15Mo3 forgings (1.5415)
Molybdenum-alloyed creep-resistant steel for boiler and pressure-vessel service, forged to shape in Jiangyin, China.
15Mo3 is a molybdenum-alloyed creep-resistant steel, material number 1.5415, used for boiler and pressure-vessel components operating at elevated temperature. It was specified in DIN 17155; EN 10028-2 replaced that standard in 1993 and renamed the grade 16Mo3, keeping the number 1.5415. Its closest American equivalent is ASTM A204 Grade B.
Jiangyin Jiangnan Metal Co., Ltd. forges 15Mo3 to shape as seamless rolled rings, tubesheets, girth flanges, channel covers, shafts and valve bodies.
Grade identity
- Material number
- 1.5415
- DIN 17155
- 15Mo3 (superseded)
- EN 10028-2
- 16Mo3
- ASTM / ASME
- A204 Gr.B / SA-204 Gr.B
- Forging standard
- EN 10222-2
- Type
- Creep-resistant Mo alloy steel
- Molybdenum
- 0.25–0.35 %
- Tensile Rm
- 440–590 MPa
- Density
- 7.85 kg/dm³
- Magnetizable
- Yes
What 15Mo3 is used for
Plain carbon steel loses strength and deforms under sustained load above roughly 400 °C. The molybdenum addition in 15Mo3 restores creep strength through this range.
- 15Mo3 carries 0.25–0.35 % molybdenum, which raises creep rupture strength and improves resistance to pitting corrosion compared with an unalloyed pressure-vessel steel of similar carbon content.
- Typical applications are steam boilers, superheater and economiser components, pressure vessels, heat exchangers, refinery and petrochemical equipment, and steam and feedwater piping systems.
- Creep rupture data is tabulated to 530 °C. Continuous service is normally limited to between 500 and 530 °C depending on the design code, wall thickness and required life.
- The grade is weldable with matching Mo-alloyed consumables, normally with preheat and with post-weld heat treatment for pressure-retaining welds.
- For forged components the governing European product standard is EN 10222-2, covering ferritic steel forgings for pressure purposes with specified elevated-temperature properties.
International equivalents
15Mo3 carries a different designation under each national standard. Common cross-references are listed below.
| Standard / system | Country | Designation | Notes |
|---|---|---|---|
| Werkstoffnummer | Germany | 1.5415 | Retained across the standard change |
| DIN 17155 | Germany | 15Mo3 | Withdrawn 1993 |
| EN 10028-2 | Europe | 16Mo3 | Current designation, flat products |
| EN 10222-2 | Europe | 16Mo3 | Forgings for pressure purposes |
| EN 10216-2 | Europe | 16Mo3 | Seamless tubes for pressure purposes |
| ASTM / ASME | USA | A204 Gr.B / SA-204 Gr.B | Plate; C–½Mo |
| ASTM A182 / A336 | USA | F1 | Nearest forging grades |
| UNI 5869 | Italy | 15Mo3 | — |
| NF A36-205 | France | 15D3 | — |
| SS | Sweden | 2912 | Obsolete, replaced by EN |
Cross-references are indicative. Chemistry limits, test temperatures and acceptance criteria differ between standards. Name the governing specification on the purchase order.
Chemical composition
Composition limits to EN 10028-2 for 16Mo3 / 1.5415, balance iron.
| Limit | C | Si | Mn | P | S | Cr | Ni | Mo | Cu | N |
|---|---|---|---|---|---|---|---|---|---|---|
| Min % | 0.12 | – | 0.40 | – | – | – | – | 0.25 | – | – |
| Max % | 0.20 | 0.35 | 0.90 | 0.025 | 0.010 | 0.30 | 0.30 | 0.35 | 0.30 | 0.012 |
Carbon is limited to 0.20 % for weldability. Sulphur is limited to 0.010 % to maintain through-thickness ductility in forged sections.
Mechanical properties
Room-temperature properties in the normalised condition.
| Property | Value |
|---|---|
| Tensile strength Rm | 440–590 MPa (64–86 ksi) |
| Yield strength Rp0.2, min | 270 MPa (39 ksi) |
| Elongation A5, min | 22 % longitudinal / 20 % transverse |
| Impact energy KV, min | 31 J at 20 °C |
| Brinell hardness | 130–170 HB30 (sections to 60 mm) |
Values are typical for normalised plate. Guaranteed properties for a forging depend on section thickness, sampling position and the agreed heat-treatment route. EN 10222-2 sets thickness-dependent minima. Jiangyin Jiangnan Metal confirms achievable values against the drawing at enquiry stage.
Physical properties at temperature
Thermal and elastic properties from room temperature to 500 °C. Thermal conductivity falls and thermal expansion rises with temperature, which governs differential-expansion stress in tubesheet and shell joints.
| Temperature °C / °F |
Specific heat J/kg·K |
Thermal conductivity W/m·K |
Electrical resistivity µΩ·m |
Modulus of elasticity kN/mm² |
Mean expansion from 20 °C 10−6/K |
|---|---|---|---|---|---|
| 20 / 68 | 461 | 48.5 | 0.20 | 210 | 11.5 |
| 300 / 572 | 517 | 43.1 | 0.412 | 192 | 12.9 |
| 400 / 752 | 538 | 39.9 | 0.514 | 184 | 13.5 |
| 500 / 932 | 556 | 38.6 | 0.633 | 176 | 13.9 |
Density is 7.85 kg/dm³ and the steel is magnetizable. The modulus of elasticity falls from 210 to 176 kN/mm² between 20 and 500 °C.
Creep rupture strength
Creep rupture strength is the stress causing rupture after a stated time at a stated temperature. These values are used when setting allowable design stresses.
| Temperature °C / °F |
10,000 h | 100,000 h | 200,000 h |
|---|---|---|---|
| 450 / 842 | 298 (43.2) | 239 (34.6) | 217 (31.4) |
| 470 / 878 | 247 (35.8) | 178 (25.8) | 159 (23.0) |
| 500 / 932 | 171 (24.8) | 101 (14.6) | 84 (12.2) |
| 510 / 950 | 147 (21.3) | 91 (13.2) | 69 (10.0) |
| 530 / 986 | 102 (14.8) | 53 (7.7) | 45 (6.5) |
Values apply to plate and ksi figures are converted. At 100,000 hours the rupture strength falls from 239 N/mm² at 450 °C to 53 N/mm² at 530 °C. Above 530 °C a chromium-molybdenum grade such as 13CrMo4-5 or 10CrMo9-10 is normally specified.
15Mo3 forged shapes we produce
All items below are forged from 15Mo3 billet or ingot, heat treated and machined to drawing. Rough-machined, semi-finished and finish-machined conditions are available.
Rings and hollow sections
Seamless rolled rings, sleeves, bushes and bushings, cylinders, shells, casings, barrels, hollow bars, pipe and tube forgings.
Tubesheets and discs
Tubesheets, tube plates and tube sheets, discs and disks, blind and blanking plates. Front, rear, fixed, stationary and floating tubesheets, including clad, weld-overlay and coated faces.
Flanges and nozzles
Girth flanges, cover flanges, channel covers, long welding neck nozzles, nozzle necks and FVC-type self-reinforced nozzles.
Valve components
Valve bodies and body blocks, bonnets, stems, closures, seat rings and associated valve parts.
Solid sections
Round bars, blocks, shafts, hubs and housings, forged to size for subsequent machining.
Heat exchanger assemblies
Matched sets of shell-and-tube heat exchanger forgings, with tubesheet, girth flange and channel cover supplied from one heat where the specification requires it.
How a 15Mo3 forging is made here
Open-die forging breaks up the cast structure and aligns grain flow with the part geometry. Forged tubesheets and flanges therefore give better fatigue performance and through-thickness ductility than plate cut-outs.
- Steelmaking and material check. Electric-arc or converter steel refined to the 1.5415 analysis, with the ladle certificate checked against the order before the billet is released.
- Heating. The billet is soaked to forging temperature in a controlled-atmosphere furnace with recorded charts.
- Open-die forging. Upsetting, drawing and punching under the press to achieve the required forging reduction ratio.
- Ring rolling. Punched blanks are expanded on the ring mill to produce seamless rolled rings with continuous circumferential grain flow.
- Heat treatment. Normalising, or quenching and tempering where the order requires it, with time-at-temperature charts retained for the certificate.
- Machining. Rough, semi-finish or finish machining to the customer drawing.
- Testing and release. Chemical analysis, mechanical testing and non-destructive examination, then documentation and packing.
Testing and documentation
15Mo3 forgings are pressure-retaining components. Test records and certification are issued with every order.
- Forgings are released with an EN 10204 3.1 inspection certificate covering heat analysis, mechanical test results and heat-treatment records. A 3.2 certificate with third-party endorsement can be arranged where the project requires it.
- Ultrasonic examination, magnetic particle inspection and dye penetrant inspection are available, with acceptance to the class stated on the enquiry.
- Charpy V-notch impact testing at sub-zero or specified temperatures, hardness surveys and through-thickness tensile testing can be added.
- Positive material identification and hardness checks can be witnessed by the customer or a nominated inspection agency before shipment.
Frequently asked questions
Common questions about the specification and supply of 15Mo3.
What is 15Mo3 steel?
15Mo3 is a molybdenum-alloyed, creep-resistant steel with material number 1.5415, used for boiler and pressure-vessel components that operate at elevated temperature. It contains roughly 0.12–0.20 % carbon and 0.25–0.35 % molybdenum.
The molybdenum addition raises creep strength so the steel retains load-bearing capacity between 400 and 530 °C, where a plain carbon steel would deform under sustained load.
Is 15Mo3 the same as 16Mo3?
They are the same steel under two standards. 15Mo3 was the designation in the German standard DIN 17155. EN 10028-2 replaced DIN 17155 in 1993 and renamed the grade 16Mo3, keeping the same material number 1.5415.
Small differences exist in specified minimum values. A drawing calling for 15Mo3 is normally satisfied by 16Mo3 material, and the governing standard should be named on the purchase order.
What is the ASTM equivalent of 15Mo3?
For plate, the closest American equivalent is ASTM A204 Grade B (ASME SA-204 Grade B), a carbon–half-molybdenum pressure vessel steel. For forgings, the nearest grades are ASTM A182 F1 and ASTM A336 F1.
These are indicative cross-references, not identical specifications. Chemistry limits and test requirements differ, so confirm the applicable standard before ordering.
What is the chemical composition of 15Mo3?
To EN 10028-2 the composition of 15Mo3 / 16Mo3 (1.5415) is: carbon 0.12–0.20 %, silicon max 0.35 %, manganese 0.40–0.90 %, phosphorus max 0.025 %, sulphur max 0.010 %, chromium max 0.30 %, nickel max 0.30 %, molybdenum 0.25–0.35 %, copper max 0.30 % and nitrogen max 0.012 %, with the balance iron.
What is the maximum service temperature of 15Mo3?
Creep rupture data for 15Mo3 is tabulated up to 530 °C. The 100,000-hour creep rupture strength is about 239 N/mm² at 450 °C and about 53 N/mm² at 530 °C.
Continuous service is therefore normally limited to between 500 and 530 °C. The allowable temperature for a given part is set by the design code, wall thickness and required life.
Can 15Mo3 be welded?
Yes. 15Mo3 is readily weldable by common arc processes using matching Mo-alloyed consumables. Because it is a creep-resistant alloy steel, preheat is normally applied and post-weld heat treatment is usually required for pressure-retaining welds, with parameters set by the fabrication code and section thickness.
Jiangyin Jiangnan Metal supplies 15Mo3 forgings in the heat-treated condition, ready for the fabricator's qualified welding procedure.
What heat treatment is applied to 15Mo3 forgings?
Normalising is the standard condition for 15Mo3 forgings, and the published mechanical properties refer to this condition. Quenching and tempering is used where the drawing or design code requires higher strength in heavy sections.
Furnace charts are recorded and issued with the inspection certificate so the heat-treatment cycle can be verified against the order.
Who supplies 15Mo3 open-die forgings?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, producing 15Mo3 (1.5415) forgings including seamless rolled rings, tubesheets, girth flanges, channel covers, shafts and valve bodies.
Enquiries go to sales@steelforgepieces.com or +86 189 2135 9659.
What forged shapes are available in 15Mo3?
Jiangyin Jiangnan Metal produces 15Mo3 as seamless rolled rings, sleeves, bushes, shells, cylinders, hollow bars, round bars and blocks; as discs, tubesheets and tube plates including clad and weld-overlay tubesheets; as girth flanges, cover flanges, long welding neck nozzles and FVC self-reinforced nozzles; and as valve bodies, bonnets, stems, closures and seat rings.
What testing and certification comes with 15Mo3 forgings?
15Mo3 forgings are normally supplied with an EN 10204 3.1 inspection certificate covering heat analysis, mechanical test results and heat-treatment records.
Ultrasonic testing, magnetic particle or dye penetrant examination, impact testing at specified temperatures and third-party witness inspection can be added on request. Confirm the exact certification scope when placing the order.
Supplier of record
15Mo3 forgings listed on this page are produced in our own works.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. It forges rings, tubesheets, flanges, shafts, valve bodies and pressure-vessel components in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys, including grade 15Mo3 (W.Nr. 1.5415).
- Company
- Jiangyin Jiangnan Metal Co., Ltd.
- Address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone
- +86 189 2135 9659 (0086-189-2135-9659)
- Website
- www.steelforgepieces.com
Technical data. Composition, physical and creep values on this page are published for engineering reference and are drawn from the standards cited in each table. Confirm all figures against the governing standard before use in design.
Datasheet revision: 8 September 2026.