Steel X8Ni9
EN X8Ni9
X8Ni9 (1.5662, ASTM A353 equivalent) is a fine-grain 9% nickel alloy steel supplied quenched and tempered (+QT) or normalized and tempered (+NT, +NNT) that retains fracture toughness down to cryogenic temperatures.
Reference datasheet — X8Ni9 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the +QT condition
X8Ni9 tempers and conditions
X8Ni9 is supplied in 3 conditions, soft to hard. +QT is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Normalized and tempered | Pick when thicker sections, better weld-zone uniformity or lower distortion are preferred over maximum yield strength. | 570 | 700 | 26 | 200 HB | — |
Double normalized and tempered | ASTM A353 route: two normalizing cycles plus temper give very fine grain and the most reliable -196 °C CVN for heavy plate. | 600 | 730 | 26 | 205 HB | — |
+QTDefault Quenched and tempered | Highest strength cryogenic condition — standard for LNG inner-tank plate where design stress and thickness savings matter. | 690 | 745 | 24 | 215 HB | — |
What is X8Ni9?
X8Ni9 (1.5662, ASTM A353 equivalent) is a fine-grain 9% nickel alloy steel supplied quenched and tempered (+QT) or normalized and tempered (+NT, +NNT) that retains fracture toughness down to cryogenic temperatures. In the default condition it gives 690 MPa yield, 745 MPa tensile, 24% elongation and about 215 HB, so tank walls can be thinner than with austenitic stainless; typical forms are heavy plate, forgings and pipe. It is not corrosion resistant, is limited to about 350 °C on the hot side, machines slowly (machinability 40) and requires nickel-base weld consumables. X7Ni9 is the lower-carbon alternative where weldability governs. X8Ni9 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,430°C (2,606 °F). X8Ni9 has a yield strength of 690 MPa (100 ksi) and a tensile strength of 745 MPa (108 ksi) — stronger than 80% of steel grades. Elongation at break is 24% and the elastic modulus is 195 GPa (28.3 Msi).
What is X8Ni9 used for?
- LNG storage tanks
- cryogenic vessels
- piping for low temperature service
Advantages
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 100% of steel grades
- High strength — 690 MPa (100 ksi), better than 80% of steel grades
Limitations
- High embodied carbon — 3.3 kg CO₂/kg, worse than 92% of steel grades
- Poor heat conductor — 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 84% of steel grades
- Low electrical conductivity — 3.8 % IACS, worse than 84% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
X8Ni9 properties
Typical room-temperature values for X8Ni9-+QT; bars are the position among steel grades.
Physical3
X8Ni9 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,430°C (2,606 °F).
Mechanical16
X8Ni9 has a yield strength of 690 MPa (100 ksi) and a tensile strength of 745 MPa (108 ksi) — stronger than 80% of steel grades. Elongation at break is 24% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
X8Ni9 is rated for continuous service to 350°C (662 °F). It conducts heat at 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 84% of steel grades. Thermal expansion is 10.2 µm/m·K (5.67 µin/in·°F).
Electrical3
X8Ni9 conducts electricity at 3.8 % IACS, worse than 84% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of X8Ni9 takes about 40 MJ of energy and emits 3.3 kg of CO₂ — more than 91% of steel grades. Typical recycled content is 25%.
Manufacturability6
X8Ni9's machinability is fair (40/100, worse than 77% of steel grades); weldability good (60/100); formability fair (52/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. X8Ni9 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with X8Ni9
Is X8Ni9 easy to machine?
Machines like a tough 200 HB low-alloy steel — rigid setups, sharp positive-rake carbide, moderate speed and heavy feed to cut under the work-hardened skin; keep tool pressure steady to avoid smearing.
Can X8Ni9 be welded?
Weld with nickel-base consumables (ENiCrMo-6 / ERNiCrMo-3 / ENiCrFe-2), low heat input and interpass ≤150 °C, no preheat needed above ~5 °C; demagnetize plate to prevent arc blow and normally weld in the as-heat-treated condition without PWHT.
Can X8Ni9 be formed, bent or molded?
Cold rolls and presses well but with high springback due to the high yield strength; hot form 850–1000 °C and then re-apply the full +NT/+QT or +NNT cycle to restore cryogenic toughness.
X8Ni9 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CEN 10028-4; ASTM A353/A553 allow ≤0.13 | ≤ 0.1 | 0.06 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.3 – 0.8 | 0.55 |
| Plow P for cryogenic toughness | ≤ 0.02 | 0.01 |
| S | ≤ 0.01 | 0 |
| NiASTM A353/A553: 8.50–9.50 | 8.5 – 10 | 9 |
| Crresidual | ≤ 0.3 | 0.05 |
| Moresidual | ≤ 0.1 | 0.02 |
| Curesidual | ≤ 0.3 | 0.05 |
| Vresidual | ≤ 0.05 | 0.01 |
| Algrain refinement (total Al) | 0.02 – 0.06 | 0.03 |
| N | ≤ 0.01 | 0.01 |
| Fe | balance |
What surface finishes work on X8Ni9?
Not a stainless — shot-blast and coat (epoxy/zinc-rich) or keep in a dry-purged insulation space; electroplating and painting behave like ordinary low-alloy steel, anodizing is not applicable.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel X8Ni9 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.5662
- Similar grades
- A353
How much does X8Ni9 cost?
X8Ni9 is a premium-cost steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
X8Ni9 — frequently asked
What is X8Ni9 used for?
X8Ni9 is typically used for LNG storage tanks, cryogenic vessels and piping for low temperature service. In short: cryogenic-tough 9% nickel steel; highest yield of the 9Ni grades; needs nickel-base filler.
What is the yield strength of X8Ni9?
X8Ni9 has a typical yield strength of 690 MPa (100 ksi) and a tensile strength of 745 MPa (108 ksi) — stronger than 80% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is X8Ni9 easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Machines like a tough 200 HB low-alloy steel — rigid setups, sharp positive-rake carbide, moderate speed and heavy feed to cut under the work-hardened skin; keep tool pressure steady to avoid smearing.
Can X8Ni9 be welded?
Yes — weldability is rated good (60/100). Weld with nickel-base consumables (ENiCrMo-6 / ERNiCrMo-3 / ENiCrFe-2), low heat input and interpass ≤150 °C, no preheat needed above ~5 °C; demagnetize plate to prevent arc blow and normally weld in the as-heat-treated condition without PWHT.
What surface finishes work on X8Ni9?
Not a stainless — shot-blast and coat (epoxy/zinc-rich) or keep in a dry-purged insulation space; electroplating and painting behave like ordinary low-alloy steel, anodizing is not applicable.
Can X8Ni9 be formed, bent or molded?
Cold rolls and presses well but with high springback due to the high yield strength; hot form 850–1000 °C and then re-apply the full +NT/+QT or +NNT cycle to restore cryogenic toughness.
What is the maximum service temperature of X8Ni9?
X8Ni9 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does X8Ni9 cost?
X8Ni9 is a premium-cost steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- EN 10028-4 Flat products of steels for pressure purposes — Nickel alloy steels with specified low temperature properties — CEN (2017)
- ASTM A353/A353M Double-Normalized and Tempered 9% Nickel Alloy Steel Plate — ASTM International (2023)
- ASTM A553/A553M Quenched and Tempered 7, 8, and 9% Nickel Alloy Steel Plate — ASTM International (2022)
- ASME BPVC Section II, Part D — Material Properties (SA-553 Type I) — ASME (2023)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- 9% nickel cryogenic steel plate datasheets (LNG tank plate) — Dillinger / JFE / Nippon Steel (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.