Steel A369 FP12 N+T
Heat-treated state · default condition
ASTM A369 FP12
N+T = normalized and tempered
Choose the usual delivery condition for forged heat-resistant piping: normalized and tempered for 320 MPa yield, 30% elongation and creep capability to 550 °C.
Values for the N+T condition
Other A369 FP12 tempers and conditions
A369 FP12 is listed in 3 conditions; see the grade overview at A369 FP12.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick the softest state, 130 HB, for forged fitting blanks needing heavy machining or cold bending, accepting 255 MPa yield and a 540 °C service limit. | 255 | 455 | 35 | 130 HB | — |
N+TDefaultThis page Normalized and tempered | Choose the usual delivery condition for forged heat-resistant piping: normalized and tempered for 320 MPa yield, 30% elongation and creep capability to 550 °C. | 320 | 510 | 30 | 150 HB | — |
Quenched and tempered | Specify this non-standard but negotiable condition when thick-wall forged pipe needs 430 MPa room-temperature yield; high-temperature creep is no better than normalized and tempered. | 430 | 585 | 24 | 12 HRC | 7.5 % IACS |
What is A369 FP12 N+T?
A369 FP12 N+T is A369 FP12 heat treated to N+T — choose the usual delivery condition for forged heat-resistant piping: normalized and tempered for 320 MPa yield, 30% elongation and creep capability to 550 °C. A369 FP12 N+T has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 81% of steel grades. Elongation at break is 30% and the elastic modulus is 207 GPa (30 Msi). A369 FP12 N+T 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).
Advantages
- Tough — resists crack growth — 150 MPa·√m (136.5 ksi·√in), better than 96% of steel grades
- High service temperature — 550°C (1,022 °F), better than 95% of steel grades
- Ductile — tolerates forming and impact — 30%, better than 93% of steel grades
Limitations
- Low strength — 320 MPa (46.4 ksi), worse than 81% of steel grades
A369 FP12 N+T properties
Typical room-temperature values for A369 FP12 N+T; 11 are specific to this condition. Other listed values are A369 FP12 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A369 FP12 N+T 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).
Mechanical15
A369 FP12 N+T has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 81% of steel grades. Elongation at break is 30% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A369 FP12 N+T is rated for continuous service to 550°C (1,022 °F). It conducts heat at 41 W/m·K (23.7 BTU/hr·ft·°F), worse than 62% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
A369 FP12 N+T conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of A369 FP12 N+T takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability6
A369 FP12 N+T's machinability is good (55/100, better than 62% of steel grades); weldability good (62/100); formability good (55/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A369 FP12 N+T
Is A369 FP12 easy to machine?
Machinability in the annealed condition is about 60% of AISI 1212; use coated carbide, moderate cutting speed and ample coolant. Tool wear is slightly higher in the normalized-and-tempered condition.
Can A369 FP12 be welded?
Weld by GTAW/SMAW with E8018-B2 or ER80S-B2 filler, preheating to 150–250 °C. Temper/stress-relieve at 690–740 °C after welding to prevent cracking in the hardened heat-affected zone.
Can A369 FP12 be formed, bent or molded?
Hot bending and hot forming at 900–1000 °C are preferred for heavy-wall pipe; cold-bent pipe must be re-normalized and tempered to restore the microstructure.
What surface finishes work on A369 FP12?
No self-passivating capability: blast the outside surface and apply a high-temperature protective coating or aluminize it. Bores are normally left in the as-machined condition.
A369 FP12 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 |
|---|---|---|
| C | 0.05 – 0.15 | 0.1 |
| Mn | 0.3 – 0.61 | 0.45 |
| Simax only | ≤ 0.5 | 0.25 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Cr | 0.8 – 1.25 | 1 |
| Mo | 0.44 – 0.65 | 0.55 |
| Fe | balance | — |
A369 FP12 N+T — frequently asked
What is A369 FP12 N+T used for?
A369 FP12 N+T is typically used for power plant high-temperature steam piping, process piping headers, boiler connecting and reheat lines, forged pipe fittings and nozzles for Cr-Mo systems, superheater outlet piping and petrochemical hot process lines. In short: entry-level Cr-Mo creep pipe; forged equivalent of P12; weldable to 550 °C service.
What is the yield strength of A369 FP12 N+T?
A369 FP12 N+T has a typical yield strength of 320 MPa (46.4 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 81% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is A369 FP12 N+T easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machinability in the annealed condition is about 60% of AISI 1212; use coated carbide, moderate cutting speed and ample coolant. Tool wear is slightly higher in the normalized-and-tempered condition.
Can A369 FP12 N+T be welded?
Yes — weldability is rated good (62/100). Weld by GTAW/SMAW with E8018-B2 or ER80S-B2 filler, preheating to 150–250 °C. Temper/stress-relieve at 690–740 °C after welding to prevent cracking in the hardened heat-affected zone.
What surface finishes work on A369 FP12 N+T?
No self-passivating capability: blast the outside surface and apply a high-temperature protective coating or aluminize it. Bores are normally left in the as-machined condition.
Can A369 FP12 N+T be formed, bent or molded?
Hot bending and hot forming at 900–1000 °C are preferred for heavy-wall pipe; cold-bent pipe must be re-normalized and tempered to restore the microstructure.
What is the maximum service temperature of A369 FP12 N+T?
A369 FP12 N+T 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 A369 FP12 N+T and A369 FP12-A?
N+T is the default condition — choose the usual delivery condition for forged heat-resistant piping: normalized and tempered for 320 MPa yield, 30% elongation and creep capability to 550 °C. A: pick the softest state, 130 HB, for forged fitting blanks needing heavy machining or cold bending, accepting 255 MPa yield and a 540 °C service limit. Yield strength is 320 MPa in N+T versus 255 MPa in A.
Sources
- ASTM A369/A369M — Carbon and Ferritic Alloy Steel Forged and Bored Pipe for High-Temperature Service — ASTM International (2018)
- ASTM A335/A335M — Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service (P12) — ASTM International (2022)
- 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)
- GB/T 5310 — (15CrMo) — SAC (2017)
- Mysteel/SMM (2025)
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.