Steel X12Ni5-NT (Normalized and tempered)
Heat-treated state
EN X12Ni5
Alternative plate/forging condition for thicker sections where quenching distortion is a problem; slightly lower strength than QT.
Values for the NT condition
Other X12Ni5 tempers and conditions
X12Ni5 is listed in 5 conditions; see the grade overview at X12Ni5.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose for maximum machinability and cold formability of bar/forging stock before final QT. | 340 | 520 | 28 | 155 HB | 6.4 % IACS |
NTThis page Normalized and tempered | Alternative plate/forging condition for thicker sections where quenching distortion is a problem; slightly lower strength than QT. | 400 | 570 | 25 | 172 HB | 6.2 % IACS |
Normalized | Intermediate mill condition; usually tempered afterwards, low-temperature impact values are not guaranteed as-normalized. | 405 | 590 | 23 | 178 HB | 6.2 % IACS |
Forged + QT (EN 10222-3 flanges, valve bodies, tube sheets) | Forging grade for cryogenic valves, flanges and nozzles; properties are section-size dependent and slightly lower than thin plate. | 420 | 600 | 22 | 180 HB | 6.2 % IACS |
QTDefault Quenched and tempered | Standard cryogenic pressure-vessel plate condition: highest strength combined with guaranteed low-temperature Charpy values. | 440 | 620 | 24 | 185 HB | 6.2 % IACS |
What is X12Ni5-NT?
X12Ni5-NT is X12Ni5 heat treated to NT — alternative plate/forging condition for thicker sections where quenching distortion is a problem; slightly lower strength than QT. X12Ni5-NT has a yield strength of 400 MPa (58 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 60% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi). X12Ni5-NT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,440°C (2,624 °F). QT is the default condition FabDigit quotes; NT is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 180 MPa·√m (163.8 ksi·√in), better than 99% of steel grades
- Forms and bends easily — 66/100, better than 83% 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 — 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades
- Low electrical conductivity — 6.2 % IACS, worse than 78% of steel grades
X12Ni5-NT properties
Typical room-temperature values for X12Ni5-NT; 22 are specific to this condition. Other listed values are X12Ni5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
X12Ni5-NT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,440°C (2,624 °F).
Mechanical16
X12Ni5-NT has a yield strength of 400 MPa (58 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 60% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
X12Ni5-NT is rated for continuous service to 350°C (662 °F). It conducts heat at 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades. Thermal expansion is 11.2 µm/m·K (6.22 µin/in·°F).
Electrical3
X12Ni5-NT conducts electricity at 6.2 % IACS, worse than 78% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of X12Ni5-NT takes about 38 MJ of energy and emits 3 kg of CO₂ — more than 91% of steel grades. Typical recycled content is 25%.
Manufacturability7
X12Ni5-NT's machinability is good (55/100, better than 62% of steel grades); weldability very good (70/100); formability good (66/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with X12Ni5-NT
Is X12Ni5 easy to machine?
Machines like a tough 500–650 MPa low-alloy steel: rigid setups, sharp positive-rake carbide, 80–150 m/min, generous coolant to avoid work hardening and gummy chips.
Can X12Ni5 be welded?
Weld with low heat input and controlled interpass (typically ≤150 °C) using matching Ni or nickel-base/high-Ni consumables; PWHT ~550–600 °C where required, and always qualify weld-metal and HAZ Charpy at the design temperature.
Can X12Ni5 be formed, bent or molded?
Cold formable plate with generous bend radii; hot forming should be followed by re-normalizing/re-quenching and tempering to restore cryogenic toughness.
What surface finishes work on X12Ni5?
No anodizing; shot-blast then epoxy/zinc-rich paint, thermal-spray aluminium or metallic plating — surface rusts readily in humid or marine air.
X12Ni5 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 |
|---|---|---|
| Cper EN 10028-4 / EN 10222-3 | ≤ 0.15 | 0.1 |
| Si | ≤ 0.35 | 0.25 |
| Mn | 0.3 – 0.8 | 0.55 |
| Plow P for cryogenic toughness | ≤ 0.02 | — |
| Slow S, Ca-treated for through-thickness toughness | ≤ 0.01 | — |
| Niprincipal alloying element | 4.75 – 5.25 | 5 |
| Moresidual; A645-type 5Ni grades add ~0.25 Mo | ≤ 0.1 | — |
| Crresidual | ≤ 0.3 | — |
| Altotal Al, grain refinement | ≥ 0.02 | 0.04 |
| Fe | balance | — |
X12Ni5-NT — frequently asked
What is X12Ni5-NT used for?
X12Ni5-NT is typically used for cryogenic vessels, low-temperature piping and storage tanks. In short: lower-cost 5% nickel grade; cryogenic to about -165 °C; softer than 9Ni steels.
What is the yield strength of X12Ni5-NT?
X12Ni5-NT has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is X12Ni5-NT easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like a tough 500–650 MPa low-alloy steel: rigid setups, sharp positive-rake carbide, 80–150 m/min, generous coolant to avoid work hardening and gummy chips.
Can X12Ni5-NT be welded?
Yes — weldability is rated very good (70/100). Weld with low heat input and controlled interpass (typically ≤150 °C) using matching Ni or nickel-base/high-Ni consumables; PWHT ~550–600 °C where required, and always qualify weld-metal and HAZ Charpy at the design temperature.
What surface finishes work on X12Ni5-NT?
No anodizing; shot-blast then epoxy/zinc-rich paint, thermal-spray aluminium or metallic plating — surface rusts readily in humid or marine air.
Can X12Ni5-NT be formed, bent or molded?
Cold formable plate with generous bend radii; hot forming should be followed by re-normalizing/re-quenching and tempering to restore cryogenic toughness.
What is the maximum service temperature of X12Ni5-NT?
X12Ni5-NT 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 X12Ni5-QT and X12Ni5-A?
QT is the default condition — standard cryogenic pressure-vessel plate condition: highest strength combined with guaranteed low-temperature Charpy values. A: choose for maximum machinability and cold formability of bar/forging stock before final QT. Yield strength is 440 MPa in QT versus 340 MPa in A.
Sources
- EN 10028-4 Flat products of steels for pressure purposes — Nickel alloy steels with specified low temperature properties — CEN (2017)
- EN 10222-3 Steel forgings for pressure purposes — Nickel steels with specified low temperature properties — CEN (1998)
- ASTM A645 5Ni-1/4Mo Alloy Steel Pressure Vessel Plates, Specially Heat Treated — ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13 — Corrosion — ASM International (2005)
- Cryogenic nickel steel plate datasheets (Ni-alloyed pressure vessel grades) — European plate mills (2022)
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.