15-5 PH Stainless Steel
A Cr-Ni-Cu martensitic PH stainless steel with a ferrite-free structure
Typical values for the temper in the title
15-5 PH is a close relative of 17-4 PH, with slightly less chromium and copper. This small change prevents delta ferrite in the structure, and the result is better toughness, especially in the transverse direction and in thick sections.
It is common in aerospace, forgings and thick parts where 17-4 PH may be less uniform. Heat treatment and aging conditions are the same as 17-4 PH.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 1000–1310 MPa | |
| Yield strength Rp0.2 | 790–1170 MPa | |
| Elongation A | 8–16% | |
| Hardness | 293–415 HB | |
| Modulus of elasticity E | 197 GPa | |
| Density ρ | 7.78 g/cm³ | |
| Machinability | 50% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Cr chromium | 14.00–15.50 | corrosion resistance |
| Ni nickel | 3.50–5.50 | martensitic structure |
| Cu copper | 2.50–4.50 | strengthening particles |
| Nb+Ta | 0.15–0.45 | ties up carbon |
| C carbon | max 0.07 | |
| Mn manganese | max 1.00 | |
| Si silicon | max 1.00 | |
| Fe iron | balance |
Ranges per ASTM A564 (bar); A693 for sheet and plate. Strength values in the conditions table are minimums per the standard.
Conditions and heat treatment
Conditions are the same as 17-4 PH: solution treatment (Condition A) and aging at the temperature shown after H.
| Condition | Properties | When to choose it |
|---|---|---|
| Condition A (solution treated) | medium strength, machinable | delivery condition: machine, then age |
| H900 (480 °C, 1 h) | Rm min 1310 MPa, Rp0.2 min 1170 MPa | maximum strength, low toughness |
| H1025 (550 °C, 4 h) | Rm min 1070 MPa, Rp0.2 min 1000 MPa | a balance of strength and toughness |
| H1150 (620 °C, 4 h) | Rm min 930 MPa, Rp0.2 min 725 MPa | good toughness and stress corrosion resistance |
Applications
- Aerospace forgings
- Thick high-strength structural parts
- Shafts and mechanism parts
- Chemical industry parts
- High-strength bolts
Fabrication
Machining and size change
As with 17-4 PH: machine in Condition A and age afterwards, with minimal distortion.
Welding
Welds well, with aging after welding.
Uniformity
Without ferrite, properties are more uniform across directions and in thick parts.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 17-4 PH (630) | 930–1310 / 725–1170 MPa | Excellent | more available and cheaper, when transverse toughness is less critical · material page |
| 13-8 PH | 1000–1450 / 930–1380 MPa | Excellent | stronger, with molybdenum and aluminum · material page |
| 431 | 860–1035 / 655–760 MPa | Difficult — Preheat 150-260°C | an ordinary martensitic grade · material page |
Common mistakes
Replacing 15-5 PH with 17-4 PH in an aerospace part without approval
Transverse toughness differs. The specification is binding.
Using H900 in a corrosive environment
As with 17-4 PH, H1025 and above are better.
Machining after aging
Better to machine in Condition A.
Equivalents, standards and supply
| EN | 1.4545 |
|---|---|
| Standards | ASTM A564 / AMS 5659 |
| Forms | plate · rod |
| Producers | Carpenter · ATI · Valbruna |
Learn more
Values are typical and for comparison only. For design, rely on the standard and on the mill certificate. Sources: ASTM A240, ASTM A276 and EN 10088 (composition), producer data sheets, and the METAL HUB materials database.
Updated: October 31, 2026