Deluxe Tool Steel & Alloy Plates
S-7 Standard
Shock Resistant Tool Steel
Precision Marshall’s S7 Standard is a premium shock resistant tool steel which provides a unique combination
of machinability, exceptional toughness, ease of heat treatment and minimum distortion. Special melting and
refining practices are utilized to produce a uniform product with high cleanliness and minimum segregation. The material is tested to rigorous tool steel standards to ensure uniformity of structure and freedom from defects.
Meets ASTM-A681.
Attributes
EDM
Electro-discharge machining is used in the production of various tooling. This process produces recast, rehardened and retempered layers on the EDM surface. It is recommended that S-7 Standard be stress relieved at 50ºF below the final tool tempering temperature, after the EDM process, to temper the rehardened layer produced by EDM.Condition
S7 Standard is supplied fully spheroidize annealed and decarb free.Finish
Oversize to typical rms 50/75, maximum 125.Sizing
Available in standard thickness increments 1/2″ thru 8″Chemistry
| ELEMENT | RANGE | AIM |
|---|---|---|
| Carbon | .48/.55 | .50 |
| Manganese | .60/.80 | .70 |
| Phosphorus | .010 max | .005 |
| Sulfur | .002 max | .005 |
| Chromium | 3.10/3.50 | 3.30 |
| Molybdenum | 1.30/1.55 | 1.35 |
| Silicon | .20/1.00 | .50 |
| Vanadium | .20/.30 | .25 |
| Nickel | .40 max | – |
| Copper | .25 max | – |
| Tungsten | .30 max | – |
Additional Information
Applications
S7 Standard is suitable for use in applications requiring high impact strength such as shears, punches, blanking dies, chisels, and zinc die casting dies.Annealing
Heat slowly and uniformly to 1500/1550ºF and hold for two hours. Cool slowly (50ºF per hour max) to 1100ºF and air cool to room temperature. Hardness 229 BHN maximum.Heat Treating
Precision Marshall’s S7 Standard is subject to decarburization during heat treatment, so protective atmosphere furnace or vacuum furnace should be used. After preheating 1200ºF/1250ºF, soak material for one half hour per inch of thickness. When material reaches this temperature, heat to 1725ºF, then soak material for one half hour per inch of thickness when material is up to this temperature. Air cool or oil quench to hand warm (approximately 150ºF) and temper immediately. Note: Sections over two inches thick should be interrupt oil quenched or full oil quenched to attain full hardness.Tempering
Double temper one hour per inch of section thickness to desired hardness, two hours minimum per temper.
Representative hardness levels after tempering are tabulated below.
Oil quenched from 1750°F • Tempered 4 hours • Section 4″×4″
| TEMPERING TEMPERATURE (°F) | ROCKWELL HARDNESS (RC) |
|---|---|
| 400 | 56/58 |
| 500 | 54/56 |
| 600 | 53/55 |
| 700 | 52/54 |
| 800 | 52/54 |
| 900 | 51/53 |
| 1000 | 49/52 |
| 1100 | 46/48 |
| 1200 | 39/41 |
