Steel 18MnMo4-5
EN 18MnMo4-5
18MnMo4-5 (1.5414, A204) is a manganese-molybdenum low-alloy pressure-vessel steel from the EN 10083/10250 family, supplied +A, +N, +NT or +QT.
Reference datasheet — 18MnMo4-5 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 +NT condition
18MnMo4-5 tempers and conditions
18MnMo4-5 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 | Soft condition for heavy machining or cold work before the final NT/QT heat treatment. | 300 | 520 | 26 | 155 HB | — |
Normalized | Normalized only — used for thinner bar/tube sections where tempering is not required by the order. | 390 | 620 | 20 | 190 HB | 7.8 % IACS |
+NTDefault Normalized and tempered | Standard delivery condition for EN 10222-2 / EN 10273 pressure forgings and bars up to moderate wall thickness. | 400 | 610 | 21 | 185 HB | — |
Quenched and tempered | Choose for heavy-wall forgings needing uniform through-thickness strength and better low-temperature toughness. | 470 | 660 | 19 | 20 HRC | — |
What is 18MnMo4-5?
18MnMo4-5 (1.5414, A204) is a manganese-molybdenum low-alloy pressure-vessel steel from the EN 10083/10250 family, supplied +A, +N, +NT or +QT. The default condition gives 400 MPa yield, 610 MPa tensile, 21% elongation and about 185 HB (90 HRB) with service to 480 °C, which suits plate, forgings and seamless pipe for boiler drums and vessel shells. Weldability is moderate (70/100) and requires preheat plus code PWHT, while corrosion resistance is negligible (12/100), so paint, aluminising or overlay is mandatory. 16Mo3 is the easier-welding, lower-strength alternative. 18MnMo4-5 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). 18MnMo4-5 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 610 MPa (88.5 ksi) — weaker than 60% of steel grades. Elongation at break is 21% and the elastic modulus is 210 GPa (30.5 Msi).
What is 18MnMo4-5 used for?
- pressure vessels
- boiler drums
- piping
Advantages
- High service temperature — 480°C (896 °F), better than 88% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
18MnMo4-5 properties
Typical room-temperature values for 18MnMo4-5-+NT; bars are the position among steel grades.
Physical3
18MnMo4-5 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).
Mechanical16
18MnMo4-5 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 610 MPa (88.5 ksi) — weaker than 60% of steel grades. Elongation at break is 21% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
18MnMo4-5 is rated for continuous service to 480°C (896 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
18MnMo4-5 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 18MnMo4-5 takes about 28 MJ of energy and emits 2.1 kg of CO₂ — less than 56% of steel grades. Typical recycled content is 25%.
Manufacturability8
18MnMo4-5's machinability is good (55/100, better than 62% of steel grades); weldability very good (70/100); 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. 18MnMo4-5 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 18MnMo4-5
Is 18MnMo4-5 easy to machine?
Machines like a 0.2 %C low-alloy steel at ~180–210 HB; carbide inserts at 120–180 m/min, rigid setups, coolant to avoid built-up edge on the tough tempered structure.
Can 18MnMo4-5 be welded?
Weldable with matching 1Mn-0.5Mo consumables (SMAW/SAW/GTAW); preheat 150–250 °C for thick sections, control hydrogen, and apply PWHT ~620–680 °C as required by the pressure code.
Can 18MnMo4-5 be formed, bent or molded?
Forge/hot form at 1150–850 °C followed by normalizing or re-austenitizing; cold bending is limited — allow generous bend radii and re-heat-treat afterwards.
18MnMo4-5 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 |
|---|---|---|
| C18 in designation = 0.18 % C | 0.15 – 0.22 | 0.18 |
| Si | 0.1 – 0.4 | 0.25 |
| Mn | 0.8 – 1.2 | 1 |
| P | ≤ 0.03 | |
| S | ≤ 0.02 | |
| Mo | 0.45 – 0.6 | 0.5 |
| Crresidual | ≤ 0.3 | 0.15 |
| Niresidual | ≤ 0.4 | 0.2 |
| Curesidual | ≤ 0.3 | |
| Algrain refinement (total Al) | 0.02 – 0.06 | 0.03 |
| Fe | balance |
What surface finishes work on 18MnMo4-5?
No self-passivation: shot blast then prime/paint, aluminise or weld-overlay with stainless/Inconel for corrosive or wet service; phosphating suits temporary protection.
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 18MnMo4-5 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.5414
- Similar grades
- A204
How much does 18MnMo4-5 cost?
18MnMo4-5 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
18MnMo4-5 — frequently asked
What is 18MnMo4-5 used for?
18MnMo4-5 is typically used for pressure vessels, boiler drums and piping. In short: higher strength than 16Mo3; elevated-temperature vessel steel; PWHT required after welding.
What is the yield strength of 18MnMo4-5?
18MnMo4-5 has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 610 MPa (88.5 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is 18MnMo4-5 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like a 0.2 %C low-alloy steel at ~180–210 HB; carbide inserts at 120–180 m/min, rigid setups, coolant to avoid built-up edge on the tough tempered structure.
Can 18MnMo4-5 be welded?
Yes — weldability is rated very good (70/100). Weldable with matching 1Mn-0.5Mo consumables (SMAW/SAW/GTAW); preheat 150–250 °C for thick sections, control hydrogen, and apply PWHT ~620–680 °C as required by the pressure code.
What surface finishes work on 18MnMo4-5?
No self-passivation: shot blast then prime/paint, aluminise or weld-overlay with stainless/Inconel for corrosive or wet service; phosphating suits temporary protection.
Can 18MnMo4-5 be formed, bent or molded?
Forge/hot form at 1150–850 °C followed by normalizing or re-austenitizing; cold bending is limited — allow generous bend radii and re-heat-treat afterwards.
What is the maximum service temperature of 18MnMo4-5?
18MnMo4-5 is rated for continuous use to about 480°C (896 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 18MnMo4-5 cost?
18MnMo4-5 is a budget-cost steel ($), cheaper than about 90% 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 10222-2 — Steel forgings for pressure purposes, ferritic and martensitic steels with elevated temperature properties — CEN (2017)
- EN 10273 — Hot rolled weldable steel bars for pressure purposes with specified elevated temperature properties — CEN (2016)
- EN 10028-2 — Flat products for pressure purposes: weldable fine grain / elevated temperature steels — CEN (2017)
- ASTM A204/A204M — Pressure Vessel Plates, Alloy Steel, Molybdenum — ASTM International (2019)
- 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)
- EN 13445-3 Annex O — Physical properties of steels — CEN (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.