Steel 18MnMoNi5-5
EN 18MnMoNi5-5
18MnMoNi5-5 (1.6308) is a heavy-section Mn-Mo-Ni alloy steel per EN 10028-2 for thick-walled, high-pressure vessels and reactor components that need high strength with good toughness.
Reference datasheet — 18MnMoNi5-5 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 QT condition
18MnMoNi5-5 tempers and conditions
18MnMoNi5-5 is supplied in 5 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest supply state for deep machining or subsequent hot work; requires re-heat-treatment to reach code properties. | 320 | 520 | 26 | 160 HB | 8 % IACS |
Normalized and tempered | Alternative for sections where full quench is impractical; lower strength and toughness than QT, sometimes used for tube/pipe and smaller forgings. | 400 | 570 | 23 | 175 HB | 7.9 % IACS |
Normalized | Intermediate mill condition for plate/forging stock before final QT; not a normal service condition. | 430 | 640 | 20 | 14 HRC | 7.8 % IACS |
QT + simulated post-weld heat treatment | Test condition/delivery for plate that will see long PWHT soaks; slight strength loss, used for design allowables of welded thick shells. | 440 | 590 | 23 | 185 HB | 7.8 % IACS |
QTDefault Quenched and tempered | Standard EN 10028-2 delivery condition for heavy pressure-vessel plate and forgings; best strength/toughness balance. | 470 | 620 | 22 | 195 HB | — |
What is 18MnMoNi5-5?
18MnMoNi5-5 (1.6308) is a heavy-section Mn-Mo-Ni alloy steel per EN 10028-2 for thick-walled, high-pressure vessels and reactor components that need high strength with good toughness. Quenched and tempered plate and forgings provide 470 MPa yield, 620 MPa tensile, 22 % elongation and about 195 HB, with service to roughly 400 °C. Weldability is moderate (score 65): 150–200 °C preheat, hydrogen control and 600–620 °C PWHT are required, and cold forming is limited by the high yield strength and section thickness. For thinner, more formable low-temperature vessels use 15NiMn6 or 13MnNi6-3. 18MnMoNi5-5 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). 18MnMoNi5-5 has a yield strength of 470 MPa (68.2 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 57% of steel grades. Elongation at break is 22% and the elastic modulus is 207 GPa (30 Msi).
What is 18MnMoNi5-5 used for?
- Nuclear/chemical reactor vessels
- Heavy-wall pressure vessels
- Power plant boiler components
Advantages
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 100% of steel grades
18MnMoNi5-5 properties
Typical room-temperature values for 18MnMoNi5-5-QT; bars are the position among steel grades.
Physical3
18MnMoNi5-5 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).
Mechanical15
18MnMoNi5-5 has a yield strength of 470 MPa (68.2 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 57% of steel grades. Elongation at break is 22% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
18MnMoNi5-5 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
18MnMoNi5-5 has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of 18MnMoNi5-5 takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 20%.
Manufacturability7
18MnMoNi5-5's machinability is good (55/100, better than 62% of steel grades); weldability good (65/100); formability fair (45/100).
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. 18MnMoNi5-5 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 18MnMoNi5-5
Is 18MnMoNi5-5 easy to machine?
Machines like Q&T 4130/A508 at ~190 HB — carbide tooling, rigid setups, moderate speeds with flood coolant; stress-relieve before final passes on thick shells.
Can 18MnMoNi5-5 be welded?
Weldable by SAW/SMAW/GTAW with matching Mn-Mo-Ni consumables; preheat 150–200 °C, control hydrogen, and PWHT 600–620 °C to restore HAZ toughness.
Can 18MnMoNi5-5 be formed, bent or molded?
Hot-form or hot-roll heavy shells at 900–1150 °C then re-quench and temper; cold forming limited by high yield strength and section thickness.
18MnMoNi5-5 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 |
|---|---|---|
| Cheat analysis | 0.15 – 0.21 | 0.18 |
| Si | 0.1 – 0.35 | 0.25 |
| Mn | 1.15 – 1.5 | 1.35 |
| Prestricted to limit temper/irradiation embrittlement | ≤ 0.01 | 0.01 |
| S | ≤ 0.01 | 0 |
| Ni | 0.5 – 0.8 | 0.65 |
| Mo | 0.4 – 0.6 | 0.5 |
| Crresidual | ≤ 0.2 | 0.1 |
| Curesidual; low Cu for irradiation resistance | ≤ 0.12 | 0.06 |
| Vresidual | ≤ 0.02 | 0.01 |
| Altotal Al, grain refining | ≤ 0.04 | 0.03 |
| N | ≤ 0.01 | 0.01 |
| Fe | balance |
What surface finishes work on 18MnMoNi5-5?
Not anodizable — protect by shot blasting plus epoxy paint, or clad the process side with 308L/309L stainless weld overlay for corrosive service.
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 18MnMoNi5-5 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.6308
How much does 18MnMoNi5-5 cost?
18MnMoNi5-5 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.
18MnMoNi5-5 — frequently asked
What is 18MnMoNi5-5 used for?
18MnMoNi5-5 is typically used for nuclear/chemical reactor vessels, heavy-wall pressure vessels and power plant boiler components. In short: heavy-section reactor steel; 470 MPa yield class; thick-wall toughness.
What is the yield strength of 18MnMoNi5-5?
18MnMoNi5-5 has a typical yield strength of 470 MPa (68.2 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 57% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is 18MnMoNi5-5 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like Q&T 4130/A508 at ~190 HB — carbide tooling, rigid setups, moderate speeds with flood coolant; stress-relieve before final passes on thick shells.
Can 18MnMoNi5-5 be welded?
Yes — weldability is rated good (65/100). Weldable by SAW/SMAW/GTAW with matching Mn-Mo-Ni consumables; preheat 150–200 °C, control hydrogen, and PWHT 600–620 °C to restore HAZ toughness.
What surface finishes work on 18MnMoNi5-5?
Not anodizable — protect by shot blasting plus epoxy paint, or clad the process side with 308L/309L stainless weld overlay for corrosive service.
Can 18MnMoNi5-5 be formed, bent or molded?
Hot-form or hot-roll heavy shells at 900–1150 °C then re-quench and temper; cold forming limited by high yield strength and section thickness.
What is the maximum service temperature of 18MnMoNi5-5?
18MnMoNi5-5 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 18MnMoNi5-5-QT and 18MnMoNi5-5-A?
QT is the default condition — standard EN 10028-2 delivery condition for heavy pressure-vessel plate and forgings; best strength/toughness balance. A: softest supply state for deep machining or subsequent hot work; requires re-heat-treatment to reach code properties. Yield strength is 470 MPa in QT versus 320 MPa in A.
How much does 18MnMoNi5-5 cost?
18MnMoNi5-5 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 10028-2 — Flat products of steels for pressure purposes, Part 2: Alloy steels with specified elevated temperature properties — CEN (2017)
- ASME BPVC Section II, Part D — Properties (Metric) — ASME (2023)
- ASTM A533/A533M — Pressure Vessel Plates, Alloy Steel, Quenched and Tempered, Mn-Mo and Mn-Mo-Ni — ASTM (2022)
- 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)
- Heavy pressure-vessel plate / forging datasheets for 1.6308 (18MnMoNi5-5) — Dillinger / JSW / Böhler (2022)
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.