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S7

Download S7 Spec sheet

ExELL S-7 SMDQ was developed by Ellwood Specialty Steel as a premium tooling quality chromium-molybdenum alloy tool steel for die and mold applications.

ExEll S-7 SMDQ is characterized by:

  • Excellent cleanliness
  • Very good honogeniety
  • High toughness
  • Good impact and wear resistance
  • Very good polishability
  • Good flame and through hardening properties
  • Good dimensional stability during hardening

 

Typical Analysis
C 0.50 Mn 0.70
Si 0.30 Cr 3.25
S 0.005max Mo 1.50

APPLICATIONS

ExELL S-7 SMDQ is very suitable for heavy duty blanking and forming tools because of the good combination of toughness and wear resistance. Typical applications include upgraded tooling for stamping, blanking, punching, cropping, shearing, trimming, cold compacting, heading and other forming tools.

With the very good cleanliness and homogenous structure, ExELL S-7 SMDQ is an excellent choice for plastic mold applications. ExELL S-7 SMDQ is regularly used for high quality plastic injection, compression and transfer molds.

CHARACTERISTICS

Physical Properties

Coefficient of Thermal Expansion, in/in/F

400 F………0.0000069

Thermal Conductivity, BTU in/ft2 hr F

70 F………201

400 F………210

Density, lbs/cu.in.

70F……….0.2833

Modulus of Elasticity, psi

70F………29,000,000

400F………28,000,000

Specific Heat, Btu/lbF

70F………0.11

Critical Temperatures

Ac3………1500F

Ac1………1360F

Ms………425F

HEAT TREATMENT (General Recommendations)

Surface Treatments

If a locally higher hardness is required, ExELL S-7 SMDQ lends itself readily to flame or induction hardening to 58-60 (air cooling. Surfaces of ExELL S-7 SMDQ can also be easily chrome plated or nitrided with typical or standard methods.

Stress Relieving

To minimize movement during heat treatment, a stress relieve can be used between the rough and finish machine opera0ons of tool making before heat treatment. After rough machining, heat treat the part(s) to equalize and hold 1 – 2 hours. Furnace cool to 900F and then air cool.

Annealing

With a protective atmosphere or vacuum furnace, heat slowly to 1530F. Equalize and hold on hour per inch of thickness. Furnace cool 20F/hr to 1000F and equalize. Air cool to room temperature.
Hardness – 217 HB max.

TOOLMAKING

For any additional information including flame hardening, welding, machining, grinding, EDM processing, nitriding, or polishing, please contact Ellwood Specialty Steel direct at 800-932-2188.

Hardening and Quenching

Preheating: Heat to 1200-1250F and equalize. Continue heating to hardening temperature.

Hardening: Protect against oxidation and decarburization. Austentizing (hardening) temperature range is 1690-1780F but hardening is usually at 1725F.
Typical response is:

 

Hardening Temperature Hold Time* As-Quenched Hardness

1700F60 Min.56-60 HRC1725F45 min.57-61 HRC1750F30 min.57-61 HRC

*Hold time = time at temperature after tool is fully heated through.

Quenching: Typical quenching media include:

  • Circulating air or atmosphere
  • Forced air or gas
  • Step quench
  • Oil (large cross sections)

Temper as soon as quenching temperature reaches 120 – 150F.

Tempering

Temper immediately after quenching to about 150F. Temper two times with intermediate cooling to room temperature.

ExELL S-7 SMDQ should be heated to the desired tempering temperature (40F minimum) and held a minimum of two hours. Select the tempering temperature based on required hardness (tempering between 700-800F should be avoided to avoid temper embrittlement). Air cool to room temperature. Check hardness and adjust temperature for additional tempering opera0ons. Repeat for second temper.

Typical tempering temperature responses follow. (Use for approximate guideline only)

 

Hardening Temperature Hardness HRC

400F58480F55930F521025F491100FF44

MECHANICAL PROPERTIES

Approximate compressive strength versus hardness at room temperature:

 

Hardness HRC Compressive Yield Strength

58300,000 psi

55295,000 psi50240,000 psi45200,000 psi40160,000 psi35120,000 psi

Typical impact strengths at room temperature versus tempering temperature are:

 

Tempering Temperature Impact Strength Charpy KCU ft lb
400F 8.5
480F 10.0
750F 6.0
930F 8.0
1025F 10.0

CAPABILITIES

Ellwood Specialty Steel is a fully integrated producer of a wide range of specialty tool steels. Our ExELL grades are made with the advanced ASEA-SKF steel making capabilities which include an ultra high powered electric arc furnace with subsequent state of the art ladle refining and vacuum degassing equipment for the most complete and modern ladle metallurgy technology.

Our steel making expertise and capability is further enhanced from a long forging history with op0mum forging and heat treating practices to develop very special material characteristics of product uniformity, cleanliness, machinability, polishability, strength, toughness, hardenability and other steel properties. All this from production facilities certified to ISO 9002.

QUALITY ASSURANCE

Ellwood Specialty Steel is committed to providing products and services which will consistently meet or exceed all quality and performance expectations. We will provide customer and technical service that will ensure complete satisfaction

Being a very flexible provider, Ellwood Specialty Steel will establish product programs to fully support industry or customer requirements. Our extensive stock programs are supported by very short mill lead times of custom forged products. Customized stock programs are and can be available for specific customer needs.

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