Bar and Rod
Plate and Sheet
Strip
Pipe and Tube
Wire
Welding
Powder Material
Cast Products
Forged Products
Fittings
Fastening
Round Bar:
φ2–500 mm, 1–6 m length
Flat/Square Bar:
4–100 mm thickness/width
Hex Bar:
A/F 3–100 mm
Hollow Bar:
OD 20–300 mm
Sheet:
0.3–6 mm thickness
Medium Plate:
6–25 mm thickness
Heavy Plate:
25–100 mm thickness
Standard Strip:
0.05–3 mm thick,
10–600 mm wide
Precision strip:
0.01–0.5 mm thick,
tight tolerance ±0.005 mm
Foil:
0.005–0.1 mm thick
Seamless Tube:
OD 6–450 mm,
WT 1–50 mm,
1–12 m length
Welded Tube:
OD 10–600 mm,
WT 1–20 mm
Capillary Tube:
OD 1–10 mm,
WT 0.1–2 mm
Wire Form:
Cold Drawn Wire,
Bright Wire,
Spring Wire,
Fine Wire,
Ultra-fine Wire
General Diameter:
φ0.1–10 mm
Coil Weight:
50–500 kg,
customizable tolerance
Solid Wire:
φ0.8–4.0 mm
Flux-cored Wire:
φ1.2–4.0 mm
Welding Rod:
φ2.0–5.0 mm
Powder Form:
AM 3D Printing Powder,
Spherical Powder,
Gas-atomized Powder,
Water-atomized Powder
Particle Size:
10–150 μm
Sphericity:
≥90% for AM grade
Cast Ingot:
φ200–800 mm
Precision Casting:
min wall 0.5 mm
Cast Pipe:
OD 100–600 mm,
WT 10–50 mm
Forged Bar:
Φ35–500 mm
Forged Ring:
OD 200–2000 mm
Forging Weight:
1–5000 kg
Fittings Form:
Elbow, Tee, Reducer, Flange, Cap, Outlet, Lap Joint
Size range:
1/2''–24'' (DN15–DN600)
Wall thickness:
Sch10–Sch160, STD, XS, XXS
Pressure Class:
150–2500 LB
Fastening Form:
Bolt, Nut, Screw, Stud, Washer, Pin, Rivet
Metric: M3–M64
Imperial: #4–2.5''
Length: 6–500 mm
X7CrNiAl17-7 is a chromium-nickel-aluminium semi-austenitic precipitation-hardening (PH) stainless steel. This datasheet presents the material within the Werkstoff-Nummer (DIN / EN) designation system.
With about 17% chromium, 7% nickel and 1% aluminium, 1.4568 is the most formable of the PH grades and reaches very high strength and hardness after heat treatment. It is supplied in the soft austenitic condition, formed, then transformed to martensite and precipitation-hardened by a multi-step heat treatment that precipitates an aluminium-rich phase. It has high fatigue strength and good elevated-temperature strength but reduced corrosion resistance, and is applicable to about 300 °C. It provides excellent spring characteristics.
Typical applications include springs and spring parts (cold-drawn wire up to about 10 mm), diaphragms, bellows, retaining rings, fasteners and aerospace components requiring high strength with good formability.
Typical values, precipitation-hardened condition, per EN reference data.
| Property | Value | Unit |
|---|---|---|
| Density | 7.81 | g/cm³ |
| Melting range | 1400–1440 | °C |
| Elastic modulus | 204 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 11.0 | µm/m·°C |
| Thermal conductivity (20 °C) | 16.4 | W/m·K |
| Specific heat (20 °C) | 460 | J/kg·K |
| Structure | Semi-austenitic (precipitation-hardening) | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Chromium | Cr | 16.0 | 18.0 | Corrosion resistance |
| Nickel | Ni | 6.50 | 7.80 | Austenite stability |
| Aluminium | Al | 0.75 | 1.50 | Precipitation-hardening phase (Ni-Al) |
| Manganese | Mn | — | 1.00 | Deoxidiser |
| Silicon | Si | — | 0.70 | Deoxidiser |
| Carbon | C | — | 0.09 | Strength |
| Phosphorus | P | — | 0.040 | Residual impurity |
| Sulphur | S | — | 0.015 | Residual impurity |
Typical values by heat-treatment condition, per EN 10088-3 / EN 10270-3 for W.Nr. 1.4568.
| Condition | Tensile strength (Rm) | 0.2% proof (Rp0.2) | Hardness |
|---|---|---|---|
| +P1100 (TH1050) | ≥1170 MPa | ≥1030 MPa | ~38 HRC |
| +P1300 (RH950) | ≥1380 MPa | ≥1210 MPa | ~43 HRC |
| +P1450 (CH900) | ≥1650 MPa | ≥1585 MPa | ~46 HRC |
| +AT (solution-annealed) | ~900 MPa | ~280 MPa | soft |
Values per EN 10088-3; confirm against the inspection certificate (EN 10204). Elongation typically ≥1–6 % in hardened conditions, higher when solution-annealed.
| Environment | Performance | Notes |
|---|---|---|
| Atmospheric / general | Good | Better than martensitic 400-series; below 1.4301 |
| Mild acids | Moderate | At low concentrations |
| Chloride pitting | Moderate | Lower than austenitic grades |
| Oxidation | Good | At elevated temperature |
| Seawater | Limited | Not recommended for prolonged exposure |
Corrosion resistance is moderate — better than the martensitic PH and 400-series grades but below the austenitic stainless steels.
A semi-austenitic precipitation-hardening alloy; supplied in the soft austenitic condition and hardened by a multi-step transformation-plus-ageing sequence.
Solution Treatment Supplied solution-treated (~1065 °C) in the soft austenitic condition for forming.
Transformation and Precipitation Hardening TH1050: austenite-conditioning at ~760 °C, cool to transform to martensite, then age at ~565 °C. RH950: condition at ~955 °C, sub-zero cool (~−73 °C) to transform, then age at ~510 °C for higher strength. Cold-rolling to martensite followed by ageing at ~480 °C gives maximum strength. Air cool after ageing.
Weldable by common fusion and resistance methods; matching filler is used. Heat treatment after welding develops full properties.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Good | Matching 17-7-type filler |
| GMAW / MIG | Good | Matching filler |
| Resistance / spot | Good | — |
Weld in the soft solution-treated condition; heat-treat after welding to develop strength.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Preferred condition | Solution-treated (soft) for best formability and machinability |
| Work hardening | High rate; positive feeds, rigid setup |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Excellent in the soft condition (most formable PH grade) |
| Hot forming | ~1150–950 °C; solution treat + age afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Spring / fastener | Springs, spring wire, clips, washers | Spring properties + fatigue resistance |
| Aerospace | Retaining rings, structural parts | High strength + formability |
| Instrumentation | Diaphragms, bellows | Formability + fatigue resistance |
| General industrial | High-strength formed components | Strength + minimal distortion |
| Product Form | DIN / EN Standard | Notes |
|---|---|---|
| Plate, sheet and strip | EN 10088-2 / EN 10151 · W.Nr. 1.4568 | X7CrNiAl17-7 |
| Bar, rod and sections | EN 10088-3 · W.Nr. 1.4568 | — |
| Spring wire | EN 10270-3 · W.Nr. 1.4568 | Cold-drawn to ~10 mm |
| Technical delivery | SEW 470 | — |
Chromium-nickel-aluminium semi-austenitic precipitation-hardening stainless steel. W.Nr. 1.4568 (X7CrNiAl17-7).
| EN Symbol | Cr % | Ni % | Al % | Other | Best Used For |
|---|---|---|---|---|---|
| X7CrNiAl17-7 | 16–18 | 6.5–7.8 | 0.75–1.5 | — | Semi-austenitic PH; springs, formability |
| X8CrNiMoAl15-7-2 | 14–16 | 6.5–7.75 | 0.75–1.5 | Mo | Semi-austenitic PH; higher strength |
| X5CrNiCuNb16-4 | 15–17 | 3–5 | — | Cu, Nb | Martensitic PH; general high strength |
| X3CrNiMoAl13-8-2 | 12.25–13.25 | 7.5–8.5 | Al | Mo | Highest-toughness PH; aerospace |
| X10CrNi18-8 | 16–19 | 6–9.5 | — | — | Work-hardening austenitic; springs |
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