Steel Mild Steel
Mild steel is the generic plain-carbon structural steel family with roughly 0.05–0.25 % C and up to ~1.0 % Mn (typified by Q235, S235, A36, 1018), supplied mostly as hot-rolled plate/section and cold-rolled sheet or cold-drawn bar.
Values for the HR condition
Mild Steel tempers and conditions
Mild Steel is supplied in 7 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Use when maximum ductility for severe forming, deep drawing or spinning is needed, or to relieve prior cold work. | 210 | 340 | 38 | 100 HB | — |
Cold rolled | Pick for thin sheet needing a clean bright surface, tight thickness tolerance and good deep-draw/bend behaviour. | 240 | 350 | 32 | 110 HB | — |
HRDefault Hot rolled | Default, cheapest form for structural plate, sections and hot-rolled bar where mill scale and loose tolerances are acceptable. | 250 | 400 | 24 | 120 HB | — |
Normalized | Choose for uniform fine-grain structure and consistent toughness in thicker plate, forgings and weldments. | 260 | 420 | 28 | 125 HB | — |
Stress relieved | Use to stabilise dimensions of welded or heavily machined mild-steel assemblies with minimal loss of strength. | 280 | 400 | 24 | 120 HB | 10.8 % IACS |
Cold drawn | Best pick for machined shafts and fixture parts: bright surface, tight diameter tolerance and ~40 % higher yield than hot-rolled. | 370 | 440 | 15 | 130 HB | — |
Carburized & quenched | Pick when a mild-steel part needs a wear-resistant surface (gears, pins, bushings) while keeping a tough low-carbon core. | 380 | 550 | 12 | 60 HRC | 10 % IACS |
Supply forms, finishes and certifications
Ways Mild Steel is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
HDG | Hot-dip galvanized sheet/section | Coating |
What is Mild Steel?
Mild steel is the generic plain-carbon structural steel family with roughly 0.05–0.25 % C and up to ~1.0 % Mn (typified by Q235, S235, A36, 1018), supplied mostly as hot-rolled plate/section and cold-rolled sheet or cold-drawn bar. It is chosen for its very low cost, excellent weldability and cold formability, and predictable ~200 GPa stiffness rather than for strength. Main limits are low strength compared with alloy steels, no useful response to through-hardening, poor corrosion resistance (needs paint, galvanizing or plating) and loss of toughness below about −20 to −30 °C. Mild Steel 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). Mild Steel has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 94% of steel grades. Elongation at break is 24% and the elastic modulus is 200 GPa (29 Msi).
What is Mild Steel used for?
- Welded frames and weldments
- Machine brackets and mounting plates
- Sheet metal enclosures and chassis
- Structural beams, base plates and gussets
- Laser-cut and formed panels
- Ducting and guarding
- Skids, carts and general fabrication
Advantages
- Readily welded — 95/100, better than 97% of steel grades
- High electrical conductivity — 10.8 % IACS, better than 94% of steel grades
- Forms and bends easily — 80/100, better than 93% of steel grades
- Conducts heat well — 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades
Limitations
- Low strength — 250 MPa (36.3 ksi), worse than 94% of steel grades
Mild Steel properties
Typical room-temperature values for Mild Steel-HR; bars are the position among steel grades.
Physical3
Mild Steel 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
Mild Steel has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 94% of steel grades. Elongation at break is 24% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
Mild Steel is rated for continuous service to 400°C (752 °F). It conducts heat at 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
Mild Steel 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 Mild Steel takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
Mild Steel's machinability is good (60/100, better than 83% of steel grades); weldability excellent (95/100); formability very good (80/100).
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. Mild Steel is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Mild Steel
Is Mild Steel easy to machine?
Easy but gummy in the annealed/hot-rolled state — use positive-rake tools, moderate speeds and flood coolant; cold-drawn bar chips and finishes noticeably better.
Can Mild Steel be welded?
Excellent by SMAW/GMAW/FCAW/TIG/resistance with no preheat below ~25 mm (CE typically <0.35); use E7018/ER70S-6 filler and remove mill scale, galvanizing or oil first.
Can Mild Steel be formed, bent or molded?
Very good cold formability — bends to 1t–2t radii, deep-draws in Al-killed CR sheet; hot forge 1050–1250 °C, allow springback and grain-direction effects.
Manufacturability
The process limits FabDigit's quote engine applies to Mild Steel. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Better60 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 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 | Excellent80 / 100 |
|---|---|
| Weldability | Excellent95 / 100 |
| Bendable | Yes |
Mild Steel 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≤0.26 % for A36 plate; 0.14–0.22 % for Q235/1018 | 0.05 – 0.25 | 0.18 |
| Mn | 0.25 – 1.2 | 0.6 |
| Si≤0.05 % in Al-killed CR sheet | 0 – 0.4 | 0.2 |
| P | ≤ 0.05 | 0.02 |
| S | ≤ 0.05 | 0.03 |
| Curesidual; 0.20 % min if copper-bearing specified | ≤ 0.35 | 0.1 |
| Fe | balance |
What surface finishes work on Mild Steel?
Not anodizable; protect with zinc plating, hot-dip galvanizing, phosphate + paint/powder coat, black oxide or oil, since 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
How much does Mild Steel cost?
Mild Steel is a standard-cost steel ($$), cheaper than about 71% 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.
Mild Steel — frequently asked
What is Mild Steel used for?
Mild Steel is typically used for welded frames and weldments, machine brackets and mounting plates, sheet metal enclosures and chassis, structural beams, base plates and gussets, laser-cut and formed panels and ducting and guarding. In short: workhorse mild-steel plate.
What is the yield strength of Mild Steel?
Mild Steel has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 94% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is Mild Steel easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Easy but gummy in the annealed/hot-rolled state — use positive-rake tools, moderate speeds and flood coolant; cold-drawn bar chips and finishes noticeably better.
Can Mild Steel be welded?
Yes — weldability is rated excellent (95/100). Excellent by SMAW/GMAW/FCAW/TIG/resistance with no preheat below ~25 mm (CE typically <0.35); use E7018/ER70S-6 filler and remove mill scale, galvanizing or oil first.
What surface finishes work on Mild Steel?
Not anodizable; protect with zinc plating, hot-dip galvanizing, phosphate + paint/powder coat, black oxide or oil, since bare surfaces flash-rust within hours in humid air.
Can Mild Steel be formed, bent or molded?
Very good cold formability — bends to 1t–2t radii, deep-draws in Al-killed CR sheet; hot forge 1050–1250 °C, allow springback and grain-direction effects.
What is the maximum service temperature of Mild Steel?
Mild Steel 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 Mild Steel-HR and Mild Steel CARB?
HR is the default condition — default, cheapest form for structural plate, sections and hot-rolled bar where mill scale and loose tolerances are acceptable. CARB: pick when a mild-steel part needs a wear-resistant surface (gears, pins, bushings) while keeping a tough low-carbon core. Yield strength is 250 MPa in HR versus 380 MPa in CARB.
How much does Mild Steel cost?
Mild Steel is a standard-cost steel ($$), cheaper than about 71% 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 Mild Steel?
Yes — Mild Steel 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
- ASTM A36/A36M — Carbon Structural Steel — ASTM International (2019)
- GB/T 700 — (Q195–Q275) — SAC (2006)
- EN 10025-2 — Non-alloy structural steels (S235JR) — CEN (2019)
- ASTM A1008/A1008M — Cold-Rolled Carbon Steel Sheet — ASTM International (2021)
- ASTM A108 / A29 — Cold-Finished and Hot-Wrought Carbon Steel Bars — ASTM International (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- Machinery's Handbook, 31st ed. — Industrial Press (2020)
- worldsteel LCI data for steel products — World Steel Association (2023)
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.