Steel P355NH +N (Normalized)
Heat-treated state · default condition
EN P355NH
Standard stocked delivery condition for EN 10028-3 pressure-vessel plate up to 16 mm; full 355 MPa yield class.
Values for the +N condition
Other P355NH tempers and conditions
P355NH is listed in 6 conditions; see the grade overview at P355NH.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+N | Heavy pressure-vessel plate; lower guaranteed strength and toughness, longer preheat/PWHT cycles. | 350 | 520 | 25 | 150 HB | 9 % IACS |
+N | Heavier plate class; specify Z-quality if through-thickness loading applies. | 370 | 535 | 26 | 155 HB | 9 % IACS |
Normalized then stress relieved / simulated PWHT | Ordered when the vessel receives post-weld heat treatment and the purchaser wants properties verified in the PWHT-simulated condition. | 375 | 530 | 29 | 152 HB | 9 % IACS |
+N | Same delivery condition, reduced guaranteed yield for medium plate thickness. | 380 | 540 | 27 | 158 HB | 9 % IACS |
+NDefaultThis page Normalized | Standard stocked delivery condition for EN 10028-3 pressure-vessel plate up to 16 mm; full 355 MPa yield class. | 390 | 545 | 28 | 160 HB | — |
Normalizing rolled | Mill-economic alternative to furnace normalizing with equivalent mechanical properties; choose when no further hot forming above ~580 °C is planned. | 400 | 550 | 27 | 163 HB | 9 % IACS |
What is P355NH +N?
P355NH +N is P355NH heat treated to +N — standard stocked delivery condition for EN 10028-3 pressure-vessel plate up to 16 mm; full 355 MPa yield class. P355NH +N has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 545 MPa (79 ksi) — weaker than 64% of steel grades. Elongation at break is 28% and the elastic modulus is 210 GPa (30.5 Msi). P355NH +N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F).
Advantages
- Ductile — tolerates forming and impact — 28%, better than 89% of steel grades
- Readily welded — 88/100, better than 87% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
- Forms and bends easily — 65/100, better than 81% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
P355NH +N properties
Typical room-temperature values for P355NH +N; 14 are specific to this condition. Other listed values are P355NH reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
P355NH +N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
P355NH +N has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 545 MPa (79 ksi) — weaker than 64% of steel grades. Elongation at break is 28% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
P355NH +N is rated for continuous service to 400°C (752 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), better than 75% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
P355NH +N 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 P355NH +N takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 22%.
Manufacturability7
P355NH +N's machinability is good (55/100, better than 62% of steel grades); weldability excellent (88/100); formability good (65/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with P355NH +N
Is P355NH easy to machine?
Machines like normalized 1020–1518 grade steel (~60 % of AISI 1212); use carbide inserts, moderate speeds and good chip control — long stringy chips on the softer heats.
Can P355NH be welded?
Excellent weldability by SAW/SMAW/GMAW with CEV ≈ 0.40–0.45; preheat 100–150 °C for thick or restrained sections, low-hydrogen consumables, PWHT at 550–620 °C per EN 13445/AD 2000.
Can P355NH be formed, bent or molded?
Cold-forms and rolls readily to vessel shells and dished heads (min bend radius ≈ 2t); hot forming above 580 °C requires re-normalizing to restore fine-grain properties.
What surface finishes work on P355NH?
No anodizing; protect by shot-blasting plus epoxy/zinc-rich paint, hot-dip galvanizing, or stainless/Inconel weld-overlay cladding for corrosive process side.
P355NH 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≤0.18 for t ≤ 30 mm in many mill practices | ≤ 0.2 | 0.16 |
| Si | ≤ 0.5 | 0.35 |
| Mn | 0.9 – 1.7 | 1.4 |
| P | ≤ 0.03 | 0.02 |
| S≤0.010 for Z-quality | ≤ 0.02 | 0.01 |
| Altotal Al, grain-refining element | ≥ 0.02 | 0.04 |
| N≤0.012 if no N-binding elements | ≤ 0.02 | 0.01 |
| Cr | ≤ 0.3 | 0.08 |
| Cu | ≤ 0.3 | 0.1 |
| Ni | ≤ 0.5 | 0.15 |
| Mo | ≤ 0.08 | 0.02 |
| NbNb+Ti+V ≤ 0.12 total | ≤ 0.05 | 0.02 |
| Ti | ≤ 0.03 | 0.01 |
| V | ≤ 0.1 | 0.02 |
| Fe | balance | — |
P355NH +N — frequently asked
What is P355NH +N used for?
P355NH +N is typically used for boiler components, pressure vessels at elevated temperature, piping flanges and reactor shells. In short: guaranteed hot proof strength; normalized fine-grain vessel plate; Z35 through-thickness option.
What is the yield strength of P355NH +N?
P355NH +N has a typical yield strength of 390 MPa (56.6 ksi) and a tensile strength of 545 MPa (79 ksi) — weaker than 64% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is P355NH +N easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like normalized 1020–1518 grade steel (~60 % of AISI 1212); use carbide inserts, moderate speeds and good chip control — long stringy chips on the softer heats.
Can P355NH +N be welded?
Yes — weldability is rated excellent (88/100). Excellent weldability by SAW/SMAW/GMAW with CEV ≈ 0.40–0.45; preheat 100–150 °C for thick or restrained sections, low-hydrogen consumables, PWHT at 550–620 °C per EN 13445/AD 2000.
What surface finishes work on P355NH +N?
No anodizing; protect by shot-blasting plus epoxy/zinc-rich paint, hot-dip galvanizing, or stainless/Inconel weld-overlay cladding for corrosive process side.
Can P355NH +N be formed, bent or molded?
Cold-forms and rolls readily to vessel shells and dished heads (min bend radius ≈ 2t); hot forming above 580 °C requires re-normalizing to restore fine-grain properties.
What is the maximum service temperature of P355NH +N?
P355NH +N 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 10028-3 — Flat products made of steels for pressure purposes, Part 3: Weldable fine grain steels, normalized — CEN (2017)
- EN 10164 — Steel products with improved deformation properties perpendicular to the surface (Z-quality) — CEN (2018)
- ASTM A516/A516M — Pressure Vessel Plates, Carbon Steel, for Moderate and Lower-Temperature Service — ASTM (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Pressure vessel plate P355NH data sheet — Dillinger / thyssenkrupp Steel (2022)
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.