Steel A335 P11 N&T (Normalized and tempered)
Heat-treated state
ASTM A335 P11 · EN 10CrMo5-5
Default stocked condition for boiler and high-temperature piping: balanced strength, toughness and creep performance with hardness kept under ~163 HB.
Values for the N&T condition
Other A335 P11 tempers and conditions
A335 P11 is listed in 5 conditions; see the grade overview at A335 P11.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full anneal or isothermal anneal (A335 heat-treated condition) | Softest code-compliant condition; choose for maximum bendability, cold expansion and lowest hardness for sour/NACE service. | 275 | 465 | 33 | 140 HB | — |
N&TThis page Normalized and tempered | Default stocked condition for boiler and high-temperature piping: balanced strength, toughness and creep performance with hardness kept under ~163 HB. | 310 | 485 | 30 | 155 HB | — |
HRDefault Hot rolled | Mill hot-finished condition before final heat treatment — used only for redraw/forming stock, since A335 requires final heat treatment for code service. | 340 | 520 | 26 | 170 HB | — |
austenitized ~900–950 °C, air cooled (no temper) | Uniform fine ferrite-bainite with higher strength than annealed; usually followed by tempering, and rarely shipped untempered for code piping. | 350 | 530 | 27 | 170 HB | — |
Quenched and tempered | Used 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 | 620 | 22 | 16 HRC | — |
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 93% 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 are specific to this condition. Other listed values are A335 P11 reference data and may not represent this condition. Bars are the position among steel grades.
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 69% 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 57% 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. Confirm any required mill or lot documentation when quoting.
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; every part is priced by an engineer rather than instantly. 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.