unit HRC, which is the measurement used below. Download our Brinell to Rockwell C hardness conversion chart.

As hardened

400°F

600°F

800°F

1000°F

60-62

58-59

55-56

54-55

53-54


Southern Tool Steel Stocks S7 in the Following:

  • Decarb Free*: S7 – Rounds, Flats, Squares, & Plate
  • Drill rod in standard 36” lengths


*Decarb Free is material that has been ground top and bottom and is oversized to finish on the thickness or diameter. (Thickness or diameter oversize approx +.015 to +.030. Thinner material, less than 1 inch, could have more stock on the thickness. Width oversize approx +.030 to +.090, depending on the vendor.)

 

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