Steel X11CrMo9-1
EN X11CrMo9-1 · ASTM A335 P9
X11CrMo9-1 (1.7386, A335 P9) is a 9 % Cr–1 % Mo martensitic heat-resistant steel for service where 2.25Cr grades run out of oxidation and creep capability; it ships as tube, pipe and fittings in +NT, +I, +A and +QT.
Reference datasheet — X11CrMo9-1 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the +NT condition
X11CrMo9-1 tempers and conditions
X11CrMo9-1 is supplied in 4 conditions, soft to hard. +NT is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Use when maximum softness for deep machining or cold bending is required; strength/creep properties must be restored by later +NT. | 245 | 455 | 30 | 150 HB | 3 % IACS |
Isothermally annealed | Pick for bar/forging stock that must be machined or cold worked before final normalizing and tempering; softest, most uniform structure. | 260 | 470 | 28 | 160 HB | — |
+NTDefault Normalized and tempered | Standard supply condition for boiler tubes, headers and P9 process piping; best creep strength and toughness combination. | 300 | 520 | 26 | 185 HB | — |
Quenched and tempered | Used for heavy-wall forgings, valve bodies and thick flanges (EN 10222-2) where through-thickness strength and toughness are needed. | 360 | 570 | 22 | 18 HRC | — |
What is X11CrMo9-1?
X11CrMo9-1 (1.7386, A335 P9) is a 9 % Cr–1 % Mo martensitic heat-resistant steel for service where 2.25Cr grades run out of oxidation and creep capability; it ships as tube, pipe and fittings in +NT, +I, +A and +QT. Default +NT values are 300 MPa yield, 520 MPa tensile, 26 % elongation and about 185 HB (90 HRB), with a service limit near 600 °C. High chromium lowers machinability (45), formability (40) and weldability (40), and welds need 200–300 °C preheat plus 730–780 °C PWHT. It resists hot oxidation but not ambient rust; 10CrMo9-10 is the cheaper choice below 570 °C. X11CrMo9-1 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 93% of steel grades. It melts at 1,420°C (2,588 °F). X11CrMo9-1 has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 86% of steel grades. Elongation at break is 26% and the elastic modulus is 213 GPa (30.9 Msi).
What is X11CrMo9-1 used for?
- Superheater and reheater tubes
- High-temperature, high-pressure process piping
- Refinery heater tubes
- Hydrogen-service piping
- Catalytic reformer piping
- Forged fittings and valve bodies
- Steam piping spools
Advantages
- High service temperature — 600°C (1,112 °F), better than 98% of steel grades
- Good corrosion resistance — 30/100, better than 95% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
Limitations
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- Low strength — 300 MPa (43.5 ksi), worse than 86% of steel grades
- Poor heat conductor — 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 84% of steel grades
X11CrMo9-1 properties
Typical room-temperature values for X11CrMo9-1-+NT; bars are the position among steel grades.
Physical3
X11CrMo9-1 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 93% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
X11CrMo9-1 has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 86% of steel grades. Elongation at break is 26% and the elastic modulus is 213 GPa (30.9 Msi).
Thermal6
X11CrMo9-1 is rated for continuous service to 600°C (1,112 °F). It conducts heat at 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 84% of steel grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
X11CrMo9-1 conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of X11CrMo9-1 takes about 31 MJ of energy and emits 2.4 kg of CO₂ — more than 64% of steel grades. Typical recycled content is 25%.
Manufacturability7
X11CrMo9-1's machinability is fair (45/100, worse than 65% of steel grades); weldability fair (40/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. X11CrMo9-1 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with X11CrMo9-1
Is X11CrMo9-1 easy to machine?
Machines like a medium-hard low-alloy steel — best in +I/+A condition with rigid setups, sharp carbide, moderate speeds and generous coolant; work-hardening tendency is low but tool wear from Cr carbides is noticeable.
Can X11CrMo9-1 be welded?
Weldable with matching 9Cr-1Mo (E505/ER90S-B8) consumables; preheat 200–300 °C, maintain interpass, avoid interruption, and apply 730–780 °C PWHT to avoid hard untempered martensite and hydrogen cracking.
Can X11CrMo9-1 be formed, bent or molded?
Hot form/bend at 900–1050 °C then re-normalize and temper; cold bending is limited and any cold work above ~5–10 % should be followed by stress relief or full +NT.
X11CrMo9-1 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 | 0.08 – 0.15 | 0.12 |
| Si | 0.25 – 1 | 0.5 |
| Mn | 0.3 – 0.6 | 0.45 |
| PEN limit; ASTM A335 P9 allows 0.025 | ≤ 0.02 | |
| SEN limit; ASTM A335 P9 allows 0.025 | ≤ 0.01 | |
| Cr | 8 – 10 | 9 |
| Mo | 0.9 – 1.1 | 1 |
| Niresidual | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on X11CrMo9-1?
No anodizing; protect with high-temperature aluminium/silicone paint, aluminizing or phosphate primer for wet service — the 9 % Cr gives oxidation resistance hot but not rust resistance cold.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel X11CrMo9-1 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- A335 P9
- EN / DIN / Werkstoff-Nr.
- 1.7386
How much does X11CrMo9-1 cost?
X11CrMo9-1 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
X11CrMo9-1 — frequently asked
What is X11CrMo9-1 used for?
X11CrMo9-1 is typically used for superheater and reheater tubes, high-temperature, high-pressure process piping, refinery heater tubes, hydrogen-service piping, catalytic reformer piping and forged fittings and valve bodies. In short: highest-temperature Cr-Mo here; 9 % Cr oxidation resistance; hardest of family to weld.
What is the yield strength of X11CrMo9-1?
X11CrMo9-1 has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 86% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is X11CrMo9-1 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machines like a medium-hard low-alloy steel — best in +I/+A condition with rigid setups, sharp carbide, moderate speeds and generous coolant; work-hardening tendency is low but tool wear from Cr carbides is noticeable.
Can X11CrMo9-1 be welded?
With care — weldability is rated fair (40/100). Weldable with matching 9Cr-1Mo (E505/ER90S-B8) consumables; preheat 200–300 °C, maintain interpass, avoid interruption, and apply 730–780 °C PWHT to avoid hard untempered martensite and hydrogen cracking.
What surface finishes work on X11CrMo9-1?
No anodizing; protect with high-temperature aluminium/silicone paint, aluminizing or phosphate primer for wet service — the 9 % Cr gives oxidation resistance hot but not rust resistance cold.
Can X11CrMo9-1 be formed, bent or molded?
Hot form/bend at 900–1050 °C then re-normalize and temper; cold bending is limited and any cold work above ~5–10 % should be followed by stress relief or full +NT.
What is the maximum service temperature of X11CrMo9-1?
X11CrMo9-1 is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does X11CrMo9-1 cost?
X11CrMo9-1 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- EN 10216-2 — Seamless steel tubes for pressure purposes, alloy steel with specified elevated temperature properties — CEN (2020)
- ASTM A335/A335M — Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service (Grade P9) — ASTM (2023)
- ASTM A213/A213M — Seamless Ferritic Alloy-Steel Boiler Tubes (Grade T9) — ASTM (2022)
- ASME BPVC Section II Part D — Materials, Properties (9Cr-1Mo) — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- GB/T 5310 — Seamless steel tubes for high pressure boilers (12Cr9Mo1 ) — SAC (2017)
- Mysteel / SMM (2026)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.