Steel S355M
EN S355M
S355M is a thermomechanically rolled (TMCP) structural plate grade to EN 10025-4, material number 1.8823, also designated Q355M, with 400 MPa yield, 520 MPa tensile, 26 % elongation and about 155 HB.
Reference datasheet — S355M is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the M condition
S355M tempers and conditions
S355M is supplied in 3 conditions, soft to hard. M is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
M | Same TMCP condition in heavy gauges where the standard allows lower minimum yield strength. | 340 | 480 | 24 | 148 HB | 9 % IACS |
MDefault Thermomechanically controlled processed | Standard TMCP delivery condition for welded structures down to -20 °C service. | 400 | 520 | 26 | 155 HB | 9 % IACS |
Thermomechanically rolled, low-temperature quality | Choose when guaranteed toughness at -40/-50 °C is required (offshore, arctic, cranes). | 400 | 520 | 27 | 155 HB | 9 % IACS |
Supply forms, finishes and certifications
Ways S355M is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Z35 | M + Z35 | Certification |
What is S355M?
S355M is a thermomechanically rolled (TMCP) structural plate grade to EN 10025-4, material number 1.8823, also designated Q355M, with 400 MPa yield, 520 MPa tensile, 26 % elongation and about 155 HB. It is the European default for welded steel structures because its low carbon equivalent and TMCP microstructure give better toughness and weldability (score 92) than normalized S355N, and it is stocked as plate, including heavy gauges and Z35 through-thickness qualities. The strength depends on the rolling schedule, so hot forming or normalizing above about 580 °C must be avoided. S460M is the next step up when weight matters more than cost. S355M 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). S355M has a yield strength of 400 MPa (58 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 60% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi).
What is S355M used for?
- bridge plate
- offshore structures
- pressure vessels
Advantages
- Readily welded — 92/100, better than 93% of steel grades
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
- Forms and bends easily — 65/100, better than 81% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
S355M properties
Typical room-temperature values for S355M-M; bars are the position among steel grades.
Physical3
S355M 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
S355M has a yield strength of 400 MPa (58 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 60% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
S355M 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
S355M 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 S355M takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability8
S355M's machinability is good (58/100, better than 75% of steel grades); weldability excellent (92/100); formability good (65/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. S355M is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S355M
Is S355M easy to machine?
Machines like a normalized C-Mn steel (~55–60 % of AISI 1212); use coated carbide, moderate speeds, and expect long stringy chips due to low sulphur.
Can S355M be welded?
Excellent weldability by SMAW/GMAW/SAW with low-hydrogen consumables; low CEV usually allows no or minimal preheat, but keep heat input and interpass temperature controlled to protect the TMCP toughness.
Can S355M be formed, bent or molded?
Good cold bending (bend radii per EN 10025-4, typically 1.5–2.5 t); avoid hot forming or normalizing above ~580 °C, which erases the thermomechanical strengthening.
S355M 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 |
|---|---|---|
| CEN 10025-4 S355M, all thicknesses | ≤ 0.14 | 0.1 |
| Si | ≤ 0.5 | 0.3 |
| Mn | ≤ 1.6 | 1.4 |
| PML: ≤0.025 | ≤ 0.03 | 0.02 |
| SML: ≤0.020 | ≤ 0.03 | 0.01 |
| Altotal Al; alternative fine-grain elements permitted | ≥ 0.02 | 0.03 |
| NbNb+V+Ti ≤ 0.22 | ≤ 0.05 | 0.03 |
| V | ≤ 0.1 | 0.02 |
| Ti | ≤ 0.05 | 0.02 |
| CrCr+Mo ≤ 0.30 | ≤ 0.3 | 0.05 |
| Ni | ≤ 0.5 | 0.05 |
| Mo | ≤ 0.1 | 0.02 |
| Cu | ≤ 0.55 | 0.1 |
| N | ≤ 0.02 | 0.01 |
| FeCEV ≤ 0.39 (t ≤ 16 mm) | balance |
What surface finishes work on S355M?
No anodizing; protect by blast-cleaning plus epoxy/PU paint systems, zinc metallizing or hot-dip galvanizing (watch Si content for galvanizing reactivity).
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel S355M in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.882310025-4
- Similar grades
- Q355M
How much does S355M cost?
S355M is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
S355M — frequently asked
What is S355M used for?
S355M is typically used for bridge plate, offshore structures and pressure vessels. In short: most weldable 355 MPa plate; tougher than normalized S355N; low-CEV TMCP structural grade.
What is the yield strength of S355M?
S355M has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is S355M easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like a normalized C-Mn steel (~55–60 % of AISI 1212); use coated carbide, moderate speeds, and expect long stringy chips due to low sulphur.
Can S355M be welded?
Yes — weldability is rated excellent (92/100). Excellent weldability by SMAW/GMAW/SAW with low-hydrogen consumables; low CEV usually allows no or minimal preheat, but keep heat input and interpass temperature controlled to protect the TMCP toughness.
What surface finishes work on S355M?
No anodizing; protect by blast-cleaning plus epoxy/PU paint systems, zinc metallizing or hot-dip galvanizing (watch Si content for galvanizing reactivity).
Can S355M be formed, bent or molded?
Good cold bending (bend radii per EN 10025-4, typically 1.5–2.5 t); avoid hot forming or normalizing above ~580 °C, which erases the thermomechanical strengthening.
What is the maximum service temperature of S355M?
S355M 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 S355M-M and S355M M-THICK?
M is the default condition — standard TMCP delivery condition for welded structures down to -20 °C service. M-THICK: same TMCP condition in heavy gauges where the standard allows lower minimum yield strength. Yield strength is 400 MPa in M versus 340 MPa in M-THICK.
How much does S355M cost?
S355M is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- EN 10025-4: Hot rolled products of structural steels — Thermomechanical rolled weldable fine grain steels — CEN (2019)
- GB/T 1591 (Q355M/Q355ML) — SAC (2018)
- EN 10164 Steel products with improved deformation properties perpendicular to the surface — CEN (2018)
- EN 1993-1-1 / EN 1993-1-2 Eurocode 3 (physical properties of structural steel) — CEN (2005)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- TMCP structural plate datasheets (Dillinger, SSAB, voestalpine) — various mills (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.