Steel ER90S-B9
UNS S50482
ER90S-B9 is a modified 9Cr-1Mo-V-Nb solid filler wire (UNS S50482) matched to P91/T91 creep-strength-enhanced ferritic steel.
Reference datasheet — ER90S-B9 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 PWHT condition
ER90S-B9 tempers and conditions
ER90S-B9 is supplied in 4 conditions, soft to hard. PWHT 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 |
|---|---|---|---|---|---|---|
extended temper 760 °C / 4–8 h (heavy-wall, hardness-controlled) | Choose for thick-wall headers or repeated PWHT cycles where hardness must be driven below ~250 HV; softer and tougher, slightly lower strength. | 540 | 670 | 22 | 15 HRC | 2.9 % IACS |
Normalized and tempered | Used when the whole fabrication is re-austenitized (e.g. forged/cast components with weld build-up), restoring uniform fine martensite and best creep response. | 570 | 700 | 22 | 19 HRC | 2.9 % IACS |
PWHTDefault Post-weld heat treated | Standard delivered/qualified condition for P91 joints: temper at 745–775 °C after cooling below ~100 °C, giving tempered martensite with balanced strength and toughness. | 590 | 720 | 20 | 21 HRC | — |
As-welded deposit | Condition immediately after welding — very hard and brittle; only an interim state, never acceptable for service on P91 pressure parts. | 850 | 1,100 | 11 | 43 HRC | — |
What is ER90S-B9?
ER90S-B9 is a modified 9Cr-1Mo-V-Nb solid filler wire (UNS S50482) matched to P91/T91 creep-strength-enhanced ferritic steel. It is the standard consumable for modern supercritical power plant high-temperature piping and is supplied as bright, copper-free spooled wire or cut GTAW rods. Deposits reach about 590 MPa yield, 720 MPa tensile, 20 % elongation, 220 HB (21 HRC) and a 600 °C service rating, with a corrosion resistance score of 30. The tight N and Al balance, mandatory PWHT and hardness verification make it process-sensitive; use a 2.25Cr-1Mo wire such as ER90S-B3 for lower-temperature P22 work. ER90S-B9 has a density of 7.77 g/cm³ (0.281 lb/in³), lighter than 92% of steel grades. It melts at 1,420°C (2,588 °F). ER90S-B9 has a yield strength of 590 MPa (85.6 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 76% of steel grades. Elongation at break is 20% and the elastic modulus is 218 GPa (31.6 Msi).
What is ER90S-B9 used for?
- P91/T91 boiler piping welding
- supercritical power plant construction
- high-temperature steam header welds
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
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
- High strength — 590 MPa (85.6 ksi), better than 76% of steel grades
Limitations
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- Poor heat conductor — 26 W/m·K (15 BTU/hr·ft·°F), worse than 87% of steel grades
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
- Difficult to machine — 35/100, worse than 84% of steel grades
ER90S-B9 properties
Typical room-temperature values for ER90S-B9-PWHT; bars are the position among steel grades.
Physical3
ER90S-B9 has a density of 7.77 g/cm³ (0.281 lb/in³), lighter than 92% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
ER90S-B9 has a yield strength of 590 MPa (85.6 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 76% of steel grades. Elongation at break is 20% and the elastic modulus is 218 GPa (31.6 Msi).
Thermal6
ER90S-B9 is rated for continuous service to 600°C (1,112 °F). It conducts heat at 26 W/m·K (15 BTU/hr·ft·°F), worse than 87% of steel grades. Thermal expansion is 10.6 µm/m·K (5.89 µin/in·°F).
Electrical3
ER90S-B9 conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of ER90S-B9 takes about 34 MJ of energy and emits 2.6 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 20%.
Manufacturability7
ER90S-B9's machinability is fair (35/100, worse than 84% of steel grades); weldability fair (45/100); formability poor (30/100).
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. ER90S-B9 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ER90S-B9
Is ER90S-B9 easy to machine?
Weld metal machines like a Q&T low-alloy steel after PWHT (~40 % of AISI 1212); in the as-welded 400+ HV state use carbide/CBN or machine only after tempering.
Can ER90S-B9 be welded?
GTAW/GMAW with Ar (or Ar+2–5 % CO₂ for GMAW); preheat and interpass 200–300 °C, cool to 80–100 °C to transform martensite, then PWHT 745–775 °C, 2 h min — never leave a P91 joint untempered.
Can ER90S-B9 be formed, bent or molded?
Supplied as drawn and copper-free (bright) wire on spools or cut rods; no forming of the deposit, but keep wire dry and clean to protect the tight N and Al balance.
ER90S-B9 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 |
| MnMn + Ni ≤ 1.40 % (AC1 control) | ≤ 1.2 | 0.6 |
| Si | 0.15 – 0.3 | 0.25 |
| P | ≤ 0.01 | 0.01 |
| S | ≤ 0.01 | 0.01 |
| Cr | 8 – 9.5 | 8.8 |
| Mo | 0.85 – 1.05 | 0.95 |
| V | 0.15 – 0.25 | 0.2 |
| Nbreported as Cb in AWS | 0.02 – 0.1 | 0.05 |
| NAl/N ratio must be kept low for creep strength | 0.03 – 0.07 | 0.05 |
| NiMn + Ni ≤ 1.40 % | ≤ 0.8 | 0.4 |
| Cu | ≤ 0.2 | 0.05 |
| Al | ≤ 0.04 | 0.01 |
| Ti | ≤ 0.01 | |
| Zr | ≤ 0.01 | |
| Fe | balance |
What surface finishes work on ER90S-B9?
Grind flush and PT/UT inspect; verify hardness ≤ ~265 HV after PWHT, then paint or insulate — the 9Cr deposit rusts in humid air like a low-alloy steel.
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 ER90S-B9 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S50482
- Other
- ER62S-B9
How much does ER90S-B9 cost?
ER90S-B9 is a high-cost steel ($$$$), pricier than about 78% 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.
ER90S-B9 — frequently asked
What is ER90S-B9 used for?
ER90S-B9 is typically used for P91/T91 boiler piping welding, supercritical power plant construction and high-temperature steam header welds. In short: matched P91/T91 filler; 600 °C creep-rated deposit; PWHT mandatory after welding.
What is the yield strength of ER90S-B9?
ER90S-B9 has a typical yield strength of 590 MPa (85.6 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 76% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is ER90S-B9 easy to machine?
Not especially — machinability is rated fair (35/100, worse than 84% of steel grades). Weld metal machines like a Q&T low-alloy steel after PWHT (~40 % of AISI 1212); in the as-welded 400+ HV state use carbide/CBN or machine only after tempering.
Can ER90S-B9 be welded?
With care — weldability is rated fair (45/100). GTAW/GMAW with Ar (or Ar+2–5 % CO₂ for GMAW); preheat and interpass 200–300 °C, cool to 80–100 °C to transform martensite, then PWHT 745–775 °C, 2 h min — never leave a P91 joint untempered.
What surface finishes work on ER90S-B9?
Grind flush and PT/UT inspect; verify hardness ≤ ~265 HV after PWHT, then paint or insulate — the 9Cr deposit rusts in humid air like a low-alloy steel.
Can ER90S-B9 be formed, bent or molded?
Supplied as drawn and copper-free (bright) wire on spools or cut rods; no forming of the deposit, but keep wire dry and clean to protect the tight N and Al balance.
What is the maximum service temperature of ER90S-B9?
ER90S-B9 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.
What is the difference between ER90S-B9 PWHT and ER90S-B9-AW?
PWHT is the default condition — standard delivered/qualified condition for P91 joints: temper at 745–775 °C after cooling below ~100 °C, giving tempered martensite with balanced strength and toughness. AW: condition immediately after welding — very hard and brittle; only an interim state, never acceptable for service on P91 pressure parts. Yield strength is 590 MPa in PWHT versus 850 MPa in AW.
How much does ER90S-B9 cost?
ER90S-B9 is a high-cost steel ($$$$), pricier than about 78% 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
- AWS A5.28/A5.28M — Low-Alloy Steel Electrodes and Rods for Gas Shielded Arc Welding (ER90S-B9) — AWS (2020)
- ASME BPVC Section II Part C, SFA-5.28 — ASME (2023)
- ASME BPVC Section II Part D — Physical properties of Grade 91 (9Cr-1Mo-V) — ASME (2023)
- EN ISO 21952-A — Wire electrodes for gas shielded arc welding of creep-resisting steels (W CrMo91) — ISO (2012)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels — ASM International (1990)
- Thermanit MTS 3 / Böhler C 9 MV-IG all-weld-metal data — voestalpine Böhler Welding (2022)
- Metrode 9CrMoV-N TIG/MIG wire datasheet — Lincoln Electric (Metrode) (2021)
- EPRI Grade 91 Steel Handbook — welding and PWHT guidance — EPRI (2015)
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.