S7 Tool Steel Round Bar Sheet Plate Material

AISI S7 tool steel be made of chromium-molybdenum alloy to satisfy the needs of high impact toughness. The chemical composition of Cr is quite high. So it has good tempering resistance, high-temperature oxidation, wire-electrode cutting property and impact toughness. After annealing softening treatment, the rolling steel bar must take the process of heating before the use. Because of the higher toughness and high-temperature oxidation, S7 steel material is widely used in the plastic mold, cold work and hot work tools that working in the high temperature and impact condition.

S7 Tool Steel Round Bar Sheet Plate Supply Range
Round BarDiameter:8-1000mm; Length: Can be customized
Other specifications can be customized.
Black Surface/Bright Surface /Grinded/Peeled/Turned
As per given requirements
Sheet/Plate/SlabThickness: 2-600mm; Width: 200–2200mm;
Length: Can be customized.
Other sizes of S7 steel per customer's requirements.
Black Surface/Bright Surface /Grinded/Peeled/Turned
As per given requirements

S7 Steel Grade Equivalent Chart

StandardASTM A681DIN EN ISO 4957

S7 Steel Chemical Composition

GradeC (%)Mn (%)P (%)S (%)Si (%)Cr (%)V (%)Mo (%)

AISI S7 Steel Physical Properties

Physical Properties
Elastic Modulus207GPa
Density7.83 g/cm³
Thermal ConductivityW/m- °K
at 95°C28.5
Thermal Properties
Critical Temperature800°C
CTE, linear 20°C12.59µm/m- °C
CTE, linear 250°C13.33µm/m- °C
CTE,linear 500°C14.27µm/m- °C
Transformation Temperature785 °C

S7 Tool Steel Mechanical Properties

Mechanical PropertiesMetric
Hardness, Rockwell C (air cooled from 941°C, 649°C temper temperature) 41
Hardness, Rockwell C (air cooled from 941°C, 449°C temper temperature) 53
Hardness, Rockwell C (air cooled from 941°C, 149°C temper temperature)57
Modulus of elasticity207 GPa
Charpy impact (V-notch; air cooled from 941°C; 425°C temper temperature) 13.6 J
Charpy impact (V-notch; air cooled from 941°C; 649°C temper temperature)16.3 J
Charpy impact (V-notch; air cooled from 941°C; 200°C temper temperature) 16.9 J
Machinability (1% carbon steel)70.0 – 75.0%
Poisson's ratio0.27-0.30

S7 Steel Application

What Is S7 Steel Used for?

  1. Punch
  2. Forging Die
  3. Hammer
  4. Chisel
  5. Cutting Tools
  6. Small Plastic Molds
  7. Gripper Dies
  8. Swaging Dies
  9. Shear Blades
  10. Hot Work and Cold Work Mold
  11. Blanking Dies
  12. Drills
  13. Drill Plates

S7 Steel Round Bar Sheet Plate Heat Treatment

Start by quickly heating to 1500 to 1550°F and hold at that temperature for an hour and a half. It is then slowly cooled to 1000°F followed by air cooling, this is for optimum processability. This annealing procedure should produce a maximum Brinell hardness of 197.

Stress Relief S7 Steel Material: When required to relieve machining strain, heat slowly to 1050°-1250°F, allow to equalize, then cool in air.

Preheating: Before hardening, S7 steel is heated slightly before being loaded into a preheat furnace at 1200°-1300°F.
Hardening: 1750°F. Air quench if cross section is 2-1/2″ or smaller; 2-1/2″ through 6″ sections should be oil quenched to black (1000°F) then air cooled to 150°F. Larger Cross-sections of S7 steel shall be oil quenched to 150°F.

Quenching in still or dry air.

Tool steel S7 is typically tempered for one hour per inch of section thickness to achieve the required heating rate of 2 hours per inch. Cool in air to room temperature between states. Tempering temperatures vary according to intended use. Recommended: 400°-500°F for cold work applications. Thermal processing applications from 900°-1000°F.

First preheat to 1200°-1300°F, forge at 2000°-2050°F, then stop at 1700°F and cool slowly.

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