Steel S355NL +N+SR (+N + stress relieved)
Heat-treated state
EN S355NL · GB Q355ND
Fabricated assemblies given post-weld heat treatment; slight strength loss but improved dimensional stability and residual-stress state.
Values for the +N+SR condition
Other S355NL tempers and conditions
S355NL is listed in 8 conditions; see the grade overview at S355NL.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+N | Maximum standard thickness; min yield 285 MPa, through-thickness testing usually specified. | 325 | 505 | 23 | 143 HB | 9 % IACS |
+N | Extra-heavy normalized plate; min yield 295 MPa and lower tensile band (450–600 MPa). | 335 | 510 | 23 | 145 HB | 9 % IACS |
+N | Very heavy plate for nodes and base plates; min yield 315 MPa. | 355 | 525 | 24 | 148 HB | 9 % IACS |
+N | Thick plate; min yield 325 MPa, preheat strongly recommended for welding. | 365 | 530 | 24 | 150 HB | 9 % IACS |
+N+SRThis page +N + stress relieved | Fabricated assemblies given post-weld heat treatment; slight strength loss but improved dimensional stability and residual-stress state. | 370 | 520 | 27 | 150 HB | 9 % IACS |
+N | Heavy plate for cold-service frames and vessel shells; min yield 335 MPa. | 375 | 535 | 25 | 152 HB | 9 % IACS |
+N | Medium plate thickness; minimum yield drops one step to 345 MPa. | 385 | 540 | 25 | 155 HB | 9 % IACS |
+N t<=16Default +N | Standard stocked condition for plate, strip and sections up to 16 mm; full 355 MPa yield with 27 J at -50 °C. | 400 | 545 | 26 | 158 HB | 9 % IACS |
What is S355NL +N+SR?
S355NL +N+SR is S355NL heat treated to +N+SR — fabricated assemblies given post-weld heat treatment; slight strength loss but improved dimensional stability and residual-stress state. S355NL +N+SR has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 70% of steel grades. Elongation at break is 27% and the elastic modulus is 210 GPa (30.5 Msi). S355NL +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
- Tough — resists crack growth — 145 MPa·√m (132 ksi·√in), better than 95% of steel grades
- Easy to machine — 62/100, better than 89% of steel grades
- Forms and bends easily — 72/100, better than 88% of steel grades
- Readily welded — 88/100, better than 87% of steel grades
- Ductile — tolerates forming and impact — 27%, better than 86% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
S355NL +N+SR properties
Typical room-temperature values for S355NL +N+SR; 22 are specific to this condition. Other listed values are S355NL reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
S355NL +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
S355NL +N+SR has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 70% of steel grades. Elongation at break is 27% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
S355NL +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
S355NL +N+SR conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of S355NL +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%.
Manufacturability8
S355NL +N+SR's machinability is good (62/100, better than 89% of steel grades); weldability excellent (88/100); formability very good (72/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with S355NL +N+SR
Is S355NL easy to machine?
Machines like normalized C-Mn steel at ~60 % of 1212; use rigid setups and coolant, chips are stringy so favor chipbreaker inserts.
Can S355NL be welded?
Excellent weldability with CEV ≤ 0.43; use low-hydrogen consumables matched for -50 °C toughness, control heat input and preheat 50–150 °C above ~40 mm.
Can S355NL be formed, bent or molded?
Good cold bending (typical min bend radius 1.5–2.5 t depending on thickness/orientation); hot forming should be followed by re-normalizing to restore -50 °C toughness.
What surface finishes work on S355NL?
No anodizing; protect with shop primer, epoxy/PU paint systems, thermal spray or hot-dip galvanizing (Si content is in the low-reactivity range for controlled coating growth).
S355NL 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 > 63 mm in some product forms | ≤ 0.18 | 0.16 |
| Si | ≤ 0.5 | 0.35 |
| Mn | 0.9 – 1.65 | 1.45 |
| Ptighter than S355N | ≤ 0.03 | 0.02 |
| Stighter than S355N | ≤ 0.02 | 0.01 |
| Nhigher allowed if enough N-binding elements | ≤ 0.02 | 0.01 |
| Altotal Al, grain refinement | ≥ 0.02 | 0.04 |
| Nb | ≤ 0.05 | 0.03 |
| V | ≤ 0.12 | 0.04 |
| TiNb+V+Ti ≤ 0.12 total | ≤ 0.05 | 0.02 |
| Cr | ≤ 0.3 | 0.08 |
| Ni | ≤ 0.5 | 0.15 |
| Mo | ≤ 0.1 | 0.02 |
| Cu | ≤ 0.35 | 0.1 |
| FeCEV ≤ 0.43 for t ≤ 63 mm | balance | — |
S355NL +N+SR — frequently asked
What is S355NL +N+SR used for?
S355NL +N+SR is typically used for cold-region steel structures, offshore platforms, pressure equipment supports, cranes in cold climates and storage tanks. In short: impact tested to -50 °C; normalized fine-grain S355; cold-climate structural grade.
What is the yield strength of S355NL +N+SR?
S355NL +N+SR has a typical yield strength of 370 MPa (53.7 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 70% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is S355NL +N+SR easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Machines like normalized C-Mn steel at ~60 % of 1212; use rigid setups and coolant, chips are stringy so favor chipbreaker inserts.
Can S355NL +N+SR be welded?
Yes — weldability is rated excellent (88/100). Excellent weldability with CEV ≤ 0.43; use low-hydrogen consumables matched for -50 °C toughness, control heat input and preheat 50–150 °C above ~40 mm.
What surface finishes work on S355NL +N+SR?
No anodizing; protect with shop primer, epoxy/PU paint systems, thermal spray or hot-dip galvanizing (Si content is in the low-reactivity range for controlled coating growth).
Can S355NL +N+SR be formed, bent or molded?
Good cold bending (typical min bend radius 1.5–2.5 t depending on thickness/orientation); hot forming should be followed by re-normalizing to restore -50 °C toughness.
What is the maximum service temperature of S355NL +N+SR?
S355NL +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.
Sources
- EN 10025-3: Hot rolled products of structural steels — normalized/normalized rolled weldable fine grain steels — CEN (2019)
- EN 10027-2 / material number 1.0546 — CEN (2015)
- GB/T 1591 High strength low alloy structural steels (Q355ND) — SAC (2018)
- ASTM A633/A633M Grade E — ASTM International (2018)
- EN 10164 Steel products with improved deformation properties perpendicular to the surface — CEN (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- EN 1993-1-1 / EN 1993-1-2 (design and thermal properties of structural steel) — CEN (2005)
- Normalized fine-grain structural plate datasheets (Dillinger, voestalpine, ) — various 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.