Steel S355K2 +N (Normalized)
Heat-treated state · default condition
EN S355K2
Standard stocked condition: normalized fine-grain plate/section with full −20 °C toughness and best weldability.
Values for the +N condition
Other S355K2 tempers and conditions
S355K2 is listed in 6 conditions; see the grade overview at S355K2.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+N | Very heavy normalized plate; reduced strength band (Rm 450–600 MPa) and lowest through-thickness toughness. | 340 | 500 | 23 | 146 HB | 10 % IACS |
+N | Thick normalized plate for heavy nodes and offshore sections; yield minimum 315–325 MPa. | 360 | 515 | 24 | 150 HB | 10 % IACS |
+N | Heavy plate band; yield minimum 335 MPa, slightly lower elongation requirement. | 375 | 525 | 25 | 153 HB | 10 % IACS |
+N | Medium plate thickness band; yield minimum steps down to 345 MPa. | 385 | 535 | 26 | 157 HB | 10 % IACS |
Hot rolled | Cheapest delivery condition, allowed by EN 10025-2 for K2 quality in thinner products where −20 °C impacts are still met. | 395 | 550 | 25 | 163 HB | — |
+NDefaultThis page Normalized | Standard stocked condition: normalized fine-grain plate/section with full −20 °C toughness and best weldability. | 400 | 545 | 26 | 160 HB | — |
What is S355K2 +N?
S355K2 +N is S355K2 heat treated to +N — standard stocked condition: normalized fine-grain plate/section with full −20 °C toughness and best weldability. S355K2 +N has a yield strength of 400 MPa (58 ksi) and a tensile strength of 545 MPa (79 ksi) — weaker than 60% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi). S355K2 +N 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).
Advantages
- Readily welded — 90/100, better than 90% of steel grades
- High electrical conductivity — 10 % IACS, better than 83% of steel grades
- Forms and bends easily — 68/100, better than 83% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
- Tough — resists crack growth — 115 MPa·√m (104.7 ksi·√in), better than 77% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
S355K2 +N properties
Typical room-temperature values for S355K2 +N; 16 are specific to this condition. Other listed values are S355K2 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
S355K2 +N 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
S355K2 +N has a yield strength of 400 MPa (58 ksi) and a tensile strength of 545 MPa (79 ksi) — weaker than 60% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
S355K2 +N is rated for continuous service to 350°C (662 °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
S355K2 +N conducts electricity at 10 % IACS, better than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of S355K2 +N takes about 26 MJ of energy and emits 2.1 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 25%.
Manufacturability7
S355K2 +N's machinability is good (55/100, better than 62% of steel grades); weldability excellent (90/100); formability good (68/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with S355K2 +N
Is S355K2 easy to machine?
Machines like ordinary C-Mn steel at ~60 % of AISI 1212; use rigid setups, moderate speeds and positive-rake carbide, expect stringy chips from low-sulphur heats.
Can S355K2 be welded?
Excellent weldability by SMAW/GMAW/SAW with CEV ≈0.43; use low-hydrogen consumables and preheat 75–150 °C for thick sections or high restraint per EN 1011-2.
Can S355K2 be formed, bent or molded?
Cold bends readily at 2t–3t inside radius transverse to rolling for t ≤ 16 mm; hot form at 900–1050 °C and re-normalize if formed below 750 °C.
What surface finishes work on S355K2?
Cannot be anodized — protect by blast cleaning to Sa 2½ plus zinc-rich epoxy paint systems (ISO 12944), hot-dip galvanizing (watch Si content for coating thickness) or thermal-spray metallizing.
S355K2 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 |
|---|---|---|
| C≤0.20 % for t ≤ 30 mm; up to 0.22 % in thicker product (ladle analysis) | ≤ 0.2 | 0.17 |
| Si | ≤ 0.55 | 0.25 |
| Mn | ≤ 1.6 | 1.4 |
| P | ≤ 0.03 | 0.02 |
| S≤0.015 % typical for Z-quality plate | ≤ 0.03 | 0.01 |
| NLimit waived if sufficient N-binding elements (Al, Nb, V, Ti) are present | ≤ 0.01 | 0.01 |
| Cu | ≤ 0.55 | 0.2 |
| AlTotal Al for fine-grain / killed practice | ≥ 0.02 | 0.03 |
| Nb+V+TiMicro-alloying, sum limited; Nb ≤0.05, V ≤0.12, Ti ≤0.05 | ≤ 0.22 | 0.03 |
| CEVCarbon equivalent (IIW), t ≤ 30 mm; up to 0.49 for heavy plate | ≤ 0.47 | 0.43 |
| Fe | balance | — |
S355K2 +N — frequently asked
What is S355K2 +N used for?
S355K2 +N is typically used for bridges, heavy machinery frames, cranes, structural steelwork and pressure-loaded structures. In short: best-welding S355 variant; −20 °C notch toughness; widely cross-referenced structural grade.
What is the yield strength of S355K2 +N?
S355K2 +N has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 545 MPa (79 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is S355K2 +N easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like ordinary C-Mn steel at ~60 % of AISI 1212; use rigid setups, moderate speeds and positive-rake carbide, expect stringy chips from low-sulphur heats.
Can S355K2 +N be welded?
Yes — weldability is rated excellent (90/100). Excellent weldability by SMAW/GMAW/SAW with CEV ≈0.43; use low-hydrogen consumables and preheat 75–150 °C for thick sections or high restraint per EN 1011-2.
What surface finishes work on S355K2 +N?
Cannot be anodized — protect by blast cleaning to Sa 2½ plus zinc-rich epoxy paint systems (ISO 12944), hot-dip galvanizing (watch Si content for coating thickness) or thermal-spray metallizing.
Can S355K2 +N be formed, bent or molded?
Cold bends readily at 2t–3t inside radius transverse to rolling for t ≤ 16 mm; hot form at 900–1050 °C and re-normalize if formed below 750 °C.
What is the maximum service temperature of S355K2 +N?
S355K2 +N is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- EN 10025-2 Hot rolled products of structural steels — Non-alloy structural steels — CEN (2019)
- EN 10164 Steel products with improved deformation properties perpendicular to the surface — CEN (2018)
- ASTM A572/A572M Grade 50 High-Strength Low-Alloy Columbium-Vanadium Structural Steel — ASTM (2021)
- EN 1993-1-1 / EN 1993-1-2 Eurocode 3 design of steel structures (physical properties) — CEN (2005)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- EN 1011-2 Welding — Recommendations for arc welding of ferritic steels — CEN (2001)
- Structural steel plate S355K2+N datasheet — European plate mills (e.g. Dillinger / ArcelorMittal) (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.