Steel S355N +N +SR (+N + stress relieved)
Heat-treated state
EN S355N · GB Q355N
Use for thick welded pressure-related fabrications requiring PWHT; slight softening but residual stresses and distortion greatly reduced.
Values for the +N +SR condition
Other S355N tempers and conditions
S355N is listed in 8 conditions; see the grade overview at S355N.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+N | Very heavy normalized plate/forged bar; yield 295 MPa (100–150 mm) / 285 MPa (150–200 mm) with reduced tensile band. | 310 | 480 | 22 | 145 HB | 10.8 % IACS |
+N | Thick-section plate where through-thickness toughness matters; yield 325 MPa (63–80 mm) / 315 MPa (80–100 mm). | 340 | 500 | 23 | 147 HB | 10.8 % IACS |
+N | Heavy plate for base plates and thick welded nodes; yield 335 MPa minimum. | 360 | 520 | 24 | 150 HB | 10.8 % IACS |
+N +SRThis page +N + stress relieved | Use for thick welded pressure-related fabrications requiring PWHT; slight softening but residual stresses and distortion greatly reduced. | 365 | 520 | 26 | 150 HB | 10.8 % IACS |
+N | Medium plate for welded girders and machine frames; yield down-rated to 345 MPa per EN 10025-3. | 370 | 530 | 24 | 152 HB | 10.8 % IACS |
+N t<=16Default +N | Standard stocked condition for plate, section and bar up to 16 mm; full 355 MPa yield with 40 J at −20 °C. | 380 | 540 | 25 | 155 HB | 10.8 % IACS |
S355NL | Choose when service or hydrotest temperature goes below −20 °C (offshore, cold-climate cranes, LPG structures); tighter P/S limits. | 380 | 540 | 25 | 155 HB | 10.8 % IACS |
Cold drawn | For close-tolerance bar and shafts; cold work raises yield and hardness but cuts elongation and adds residual stress. | 470 | 590 | 14 | 11 HRC | 10.5 % IACS |
What is S355N +N +SR?
S355N +N +SR is S355N heat treated to +N +SR — use for thick welded pressure-related fabrications requiring PWHT; slight softening but residual stresses and distortion greatly reduced. S355N +N +SR has a yield strength of 365 MPa (52.9 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 71% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi). S355N +N +SR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). +N t<=16 is the default condition FabDigit quotes; +N +SR is available on request or by drawing note.
Advantages
- High electrical conductivity — 10.8 % IACS, better than 94% of steel grades
- Tough — resists crack growth — 135 MPa·√m (122.9 ksi·√in), better than 93% of steel grades
- Readily welded — 88/100, better than 87% of steel grades
- Forms and bends easily — 67/100, better than 83% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
S355N +N +SR properties
Typical room-temperature values for S355N +N +SR; 22 are specific to this condition. Other listed values are S355N reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
S355N +N +SR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
S355N +N +SR has a yield strength of 365 MPa (52.9 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 71% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
S355N +N +SR is rated for continuous service to 400°C (752 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 66% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
S355N +N +SR conducts electricity at 10.8 % IACS, better than 94% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of S355N +N +SR takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
S355N +N +SR's machinability is good (60/100, better than 83% of steel grades); weldability excellent (88/100); formability good (67/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with S355N +N +SR
Is S355N easy to machine?
Machines like a normalized C-Mn steel at ~60 % of AISI 1212; use rigid setups, coolant and coated carbide, and expect stringy chips at low sulphur levels.
Can S355N be welded?
Excellent weldability by SMAW/GMAW/SAW with matched low-hydrogen consumables; CEV ≤ 0.43 means little or no preheat below ~30 mm, preheat 100–150 °C for heavy sections, keep heat input moderate to protect fine-grain HAZ toughness.
Can S355N be formed, bent or molded?
Good cold bending (typical minimum bend radius 1.5–2.5 t depending on thickness and orientation); hot forming above 900 °C should be followed by re-normalizing at 890–940 °C to restore properties.
What surface finishes work on S355N?
No natural corrosion resistance — shot blast to Sa 2½ then zinc-rich primer/epoxy per ISO 12944, or hot-dip galvanize (Si content controls coating thickness); not anodizable.
S355N 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 |
|---|---|---|
| Cmax 0.20 % for t ≤ 250 mm | ≤ 0.2 | 0.17 |
| Si | ≤ 0.5 | 0.35 |
| Mn | 0.9 – 1.65 | 1.4 |
| P0.025 max for S355NL | ≤ 0.03 | 0.02 |
| S0.020 max for S355NL | ≤ 0.03 | 0.01 |
| Nlimit may be exceeded if sufficient N-binding elements present | ≤ 0.02 | 0.01 |
| Altotal Al, min for grain refinement | ≥ 0.02 | 0.03 |
| NbNb+Ti+V ≤ 0.22 % | ≤ 0.05 | 0.03 |
| V | ≤ 0.12 | 0.04 |
| Ti | ≤ 0.05 | 0.02 |
| Cr | ≤ 0.3 | 0.1 |
| Ni | ≤ 0.5 | 0.1 |
| Mo | ≤ 0.1 | 0.02 |
| Cu | ≤ 0.35 | 0.15 |
| FeCEV ≤ 0.43 for t ≤ 63 mm | balance | — |
S355N +N +SR — frequently asked
What is S355N +N +SR used for?
S355N +N +SR is typically used for bridges, offshore structures, pressure-related steel fabrications, heavy welded frames and penstocks. In short: normalized fine-grain S355; weldable at CEV ≤ 0.43; tougher than plain S355.
What is the yield strength of S355N +N +SR?
S355N +N +SR has a typical yield strength of 365 MPa (52.9 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 71% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is S355N +N +SR easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Machines like a normalized C-Mn steel at ~60 % of AISI 1212; use rigid setups, coolant and coated carbide, and expect stringy chips at low sulphur levels.
Can S355N +N +SR be welded?
Yes — weldability is rated excellent (88/100). Excellent weldability by SMAW/GMAW/SAW with matched low-hydrogen consumables; CEV ≤ 0.43 means little or no preheat below ~30 mm, preheat 100–150 °C for heavy sections, keep heat input moderate to protect fine-grain HAZ toughness.
What surface finishes work on S355N +N +SR?
No natural corrosion resistance — shot blast to Sa 2½ then zinc-rich primer/epoxy per ISO 12944, or hot-dip galvanize (Si content controls coating thickness); not anodizable.
Can S355N +N +SR be formed, bent or molded?
Good cold bending (typical minimum bend radius 1.5–2.5 t depending on thickness and orientation); hot forming above 900 °C should be followed by re-normalizing at 890–940 °C to restore properties.
What is the maximum service temperature of S355N +N +SR?
S355N +N +SR 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 S355N +N t<=16 and S355N-CD?
+N t<=16 is the default condition — standard stocked condition for plate, section and bar up to 16 mm; full 355 MPa yield with 40 J at −20 °C. CD: for close-tolerance bar and shafts; cold work raises yield and hardness but cuts elongation and adds residual stress. Yield strength is 380 MPa in +N t<=16 versus 470 MPa in CD.
Sources
- EN 10025-3 Hot rolled products of structural steels — Normalized/normalized rolled weldable fine grain steels — CEN (2019)
- EN 10027-2 / 1.0545 material number designation — CEN (2015)
- ASTM A633/A633M Normalized High-Strength Low-Alloy Structural Steel Plates — ASTM (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- EN 1993-1-1 / EN 1993-1-2 Eurocode 3 design and thermal properties of structural steel — CEN (2005)
- Normalized fine-grain structural steel plate datasheets (S355N/NL) — European plate mills (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.