Premium Grade S7
| Typical Chemistry | |
| Carbon | 0.55% |
| Manganese | 0.70% |
| Silicon | 0.35% |
| Chromium | 3.25% |
| Molybdenum | 1.40% |
| Vanadium | 0.25% |
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Sulfur
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less than 0.005% |
| Typical Applications | |
| Plastic Injection Molds | |
| Rubber Molds | |
| Highly Polished Molds | |
| Etched or Textured Molds | |
| High Wear Molds | |
| Extrusion Dies | |
- Hardening
Preheat: 1350/1400F, equalize.
High Heat: 1725/1750F, hold 30/45 minutes at temperature.
Quench: Air, positive pressure vacuum, interrupted oil to 150F. Sections over about 3" thick may require oil quenching to attain full hardness.
Temper: 350/1000F, hold one hour per inch of thickness (two hours minimum), air cool to room temperature. Double tempering is recommended.
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Toughness, Charpy C-Notch |
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ft-lbs |
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| 300 | 59 | 85 |
| 400 | 57 | 125 |
| 500 | 55 | 125 |
| 600 | 54 | 115 |
| 700 | 53 | 105 |
| 800 | 53 | 105 |
| 900 | 52 | 120 |
| 1000 | 51 | 150 |
| 1100 | 47 | 190 |
| 1200 | 41 | – |
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Because of the low tempering temperatures normally used, S7 XL is not typically suitable for nitriding or similar treatments.
Annealing
A. Heat to 1550F, hold two hours, slow cool (50F/hour maximum) to 1000F, then air cool to room temperature.
Or
B. Heat to 1550F, hold two hours, cool to 1400F, hold 4 hours, then air cool to room temperature.
Typical annealed hardness: 187/220 BHN
Stress Relieving
Annealed Material: Heat to 1200/1250F, hold two hours, cool in still air.
Hardened Material: Heat to 25/50F below tempering temperature, hold two hours, cool in still air.
Welding
Use hot work tool steel filler material 4140 or 4150 type filler material may be satisfactory for small repairs or welds away from working surface of tool.
Annealed Material: Preheat to 400/600F. Maintain above 400F during welding. Reanneal or temper 1400F for four hours after welding.
Hardened Material: Preheat to original tempering temperature, (300F minimum). Maintain above 300F during welding. Cool to 150F. Temper at 25/50F below original tempering temperature (300F minimum).
Physical Properties
Modulus of Elasticity ...................................................................30 psi x 106
Density .............................................................................................0.283 lb/in3
Thermal Conductivity .....................(200F)......................... 16.5 BTU/hr/ft/°F
Thermal Expansion
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