Steel Q235B · heat-treated state
Steel Q235B-N
Properties of the N condition, compared with the other Q235B tempers.
Specified for thick plate or pressure parts where uniform fine grain and better impact toughness are needed after hot forming.
What is Q235B-N?
Q235B-N is Q235B heat treated to N — specified for thick plate or pressure parts where uniform fine grain and better impact toughness are needed after hot forming. Q235B-N has a yield strength of 245 MPa (35.5 ksi) and a tensile strength of 410 MPa (59.5 ksi) — weaker than 95% of steel grades. Elongation at break is 31% and the elastic modulus is 206 GPa (29.9 Msi). Q235B-N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,495°C (2,723 °F). HR is the default condition FabDigit quotes; N is available on request or by drawing note.
Advantages
- Readily welded — 96/100, better than 100% of steel grades
- Forms and bends easily — 85/100, better than 96% of steel grades
- Ductile — tolerates forming and impact — 31%, better than 94% of steel grades
- High electrical conductivity — 10.8 % IACS, better than 94% of steel grades
- Easy to machine — 65/100, better than 93% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
- Low strength — 245 MPa (35.5 ksi), worse than 95% of steel grades
Q235B-N properties
Typical room-temperature values for Q235B-N — 8 properties are specific to this condition; the rest are grade-level values shared by every Q235B temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
Q235B-N has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,495°C (2,723 °F).
Mechanical16
Q235B-N has a yield strength of 245 MPa (35.5 ksi) and a tensile strength of 410 MPa (59.5 ksi) — weaker than 95% of steel grades. Elongation at break is 31% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
Q235B-N is rated for continuous service to 350°C (662 °F). It conducts heat at 50 W/m·K (28.9 BTU/hr·ft·°F), better than 88% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
Q235B-N conducts electricity at 10.8 % IACS, better than 94% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 87% of steel grades.
Sustainability4
Producing a kilogram of Q235B-N takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability8
Q235B-N's machinability is good (65/100, better than 93% of steel grades); weldability excellent (96/100); formability excellent (85/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Q235B tempers and conditions
Q235B is also supplied in 5 other conditions. The full side-by-side table is on the Q235B overview.
- HRDefaultDefault stock condition for structural plate, angle, channel, beam and hot-rolled coil; cheapest and most widely available.250 MPa yield · 120 HB
- CDPick for turned/machined shafts and fasteners where bright surface, straightness and higher yield strength are required.380 MPa yield · 150 HB
- CRPick for thin gauge (0.3–3 mm) parts needing a clean bright surface, tight thickness tolerance and good bend/stamping behaviour.280 MPa yield · 130 HB
- GalvanizedChoose for outdoor or humid service where painting is impractical; zinc gives sacrificial protection for years without maintenance.250 MPa yield · 120 HB
- NSpecified for thick plate or pressure parts where uniform fine grain and better impact toughness are needed after hot forming.245 MPa yield · 115 HB
Working with Q235B-N
Is Q235B easy to machine?
Easy but gummy — low-carbon steel tears and builds up on the edge; use sharp positive-rake tooling, generous feed and coolant, expect ~70 % of 1212 speeds.
Can Q235B be welded?
Prequalified for all arc processes (SMAW/GMAW/FCAW/SAW) with E43xx/ER70S-6 consumables, no preheat needed below ~30 mm and no PWHT; remove mill scale, zinc or oil first.
Can Q235B be formed, bent or molded?
Excellent cold bending, roll forming and stamping; keep bend radius ≥1×t for HR plate, and bend across the rolling direction on thick sections.
What surface finishes work on Q235B?
No anodizing; protect by shot-blast + primer/paint, phosphate, zinc plating or hot-dip galvanizing — bare surfaces flash-rust within hours in humid air.
Q235B 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 700-2006 Q235B | 0.12 – 0.2 | 0.17 |
| Si | ≤ 0.35 | 0.25 |
| Mn | ≤ 1.4 | 0.5 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Febalance, residual Cu/Cr/Ni/Mo as tramp elements | balance | — |
Q235B-N — frequently asked
What is Q235B-N used for?
Q235B-N is typically used for welded structural frames, building and platform framing, base plates and gussets, brackets and mounting plates, machine bases and weldments and bridge structural members. In short: chinese mild-steel sheet.
What is the yield strength of Q235B-N?
Q235B-N has a typical yield strength of 245 MPa (35.5 ksi) and a tensile strength of 410 MPa (59.5 ksi) — weaker than 95% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is Q235B-N easy to machine?
Reasonably — machinability is rated good (65/100, better than 93% of steel grades). Easy but gummy — low-carbon steel tears and builds up on the edge; use sharp positive-rake tooling, generous feed and coolant, expect ~70 % of 1212 speeds.
Can Q235B-N be welded?
Yes — weldability is rated excellent (96/100). Prequalified for all arc processes (SMAW/GMAW/FCAW/SAW) with E43xx/ER70S-6 consumables, no preheat needed below ~30 mm and no PWHT; remove mill scale, zinc or oil first.
What surface finishes work on Q235B-N?
No anodizing; protect by shot-blast + primer/paint, phosphate, zinc plating or hot-dip galvanizing — bare surfaces flash-rust within hours in humid air.
Can Q235B-N be formed, bent or molded?
Excellent cold bending, roll forming and stamping; keep bend radius ≥1×t for HR plate, and bend across the rolling direction on thick sections.
What is the maximum service temperature of Q235B-N?
Q235B-N is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Q235B-HR and Q235B-CD?
HR is the default condition — default stock condition for structural plate, angle, channel, beam and hot-rolled coil; cheapest and most widely available. CD: pick for turned/machined shafts and fasteners where bright surface, straightness and higher yield strength are required. Yield strength is 250 MPa in HR versus 380 MPa in CD.
Can FabDigit make parts in Q235B-N?
Yes — Q235B-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 3274 / GB/T 709 hot-rolled plate & coil dimensions and quality — SAC (China) (2017)
- EN 10025-2 (S235JR comparison grade) — CEN (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- GB 50017 (elastic constants, allowable stress) — MOHURD (2017)
- worldsteel LCI methodology report (steel embodied energy/carbon) — World Steel Association (2023)
- Mysteel / 1688 Q235B — Mysteel (2026)
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.