Steel X10Ni9-QLT
Heat-treated state
EN X10Ni9
Three-step treatment maximising retained austenite and -196 °C toughness in heavy sections; used for thick LNG inner-tank plate.
Values for the QLT condition
Other X10Ni9 tempers and conditions
X10Ni9 is listed in 6 conditions; see the grade overview at X10Ni9.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
normalized and tempered | Standard EN 10028-4 delivery condition for moderate thickness plate where Q&T facilities are not used. | 540 | 700 | 26 | 15 HRC | 5 % IACS |
Hot rolled | Mill intermediate condition supplied only for further forming and subsequent NT/QT — not for cryogenic service as-is. | 560 | 780 | 20 | 22 HRC | 5 % IACS |
double normalized and tempered (ASTM A353) | Classic LNG plate route giving very uniform fine grain and good -196 °C toughness in thick plate at slightly lower yield than Q&T. | 570 | 720 | 26 | 18 HRC | — |
quenched and tempered forgings/flanges (EN 10222-3, ASTM A522/A350 style) | For flanges, valve bodies and tube sheets in cryogenic service where forged product form is specified. | 610 | 720 | 22 | 19 HRC | 5 % IACS |
QLTThis page quench, intercritical (lamellarizing) treatment and temper | Three-step treatment maximising retained austenite and -196 °C toughness in heavy sections; used for thick LNG inner-tank plate. | 630 | 730 | 25 | 19 HRC | 5 % IACS |
QTDefault Quenched and tempered | Highest strength LNG-tank plate condition; pick when 585 MPa minimum yield is required at -196 °C. | 640 | 750 | 24 | 20 HRC | — |
What is X10Ni9-QLT?
X10Ni9-QLT is X10Ni9 heat treated to QLT — three-step treatment maximising retained austenite and -196 °C toughness in heavy sections; used for thick LNG inner-tank plate. X10Ni9-QLT has a yield strength of 630 MPa (91.4 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 79% of steel grades. Elongation at break is 25% and the elastic modulus is 190 GPa (27.6 Msi). X10Ni9-QLT 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). QT is the default condition FabDigit quotes; QLT is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 210 MPa·√m (191.1 ksi·√in), better than 100% of steel grades
- High strength — 630 MPa (91.4 ksi), better than 79% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- High embodied carbon — 3 kg CO₂/kg, worse than 91% of steel grades
- Poor heat conductor — 30 W/m·K (17.3 BTU/hr·ft·°F), worse than 83% of steel grades
- Low electrical conductivity — 5 % IACS, worse than 82% of steel grades
X10Ni9-QLT properties
Typical room-temperature values for X10Ni9-QLT; 24 are specific to this condition. Other listed values are X10Ni9 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
X10Ni9-QLT 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
X10Ni9-QLT has a yield strength of 630 MPa (91.4 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 79% of steel grades. Elongation at break is 25% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal6
X10Ni9-QLT is rated for continuous service to 350°C (662 °F). It conducts heat at 30 W/m·K (17.3 BTU/hr·ft·°F), worse than 83% of steel grades. Thermal expansion is 10.2 µm/m·K (5.67 µin/in·°F).
Electrical3
X10Ni9-QLT conducts electricity at 5 % IACS, worse than 82% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of X10Ni9-QLT takes about 40 MJ of energy and emits 3 kg of CO₂ — more than 91% of steel grades. Typical recycled content is 30%.
Manufacturability8
X10Ni9-QLT's machinability is fair (43/100, worse than 71% of steel grades); weldability good (60/100); formability good (56/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with X10Ni9-QLT
Is X10Ni9 easy to machine?
Machines like a tough 600–750 MPa alloy steel: rigid setups, sharp positive-rake carbide, moderate speed with heavy feed to cut under the work-hardened layer, flood coolant.
Can X10Ni9 be welded?
Weld with Ni-base fillers (ERNiCrMo-3/6, ENiCrMo-6) or matched 9Ni consumables, low heat input, interpass typically ≤150 °C, no preheat normally required and PWHT usually avoided to preserve retained austenite; avoid magnetic arc blow by demagnetizing.
Can X10Ni9 be formed, bent or molded?
Cold-form plate with generous bend radii (≥3t) or hot-form 550–650 °C then re-heat-treat; heavy cold work reduces cryogenic toughness.
What surface finishes work on X10Ni9?
Not anodizable; grit-blast and apply epoxy/zinc-rich primer or metallize on exposed faces — inner LNG tank surfaces are typically left bare in the dry cryogenic environment.
X10Ni9 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 |
|---|---|---|
| Chigher C than X8Ni9 (1.5662) | ≤ 0.13 | 0.1 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.3 – 0.8 | 0.55 |
| Plow P for cryogenic toughness | ≤ 0.02 | 0.01 |
| Soften restricted to 0.005 max | ≤ 0.01 | 0 |
| Ni | 8.5 – 10 | 9 |
| Crresidual | ≤ 0.3 | 0.1 |
| Moresidual | ≤ 0.1 | 0.03 |
| Curesidual | ≤ 0.3 | 0.05 |
| Algrain refining, total Al | 0.02 – 0.06 | 0.03 |
| Fe | balance | — |
X10Ni9-QLT — frequently asked
What is X10Ni9-QLT used for?
X10Ni9-QLT is typically used for LNG storage, cryogenic tanks and pressure vessels. In short: highest tensile 9Ni cryogenic steel; QLT condition available; not corrosion resistant.
What is the yield strength of X10Ni9-QLT?
X10Ni9-QLT has a typical yield strength of 630 MPa (91.4 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 79% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is X10Ni9-QLT easy to machine?
Not especially — machinability is rated fair (43/100, worse than 71% of steel grades). Machines like a tough 600–750 MPa alloy steel: rigid setups, sharp positive-rake carbide, moderate speed with heavy feed to cut under the work-hardened layer, flood coolant.
Can X10Ni9-QLT be welded?
Yes — weldability is rated good (60/100). Weld with Ni-base fillers (ERNiCrMo-3/6, ENiCrMo-6) or matched 9Ni consumables, low heat input, interpass typically ≤150 °C, no preheat normally required and PWHT usually avoided to preserve retained austenite; avoid magnetic arc blow by demagnetizing.
What surface finishes work on X10Ni9-QLT?
Not anodizable; grit-blast and apply epoxy/zinc-rich primer or metallize on exposed faces — inner LNG tank surfaces are typically left bare in the dry cryogenic environment.
Can X10Ni9-QLT be formed, bent or molded?
Cold-form plate with generous bend radii (≥3t) or hot-form 550–650 °C then re-heat-treat; heavy cold work reduces cryogenic toughness.
What is the maximum service temperature of X10Ni9-QLT?
X10Ni9-QLT 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.
What is the difference between X10Ni9-QT and X10Ni9-NT?
QT is the default condition — highest strength LNG-tank plate condition; pick when 585 MPa minimum yield is required at -196 °C. NT: standard EN 10028-4 delivery condition for moderate thickness plate where Q&T facilities are not used. Yield strength is 640 MPa in QT versus 540 MPa in NT.
Sources
- EN 10028-4 Flat products of steels for pressure purposes — Nickel alloy steels with specified low temperature properties — CEN (2017)
- ASTM A553/A553M Pressure Vessel Plates, Alloy Steel, Quenched and Tempered 8 and 9 % Nickel — ASTM International (2022)
- ASTM A353/A353M Pressure Vessel Plates, Alloy Steel, Double-Normalized and Tempered 9 % Nickel — ASTM International (2022)
- EN 10222-3 Steel forgings for pressure purposes — Nickel steels with specified low temperature properties — CEN (1998)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- 9% Ni cryogenic plate datasheets (Dillinger / JFE / Nippon Steel typical property tables) — various producers (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.