Steel Q355C · heat-treated state
Steel Q355C-N
Properties of the N condition, compared with the other Q355C tempers.
Pick for thick plate (>40 mm) or when finer grain and higher, more uniform through-thickness toughness is required.
What is Q355C-N?
Q355C-N is Q355C heat treated to N — pick for thick plate (>40 mm) or when finer grain and higher, more uniform through-thickness toughness is required. Q355C-N has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 64% of steel grades. Elongation at break is 28% and the elastic modulus is 206 GPa (29.9 Msi). Q355C-N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,500°C (2,732 °F). HR is the default condition FabDigit quotes; N is available on request or by drawing note.
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Ductile — tolerates forming and impact — 28%, better than 88% of steel grades
- Forms and bends easily — 72/100, better than 88% of steel grades
- Readily welded — 86/100, better than 85% of steel grades
- Easy to machine — 60/100, better than 83% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
Q355C-N properties
Typical room-temperature values for Q355C-N — 10 properties are specific to this condition; the rest are grade-level values shared by every Q355C temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
Q355C-N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,500°C (2,732 °F).
Mechanical16
Q355C-N has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 64% of steel grades. Elongation at break is 28% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
Q355C-N 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
Q355C-N conducts electricity at 8.2 % IACS, better than 60% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of Q355C-N takes about 24 MJ of energy and emits 1.9 kg of CO₂ — less than 97% of steel grades. Typical recycled content is 25%.
Manufacturability6
Q355C-N's machinability is good (60/100, better than 83% of steel grades); weldability excellent (86/100); formability very good (72/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Q355C tempers and conditions
Q355C is also supplied in 2 other conditions. The full side-by-side table is on the Q355C overview.
- HRDefaultDefault stock condition for plate, section, coil and bar; use for general welded structures at ≥0 °C.380 MPa yield · 150 HB
- CDChoose for round/square bar needing tight tolerance and bright surface; strength up, ductility and toughness down.520 MPa yield · 185 HB
- NPick for thick plate (>40 mm) or when finer grain and higher, more uniform through-thickness toughness is required.390 MPa yield · 155 HB
Working with Q355C-N
Is Q355C easy to machine?
Cuts like a 0.17 %C Mn steel at ~150 HB — carbide inserts, 120–200 m/min turning; slightly gummy chips, so use positive rake and good coolant.
Can Q355C be welded?
Excellent for SMAW/GMAW/SAW with E50 (490 MPa class) consumables; preheat 80–150 °C only for thick sections or restraint, no PWHT needed for normal thicknesses.
Can Q355C be formed, bent or molded?
Cold-bends to the GB/T 1591 mandrel requirement (d = 2a for t ≤ 16 mm); hot forming 900–1100 °C, avoid finishing below 800 °C to keep grain size.
What surface finishes work on Q355C?
Must be protected — shot blast to Sa 2.5 then epoxy/zinc-rich primer, or hot-dip galvanize (Si held below 0.55 % keeps coating growth reasonable).
Q355C 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 |
|---|---|---|
| CGB/T 1591-2018, hot-rolled Q355C | ≤ 0.2 | 0.17 |
| Si | ≤ 0.55 | 0.3 |
| Mn | ≤ 1.6 | 1.4 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| NbNb+V+Ti ≤ 0.22 total | ≤ 0.05 | 0.02 |
| V | ≤ 0.1 | 0.02 |
| Ti | ≤ 0.05 | 0.01 |
| Altotal Al (Als), when Nb/V/Ti not added | ≥ 0.02 | 0.03 |
| Crresidual | ≤ 0.3 | 0.05 |
| Niresidual | ≤ 0.3 | 0.03 |
| Curesidual | ≤ 0.4 | 0.05 |
| Moresidual | ≤ 0.1 | 0.01 |
| N | ≤ 0.01 | 0.01 |
| Fe | balance | — |
Q355C-N — frequently asked
What is Q355C-N used for?
Q355C-N is typically used for welded bridge girders, crane and hoist structures, building and platform framing, heavy machine frames and bases, pressure parts for above-zero service and baseplates and gussets. In short: high-strength structural plate.
What is the yield strength of Q355C-N?
Q355C-N has a typical yield strength of 390 MPa (56.6 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 64% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is Q355C-N easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Cuts like a 0.17 %C Mn steel at ~150 HB — carbide inserts, 120–200 m/min turning; slightly gummy chips, so use positive rake and good coolant.
Can Q355C-N be welded?
Yes — weldability is rated excellent (86/100). Excellent for SMAW/GMAW/SAW with E50 (490 MPa class) consumables; preheat 80–150 °C only for thick sections or restraint, no PWHT needed for normal thicknesses.
What surface finishes work on Q355C-N?
Must be protected — shot blast to Sa 2.5 then epoxy/zinc-rich primer, or hot-dip galvanize (Si held below 0.55 % keeps coating growth reasonable).
Can Q355C-N be formed, bent or molded?
Cold-bends to the GB/T 1591 mandrel requirement (d = 2a for t ≤ 16 mm); hot forming 900–1100 °C, avoid finishing below 800 °C to keep grain size.
What is the maximum service temperature of Q355C-N?
Q355C-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.
What is the difference between Q355C-HR and Q355C-CD?
HR is the default condition — default stock condition for plate, section, coil and bar; use for general welded structures at ≥0 °C. CD: choose for round/square bar needing tight tolerance and bright surface; strength up, ductility and toughness down. Yield strength is 380 MPa in HR versus 520 MPa in CD.
Can FabDigit make parts in Q355C-N?
Yes — Q355C-N is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- GB/T 700-2006 (comparison basis) — SAC (2006)
- ASTM A572/A572M Grade 50 (equivalent HSLA plate) — ASTM (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
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.