| AISI A9 | |
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| Category | Steel |
| Class | Tool steel |
| Type | Air-hardening medium-alloy cold work steel |
| Designations | United States: ASTM A681 , FED QQ-T-570 , UNS T30109 |
| Composition | |
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| Element | Weight % |
| C | 0.45-0.55 |
| Mn | 0.50 |
| Si | 0.95-1.15 |
| Cr | 4.75-5.50 |
| Ni | 1.25-1.75 |
| Mo | 1.30-1.80 |
| V | 0.80-1.40 |
| Cu | 0.25 |
| P | 0.03 |
| S | 0.03 |
| Mechanical Properties | |
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| Properties | Conditions | ||
| T (°C) | Treatment | ||
| Density (×1000 kg/m3) | 7.78 | 25 | |
| Poisson's Ratio | 0.27-0.30 | 25 | |
| Elastic Modulus (GPa) | 190-210 | 25 | |
| Thermal Properties | |
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