15-5PH – UNS S15500 (XM-12)
Martensitic precipitation-hardening stainless steel (Cr-Ni-Cu)
Version of 17-4PH with less Cr and practically no delta ferrite, which gives better transverse toughness and toughness in large sections. It hardens by copper precipitation in a single aging between 480 and 620 °C, with corrosion resistance comparable to 304 in many media.
Designations and equivalents
| System | Designation |
|---|---|
| UNS | S15500 |
| W.Nr./EN | 1.4545 (X5CrNiCu15-5) |
| DIN | X5CrNiCu15-5 |
| Trade names | 15-5 PH (registered trademark of Cleveland-Cliffs, formerly Armco/AK Steel), ATI 15-5, XM-12 |
| Others | AMS 5659 (VAR/ESR bar/forging) |
Standards by product form
| Form | Standard |
|---|---|
| Bar | ASTM A564 XM-12; AMS 5659 |
| Forging | ASTM A705 XM-12; AMS 5659 |
| Plate | ASTM A693 XM-12; AMS 5862 |
| Equivalent casting | ASTM A747 CB7Cu-2 |
Tolerances and HS codes
- Forged bars (round and square): machining allowance from 2 mm (Ø 6–16 mm) to 24 mm (Ø 400–500 mm) on the diameter. E.g. Ø 100–125 mm finished: +7 mm, tolerance +6 / −0 (length up to 3,500 mm).
- Forged discs: allowance of 4 to 9 mm on the diameter and 3 to 11 mm on the height, plus-only tolerance.
- Cutting and machining: band saw −0 / +5 to +15 mm on length; waterjet +10 % of thickness on the diameter (min. 2 mm); machined parts −0 / +2 to +5 mm on the diameter. See the full tables (INF 002 and INF 003, the same for every alloy).
| Form | NCM (Brazil, 8 digits) | HS (international, 6 digits) | HTS (USA, 10 digits)* | CN (European Union, 8 digits)* |
|---|---|---|---|---|
| Forged bar | 7222.30.00 | 7222.30 | 7222.30.0024 | 7222 30 51 |
| Hot-rolled bar | 7222.11.00 | 7222.11 | 7222.11.0059 | 7222 11 11 |
| Plate (> 10 mm, width ≥ 600 mm) | 7219.21.00 | 7219.21 | 7219.21.0020 | 7219 21 10 |
| Flange and fitting | 7307.21.00 | 7307.21 | 7307.21.5000 | 7307 21 00 |
Tariff class: stainless steel (by chemical composition, under the Chapter 72 Notes and Section XV Note 5).
*: US and EU codes for reference. NCM per current legislation (General Rules of Interpretation, Notes to Chapters 72, 74 and 75 and Section XV Note 5). Confirm the final code with your customs broker according to the item size and finish. HS = first 6 digits of the NCM.
Chemical composition (%)
ASTM A564 XM-12
| Element | Range (%) |
|---|---|
| C | ≤ 0.07 |
| Mn | ≤ 1.00 |
| Si | ≤ 1.00 |
| P | ≤ 0.040 |
| S | ≤ 0.030 |
| Cr | 14.0 – 15.5 |
| Ni | 3.5 – 5.5 |
| Cu | 2.5 – 4.5 |
| Nb + Ta | 0.15 – 0.45 |
| Fe | balance |
Mechanical properties
Aged – ASTM A564 minimums (bar, longitudinal); other conditions in the aging table
| Property | Value |
|---|---|
| H900 – Rp0.2 / Rm | ≥ 1,170 / ≥ 1,310 MPa; A ≥ 10%; ≥ 40 HRC |
| H1025 – Rp0.2 / Rm | ≥ 1,000 / ≥ 1,070 MPa; A ≥ 12%; ≥ 35 HRC |
| H1075 – Rp0.2 / Rm | ≥ 860 / ≥ 1,000 MPa; A ≥ 13%; ≥ 32 HRC |
| H1150 – Rp0.2 / Rm | ≥ 725 / ≥ 930 MPa; A ≥ 16%; ≥ 28 HRC |
| H1150M – Rp0.2 / Rm | ≥ 515 / ≥ 795 MPa; A ≥ 18% |
| Condition A (solution annealed) | ≤ 38 HRC / 363 HB |
Typical physical properties
| Property | Value |
|---|---|
| Density | 7.78 g/cm³ (A) / 7.81 g/cm³ (H900) |
| Melting range | 1,400 – 1,440 °C |
| Modulus of elasticity | 196 GPa |
| Thermal conductivity (100 °C) | 17.8 W/m·K |
| Thermal expansion (20–100 °C) | 10.8 µm/m·K |
Aging conditions
| Condition | Aging | Min. Rp0.2 | Min. Rm | Min. A | Min. hardness |
|---|---|---|---|---|---|
| A (solution annealed) | 1,040 ± 15 °C, cool < 30 °C | – | – | – | ≤ 363 HB / 38 HRC max. |
| H900 | 482 °C / 1 h / air | 1,170 MPa | 1,310 MPa | 10% | 388 HB / 40 HRC |
| H925 | 496 °C / 4 h / air | 1,070 MPa | 1,170 MPa | 10% | 375 HB / 38 HRC |
| H1025 | 552 °C / 4 h / air | 1,000 MPa | 1,070 MPa | 12% | 331 HB / 35 HRC |
| H1075 | 579 °C / 4 h / air | 860 MPa | 1,000 MPa | 13% | 311 HB / 32 HRC |
| H1100 | 593 °C / 4 h / air | 795 MPa | 965 MPa | 14% | 302 HB / 31 HRC |
| H1150 | 621 °C / 4 h / air | 725 MPa | 930 MPa | 16% | 277 HB / 28 HRC |
| H1150M | 760 °C / 2 h / air + 621 °C / 4 h / air | 515 MPa | 795 MPa | 18% | ≈ 255 HB (typical) |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | Up to ≈ 315 °C; prolonged exposure above that causes embrittlement (475 °C aging). |
| Heat treatment | Solution annealing (condition A) at 1,040 ± 15 °C, air or oil cooling to < 30 °C; machine in A and age afterwards. Aging (ASTM A564, bar minimums): H900 482 °C/1 h → Rp0.2 1,170 / Rm 1,310 MPa, 40 HRC; H925 496 °C/4 h → 1,070/1,170 MPa, 38 HRC; H1025 552 °C/4 h → 1,000/1,070 MPa, 35 HRC; H1075 579 °C/4 h → 860/1,000 MPa, 32 HRC; H1100 593 °C/4 h → 795/965 MPa, 31 HRC; H1150 621 °C/4 h → 725/930 MPa, 28 HRC; H1150M 760 °C/2 h + 621 °C/4 h → 515/795 MPa (≈ 255 HB). Same cycles and minimums as 17-4PH (A564 treats 630 and XM-12 together). |
| Welding | Good: weld in condition A or H1150, without preheat; re-age (or solution anneal + age) after welding. Consumable AWS ER630 (17-4PH) for strength; ER308L/ER309L when the joint does not need the strength of the base metal. |
| Machining | Good in condition A or H1150; finishing after aging, with a contraction of ≈ 0.05% (H900) to allow for. |
Filler metal for welding
The wire composition is usually not identical to the material: each page explains why.
Typical applications
- Aircraft structures and fittings
- Shafts and valve stems
- Pump and compressor components
- Gears and couplings
- Large-section parts needing transverse toughness
- Tooling and plastic molds
- Hydrojetting: high-pressure pumps and components (high strength allows thinner walls, with corrosion resistance)*
- Load cells and scale cells: high-strength, corrosion-resistant spring element with low hysteresis and creep*
Alternatives: 17-4PH when transverse toughness is not critical (more available); 13-8Mo (XM-13) for higher toughness and strength; 431 or F6NM when 900 MPa is enough and lower cost is sought.
15-5PH: complete guide
What 15-5PH stainless steel is
15-5PH belongs to the family of special stainless steels, in the precipitation-hardening (PH) group. It was developed as an evolution of 17-4PH: with slightly less chromium and more nickel, and produced by vacuum remelting, it eliminates the stringers of delta ferrite that impair the transverse toughness of 17-4PH. The structure is low-carbon martensite; the strength comes from very fine copper precipitates formed during aging.
Chemical composition
Chromium from 14 to 15.5%, nickel from 3.5 to 5.5%, copper from 2.5 to 4.5% and niobium from 0.15 to 0.45%, with carbon up to 0.07%.
Heat treatment
Solution annealing is done at 1,040 °C with cooling to below 30 °C, which completes the transformation to martensite; aging ranges from 482 °C (H900) to 621 °C (H1150) for 1 to 4 hours, and H1150M adds a prior step at 760 °C. Dustre performs these cycles in its own furnaces as part of its heat treatment service, with a certificate of the delivered condition.
Corrosion and limits of use
Corrosion resistance is similar to 304 in most media, with a PREN of 14 to 16, and superior to conventional martensitic grades. In the harder conditions (H900) the steel is sensitive to stress corrosion cracking and hydrogen embrittlement; for corrosive media H1025 or above is used, and for H2S the H1150D with hardness up to 33 HRC. At temperature, use under load goes up to about 315 °C.
Applications
Landing gear components, aircraft fittings and fasteners, oil and gas valve shafts and stems, pump and compressor components, medical and food equipment parts and high-strength components that require toughness in thick sections.
Supply forms and Dustre services
Round bars and blocks forged in open die, cut to size on a band saw, with rough or finish machining, heat treatment (quenching and tempering, annealing, solution annealing and aging) in our own furnaces and hardness, tensile and impact testing. All material is supplied with a 3.1 inspection certificate and heat traceability.
Frequently asked questions
What is the chemical composition of 15-5PH?
Per ASTM A564 XM-12: C ≤ 0.07; Mn ≤ 1.00; Si ≤ 1.00; P ≤ 0.040; S ≤ 0.030; Cr 14.0 – 15.5.
Which standards cover 15-5PH?
Bar: ASTM A564 XM-12; AMS 5659. Forging: ASTM A705 XM-12; AMS 5659. Plate: ASTM A693 XM-12; AMS 5862. Equivalent casting: ASTM A747 CB7Cu-2.
Up to what temperature can 15-5PH be used?
Up to ≈ 315 °C; prolonged exposure above that causes embrittlement (475 °C aging).
Which materials can replace 15-5PH?
17-4PH when transverse toughness is not critical (more available); 13-8Mo (XM-13) for higher toughness and strength; 431 or F6NM when 900 MPa is enough and lower cost is sought.
Is 15-5PH used for load cells?
Yes. Aged 15-5PH is used for the spring element of load cells and scale cells: its high strength lets it work in the elastic range with enough strain for the strain gauges, it resists corrosion without coating and it has low hysteresis and creep*. Load cell makers list 17-4PH and 15-5PH as element materials.
