Steel A369 FP92-ANN (Annealed)
Heat-treated state
ASTM A369 FP92
Intermediate softened state supplied for heavy machining or cold work; must be re-normalized and tempered before pressure service.
Values for the ANN condition
Other A369 FP92 tempers and conditions
A369 FP92 is listed in 5 conditions; see the grade overview at A369 FP92.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNThis page Annealed | Intermediate softened state supplied for heavy machining or cold work; must be re-normalized and tempered before pressure service. | 400 | 600 | 26 | 10 HRC | 3 % IACS |
N+T | Use where hardness must stay well below 250 HB (heavy field welding, NDE hardness surveys) and maximum Charpy energy is wanted. | 470 | 655 | 24 | 14 HRC | 2.9 % IACS |
N+TDefault Normalized and tempered | Standard delivery condition for all A369 FP92 pipe — the only state accepted for pressure service. | 510 | 700 | 22 | 19 HRC | — |
N+T | Pick when the purchaser wants the top of the strength band (thick headers, high design stress) and can accept hardness near the 250 HB limit. | 570 | 770 | 19 | 23 HRC | 2.9 % IACS |
As-forged / as-quenched | Condition of the forged and bored shell before final N+T; hard and brittle, listed only for shop handling and machining planning. | 950 | 1,300 | 9 | 43 HRC | 2.5 % IACS |
What is A369 FP92-ANN?
A369 FP92-ANN is A369 FP92 heat treated to ANN — intermediate softened state supplied for heavy machining or cold work; must be re-normalized and tempered before pressure service. A369 FP92-ANN has a yield strength of 400 MPa (58 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 60% of steel grades. Elongation at break is 26% and the elastic modulus is 218 GPa (31.6 Msi). A369 FP92-ANN has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,420°C (2,588 °F). N+T is the default condition FabDigit quotes; ANN is available on request or by drawing note.
Advantages
- Good corrosion resistance — 30/100, better than 95% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
Limitations
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
- Poor heat conductor — 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades
A369 FP92-ANN properties
Typical room-temperature values for A369 FP92-ANN; 23 are specific to this condition. Other listed values are A369 FP92 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A369 FP92-ANN has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
A369 FP92-ANN has a yield strength of 400 MPa (58 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 60% of steel grades. Elongation at break is 26% and the elastic modulus is 218 GPa (31.6 Msi).
Thermal6
A369 FP92-ANN is rated for continuous service to 400°C (752 °F). It conducts heat at 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades. Thermal expansion is 10.8 µm/m·K (6 µin/in·°F).
Electrical2
A369 FP92-ANN has an electrical resistivity of 5.8×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of A369 FP92-ANN takes about 34 MJ of energy and emits 2.6 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability6
A369 FP92-ANN's machinability is fair (50/100, worse than 53% of steel grades); weldability fair (40/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A369 FP92-ANN
Is A369 FP92 easy to machine?
Machine in the N+T (200–230 HB) state with rigid setups, coated carbide, moderate speed and heavy positive feed; Nb/V carbides are abrasive and the steel work-hardens if feeds are too light.
Can A369 FP92 be welded?
GTAW root + SMAW/FCAW/SAW with matching 9Cr-2W consumables, 200–250 °C preheat, interpass ≤300 °C, cool to <100 °C then PWHT 750–770 °C for 2–4 h; avoid over-alloyed weld metal and minimize heat input to limit Type IV HAZ cracking.
Can A369 FP92 be formed, bent or molded?
Hot bend/forge at 1050–1150 °C followed by full re-normalizing and tempering; cold bending is limited and any significant cold strain requires re-heat treatment.
What surface finishes work on A369 FP92?
Supplied machined/bored or shot-blast finished; use high-temperature aluminide or Al-rich paint plus insulation for outer surfaces — the steel is not stainless and rusts freely in wet ambient storage.
A369 FP92 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 | 0.07 – 0.13 | 0.11 |
| Mn | 0.3 – 0.6 | 0.45 |
| Si | ≤ 0.5 | 0.25 |
| P | ≤ 0.02 | 0.01 |
| S | ≤ 0.01 | 0 |
| Cr | 8.5 – 9.5 | 9 |
| Mo | 0.3 – 0.6 | 0.45 |
| Wsolid-solution strengthener, key P92 addition | 1.5 – 2 | 1.75 |
| V | 0.15 – 0.25 | 0.2 |
| Nb | 0.04 – 0.09 | 0.06 |
| N | 0.03 – 0.07 | 0.05 |
| Bstabilizes M23C6 at grain boundaries | 0 – 0.01 | 0 |
| Ni | ≤ 0.4 | 0.15 |
| Allow Al to keep N available for MX | ≤ 0.04 | 0.02 |
| Ti | ≤ 0.01 | — |
| Zr | ≤ 0.01 | — |
| Fe | balance | — |
A369 FP92-ANN — frequently asked
What is A369 FP92-ANN used for?
A369 FP92-ANN is typically used for ultra-supercritical boiler piping, high-pressure steam headers, main steam and hot reheat lines, superheater and reheater outlet headers, forged and bored thick-wall pipe spools and high-temperature pipe fittings and elbows. In short: higher creep strength than P91; 620 °C service capability; most demanding weld procedure.
What is the yield strength of A369 FP92-ANN?
A369 FP92-ANN has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A369 FP92-ANN easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the N+T (200–230 HB) state with rigid setups, coated carbide, moderate speed and heavy positive feed; Nb/V carbides are abrasive and the steel work-hardens if feeds are too light.
Can A369 FP92-ANN be welded?
With care — weldability is rated fair (40/100). GTAW root + SMAW/FCAW/SAW with matching 9Cr-2W consumables, 200–250 °C preheat, interpass ≤300 °C, cool to <100 °C then PWHT 750–770 °C for 2–4 h; avoid over-alloyed weld metal and minimize heat input to limit Type IV HAZ cracking.
What surface finishes work on A369 FP92-ANN?
Supplied machined/bored or shot-blast finished; use high-temperature aluminide or Al-rich paint plus insulation for outer surfaces — the steel is not stainless and rusts freely in wet ambient storage.
Can A369 FP92-ANN be formed, bent or molded?
Hot bend/forge at 1050–1150 °C followed by full re-normalizing and tempering; cold bending is limited and any significant cold strain requires re-heat treatment.
What is the maximum service temperature of A369 FP92-ANN?
A369 FP92-ANN is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A369 FP92 N+T and A369 FP92-AF?
N+T is the default condition — standard delivery condition for all A369 FP92 pipe — the only state accepted for pressure service. AF: condition of the forged and bored shell before final N+T; hard and brittle, listed only for shop handling and machining planning. Yield strength is 510 MPa in N+T versus 950 MPa in AF.
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 (Grade P92) — ASTM International (2022)
- EN 10216-2 — Seamless steel tubes for pressure purposes, X10CrWMoVNb9-2 (1.4901) — CEN (2020)
- ASME BPVC Section II Part D / B31.1 allowable stresses for Grade 92 — ASME (2023)
- NIMS Creep Data Sheet series, 9Cr-1.8W-0.5Mo-VNb steel — NIMS (2014)
- ASM Handbook Vol.1 — Properties of Heat-Resistant Ferritic Steels — ASM International (1990)
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.