What is 15-5PH stainless steel?
Aug 01, 2025
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This article explains everything you need to know about 15-5PH stainless steel, from chemical composition to common applications.
What is 15-5PH stainless steel?
15-5PH stainless steel (UNS S15500) is a high-strength, precipitation-hardened (PH) martensitic stainless steel that combines excellent mechanical strength, toughness, and moderate corrosion resistance. It is widely used in aerospace, petrochemical, power generation, and high-performance structural applications.
What is 15 5PH stainless steel equivalent to?
15-5 PH stainless steel is very common grade used in aerospace parts. This grade is written as 1.4545 or 1.4548 or X5CrNiCuNb15-5 according to EN norm and it is written as UNS S15500 according to UNS norm. We can think that 15-5 PH stainless is a better version of 17-4 PH (630 - 1.4542)
15-5 PH Stainless Steel Chemical Composition (Typical, %)
15-5PH is a refined version of 17-4PH (UNS S17400) with improved toughness and microstructure due to better control of impurities and reduced delta ferrite content.
| Element | Content |
|---|---|
| Chromium (Cr) | 14.0 – 15.5 |
| Nickel (Ni) | 3.5 – 5.5 |
| Copper (Cu) | 2.5 – 4.5 |
| Manganese (Mn) | ≤ 1.0 |
| Silicon (Si) | ≤ 1.0 |
| Carbon (C) | ≤ 0.07 |
| Niobium (Nb) | 0.15 – 0.45 |
Mechanical Properties of 15-5 PH Stainless Steel
| Property | Typical Values (H900 Condition) | Typical Values (H1150 Condition) |
|---|---|---|
| Tensile Strength | ≥ 1100 MPa (160 ksi) | ≥ 860 MPa (125 ksi) |
| Yield Strength (0.2% Offset) | ≥ 1000 MPa (145 ksi) | ≥ 725 MPa (105 ksi) |
| Elongation (in 50 mm) | ≥ 8% | ≥ 15% |
| Reduction of Area | ≥ 25% | ≥ 40% |
| Hardness (Rockwell C) | 38 – 42 | 30 – 36 |
| Modulus of Elasticity | ~200 GPa (29 × 10⁶ psi) | ~200 GPa (29 × 10⁶ psi) |
| Fatigue Strength (10⁷ cycles) | ~480 MPa (70 ksi) | ~415 MPa (60 ksi) |
15-5 PH Stainless Steel Heat Treatment and Conditions
15-5PH can be optimized through heat treatments, including:
Solution annealing: Heating at 1038°C ± 14°C for 1/2 hour, followed by cooling to 32°C to achieve complete transformation to martensite.
Age hardening: Aging treatments at various temperatures, such as 482°C, 496°C, and 552°C, are performed to enhance strength.
| Heat Treatment | Typical Tensile Strength | Hardness (HRC) |
|---|---|---|
| H900 | ~1380 MPa | ~45 HRC |
| H1025 | ~1170 MPa | ~38 HRC |
| H1150 | ~1060 MPa | ~32 HRC |
Surface treatments for 15-5PH include:
Polishing, sandblasting, anodizing, electroplating, chemical treatment, and coating to enhance its appearance, corrosion resistance, and functionality.
15-5PH vs 17-4PH Stainless Steel
While both are PH martensitic stainless steels, 15-5PH offers better transverse toughness, improved weldability, and a finer, more uniform microstructure. It is often preferred in critical aerospace and engineering applications where impact resistance and reliability are key.
If you're looking for high-strength, corrosion-resistant stainless steel for aerospace, engineering, or energy applications, 15-5PH may be your ideal solution.
What GNEE Offers
As a trusted stainless steel supplier, GNEE provides a full range of 15-5PH stainless steel plates, round bars, and forgings, with:
✅ Heat-treated conditions: H900, H1025, H1150, H1150M
✅ Certified Mill Test Reports (EN 10204 3.1 / 3.2)
✅ Precision cutting and machining services
✅ Ultrasonic & NDT inspection on request
✅ Global shipping with export-standard packaging
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