Steel Q235B
GB Q235B · ASTM A36 · EN S235JR · JIS SS400
Q235B is the workhorse Chinese carbon structural steel (GB/T 700), a low-carbon killed/semi-killed grade with a specified minimum yield of 235 MPa and guaranteed +20 °C Charpy V-notch impact energy of 27 J.
Values for the HR condition
Q235B tempers and conditions
Q235B is supplied in 5 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Normalized | Specified for thick plate or pressure parts where uniform fine grain and better impact toughness are needed after hot forming. | 245 | 410 | 31 | 115 HB | 10.8 % IACS |
HRDefault Hot rolled | Default stock condition for structural plate, angle, channel, beam and hot-rolled coil; cheapest and most widely available. | 250 | 420 | 28 | 120 HB | — |
Hot rolled, pickled and oiled | Use when hot-rolled strength/price is wanted but mill scale must be gone for welding, painting or stamping. | 250 | 420 | 28 | 120 HB | 10.8 % IACS |
Cold rolled | Pick for thin gauge (0.3–3 mm) parts needing a clean bright surface, tight thickness tolerance and good bend/stamping behaviour. | 280 | 420 | 26 | 130 HB | — |
Cold drawn | Pick for turned/machined shafts and fasteners where bright surface, straightness and higher yield strength are required. | 380 | 500 | 15 | 150 HB | — |
Supply forms, finishes and certifications
Ways Q235B is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Galvanized | Hot-dip zinc coated | Coating |
What is Q235B?
Q235B is the workhorse Chinese carbon structural steel (GB/T 700), a low-carbon killed/semi-killed grade with a specified minimum yield of 235 MPa and guaranteed +20 °C Charpy V-notch impact energy of 27 J. It is chosen for general welded structures, frames, brackets, plate and section work because it is cheap, universally stocked and welds/forms with no preheat or post-weld treatment. Its limits are low strength, no meaningful corrosion resistance without paint or galvanizing, and poor low-temperature toughness compared with the C/D quality levels. Q235B 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). Q235B has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 94% of steel grades. Elongation at break is 28% and the elastic modulus is 206 GPa (29.9 Msi).
What is Q235B used for?
- Welded structural frames
- Building and platform framing
- Base plates and gussets
- Brackets and mounting plates
- Machine bases and weldments
- Bridge structural members
- Fabricated enclosures and ducting
Advantages
- Readily welded — 95/100, better than 97% of steel grades
- Forms and bends easily — 85/100, better than 96% 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
- Ductile — tolerates forming and impact — 28%, better than 89% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
- Low strength — 250 MPa (36.3 ksi), worse than 94% of steel grades
Q235B properties
Typical room-temperature values for Q235B-HR; bars are the position among steel grades.
Physical3
Q235B 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 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 94% of steel grades. Elongation at break is 28% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
Q235B 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 87% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
Q235B conducts electricity at 10.8 % IACS, better than 94% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of Q235B 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's machinability is good (65/100, better than 93% of steel grades); weldability excellent (95/100); formability excellent (85/100).
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. Q235B is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Q235B
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.
Manufacturability
The process limits FabDigit's quote engine applies to Q235B. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Better65 / 100 |
|---|---|
| ISO material group | P.1 |
| Cutting speed (rough / finish) | 220 / 260 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Excellent85 / 100 |
|---|---|
| Weldability | Excellent95 / 100 |
| Bendable | Yes |
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 |
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.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel Q235B in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does Q235B cost?
Q235B is a budget-cost steel ($), cheaper than about 99% 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.
Q235B — frequently asked
What is Q235B used for?
Q235B 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?
Q235B has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 94% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is Q235B 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 be welded?
Yes — weldability is rated excellent (95/100). 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?
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 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?
Q235B 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.
How much does Q235B cost?
Q235B is a budget-cost steel ($), cheaper than about 99% 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.
Can FabDigit make parts in Q235B?
Yes — Q235B 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; 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.