15-5PH Stainless Steel
15-5PH is a precipitation-hardening stainless steel used for high-strength parts that must keep reliable toughness and stable dimensions. It is often selected as an upgrade route when engineers want a more consistent toughness profile than 17-4PH in critical specs.
The grade is widely used in aerospace and high-end industrial hardware, where strength, corrosion resistance, and quality control must work together.
Grade family
PH stainless steel
Strength is developed through aging heat treatment.
Typical strength
Very high
Used for load-bearing components and precision parts.
Buyer focus
Toughness control
Often chosen for critical hardware and safety parts.
Magnetic
Yes
Typically shows magnetic response after processing.
15-5PH is used in applications that need strong mechanical performance with reliable manufacturing repeatability. It is often specified when parts are safety-related, weight-sensitive, or require high confidence under load.
- Aerospace: structural fittings, fasteners, brackets, actuator and landing gear hardware
- Industrial equipment: shafts, couplings, precision fixtures, wear-resistant moving parts
- Oil and gas: valve stems, pump components, high-pressure mechanical parts
- Marine atmosphere: high-strength hardware in coastal environments
15-5PH may appear under different standard systems. Equivalents help alignment, but ordering must follow the required specification and the required heat treatment condition.
| System | Designation | Note |
|---|---|---|
| ASTM / AISI | 15-5PH | Common grade name in aerospace supply |
| UNS | S15500 | Used in many material specifications |
| EN | 1.4545 | European grade number |
| DIN | X5CrNiCuNb15-5 | European naming format |
- High strength: supports compact designs and high-load parts.
- Good corrosion resistance: suitable for many industrial and coastal atmospheres.
- Strong toughness control: often selected for critical hardware and tight QA programs.
- Stable dimensions: consistent performance after aging heat treatment.
- Heat-treatable: aging condition can be selected for strength or toughness balance.
Limits can vary by standard and product form. Use the Mill Test Certificate as the final verification for your delivered heat. 15-5PH chemistry is similar to 17-4PH, but the grade is tuned for consistent performance in many critical specifications.
| Element | Typical range / limit (%) | Purpose |
|---|---|---|
| Cr | 14.0–15.5 | Corrosion resistance base |
| Ni | 3.5–5.5 | Toughness and structure control |
| Cu | 2.5–4.5 | Precipitation strengthening |
| Nb (Cb) | 0.15–0.45 | Strength and stability support |
| C | ≤ 0.07 | Controlled for toughness and weld behavior |
| Mn / Si | ≤ 1.0 / ≤ 1.0 | Processing support |
| P / S | Low (per spec) | Quality and ductility control |
| Fe | Balance | Base metal |
Strength and hardness depend heavily on the aging condition. The values below are general reference points for sourcing discussion. Final acceptance should follow the ordered condition and the governing specification.
| Condition | Typical focus | Buyer note |
|---|---|---|
| H900 | Maximum strength | Common for compact parts and high-load hardware |
| H1025 / H1075 | Strength + toughness balance | Often chosen for safety parts and stable performance |
| H1150 | Higher toughness | Lower strength, but improved toughness in many specs |
15-5PH provides good corrosion resistance for many industrial environments and marine atmosphere exposure. For severe chlorides or hot seawater immersion, 316L or duplex stainless grades often provide a higher safety margin.
As a PH grade, 15-5PH is typically used at moderate service temperatures. Long-term exposure to high heat can change the aging condition and affect mechanical performance.
- Machining: easiest in solution-treated condition; after aging, tool wear increases.
- Forming: limited cold forming; plan shaping in softer condition when possible.
- Welding: weldable with good practice; post-weld aging may be required for full strength.
- Surface care: cleaning and passivation support corrosion performance.
15-5PH can be supplied in standard stainless product forms. Availability depends on finish, tolerance, straightness, and inspection scope.
| Form | Typical supply | Notes |
|---|---|---|
| Plate / sheet | Project-based thickness, width 1000–2000 mm | Used for machining and fabricated parts |
| Coil / strip | Cut-to-length and slitting available | For stamped and formed components |
| Round bar | Diameter 1–200 mm, length 100–12000 mm | Common for shafts and valve parts |
| Flat bar | Width 20–800 mm, thickness 3–60 mm | Frames and machined blanks |
| Pipe / tube | Seamless or welded, project-based | Define NDT, heat treatment, and inspection scope |
These grades are often used for similar parts. Both provide high strength and good corrosion resistance. Many buyers choose 15-5PH when the specification emphasizes toughness consistency and critical hardware performance.
| Item | 15-5PH | 17-4PH | Buyer guidance |
|---|---|---|---|
| Strength | Very high | Very high | Choose condition based on part duty |
| Toughness control | Often preferred | Good | Critical hardware may prefer 15-5PH |
| Corrosion resistance | Good | Good | For severe chlorides, consider 316L or duplex |
| Machining | Best before aging | Best before aging | Order solution treated for machining when possible |
| Common industries | Aerospace, critical hardware | General industrial, valves | Both are common; follow the project spec |
Use these internal tools to confirm equivalents, check tolerances, and prepare a clear RFQ before purchasing.
What is 15-5PH stainless steel used for?
It is used for high-strength parts such as aerospace fittings, fasteners, shafts, valve parts, and precision components where toughness and repeatability are important.
Is 15-5PH stainless steel magnetic?
Yes. 15-5PH typically shows magnetic response due to its structure and heat treatment route.
How is 15-5PH strengthened?
It is strengthened by precipitation hardening through aging heat treatment. Common conditions include H900, H1025/H1075, and H1150.
Is 15-5PH better than 17-4PH?
They are both strong PH grades. Many engineers choose 15-5PH when the specification focuses on toughness consistency and critical hardware requirements. Follow your project standard for final selection.
What details help you quote 15-5PH faster?
Please share standard, ordered condition, product form, size, finish, tolerance, quantity, inspection scope, packing, and destination port.
