Stainless Steel 1.4901-AW (As-welded deposit)
Heat-treated state
EN 1.4901
Transient condition only — hard, brittle untempered martensite; never acceptable for service, PWHT is mandatory.
Values for the AW condition
Other 1.4901 tempers and conditions
1.4901 is listed in 5 conditions; see the grade overview at 1.4901.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Interim softened condition for heavy machining or cold bending; must be re-normalized and tempered before creep service. | 370 | 570 | 26 | 9 HRC | 3.1 % IACS |
N+T + PWHT | Condition of a fabricated/welded assembly after mandatory subcritical PWHT; slightly softened base metal, code-required before service. | 480 | 660 | 23 | 17 HRC | 3 % IACS |
N+TDefault Normalized and tempered | Standard mill delivery condition for P92/T92 seamless pipe and tube; use for all code-design creep applications. | 520 | 700 | 22 | 20 HRC | — |
Quenched and tempered | For thick forgings, valve bodies and headers where liquid/accelerated quenching is needed to obtain fully martensitic through-thickness structure. | 550 | 730 | 20 | 22 HRC | 3 % IACS |
AWThis page As-welded deposit | Transient condition only — hard, brittle untempered martensite; never acceptable for service, PWHT is mandatory. | 720 | 950 | 12 | 43 HRC | 2.8 % IACS |
What is 1.4901-AW?
1.4901-AW is 1.4901 heat treated to AW — transient condition only — hard, brittle untempered martensite; never acceptable for service, PWHT is mandatory. 1.4901-AW has a yield strength of 720 MPa (104 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 93% of stainless steel grades. Elongation at break is 12% and the elastic modulus is 216 GPa (31.3 Msi). 1.4901-AW has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 57% of stainless steel grades. It melts at 1,425°C (2,597 °F). N+T is the default condition FabDigit quotes; AW is available on request or by drawing note.
Advantages
- Low embodied carbon — 2.6 kg CO₂/kg, better than 100% of stainless steel grades
- High strength — 720 MPa (104 ksi), better than 93% of stainless steel grades
- Conducts heat well — 24 W/m·K (13.9 BTU/hr·ft·°F), better than 81% of stainless steel grades
Limitations
- Limited service temperature — 0°C (32 °F), worse than 100% of stainless steel grades
- Needs corrosion protection — 27/100, worse than 100% of stainless steel grades
- Difficult to machine — 18/100, worse than 99% of stainless steel grades
- Limited formability — 8/100, worse than 97% of stainless steel grades
- Limited ductility — 12%, worse than 95% of stainless steel grades
1.4901-AW properties
Typical room-temperature values for 1.4901-AW; 22 are specific to this condition. Other listed values are 1.4901 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4901-AW has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 57% of stainless steel grades. It melts at 1,425°C (2,597 °F).
Mechanical17
1.4901-AW has a yield strength of 720 MPa (104 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 93% of stainless steel grades. Elongation at break is 12% and the elastic modulus is 216 GPa (31.3 Msi).
Thermal6
1.4901-AW is rated for continuous service to 0°C (32 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), better than 81% of stainless steel grades. Thermal expansion is 10.8 µm/m·K (6 µin/in·°F).
Electrical2
1.4901-AW has an electrical resistivity of 6.1×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (27/100), worse than 100% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4901-AW takes about 33 MJ of energy and emits 2.6 kg of CO₂ — less than 100% of stainless steel grades. Typical recycled content is 45%.
Manufacturability7
1.4901-AW's machinability is poor (18/100, worse than 99% of stainless steel grades); weldability poor (25/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4901-AW
Is 1.4901 easy to machine?
Machines like a 200–230 HB Q&T alloy steel — rigid setups, coated carbide, moderate speed with generous feed; avoid overheating the surface which can locally re-harden.
Can 1.4901 be welded?
GTAW root + SMAW/FCAW fill with matching 9Cr-2W filler, preheat 200–250 °C, interpass ≤300 °C, cool to <100 °C then mandatory PWHT 750–775 °C; strict control needed to limit Type IV HAZ cracking.
Can 1.4901 be formed, bent or molded?
Hot form/bend at 950–1150 °C followed by full re-normalizing and tempering; cold bends above a few percent strain also require re-N+T.
What surface finishes work on 1.4901?
Not corrosion resistant — shot blast plus primer/paint or preservation oil for storage; internal steam-side relies on the chromia/magnetite oxide, external hot surfaces may be aluminized.
1.4901 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 | 0.1 |
| Si | ≤ 0.5 | 0.3 |
| Mn | 0.3 – 0.6 | 0.45 |
| P | ≤ 0.02 | 0.01 |
| S | ≤ 0.01 | 0 |
| Cr | 8.5 – 9.5 | 9 |
| Mo | 0.3 – 0.6 | 0.45 |
| Wkey creep-strengthening addition vs P91 | 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 during creep | 0 – 0.01 | 0 |
| Ni | ≤ 0.4 | 0.15 |
| Allow Al so that AlN does not consume nitrogen | ≤ 0.02 | 0.01 |
| Ti | ≤ 0.01 | — |
| Zr | ≤ 0.01 | — |
| Fe | balance | — |
1.4901-AW — frequently asked
What is 1.4901-AW used for?
1.4901-AW is typically used for power plant superheater tubing, high-pressure steam piping and boiler headers. In short: P92 creep-resisting 9Cr steel; service to 620 °C; mandatory post-weld heat treatment.
What is the yield strength of 1.4901-AW?
1.4901-AW has a typical yield strength of 720 MPa (104 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 93% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is 1.4901-AW easy to machine?
Not especially — machinability is rated poor (18/100, worse than 99% of stainless steel grades). Machines like a 200–230 HB Q&T alloy steel — rigid setups, coated carbide, moderate speed with generous feed; avoid overheating the surface which can locally re-harden.
Can 1.4901-AW be welded?
Not readily — weldability is rated poor (25/100). GTAW root + SMAW/FCAW fill with matching 9Cr-2W filler, preheat 200–250 °C, interpass ≤300 °C, cool to <100 °C then mandatory PWHT 750–775 °C; strict control needed to limit Type IV HAZ cracking.
What surface finishes work on 1.4901-AW?
Not corrosion resistant — shot blast plus primer/paint or preservation oil for storage; internal steam-side relies on the chromia/magnetite oxide, external hot surfaces may be aluminized.
Can 1.4901-AW be formed, bent or molded?
Hot form/bend at 950–1150 °C followed by full re-normalizing and tempering; cold bends above a few percent strain also require re-N+T.
What is the maximum service temperature of 1.4901-AW?
1.4901-AW is rated for continuous use to about 0°C (32 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.4901 N+T and 1.4901-AW?
N+T is the default condition — standard mill delivery condition for P92/T92 seamless pipe and tube; use for all code-design creep applications. AW: transient condition only — hard, brittle untempered martensite; never acceptable for service, PWHT is mandatory. Yield strength is 520 MPa in N+T versus 720 MPa in AW.
Sources
- EN 10216-2 — Seamless steel tubes for pressure purposes, alloy steels with specified elevated-temperature properties (X10CrWMoVNb9-2, 1.4901) — CEN (2020)
- ASTM A335/A335M Grade P92 — Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service — ASTM International (2022)
- ASTM A213/A213M Grade T92 and A182 Grade F92 — ASTM International (2022)
- GB/T 5310 — (10Cr9MoW2VNbBN) — SAC (2017)
- ASME BPVC Section II Part D — allowable stresses and physical properties for 9Cr-2W steel — ASME (2023)
- NIMS Creep Data Sheet series on ASME Gr.92 (9Cr-0.5Mo-1.8W-V-Nb) steel — NIMS (2014)
- Seamless P92/T92 boiler tube datasheets — Vallourec / Sandvik / Baosteel (2022)
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.