Steel 12CrMo-N (Normalized)
Heat-treated state
GB 12CrMo · ASTM A335 Grade P12
Slightly stronger and harder than N+T; used for plate and forgings where a temper step is added later or where hardness limits are looser.
Values for the N condition
Other 12CrMo tempers and conditions
12CrMo is listed in 6 conditions; see the grade overview at 12CrMo.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — pick for deep machining, cold forming or as an intermediate state before final heat treatment. | 250 | 430 | 30 | 130 HB | — |
Hot rolled | Cheapest mill condition for bar and plate that will be re-heat-treated after machining or forming. | 295 | 490 | 24 | 155 HB | 7.8 % IACS |
N+TDefault Normalized and tempered | Standard supply condition for boiler tube, pipe, plate and forgings in creep service to ~550 °C. | 305 | 480 | 27 | 145 HB | — |
NThis page Normalized | Slightly stronger and harder than N+T; used for plate and forgings where a temper step is added later or where hardness limits are looser. | 335 | 520 | 24 | 160 HB | 7.8 % IACS |
Quenched and tempered | Choose for high-temperature bolting, valve bodies and forgings needing higher yield strength with retained toughness. | 410 | 570 | 21 | 12 HRC | — |
Cold drawn | Bright, dimensionally accurate bar with raised yield strength — for machined fittings and studs, not for creep-critical parts unless re-normalized. | 460 | 570 | 13 | 180 HB | 7.8 % IACS |
What is 12CrMo-N?
12CrMo-N is 12CrMo heat treated to N — slightly stronger and harder than N+T; used for plate and forgings where a temper step is added later or where hardness limits are looser. 12CrMo-N has a yield strength of 335 MPa (48.6 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 77% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi). 12CrMo-N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F). N+T is the default condition FabDigit quotes; N is available on request or by drawing note.
Advantages
- High service temperature — 550°C (1,022 °F), better than 95% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
Limitations
- Low strength — 335 MPa (48.6 ksi), worse than 77% of steel grades
12CrMo-N properties
Typical room-temperature values for 12CrMo-N; 22 are specific to this condition. Other listed values are 12CrMo reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
12CrMo-N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
12CrMo-N has a yield strength of 335 MPa (48.6 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 77% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
12CrMo-N is rated for continuous service to 550°C (1,022 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
12CrMo-N conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of 12CrMo-N takes about 29 MJ of energy and emits 2.3 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability7
12CrMo-N's machinability is good (56/100, better than 71% of steel grades); weldability good (62/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 12CrMo-N
Is 12CrMo easy to machine?
Machines like annealed 4130 — rigid setups, carbide inserts at moderate speed, generous coolant; work-hardening is mild but Mo carbides shorten tool life versus plain carbon steel.
Can 12CrMo be welded?
P-No.4 material: preheat 150–250 °C, use matched 1Cr-0.5Mo filler (E8018-B2 / ER80S-B2), keep interpass ≥150 °C and apply 680–720 °C PWHT to soften the HAZ and avoid hydrogen cracking.
Can 12CrMo be formed, bent or molded?
Hot form at 1100–850 °C then re-normalize and temper; cold bending of tube is feasible at generous radii but tight bends should be stress-relieved.
What surface finishes work on 12CrMo?
No anodizing (ferrous) — protect with phosphate plus high-temperature aluminium/silicone paint, aluminising or spray coatings for external oxidation; internal steam side relies on the protective magnetite film.
12CrMo 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 |
|---|---|---|
| CGB/T 3077 12CrMo; A335 P12 allows 0.05–0.15 | 0.08 – 0.15 | 0.12 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.4 – 0.7 | 0.55 |
| CrA335 P12 requires 0.80–1.25 Cr — check the governing standard before substitution | 0.4 – 0.7 | 0.55 |
| Mo | 0.4 – 0.55 | 0.48 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.2 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
12CrMo-N — frequently asked
What is 12CrMo-N used for?
12CrMo-N is typically used for boiler tubes, pressure vessels and steam piping. In short: creep-resistant 1Cr-0.5Mo steel; A335 P12 equivalent; service to 550 °C.
What is the yield strength of 12CrMo-N?
12CrMo-N has a typical yield strength of 335 MPa (48.6 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 77% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 12CrMo-N easy to machine?
Reasonably — machinability is rated good (56/100, better than 71% of steel grades). Machines like annealed 4130 — rigid setups, carbide inserts at moderate speed, generous coolant; work-hardening is mild but Mo carbides shorten tool life versus plain carbon steel.
Can 12CrMo-N be welded?
Yes — weldability is rated good (62/100). P-No.4 material: preheat 150–250 °C, use matched 1Cr-0.5Mo filler (E8018-B2 / ER80S-B2), keep interpass ≥150 °C and apply 680–720 °C PWHT to soften the HAZ and avoid hydrogen cracking.
What surface finishes work on 12CrMo-N?
No anodizing (ferrous) — protect with phosphate plus high-temperature aluminium/silicone paint, aluminising or spray coatings for external oxidation; internal steam side relies on the protective magnetite film.
Can 12CrMo-N be formed, bent or molded?
Hot form at 1100–850 °C then re-normalize and temper; cold bending of tube is feasible at generous radii but tight bends should be stress-relieved.
What is the maximum service temperature of 12CrMo-N?
12CrMo-N is rated for continuous use to about 550°C (1,022 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 12CrMo N+T and 12CrMo-CD?
N+T is the default condition — standard supply condition for boiler tube, pipe, plate and forgings in creep service to ~550 °C. CD: bright, dimensionally accurate bar with raised yield strength — for machined fittings and studs, not for creep-critical parts unless re-normalized. Yield strength is 305 MPa in N+T versus 460 MPa in CD.
Sources
- ASTM A335/A335M Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service — ASTM International (2023)
- ASME BPVC Section II Part D — Materials, Properties — ASME (2023)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- API RP 941 — Steels for Hydrogen Service (Nelson curves) — API (2016)
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.