S45000 is a low-alloy martensitic age-hardenable (precipitation-hardening) stainless steel. This datasheet presents the material within the American (ASTM / ASME / AMS / UNS) standard system.
With about 15% chromium, 6% nickel, 1.5% copper plus molybdenum and niobium, Custom 450 combines corrosion resistance similar to type 304 with moderate strength similar to type 410, and is easily fabricated. It has a yield strength somewhat above 690 MPa in the annealed condition, and a single low-temperature ageing treatment develops higher strength with good ductility and toughness. Because of its low work-hardening rate it can be extensively cold-formed, and it offers a particular advantage in ease of welding and brazing. It is generally supplied in the annealed condition and requires no further heat treatment for many applications, with a maximum continuous service temperature of about 425 °C.
Typical applications include aerospace components, gas- and steam-turbine blades, pump and valve parts, shafting, and pulp-and-paper, nuclear and chemical-process hardware requiring corrosion resistance with moderate strength.
Typical values, H1000 condition.
| Property | Value | Unit |
|---|---|---|
| Density | 7.75 | g/cm³ |
| Melting range | 1400–1440 | °C |
| Elastic modulus | 200 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 10.8 | µm/m·°C |
| Thermal conductivity (20 °C) | 16.3 | W/m·K |
| Specific heat (20 °C) | 460 | J/kg·K |
| Structure | Martensitic (precipitation-hardening) | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Chromium | Cr | 14.0 | 16.0 | Corrosion resistance; martensite former |
| Nickel | Ni | 5.0 | 7.0 | Toughness; martensite stability |
| Copper | Cu | 1.25 | 1.75 | Precipitation-hardening phase |
| Molybdenum | Mo | 0.50 | 1.00 | Strength; corrosion resistance |
| Niobium | Nb | — | — | Stabiliser (8 × C minimum) |
| Manganese | Mn | — | 1.00 | Deoxidiser |
| Silicon | Si | — | 1.00 | Deoxidiser |
| Carbon | C | — | 0.05 | Low (toughness) |
| Phosphorus | P | — | 0.030 | Residual impurity |
| Sulphur | S | — | 0.030 | Residual impurity |
Typical values by ageing (H) condition, per ASTM A564 / AMS 5763 for UNS S45000.
| Condition | Tensile strength | 0.2% Yield | Hardness |
|---|---|---|---|
| H900 | ≥1240 MPa (180 ksi) | ≥1170 MPa (170 ksi) | ~40 HRC |
| H950 | ≥1170 MPa (170 ksi) | ≥1100 MPa (160 ksi) | ~36 HRC |
| H1000 | ≥1100 MPa (160 ksi) | ≥1030 MPa (150 ksi) | ~34 HRC |
| H1150 | ≥860 MPa (125 ksi) | ≥725 MPa (105 ksi) | ~28 HRC |
| Annealed (Condition A) | ~965 MPa (140 ksi) | ≥690 MPa (100 ksi) | ~B96 HRB |
Confirm against the mill test report. Elongation typically ≥10–14% depending on condition; Charpy toughness is high (≥68 J typical).
| Environment | Performance | Notes |
|---|---|---|
| Atmospheric / general | Very Good | Comparable to type 304; superior to 17-4PH |
| Salt spray (5 / 20% NaCl) | Very Good | Resists rusting and pitting at 35 °C |
| Mild acids | Good | At low concentrations |
| Oxidation | Good | Up to about 650 °C |
| Seawater | Moderate | Better than other martensitic PH grades |
Corrosion resistance is similar to type 304 and notably better than 17-4PH, with high toughness; best resistance is obtained in the over-aged conditions.
A martensitic precipitation-hardening alloy; supplied in the annealed (solution-treated) condition and hardened by a single low-temperature ageing treatment.
Solution Treatment (Condition A) Approximately 1025–1050 °C, hold, then cool rapidly (water quench preferred) to form a martensitic structure. Generally supplied solution-annealed.
Precipitation Hardening (Ageing) A single ageing treatment at 427–538 °C for ~4 hours, then air cool, develops higher strength. Ageing at ~482 °C gives the best combination of strength, ductility and toughness; over-ageing toward 538 °C raises ductility and lowers strength. Dimensional shrinkage of about 0.001 in/in occurs on ageing at 482 °C.
Readily welded and brazed — a particular advantage of this alloy — using shielded methods to limit contamination. A post-weld heat treatment restores full properties.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Excellent | Matching Custom 450-type filler |
| GMAW / MIG | Good | Matching filler |
| SMAW / stick | Good | Matching electrode |
Weld in the annealed condition; re-age after welding to restore strength.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Preferred condition | Annealed (machinable in Condition A) |
| Work hardening | Low rate — allows extensive cold forming |
| Tooling | Positive feeds, slow speeds; carbide tooling |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Extensive cold forming possible (low work-hardening rate) |
| Hot forming | ~1150–950 °C; solution treat + age afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Aerospace | Structural and machined components | Corrosion resistance + moderate strength |
| Power generation | Gas/steam turbine blades, shafts | Strength + corrosion resistance |
| Pulp & paper | Process equipment, shafts | Corrosion resistance + toughness |
| Nuclear / chemical | Valve and pump components | Corrosion resistance + fabricability |
| Product Form | ASTM Standard | ASME / AMS |
|---|---|---|
| Bar, forgings, tubing and rings | ASTM A564 grade XM-25 | ASME SA-564 / AMS 5763 / 5773 |
| Plate, sheet and strip | ASTM A693 grade XM-25 | AMS 5863 / 5859 |
| Forgings | ASTM A705 grade XM-25 | ASME SA-705 |
| Spring wire | ASTM A313 (XM-25) | — |
Low-alloy martensitic precipitation-hardening stainless steel. UNS S45000.
| UNS | Cr % | Ni % | Cu % | Other | Best Used For |
|---|---|---|---|---|---|
| S45000 | 14–16 | 5–7 | 1.25–1.75 | Mo, Nb | PH with 304-like corrosion resistance; fabricable |
| S45500 | 11.0–12.5 | 7.5–9.5 | 1.5–2.5 | Ti, Nb | Ultra-high-strength PH |
| S17400 | 15–17.5 | 3–5 | 3–5 | Nb | General-purpose martensitic PH |
| S15500 | 14–15.5 | 3.5–5.5 | 2.5–4.5 | Nb | High-strength PH; transverse toughness |
| S41000 | 11.5–13.5 | — | — | — | Martensitic, lower strength |




