Steel Q355D · heat-treated state
Steel Q355D-N
Properties of the N condition, compared with the other Q355D tempers.
Choose for thick plate, pressure or low-temperature duty where uniform fine grain and higher, more consistent impact energy are needed.
What is Q355D-N?
Q355D-N is Q355D heat treated to N — choose for thick plate, pressure or low-temperature duty where uniform fine grain and higher, more consistent impact energy are needed. Q355D-N has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 64% of steel grades. Elongation at break is 27% and the elastic modulus is 210 GPa (30.5 Msi). Q355D-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). HR is the default condition FabDigit quotes; N is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 140 MPa·√m (127.4 ksi·√in), better than 94% of steel grades
- Readily welded — 90/100, better than 90% of steel grades
- Forms and bends easily — 75/100, better than 90% of steel grades
- Ductile — tolerates forming and impact — 27%, better than 85% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
Q355D-N properties
Typical room-temperature values for Q355D-N — 9 properties are specific to this condition; the rest are grade-level values shared by every Q355D temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
Q355D-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
Q355D-N has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 64% of steel grades. Elongation at break is 27% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
Q355D-N is rated for continuous service to 400°C (752 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
Q355D-N conducts electricity at 8.6 % IACS, better than 66% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of Q355D-N takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability6
Q355D-N's machinability is good (55/100, better than 62% of steel grades); weldability excellent (90/100); formability very good (75/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Q355D tempers and conditions
Q355D is also supplied in 3 other conditions. The full side-by-side table is on the Q355D overview.
- HRDefaultStandard stocked condition for plate, section and bar; cheapest and adequate for most welded structures up to ~40 mm.380 MPa yield · 155 HB
- MPick for heavy welded fabrication: lowest carbon equivalent, best toughness and least preheat, but avoid hot forming or PWHT above ~580 °C.400 MPa yield · 150 HB
- NChoose for thick plate, pressure or low-temperature duty where uniform fine grain and higher, more consistent impact energy are needed.390 MPa yield · 150 HB
Working with Q355D-N
Is Q355D easy to machine?
Machines like A572-50 mild-alloy steel — use carbide at ~120–180 m/min with good chip breaking; sticky, stringy chips in the as-rolled condition, so favour positive rake and adequate feed.
Can Q355D be welded?
Excellent weldability with Ceq ≤0.45 (E5015/ER50-6 or matching); preheat 50–100 °C only for thick sections or restraint, and use low-hydrogen practice to protect the −20 °C toughness.
Can Q355D be formed, bent or molded?
Cold bends to 2a–3a mandrel radius across the grain; hot forming 900–1050 °C followed by normalizing is fine for AR/N material, but avoid hot forming TMCP plate.
What surface finishes work on Q355D?
No inherent corrosion resistance — shot blast to Sa 2½ then zinc-rich primer, hot-dip galvanize (watch Si level for coating thickness) or metallize; welds and cut edges need the same protection.
Q355D 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 ≤150 mm sections per GB/T 1591-2018 | ≤ 0.2 | 0.16 |
| Si | ≤ 0.55 | 0.3 |
| Mn | ≤ 1.6 | 1.4 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.02 | 0.01 |
| Nbmicroalloying, optional | ≤ 0.05 | 0.02 |
| Vmicroalloying, optional | ≤ 0.1 | 0.03 |
| Timicroalloying, optional | ≤ 0.05 | 0.02 |
| Crresidual | ≤ 0.3 | 0.1 |
| Niresidual | ≤ 0.5 | 0.1 |
| Curesidual | ≤ 0.4 | 0.1 |
| Moresidual | ≤ 0.1 | 0.02 |
| N | ≤ 0.01 | 0.01 |
| Altotal Al, for fine-grain/killed practice | ≥ 0.02 | 0.03 |
| FeCeq (IIW) ≤ 0.45 % typical for Q355D | balance | — |
Q355D-N — frequently asked
What is Q355D-N used for?
Q355D-N is typically used for bridge girders and plate weldments, crane and hoist structures, cold-climate structural frames, pressure-bearing welded structures, mobile equipment chassis and booms and machine bases and heavy frames. In short: workhorse structural plate.
What is the yield strength of Q355D-N?
Q355D-N has a typical yield strength of 390 MPa (56.6 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 64% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is Q355D-N easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like A572-50 mild-alloy steel — use carbide at ~120–180 m/min with good chip breaking; sticky, stringy chips in the as-rolled condition, so favour positive rake and adequate feed.
Can Q355D-N be welded?
Yes — weldability is rated excellent (90/100). Excellent weldability with Ceq ≤0.45 (E5015/ER50-6 or matching); preheat 50–100 °C only for thick sections or restraint, and use low-hydrogen practice to protect the −20 °C toughness.
What surface finishes work on Q355D-N?
No inherent corrosion resistance — shot blast to Sa 2½ then zinc-rich primer, hot-dip galvanize (watch Si level for coating thickness) or metallize; welds and cut edges need the same protection.
Can Q355D-N be formed, bent or molded?
Cold bends to 2a–3a mandrel radius across the grain; hot forming 900–1050 °C followed by normalizing is fine for AR/N material, but avoid hot forming TMCP plate.
What is the maximum service temperature of Q355D-N?
Q355D-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 Q355D-HR and Q355D-CD?
HR is the default condition — standard stocked condition for plate, section and bar; cheapest and adequate for most welded structures up to ~40 mm. CD: use for shafts and machined parts needing tight size and straightness; strength and hardness rise, ductility and toughness drop. Yield strength is 380 MPa in HR versus 500 MPa in CD.
Can FabDigit make parts in Q355D-N?
Yes — Q355D-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 / GB 50017 (elastic constants, thermal data) — MOHURD / SAC (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- EN 10025-2 S355J2 (comparison grade) — CEN (2019)
- worldsteel LCI data for steel plate — World Steel Association (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.