9Ni / X8Ni9 / X7Ni9 / 9N490 Cryogenic Steel Plate
Overview
9Ni steel (9% nickel steel) is a low-carbon nickel alloy steel plate designed for ultra-low temperature service down to -196 °C. Compliant with EN 10028-4 (X8Ni9 / X7Ni9), GB 24510 (9Ni490 / 9Ni590A / 9Ni590B), GB/T 3531 (06Ni9DR), ASTM A553 / A353 and JIS G3127 (SL9N520 / SL9N590), it retains outstanding notch toughness and strength at liquid-nitrogen temperature — far below the boiling point of LNG (-162 °C) — making it the standard material for LNG storage tanks and cryogenic pressure vessels.
Key Features
- Ultra-low temperature toughness: guaranteed Charpy V-notch impact energy at -196 °C (40–100 J depending on grade).
- High strength: yield strength 490–590 MPa depending on delivery condition.
- Excellent weldability: low carbon content minimizes cold cracking; suitable for large tank field welding.
- Full grade coverage: 9Ni490 / 9Ni590A / 9Ni590B (GB 24510), X8Ni9+NT640 / X8Ni9+QT680 / X7Ni9+QT680 (EN 10028-4), A353 / A553 Type I (ASTM), 06Ni9DR (GB/T 3531), SL9N520 / SL9N590 (JIS G3127).
- Wide thickness range: 5–50 mm and beyond, in normalizing + tempering (NT) or quenching + tempering (QT) condition.
Chemical Composition (EN 10028-4 X8Ni9, mass %)
| Grade | C | Si | Mn | P | S | Ni | Mo | V |
|---|---|---|---|---|---|---|---|---|
| X8Ni9 / X7Ni9 (EN) | ≤0.10 | ≤0.35 | 0.30–0.80 | ≤0.020 | ≤0.005 | 8.50–10.00 | ≤0.10 | ≤0.05 |
| A553 Type I (ASTM) | ≤0.13 | 0.15–0.30 | ≤0.90 | ≤0.035 | ≤0.040 | 8.50–9.50 | — | — |
Mechanical Properties (Transverse, -196 °C Charpy V-notch)
| Grade / Condition | Thickness (mm) | Tensile Strength Rm (MPa) | Yield Strength ReL (MPa) | Elongation A (%) | Impact KV2 at -196 °C (J) |
|---|---|---|---|---|---|
| 9Ni490 / X8Ni9+NT640 (double normalized + tempered) | ≤30 | 640–830 | ≥490 | ≥18 | ≥40 |
| 9Ni490 / X8Ni9+NT640 | 30–50 | 640–830 | ≥480 | ≥18 | ≥40 |
| X8Ni9+QT640 (quenched + tempered) | ≤30 / 30–125 | 640–830 | ≥490 / ≥480 | ≥18 | ≥40 |
| 9Ni590A / X8Ni9+QT680 | ≤30 / 30–50 | 680–820 | ≥590 / ≥575 | ≥18 | ≥50 |
| 9Ni590B / X7Ni9+QT680 | ≤30 / 30–50 | 680–820 | ≥590 / ≥575 | ≥18 | ≥80 |
| A553 Type I (ASTM) | ≤50 | 690–825 | ≥585 | ≥20 | ≥40 (lateral expansion ≥0.38 mm) |
| 06Ni9DR (GB/T 3531) | 5–30 | 680–820 | ≥560 | ≥18 | ≥100 |
Grade Equivalent
| GB 24510 | EN 10028-4 | ASTM / ASME | JIS G3127 | GB/T 3531 | CCS |
|---|---|---|---|---|---|
| 9Ni490 | X8Ni9+NT640 | SA-353 | SL9N520 | — | 9Ni |
| 9Ni590A | X8Ni9+QT680 | SA-553 Type I | SL9N590 | — | — |
| 9Ni590B | X7Ni9+QT680 | SA-553 Type I | SL9N590 | — | — |
| — | — | — | — | 06Ni9DR | — |
Applications
- LNG industry:
- Inner tanks of onshore LNG storage tanks
- LNG carrier type B and type C cargo tanks
- LNG receiving terminals and peak-shaving plants
- Cryogenic pressure vessels:
- Ethylene and liquefied gas storage
- Air separation and low-temperature equipment
- Shipbuilding:
- Cryogenic containment systems
- Offshore LNG floating facilities (FLNG / FSRU)
Heat Treatment & Welding
Delivery conditions: double normalized + tempered (NT640) or quenched + tempered (QT640 / QT680).
Welding guidelines:
- Consumables: matching 9Ni filler metals (e.g. ENiCrMo-6 type electrodes), or austenitic stainless fillers for certain joints.
- Heat input control: keep interpass temperature low to preserve cryogenic toughness in the HAZ.
- No post-weld heat treatment normally required for 9Ni steel tanks.
Why Baohui Steel
- Mill-direct supply with EN 10204 3.1/3.2 mill certificates and -196 °C impact test reports.
- Full traceability from heat number to finished plate.
- Custom cutting, beveling and export packaging for LNG project shipments.
- 20+ years of steel export experience serving energy and shipbuilding clients worldwide.
