Stainless Steel 15-5 PH (UNS S15500)
Stainless Steel 15-5 PH is a martensitic, precipitation-hardening alloy that serves as a high-integrity evolution of the classic 17-4 PH. While it shares a similar chemical foundation, 15-5 PH is specifically designed to provide greater structural uniformity and superior transverse toughness. By utilizing Vacuum Arc Remelting (VAR) or Electroslag Refining (ESR), the material is purged of many internal impurities, resulting in an exceptionally "clean" alloy that resists crack propagation in all directions.
At Aries Alloys, we supply 15-5 PH to the aerospace and nuclear sectors where multi-directional stress is a factor. It is the material of choice when you require the high strength of a precipitation-hardening steel but cannot compromise on internal metallurgical quality.
Key Performance Benefits
- Superior Transverse Properties: Unlike many high-strength steels that are weaker across the grain, 15-5 PH offers high toughness in both longitudinal and transverse directions.
- Exceptional Cleanliness: The refining process reduces non-metallic inclusions, making it ideal for components subjected to rigorous non-destructive testing (NDT).
- High-Strength Duality: Capable of reaching tensile strengths exceeding 180,000 psi through low-temperature aging treatments.
- Corrosion Excellence: Provides corrosion resistance comparable to 17-4 PH and Type 304, outperforming standard 400-series martensitic steels.
- Minimal Distortion: The low-temperature hardening process (900°F to 1150°F) ensures that complex machined parts retain their dimensional accuracy.
Technical Profile & Composition
The VAR/ESR Difference:
The primary differentiator for 15-5 PH is the refining method. By melting the alloy under vacuum or slag, the chemistry is tightly controlled, and the delta ferrite content is minimized. This leads to a more homogenous microstructure, which is why 15-5 PH is often specified over 17-4 PH for critical forged parts.
Mechanical & Physical Data:
- Density: 7.80 g/cm^3
- Magnetic Property: Strongly magnetic in all conditions.
- Hardening Conditions: Available in various "H" conditions (H900, H1025, H1050, H1150) to achieve a precise balance of hardness and impact strength.
- Elastic Modulus: 28.5 × 10^6 psi.
Primary Industrial Use Cases
Aries Alloys is a strategic supplier of 15-5 PH for high-consequence engineering:
- Aerospace Components: Landing gear parts, engine pylons, flight control actuators, and structural airframe members.
- High-Pressure Systems: Valve bodies, pump shafts, and manifolds for the oil and gas industry.
- Nuclear Engineering: Fasteners and structural hardware requiring high purity and radiation resistance.
- Chemical Processing: High-strength reactor components and specialized mixing equipment.
- Medical Equipment: Components for high-stress orthopedic or surgical tools that require repeated sterilization.
Product Availability at Aries Alloys
We stock and supply Stainless Steel 15-5 PH in accordance with ASTM A564 and AMS 5659:
- Round Bars: Precision-ground rods, often supplied in the VAR condition for aerospace machining.
- Plates & Sheets: High-strength flat products for structural brackets and enclosures.
- Forged Rings & Blocks: Custom shapes designed for high-pressure, multi-directional stress applications.
- Seamless Tubing: High-durability tubing for hydraulic and aerospace fluid systems.