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Technical Information for S-7 Tool Steel
 | S-7 is an air- or oil-hardening tool
steel with a nice combination of exceptional toughness and wear resistance properties. S-7
is an excellent choice for blanking and die forming applications, as well as applications
needing shock and impact resistant tools. Typical analysis is shown in the chart below:
|
| Carbon |
Silicon |
Manganese |
Chromium |
Molybdenum |
| 0.50% |
0.25% |
0.75% |
3.25% |
1.40% |
| S-7 is used in both cold and hot tooling
applications.Typical applications include:
 | Chisels |
| Punches |
| Moil Points |
| Blanking & Forming Dies |
| Engraving Dies |
| Plastic Mold Dies |
| Shear Blades |
| Low-Temp Die-Casting Dies |
|
| Heat Treatment:
| Forging:
 | Preheat slowly to 1700º F until piece is thoroughly heated
through, then increase heat to 1950ºF - 2050ºF. |
| NOT hot work S-7 below 1700ºF.
|
| After forging, allow S-7 to cool slowly, packed in lime or
other insulating material.
|
| Anneal as soon as possible.
|
|
| Annealing:
| Surface protection - Anneal in controlled atmosphere
furnace or pack in an inert material. |
| Slowly heat S-7 to 1500º - 1550º. Hold at temperature for one
hour per inch of smallest dimension of the container. |
| Annealed hardness range is 187 - 223 Brinell. |
|
| Hardening:
| Pack in insert mat'l or use controlled atmosphere
furnace to control decarburization.
|
| Pre-heat slowly to 1200ºF - 1300ºF, and ensure
equal temperature throughout the piece.
|
| Increase heat more rapidly
to 1700ºF-1750ºF.
|
| Hold steel at temperature for one half hour per inch of maximum
thickness, up to 2.5", and then air-quench.
|
| Pieces larger than 2.5" thick should be oil-quenched until
black, followed by air-cooling.
|
| Temper immediately after the piece has cooled to 125ºF.
|
|
| Tempering:
| Temper immediately when piece reaches 150ºF or
when comfortably hand-held. |
| For cold work applications, tempering temperature is
usually in the range of 400ºF - 500ºF; for
hot working tools, the range is 900ºF - 1000ºF. |
| Heat slowly to temperature, hold tools at heat for 2
hours before air cooling.
|
|
|
| Physical & Mechanical Properties
(approx.)
| Density, lb per cu in:
.2813 |
| Specific Gravity
7.786 |
| Critical Points:
| Heating (Ac) 100°/hr - begins 1440°F;
ends 1508°F |
| Cooling (Ar) 50°/hr - begins 1346°F; ends
1270°F |
|
|
| Mean Thermal Coefficient of Expansion |
| Range °F |
Coefficient x 10-6,
in./in./°F |
Range, °F |
Coefficient x 10-6,
in./in./°F |
| 70-200 |
5.77 |
70-900 |
6.86 |
| 70-300 |
6.09 |
70-1000 |
6.99 |
| 70-400 |
6.36 |
70-1100 |
7.09 |
| 70-500 |
6.40 |
70-1200 |
7.17 |
| 70-600 |
6.51 |
70-1300 |
7.24 |
| 70-700 |
6.75 |
70-1400 |
7.29 |
| 70-800 |
6.85 |
70-1499 |
7.41 |
| Maximum Shock Resistance
| Charpy Impact specimens preheated to 1300°F |
| Air-quenched from 1725°F |
| Tempered at increasing rates (see table) |
| Tempering
Temperature, °F |
Rockwell C |
Charpy Ft.-lb. |
| As quenched |
60 |
15.7 |
| 300 |
59 |
143.5 |
| 350 |
58.5 |
100.3 |
| 400 |
58 |
Past Machine Cap. |
| 500 |
56 |
220.1 |
| 600 |
55 |
219.7 |
| 700 |
54 |
221.8 |
| 800 |
53 |
209 |
| 900 |
52 |
189.8 |
| 1000 |
51 |
213.6 |
| 1100 |
47 |
Past Machine Cap. |
| 1200 |
38 |
Past Machine Cap. |
| 1300 |
31 |
Past Machine Cap. |
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For More information please call us at 800-654-2901 or fax us
(806) 684-6354
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