ATI 15-7 PH (Semi-Austenitic) vs ATI S240 (Martensitic PH)
Property comparison of ATI 15-7 PH (Semi-Austenitic) and ATI S240 (Martensitic PH), both stainless steel.
| Property | ATI 15-7 PH (Semi-Austenitic) | ATI S240 (Martensitic PH) | Difference |
|---|---|---|---|
| Yield strength | 1,380 MPa | 1,600 MPa | +16% |
| Tensile strength | 1,450 MPa | 1,689 MPa | +16% |
| Elongation | 6 % | 12 % | +100% |
| Elastic modulus | 195,000 MPa | 179,300 MPa | -8% |
| Density | 7,670 kg/m³ | 7,770 kg/m³ | +1% |
| Thermal conductivity | 15.1 W/m·K | 15 W/m·K | -1% |
Difference is ATI S240 (Martensitic PH) relative to ATI 15-7 PH (Semi-Austenitic). Values are taken from the representative row of each material; both materials may have multiple heat treatments or conditions on their individual pages.
Identification
- grade
- UNS S15700
- standard
- AMS 5520
- heat treatment
- Condition TH 1050 (1400°F hold / cool to 55°F / 1050°F age)
- grade
- UNS S11900
- standard
- AMS 5929
- heat treatment
- Solution Annealed + Aged H950 (510°C)
About precipitation-hardening stainless steels
PH grades reach high strength through aging at intermediate temperatures while keeping the corrosion resistance of austenitic or martensitic grades. 17-4 PH and 15-5 PH are the common bar and forging stocks for aerospace and pump shafts. Mechanical properties depend strongly on the aging condition (H900, H1025, H1150).
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