630 / 17-4PH
1.4542Precipitation-hardening martensitic stainless steel — the highest-strength stainless in common use. Solution anneal at 1040°C then age at 480-620°C for UTS >1300 MPa. Corrosion resistance similar to 304. Cu+Nb precipitation hardening. Trade names include 17-4PH, SUS630. Used for aerospace structural parts, turbine blades, valve components, nuclear waste casks, medical instruments, and oil/gas equipment.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 630 / UNS S17400 | S17400 | REF |
| 🇪🇺 | EN | Europe | X5CrNiCuNb16-4 (1.4542) | 1.4542 | 100% |
| 🇯🇵 | JIS | Japan | SUS630 | — | 100% |
| 🇺🇸 | TRADE | USA | 17-4PH | — | 100% |
Sources: ASTM A564, EN 10088-3, JIS G4303, AMS 5643
Chemical composition comparison (wt%)
Side-by-side: 630 / 17-4PH (EN) (EN 10088-3) vs X5CrNiCuNb16-4 (1.4542) (EN) (EN 10088-3)
| Element | 630 / 17-4PH (EN) | X5CrNiCuNb16-4 (1.4542) (EN) | Overlap |
|---|---|---|---|
| C | 0–0.07% | 0–0.07% | OK |
| Si | 0–0.7% | 0–0.7% | OK |
| Mn | 0–1.5% | 0–1.5% | OK |
| P | 0–0.04% | 0–0.04% | OK |
| S | 0–0.015% | 0–0.015% | OK |
| Cr | 15–17% | 15–17% | OK |
| Ni | 3–5% | 3–5% | OK |
| Cu | 3–5% | 3–5% | OK |
| Nb | 0.15–0.45% | 0.15–0.45% | OK |
Mechanical properties
H900
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | ≥ 1310 | MPa |
| Yield Strength | ≥ 1170 | MPa |
| Elongation | ≥ 10 | % |
| Hardness HRC | 40–47 | HRC |
| Elastic Modulus | ≥ 197 | GPa |
| Density | ≥ 7.78 | g/cm3 |
H1150
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | ≥ 860 | MPa |
| Yield Strength | ≥ 725 | MPa |
| Elongation | ≥ 16 | % |
| Hardness HRC | 28–38 | HRC |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| solution_annealing | 1020–1060 °C | air or oil | 30 min/25mm | Cool to below 30°C before aging |
| aging_H900 | 480–480 °C | air | 1 hour | Peak strength — HRC 40-47 |
| aging_H1150 | 620–620 °C | air | 4 hours | Max toughness + SCC resistance |
Compatibility verdict
630 / 17-4PH and X5CrNiCuNb16-4 (1.4542): 100% composition match
Close equivalents but NOT identical.
Related materials
304 Stainless Steel
1.4301The most widely used austenitic stainless steel. Excellent corrosion resistance, good formability and weldability. Standard choice for food processing, chemical, and architectural applications.
316L
1.4404Low-carbon austenitic stainless steel with molybdenum addition. Superior corrosion resistance to 304, especially against chlorides and pitting. Standard choice for chemical processing, marine, medical implants, and pharmaceutical equipment.
430 Stainless Steel
1.4016Ferritic chromium stainless steel with good corrosion resistance and formability. Lower cost than austenitic grades. Used for automotive trim, kitchen sinks, architectural panels, and appliance components.
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