Mild Steel 101: Grades, Uses & Facts
13 Jun 2025
Mild steel. It’s everywhere – from the frame of your car to the shelves in your garage. And for good reason. It’s affordable, strong and easy to work with. But if you’re wondering what makes mild steel so popular – or which grade to use for your project – this no-nonsense guide is here to clear things up.
Whether you’re a builder, fabricator or weekend DIY warrior, understanding the ins and outs of mild steel means better choices, cleaner cuts and a smoother job from start to finish.
Article in brief
Mild steel is low-carbon steel – strong, affordable and easy to cut, weld or shape.
It’s magnetic, highly workable, widely used and one of the most recycled metals worldwide.
Key grades include S235JR (structural), EN1A (machining), EN8 (automotive) and 500B rebar (reinforcement).
Found in construction, fabrication, vehicles, furniture and outdoor gear (especially when galvanised).
Reliable, versatile and cost-effective – mild steel is a go-to material across every trade.
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What is mild steel?
Mild steel is a type of low-carbon steel. It typically contains between 0.16% and 0.29% carbon – just enough to give it strength without making it brittle. That’s what makes it "mild" compared to other steels.
You won’t find any fancy alloying elements like chromium or nickel in standard mild steel. Just good old-fashioned iron and carbon, sometimes with a dash of manganese or silicon depending on the grade.
It’s strong but not hard to shape. Tough but not impossible to cut. And it won’t cost you the earth either.
Bonus? It’s magnetic, fully recyclable and used across practically every industry – from construction and cars to fencing and furniture.
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Key properties of mild steel
Mild steel’s popularity comes down to its solid mix of features:
- Workability – You can cut it, bend it, drill it and weld it with ease. Ideal for fabrication and forming.
- Strength & ductility – It’s strong enough for structural jobs but flexible enough to shape without cracking.
- Cost-effective – It’s one of the most budget-friendly metals you can buy.
- Weldability – Thanks to its low carbon content, mild steel welds cleanly without needing preheat or post-heat treatment.
- Magnetic – Mild steel is ferromagnetic, which is useful for certain mechanical and electronic applications.
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Mild steel grades, made simple
Not all mild steel is the same. Different grades suit different jobs – and knowing which to pick saves time, money and stress. Here are the ones worth remembering:
- S235JR – A low carbon structural steel with good weldability and impact resistance. Common in base plates, brackets, and general construction work.
- S355JR – Stronger than S235. Ideal for heavy-duty structural applications, frames, and load-bearing elements.
- EN1A (Free-Cutting Mild Steel) – Designed for machining. Contains sulphur and/or lead to make it cut like butter. Perfect for precision parts, nuts and bolts.
- EN3B – General-purpose bright mild steel. Easy to machine, weld and form. A go-to for axles, fasteners and light-duty engineering.
- EN8 – Higher carbon than typical mild steel. Tougher and stronger, but still workable. Great for automotive parts and shafts.
- 500B Rebar (BS 4449) – Mild steel made for reinforcing concrete. Delivers tensile strength where concrete needs it most.
- Galvanised Mild Steel (to BS EN ISO 1461) – Mild steel with a protective zinc coating. Ideal for outdoor and exposed applications where rust is a concern.
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Common uses for mild steel
Thanks to its versatility and price point, mild steel is a favourite across trades and industries. You’ll find it in:
- Construction – Beams, columns, frames and brackets. S275JR is especially common in structural builds.
- Fabrication – From custom gates and fences to warehouse racking, mild steel gets the job done.
- Automotive – Chassis components, axles and engine parts often rely on EN8 and EN3B grades.
- Machining – EN1A’s free-cutting properties make it ideal for nuts, bolts, pins and turned parts.
- Concrete reinforcement – Rebar (like 500B) strengthens slabs, walls and columns in everything from housing to bridges.
- Furniture & fixtures – Shelving, supports and frameworks. Mild steel is popular in both functional and decorative forms.
- Outdoor applications – Galvanised mild steel holds up well in sheds, trailers, gates and guardrails.
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How mild steel compares to other metal
Not sure if mild steel is the right fit? Here’s how it stacks up:
- Mild steel vs stainless steel – Stainless resists rust and looks sleeker, but it’s pricier and harder to machine. Mild steel wins on cost and ease of use.
- Mild steel vs aluminium – Aluminium is lightweight and corrosion-resistant but nowhere near as strong. Mild steel’s better for load-bearing work.
- Mild steel vs brass – Brass looks better and is easier to machine in some cases, but it’s softer and costlier. Mild steel’s the practical pick for structural jobs.
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Working with mild steel
Whether you’re cutting, welding or machining, here’s what to expect:
- Cutting – Mild steel cuts easily with standard saws, grinders or plasma cutters. For smoother edges, use carbide-tipped tools or laser cutting.
- Welding – Most mild steels weld without fuss. EN1A is trickier due to its sulphur content, but others like EN3B and S275JR weld cleanly.
- Drilling – Standard HSS bits work well. For faster, cleaner holes, use cutting fluid and moderate speed.
- Forming & bending – Mild steel is ductile, especially in hot-rolled or annealed form. It bends easily in sheet or bar form.
Finishing, rust prevention and care
Raw mild steel will rust if exposed to moisture. Luckily, it’s easy to protect:
- Paint & primers – Red oxide primer followed by metal paint gives long-term corrosion resistance.
- Galvanising – Zinc-coating adds rust protection, especially for outdoor gear. Look for galvanised box section, angle or sheet.
- Powder coating – Adds colour and protection in one durable layer, but can be prone to chipping. This exposes the mild steel underneath, so careful installation and maintenance are required.
- Pickling – Removes mill scale or rust using acid. Ideal prep for painting or coating.
- Storage tips – Keep dry, covered and off damp floors to reduce rust before use.
Related: Can You Paint Galvanised Steel?
Mild steel sustainability
Mild steel isn’t just tough – it’s recyclable. In fact, it’s one of the world’s most recycled materials. Offcuts, swarf and scrap all go back into the supply chain without losing strength. That’s good news for your budget and the planet.
Strong, simple and ready for anything
If your project needs a metal that’s strong, easy to work and doesn’t cost a fortune, mild steel delivers. From structural jobs to small components, it’s a workhorse material trusted by pros and DIYers alike.
At The Metal Store, we stock a massive range of mild steel – from angle, box section and sheet to flat bar, round bar and tube. We’ll cut it to size for free and deliver it fast, anywhere in the UK.
Shop mild steel at The Metal Store today and get cracking on your next project.
