Steel A335 P11 · heat-treated state
Steel A335 P11 N&T
Properties of the N&T condition, compared with the other A335 P11 tempers.
Default stocked condition for boiler and high-temperature piping: balanced strength, toughness and creep performance with hardness kept under ~163 HB.
What is A335 P11 N&T?
A335 P11 N&T is A335 P11 heat treated to N&T — default stocked condition for boiler and high-temperature piping: balanced strength, toughness and creep performance with hardness kept under ~163 HB. A335 P11 N&T has a yield strength of 310 MPa (45 ksi) and a tensile strength of 485 MPa (70.3 ksi) — weaker than 83% of steel grades. Elongation at break is 30% and the elastic modulus is 205 GPa (29.7 Msi). A335 P11 N&T has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,450°C (2,642 °F). HR is the default condition FabDigit quotes; N&T is available on request or by drawing note.
Advantages
- High service temperature — 580°C (1,076 °F), better than 97% of steel grades
- Tough — resists crack growth — 140 MPa·√m (127.4 ksi·√in), better than 94% of steel grades
- Ductile — tolerates forming and impact — 30%, better than 92% of steel grades
Limitations
- Low strength — 310 MPa (45 ksi), worse than 83% of steel grades
A335 P11 N&T properties
Typical room-temperature values for A335 P11 N&T — 16 properties are specific to this condition; the rest are grade-level values shared by every A335 P11 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
A335 P11 N&T has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
A335 P11 N&T has a yield strength of 310 MPa (45 ksi) and a tensile strength of 485 MPa (70.3 ksi) — weaker than 83% of steel grades. Elongation at break is 30% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A335 P11 N&T is rated for continuous service to 580°C (1,076 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 68% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
A335 P11 N&T conducts electricity at 7.8 % IACS, worse than 58% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of A335 P11 N&T takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 25%.
Manufacturability7
A335 P11 N&T's machinability is good (55/100, better than 62% of steel grades); weldability good (60/100); formability good (58/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other A335 P11 tempers and conditions
A335 P11 is also supplied in 4 other conditions. The full side-by-side table is on the A335 P11 overview.
- HRDefaultMill hot-finished condition before final heat treatment — used only for redraw/forming stock, since A335 requires final heat treatment for code service.340 MPa yield · 170 HB
- Q&TUsed for heavy-wall forgings/pipe or bolting-type parts where higher room-temperature strength is needed; check code allowables, since creep strength is set by chemistry not by quenching.470 MPa yield · 16 HRC
- NormalizedUniform fine ferrite-bainite with higher strength than annealed; usually followed by tempering, and rarely shipped untempered for code piping.350 MPa yield · 170 HB
- N&TDefault stocked condition for boiler and high-temperature piping: balanced strength, toughness and creep performance with hardness kept under ~163 HB.310 MPa yield · 155 HB
- AnnealedSoftest code-compliant condition; choose for maximum bendability, cold expansion and lowest hardness for sour/NACE service.275 MPa yield · 140 HB
Working with A335 P11 N&T
Is A335 P11 easy to machine?
Machines like normalized 4130-class low-alloy steel at ~60 % of 1212 — use rigid setups, carbide tooling, moderate speeds and flood coolant; keep hardness ≤163 HB for easy threading and bevelling.
Can A335 P11 be welded?
Readily welded with matching 1.25Cr-0.5Mo filler (E8018-B2 / ER80S-B2), preheat 150–200 °C, interpass control and PWHT 700–750 °C to restore toughness and avoid hydrogen cracking.
Can A335 P11 be formed, bent or molded?
Hot bend 900–1000 °C or cold bend with generous radii followed by re-normalizing/tempering; cold-formed pipe bends normally require post-form heat treatment per ASME B31.1.
What surface finishes work on A335 P11?
No anodizing; protect with high-temperature aluminium/silicone paint, phosphate or aluminizing, and remove mill scale by pickling or blasting before insulation to limit CUI.
A335 P11 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 | 0.12 |
| Si | 0.5 – 1 | 0.7 |
| Mn | 0.3 – 0.6 | 0.45 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Cr | 1 – 1.5 | 1.25 |
| Mo | 0.44 – 0.65 | 0.55 |
| Fe | balance | — |
A335 P11 N&T — frequently asked
What is A335 P11 N&T used for?
A335 P11 N&T is typically used for main steam and reheat piping, boiler superheater and economizer headers, refinery hydroprocessing pipework, hydrocracker transfer lines, high-temperature process manifolds and pipe elbows and fittings. In short: low-alloy chrome-moly pipe.
What is the yield strength of A335 P11 N&T?
A335 P11 N&T has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 485 MPa (70.3 ksi) — weaker than 83% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A335 P11 N&T easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like normalized 4130-class low-alloy steel at ~60 % of 1212 — use rigid setups, carbide tooling, moderate speeds and flood coolant; keep hardness ≤163 HB for easy threading and bevelling.
Can A335 P11 N&T be welded?
Yes — weldability is rated good (60/100). Readily welded with matching 1.25Cr-0.5Mo filler (E8018-B2 / ER80S-B2), preheat 150–200 °C, interpass control and PWHT 700–750 °C to restore toughness and avoid hydrogen cracking.
What surface finishes work on A335 P11 N&T?
No anodizing; protect with high-temperature aluminium/silicone paint, phosphate or aluminizing, and remove mill scale by pickling or blasting before insulation to limit CUI.
Can A335 P11 N&T be formed, bent or molded?
Hot bend 900–1000 °C or cold bend with generous radii followed by re-normalizing/tempering; cold-formed pipe bends normally require post-form heat treatment per ASME B31.1.
What is the maximum service temperature of A335 P11 N&T?
A335 P11 N&T is rated for continuous use to about 580°C (1,076 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in A335 P11 N&T?
Yes — A335 P11 N&T is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A335/A335M — Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service — ASTM International (2023)
- ASME BPVC Section II Part D — Properties (Metric) — ASME (2023)
- GB 5310 — (15CrMoG) — SAC (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- API RP 941 — Steels for Hydrogen Service at Elevated Temperatures — 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.