Steel S355M M-THICK
Grade
EN S355M
Same TMCP condition in heavy gauges where the standard allows lower minimum yield strength.
Values for the M-THICK condition
Other S355M tempers and conditions
S355M is listed in 3 conditions; see the grade overview at S355M.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
M-THICKThis page 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 |
What is S355M M-THICK?
S355M M-THICK is S355M in the M-THICK grade — same TMCP condition in heavy gauges where the standard allows lower minimum yield strength. S355M M-THICK has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 76% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi). S355M M-THICK 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). M is the default condition FabDigit quotes; M-THICK is available on request or by drawing note.
Advantages
- Readily welded — 88/100, better than 87% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
- Low strength — 340 MPa (49.3 ksi), worse than 76% of steel grades
S355M M-THICK properties
Typical room-temperature values for S355M M-THICK; 22 are specific to this condition. Other listed values are S355M reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
S355M M-THICK 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 M-THICK has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 76% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
S355M M-THICK 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 M-THICK 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 M-THICK 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 M-THICK's machinability is good (60/100, better than 83% of steel grades); weldability excellent (88/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with S355M M-THICK
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.
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).
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 | — |
S355M M-THICK — frequently asked
What is S355M M-THICK used for?
S355M M-THICK 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 M-THICK?
S355M M-THICK has a typical yield strength of 340 MPa (49.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 76% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is S355M M-THICK easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% 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 M-THICK be welded?
Yes — weldability is rated excellent (88/100). 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 M-THICK?
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 M-THICK 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 M-THICK?
S355M M-THICK 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.