S355JR steel (1.0045): properties, composition, equivalents
S355JR (1.0045): 355 MPa minimum yield, 470–630 MPa tensile, 27 J at +20 °C. The base S355 grade — composition by thickness, ASTM A572/JIS/GB equivalents, old St52 names.
What is S355JR?
S355JR is the strength workhorse of European structural steel: 355 MPa minimum yield, 470–630 MPa tensile, 27 J Charpy at +20 °C, Werkstoff number 1.0045. It is still a non-alloy steel — strength comes from up to 0.24 % C and 1.60 % Mn rather than micro-alloying — which is why the carbon equivalent limit rises to 0.45 % and welding thick sections calls for a preheat check.
The S355 family (JR, J0, J2, K2) shares one strength table and differs only in impact temperature and cleanliness. JR is the coil and section grade for mild climates; plate for cranes, bridges and offshore is almost always ordered as J2 or K2. If a specification simply says "S355", ask which suffix — the difference decides whether the steel is accepted at −20 °C.
S355JR replaced DIN St52-3 U and BS 4360 50B; the US counterpart is ASTM A572 Grade 50, the Chinese Q355B (formerly Q345B).
S355JR chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | ≤ 0.24 | ≤ 40 mm; 0.24 % above 40 mm |
| Si | ≤ 0.55 | |
| Mn | ≤ 1.6 | |
| P | ≤ 0.035 | |
| S | ≤ 0.035 | |
| N | ≤ 0.012 | |
| Cu | ≤ 0.55 |
Ladle analysis, EN 10025-2:2019 Table 2. CEV max 0.45 % up to 30 mm, 0.47 % 30–40 mm, 0.47 % 40–150 mm.
S355JR mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| ≤ 16 mm | 355 (51.5) | 470–630 (68.2–91.4) | 22 | ≈ 140–190 HB (typical) |
| > 16 ≤ 40 mm | 345 (50.0) | 470–630 (68.2–91.4) | 22 | — |
| > 40 ≤ 63 mm | 335 (48.6) | 470–630 (68.2–91.4) | 21 | — |
| > 63 ≤ 80 mm | 325 (47.1) | 470–630 (68.2–91.4) | 20 | — |
| > 80 ≤ 100 mm | 315 (45.7) | 470–630 (68.2–91.4) | 20 | — |
| > 100 ≤ 150 mm | 295 (42.8) | 450–600 (65.3–87.0) | 18 | — |
Rm range for 3–100 mm; longitudinal elongation, L0 = 5.65√S0.
Impact toughness
S355JR requires a minimum Charpy V-notch energy of 27 J at 20 °C (longitudinal). S355J0 (0 °C), S355J2 (−20 °C) and S355K2 (40 J at −20 °C) are the low-temperature variants; S355J2 is the common ordering grade for plate.
S355JR equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| A572 Gr. 50 | ASTM / ASME | Near | Yield 345 MPa (50 ksi), Rm 450 MPa min; HSLA with Nb/V, no impact requirement unless supplementary S5 is ordered. |
| A992 | ASTM / ASME | Near | Yield 345–450 MPa, Rm 450 MPa min; shapes only, with a yield/tensile ratio cap of 0.85. |
| St52-3 | DIN (superseded German) | Near | Successor of St52-3 U (impact at +20 °C). |
| S355J2 | EN (European) | Near | Same strength; impact at −20 °C, P/S ≤ 0.025 %, fully killed. |
| Q355B | GB/T (China) | Near | GB/T 1591 Q355B: yield 355 MPa, Rm 470–630 MPa, 34 J at +20 °C — the direct successor of Q345B and the closest Chinese match. |
| 09G2S | GOST (Russia/CIS) | Near | GOST 19281 09G2S: yield 325–345 MPa, Rm 470–490 MPa; low-alloy Mn-Si steel, better cold toughness. |
| IS 2062 E350 BR | IS (India) | Near | Yield 350 MPa, Rm 490 MPa min, room-temperature impact. |
| SM490A | JIS (Japan) | Near | JIS G3106 SM490A: yield 325 MPa (≤ 16 mm), Rm 490–610 MPa; A = no impact requirement, B = 27 J at 0 °C. |
| S275JR | EN (European) | Functional | Higher class; same delivery conditions. |
| S350GD | EN (European) | Functional | Uncoated hot-rolled equivalent by yield, for profiles hot-dip galvanized after forming. |
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 S355JR →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| St52-3 U | DIN 17100 | St52-3 U (unkilled-tested at +20 °C) ≈ S355JR; St52-3 N ≈ S355J2. |
| Fe510B | EN 10025:1990 | |
| 50B | BS 4360 | |
| E36-2 | NF A 35-501 |
Product forms and tolerance standards
Product forms: hot-rolled plate, hot-rolled coil and sheet, sections (IPE, HE, UPN, angles), bar, hollow sections (S355JRH).
Dimensional tolerances: plate: EN 10029; coil/sheet: EN 10051; sections: EN 10034 / EN 10279.
Key property values
S355JR yield strength
Minimum ReH 355 MPa (51.5 ksi) ≤ 16 mm, 345 MPa to 40 mm, 335 MPa to 63 mm, 325 MPa to 80 mm, 315 MPa to 100 mm. EN 1993-1-1: fy = 355 MPa (t ≤ 40 mm), 335 MPa (40–80 mm).
S355JR tensile strength
Rm 470–630 MPa (68–91 ksi) for 3–100 mm; typical mill values 510–560 MPa.
S355JR hardness
Not specified; as-rolled S355 measures about 140–190 HB (150–200 HV).
Carbon equivalent
CEV max 0.45 % ≤ 30 mm, 0.47 % for 30–150 mm. Above ~25 mm or with high restraint, preheat 50–100 °C is common practice per EN 1011-2.
Weldability
Weldable with E46 / G46 consumables (EN ISO 2560 / 14341). Because CEV may reach 0.45 %, calculate preheat with EN 1011-2 Method A for t > 25 mm; low-hydrogen processes are standard. Post-weld heat treatment is not normally required.
Machining, forming and heat treatment
Machinability index ≈ 60 %; carbide tooling recommended for sections above 20 mm. Minimum transverse bend radius per EN 10025-2 Table 7: 1.0 t (≤ 2.5 mm) to 3.0 t (8–16 mm). Hot forming 950–1100 °C; normalizing 880–920 °C restores properties after hot work. Not hardenable in the useful sense — it is not a heat-treatable grade.
Typical applications
- Primary steel structures: beams, columns, trusses, portal frames
- Crane girders and lifting-equipment structures (as S355J2/K2)
- Bridges (S355J2+N, S355K2+N or S355N/NL)
- Heavy transport and trailer chassis
- Wind-tower sections and offshore secondary steel (S355J2 or S355ML)
- Hollow sections S355J2H for architectural structures
S355JR compared with related grades
Frequently asked questions
What is the difference between S355JR and S355J2?
Strength is identical. S355J2 is impact tested at −20 °C (JR at +20 °C), has P and S limited to 0.025 % and is always fully killed. Plate for cranes, bridges and cold climates is ordered as J2.
What is the ASTM equivalent of S355JR?
ASTM A572 Grade 50 (345 MPa / 50 ksi yield) is the standard substitute; A992 for rolled shapes. Both are HSLA steels without a default Charpy requirement, so they are graded 'near'.
Is S355 the same as St52?
Yes in ordering practice: St52-3 (DIN 17100) became S355 in EN 10025:1993. St52-3 U corresponds to S355JR and St52-3 N to S355J2.
Does S355JR need preheat for welding?
Not below ~25 mm in ordinary joints. Above that, or with high restraint and CEV near 0.45 %, EN 1011-2 typically gives 50–100 °C preheat with low-hydrogen consumables.
Related grades
Verified against EN 10025-2:2019; EN 10025-2:2019 Tables 2, 4, 7 and 8; EN 1993-1-1:2005 Table 3.1. Last checked: September 2026.