Steel 15NiCuMoNb5-6-4
EN 15NiCuMoNb5-6-4 · also WB36
15NiCuMoNb5-6-4 (1.6368, trade name WB36) is a Ni-Cu-Mo-Nb creep-resistant low-alloy steel developed for high-temperature boiler and steam service, where copper and niobium additions raise elevated-temperature strength over plain Mn-Mo grades.
Reference datasheet — 15NiCuMoNb5-6-4 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
15NiCuMoNb5-6-4 tempers and conditions
15NiCuMoNb5-6-4 is supplied in 2 conditions, soft to hard. NT is the default FabDigit quotes; the values on this page are for it.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
NTDefault normalized and tempered | Standard delivery condition for WB36 seamless tube, pipe and plate for boiler feedwater and steam service. | 480 | 660 | 23 | 18 HRC | — |
Quenched and tempered | Chosen for heavy-wall headers, forgings and thick plate where through-thickness strength and low-temperature toughness must be maintained. | 530 | 700 | 21 | 20 HRC | — |
What is 15NiCuMoNb5-6-4?
15NiCuMoNb5-6-4 (1.6368, trade name WB36) is a Ni-Cu-Mo-Nb creep-resistant low-alloy steel developed for high-temperature boiler and steam service, where copper and niobium additions raise elevated-temperature strength over plain Mn-Mo grades. In the default condition it gives 480 MPa yield, 660 MPa tensile, 23 % elongation and about 205 HB (18 HRC, 94 HRB), with service to 400 °C, and is used as seamless piping, headers, plate and forgings. Corrosion resistance is minimal (score 18), formability is moderate, and preheat of 150–250 °C with PWHT near 580–620 °C is normally specified. For lower-temperature vessel work, 20MnMoNi4-5 is the common substitute. 15NiCuMoNb5-6-4 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F). 15NiCuMoNb5-6-4 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 59% of steel grades. Elongation at break is 23% and the elastic modulus is 211 GPa (30.6 Msi).
What is 15NiCuMoNb5-6-4 used for?
- Main steam piping
- Boiler headers
- High-temperature pressure components
Advantages
- Tough — resists crack growth — 150 MPa·√m (136.5 ksi·√in), better than 96% of steel grades
15NiCuMoNb5-6-4 properties
Typical room-temperature values for 15NiCuMoNb5-6-4-NT; bars are the position among steel grades.
Physical3
15NiCuMoNb5-6-4 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F).
Mechanical17
15NiCuMoNb5-6-4 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 59% of steel grades. Elongation at break is 23% and the elastic modulus is 211 GPa (30.6 Msi).
Thermal6
15NiCuMoNb5-6-4 is rated for continuous service to 400°C (752 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical2
15NiCuMoNb5-6-4 has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of 15NiCuMoNb5-6-4 takes about 27 MJ of energy and emits 2.1 kg of CO₂ — less than 59% of steel grades. Typical recycled content is 25%.
Manufacturability5
15NiCuMoNb5-6-4's machinability is good (55/100, better than 62% of steel grades); weldability good (62/100); formability fair (50/100).
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. 15NiCuMoNb5-6-4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 15NiCuMoNb5-6-4
Is 15NiCuMoNb5-6-4 easy to machine?
Machines like 4130/4140-class low-alloy steel at ~50–55 % of AISI 1212; use rigid setups, carbide inserts and moderate speeds with good coolant.
Can 15NiCuMoNb5-6-4 be welded?
Weldable by TIG/SMAW/SAW with matched Ni-Cu-Mo consumables; preheat about 150–250 °C and a post-weld heat treatment near 580–620 °C are normally specified to restore HAZ toughness.
Can 15NiCuMoNb5-6-4 be formed, bent or molded?
Hot forming above ~950 °C followed by re-normalizing and tempering is preferred; cold bending of tube is possible but requires generous radii and subsequent stress relief.
15NiCuMoNb5-6-4 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 | 0.1 – 0.17 | 0.14 |
| Si | 0.25 – 0.5 | 0.35 |
| Mn | 0.8 – 1.2 | 1 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.01 | 0 |
| Cr | ≤ 0.3 | 0.15 |
| Mo | 0.25 – 0.5 | 0.35 |
| Ni | 1 – 1.3 | 1.15 |
| Cuprecipitation strengthening | 0.5 – 0.8 | 0.65 |
| Nbgrain refinement | 0.02 – 0.05 | 0.03 |
| Altotal Al | ≤ 0.05 | 0.03 |
| N | ≤ 0.02 | 0.01 |
| Fe | balance |
What surface finishes work on 15NiCuMoNb5-6-4?
No inherent corrosion protection — shot-blast and paint or metallize external surfaces; internal protection relies on boiler water chemistry rather than coatings.
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 15NiCuMoNb5-6-4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.6368
- Trade names
- WB36
How much does 15NiCuMoNb5-6-4 cost?
15NiCuMoNb5-6-4 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.
15NiCuMoNb5-6-4 — frequently asked
What is 15NiCuMoNb5-6-4 used for?
15NiCuMoNb5-6-4 is typically used for main steam piping, boiler headers and high-temperature pressure components. In short: creep-resistant boiler steel; service to 400 °C; stronger than Mn-Mo vessel steels.
What is the yield strength of 15NiCuMoNb5-6-4?
15NiCuMoNb5-6-4 has a typical yield strength of 480 MPa (69.6 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 59% of steel grades. Strength varies by condition: see the 2 listed tempers.
Is 15NiCuMoNb5-6-4 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like 4130/4140-class low-alloy steel at ~50–55 % of AISI 1212; use rigid setups, carbide inserts and moderate speeds with good coolant.
Can 15NiCuMoNb5-6-4 be welded?
Yes — weldability is rated good (62/100). Weldable by TIG/SMAW/SAW with matched Ni-Cu-Mo consumables; preheat about 150–250 °C and a post-weld heat treatment near 580–620 °C are normally specified to restore HAZ toughness.
What surface finishes work on 15NiCuMoNb5-6-4?
No inherent corrosion protection — shot-blast and paint or metallize external surfaces; internal protection relies on boiler water chemistry rather than coatings.
Can 15NiCuMoNb5-6-4 be formed, bent or molded?
Hot forming above ~950 °C followed by re-normalizing and tempering is preferred; cold bending of tube is possible but requires generous radii and subsequent stress relief.
What is the maximum service temperature of 15NiCuMoNb5-6-4?
15NiCuMoNb5-6-4 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 15NiCuMoNb5-6-4-NT and 15NiCuMoNb5-6-4-QT?
NT is the default condition — standard delivery condition for WB36 seamless tube, pipe and plate for boiler feedwater and steam service. QT: chosen for heavy-wall headers, forgings and thick plate where through-thickness strength and low-temperature toughness must be maintained. Yield strength is 480 MPa in NT versus 530 MPa in QT.
How much does 15NiCuMoNb5-6-4 cost?
15NiCuMoNb5-6-4 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, non-alloy and alloy steels with specified elevated temperature properties — CEN (2020)
- VdTÜV Werkstoffblatt 377 / WB 36 (15NiCuMoNb5-6-4) — VdTÜV (2011)
- DIN 17175 — Seamless tubes of heat-resistant steels (historic) — DIN (1979)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Seamless boiler tube datasheets for WB36/1.6368 — European seamless tube producers (2021)
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.