16Mo3 steel (1.5415): properties, composition, equivalents
16Mo3 (1.5415, ex 15Mo3) is the 0.3 % Mo creep-resisting pressure steel of EN 10028-2: 275 MPa yield, 440–590 MPa tensile, Rp0.2 guaranteed to 500 °C. Composition, temperature table, A204/SA-204 and 15Mo3 equivalents.
What is 16Mo3?
16Mo3 is the first alloy step above carbon steel in the European pressure-vessel range: 0.3 % molybdenum in a 0.16 % carbon matrix, Werkstoff number 1.5415, specified in EN 10028-2 (plate), EN 10216-2 (seamless tube), EN 10222-2 (forgings) and EN 10273 (bar). The old DIN 17155 name 15Mo3 is still heard daily.
Molybdenum does two things: it raises the yield strength that can be guaranteed at 400–500 °C (148 MPa at 500 °C, versus P265GH's table ending at 400 °C) and it slows creep, so 16Mo3 is the economical choice for boiler tubes, superheater headers, steam drums, hot-gas ducting and refinery vessels operating between roughly 400 and 530 °C. Room-temperature values are 275 MPa yield, 440–590 MPa tensile, 24 % elongation, 27 J at −20 °C.
The ASME counterparts are C-½Mo grades — A204 (plate), A335 P1 (pipe), A182 F1 (forgings) — which carry 0.45–0.60 % Mo, so the match is 'near'; note that ASME has restricted C-½Mo in hydrogen service (API 941), a caution that applies equally to 16Mo3.
16Mo3 chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | 0.12 – 0.2 | |
| Si | ≤ 0.35 | |
| Mn | 0.4 – 0.9 | |
| P | ≤ 0.025 | |
| S | ≤ 0.01 | |
| N | ≤ 0.012 | |
| Cr | ≤ 0.3 | |
| Cu | ≤ 0.3 | |
| Mo | 0.25 – 0.35 | |
| Ni | ≤ 0.3 |
EN 10028-2:2017 Table 1. Al is not deliberately added (Al ≤ 0.040 % — fine Al-nitrides would reduce creep strength). CEV max 0.45 %.
16Mo3 mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| ≤ 16 mm, +N | 275 (39.9) | 440–590 (63.8–85.6) | 24 | ≈ 130–170 HB (typ.) |
| > 16 ≤ 40 mm | 270 (39.2) | 440–590 (63.8–85.6) | 24 | — |
| > 40 ≤ 60 mm | 260 (37.7) | 440–590 (63.8–85.6) | 24 | — |
| > 60 ≤ 100 mm | 240 (34.8) | 430–580 (62.4–84.1) | 23 | — |
| > 100 ≤ 150 mm | 220 (31.9) | 420–570 (60.9–82.7) | 22 | — |
| Rp0.2 at 100 °C (≤ 60 mm) | 243 (35.2) | — | — | — |
| Rp0.2 at 200 °C | 218 (31.6) | — | — | — |
| Rp0.2 at 300 °C | 193 (28.0) | — | — | — |
| Rp0.2 at 400 °C | 169 (24.5) | — | — | — |
| Rp0.2 at 450 °C | 159 (23.1) | — | — | — |
| Rp0.2 at 500 °C | 148 (21.5) | — | — | — |
EN 10028-2 Tables 2–4; transverse for plate. Creep-rupture strength (mean, 100 000 h): ≈ 122 MPa at 450 °C, 74 MPa at 500 °C, 41 MPa at 530 °C (EN 10028-2 Annex, informative).
Impact toughness
16Mo3 requires a minimum Charpy V-notch energy of 27 J at -20 °C (transverse; 40 J longitudinal; also 31 J at 0 °C, 34 J at +20 °C transverse). Impact requirements are the same as for the P…GH grades.
16Mo3 equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| 16Mo | GB/T (China) | Identical | GB/T 713 16Mo (formerly 16MnMoR-type usage); GB adopted the EN name for Mo pressure plate. |
| A204 Gr. A | ASTM / ASME | Near | ASTM/ASME A204 Grade A (SA-204-A): C ≤ 0.18, Mo 0.45–0.60, yield 255 MPa, Rm 450–585 MPa. Higher Mo than 16Mo3; Grade B (yield 275) is closer on strength. |
| A204 Gr. B | ASTM / ASME | Near | Yield 275 MPa, Rm 485–620 MPa, Mo 0.45–0.60. |
| A335 P1 | ASTM / ASME | Near | Seamless pipe: C 0.10–0.20, Mo 0.44–0.65, yield 205 MPa — the ASME C-½Mo pipe grade corresponding to 16Mo3 tube (EN 10216-2). |
| A182 F1 | ASTM / ASME | Near | C-½Mo forging grade (flanges, fittings). |
| 15KhM / 16M | GOST (Russia/CIS) | Near | GOST 20072 / 5520 grade 16M (Mo 0.25–0.35) is close; 15KhM adds Cr. |
| STPA12 / SB450M | JIS (Japan) | Near | JIS G3462 STPA12 (0.5 Mo pipe) and G3103 SB450M (Mo boiler plate). |
| P265GH | EN (European) | Functional | Non-alloy grade below 400–450 °C; 16Mo3 is the step up. |
| 13CrMo4-5 | EN (European) | Functional | 1.7335 Cr-Mo grade for 500–570 °C and hydrogen service. |
Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for 16Mo3 →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| 15Mo3 | DIN 17155 (withdrawn 1992) | Same number 1.5415; still widely used name. Renamed 16Mo3 with the EN edition. |
| 16Mo3 | DIN 17175 (tubes) | |
| 1503-243B / 1501-240 | BS 1501 / BS 3059 | BS 3059 Part 2 grade 243 (tubes). |
| 15D3 | NF A 36-205 |
Product forms and tolerance standards
Product forms: plate (EN 10028-2), seamless tube and pipe (EN 10216-2), welded tube (EN 10217-2), forgings (EN 10222-2), fittings (EN 10253-2), bar for flanges and bolting (EN 10273).
Dimensional tolerances: plate: EN 10029; tube: EN 10216-2 / EN ISO 1127; forgings: EN 10222-1.
Key property values
16Mo3 yield strength
275 MPa (39.9 ksi) ≤ 16 mm, 270 to 40 mm, 260 to 60 mm, 240 to 100 mm, 220 to 150 mm. Elevated temperature (≤ 60 mm): 243 MPa at 100 °C, 218 at 200, 193 at 300, 169 at 400, 159 at 450 and 148 MPa at 500 °C.
16Mo3 tensile strength
440–590 MPa (64–86 ksi) to 60 mm; 430–580 MPa to 100 mm; 420–570 MPa to 150 mm.
16Mo3 creep strength
Mean creep-rupture strength for 100 000 h: ≈ 122 MPa at 450 °C, 74 MPa at 500 °C, 41 MPa at 530 °C. 1 % creep strain limits are about 70 % of these. Practical upper service limit ≈ 530 °C.
16Mo3 hardness
Not specified; normalized plate ≈ 130–170 HB. Weld HAZ can reach 250–300 HV without PWHT.
Physical properties
Density 7.85 g/cm³, E = 212 GPa (20 °C), 190 GPa (400 °C); expansion 12.4 × 10⁻⁶/K (20–100 °C), 14.0 (20–500 °C); conductivity ≈ 45 W/m·K.
Heat treatment
Delivery condition normalized (+N) at 900–950 °C, air cooled; stress relief / PWHT 570–650 °C. Ac1 ≈ 730 °C, Ac3 ≈ 850 °C.
Weldability
Good weldability with matching Mo consumables (E Mo B / G Mo Si, EN ISO 3580 / 21952 — e.g. E 7018-A1 / ER70S-A1 type). Preheat 100–150 °C above ~15 mm thickness; PWHT 570–620 °C is normally required by EN 13445 / AD 2000 for pressure parts above about 15–20 mm and for all creep-range service. Avoid welding with unalloyed filler in creep service (weld would be the weak point).
Machining, forming and heat treatment
Machinability similar to P265GH/P295GH (index ≈ 65 %). Cold forming within code strain limits followed by normalizing when strain exceeds ~5 %; hot forming 1050–900 °C then re-normalize. Flame cutting with 100 °C preheat above 30 mm. Not intended for hardening; surface treatments uncommon.
Typical applications
- Boiler drums, headers, economizer and evaporator tubes (EN 10216-2 16Mo3)
- Superheater and reheater tubes up to ~500 °C metal temperature
- Refinery and petrochemical vessels, columns and heat exchangers 400–500 °C
- Hot-gas ducts, flue-gas and waste-heat boilers
- Steam piping, flanges (EN 10273 16Mo3) and fittings
- Hydrocracker and reformer components below API 941 C-½Mo limits
Frequently asked questions
Is 16Mo3 the same as 15Mo3?
Yes. 15Mo3 was the DIN 17155 name; EN 10028-2 renamed it 16Mo3 (nominal carbon 0.16 %) in 1992 with the same number 1.5415 and effectively the same limits.
What is the ASTM equivalent of 16Mo3?
C-½Mo grades: A204 Grade A/B (plate), A335 P1 (seamless pipe), A182 F1 (forgings), A217 WC1 (castings). They contain 0.45–0.60 % Mo versus 0.25–0.35 % in 16Mo3, so strength and creep values are close but not identical.
What is the maximum working temperature of 16Mo3?
Design tables give yield to 500 °C; creep-rupture data support use to about 530 °C. Above that, 13CrMo4-5 (≈ 570 °C) or 10CrMo9-10 (≈ 600 °C) are used.
Does 16Mo3 need preheat and PWHT?
Preheat 100–150 °C above ~15 mm; PWHT at 570–620 °C is required by European vessel codes for most pressure-retaining welds in 16Mo3, and is always advisable for creep service.
Can 16Mo3 be used in hydrogen service?
Only within the C-½Mo limits of API RP 941 (Nelson curves); many operators now specify 13CrMo4-5 instead because of hydrogen attack incidents in C-½Mo steels.
Related grades
Verified against EN 10028-2:2017; EN 10028-2:2017 Tables 1–4 and Annex; EN 10216-2:2020; ASME SA-204 / SA-335 (comparison). Last checked: September 2026.