X7CrNiAl17-7
1.4568Semi-austenitic precipitation-hardening stainless steel equivalent to AISI 631 / 17-7PH. Hardens through aluminum-induced precipitation during aging. Can be supplied in various conditions (A, TH1050, CH900, RH950). Combines high strength (up to 1300 MPa) with good corrosion resistance and formability in the annealed condition. Used for aerospace components, flat springs, diaphragms, surgical instruments, and high-performance fasteners.
Chemical composition comparison (wt%)
Side-by-side: X7CrNiAl17-7 (EN) (EN 10088-2) vs ASTM
| Element | X7CrNiAl17-7 (EN) | ASTM | Overlap |
|---|---|---|---|
| C | ≤ 0.09% | — | — |
| Si | ≤ 1% | — | — |
| Mn | ≤ 1% | — | — |
| P | ≤ 0.04% | — | — |
| S | ≤ 0.015% | — | — |
| Cr | 16–18% | — | — |
| Ni | 6.5–7.8% | — | — |
| Al | 0.7–1.5% | — | — |
Mechanical properties
Precipitation hardened
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 1030–1300 | MPa |
| Yield Strength | ≥ 960 | MPa |
| Elongation | ≥ 5 | % |
| Density | ≥ 7.8 | g/cm3 |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| solution_annealing | 1050–1100 °C | air | — | Condition A (austenitic) |
| conditioning | 760–760 °C | air | — | TH1050: 760°C/90min → cool to 15°C → age |
| aging | 510–565 °C | air | — | Precipitation hardening, 1-4h |
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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