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Mild Steel

Mild steel (also known as low-carbon steel) is the workhorse of the manufacturing industry. It offers an excellent balance of strength, formability, and cost, making it the default choice for everything from structural brackets to decorative panels. With carbon content typically below 0.25%, mild steel is easy to weld, bend, and laser cut. It machines well, accepts a wide range of surface finishes, and is readily available in sheet, plate, tube, and bar forms across Australia.

Key Properties

Density7.85 g/cm³
Tensile Strength400–550 MPa
Yield Strength~250 MPa
Elongation~20%
Melting Point1,425–1,540°C
MagneticYes

Grades

PropertyHA250HA300HA350
Yield Strength≥250 MPa≥300 MPa≥350 MPa
Tensile Strength≥350 MPa≥400 MPa≥450 MPa
Elongation22%18%15%
Typical UseGeneral fabrication, brackets, enclosuresStructural, machinery, moderate loadsHeavy structural, mining, high-load

HA250

The standard grade for general sheet metal fabrication. Good formability and weldability.

HA300

Higher strength grade for structural applications where more load-bearing capacity is needed.

HA350

High-strength structural grade used in demanding applications. Less formable than HA250.

Available Thicknesses

Common laser cutting thicknesses: 1.2mm, 1.6mm, 2mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 16mm, 20mm. Thinner gauges available for light fabrication; heavier plate up to 25mm+ for structural work.

Fabrication Notes

Mild steel is one of the easiest metals to fabricate. It laser cuts cleanly across all common thicknesses, bends predictably with standard tooling, and welds readily using MIG, TIG, or stick methods. It is magnetic, which is relevant for fixturing and some applications. Machining is straightforward with standard HSS or carbide tooling.

Surface Finishes

Powder coating (most common), wet paint, zinc plating, hot-dip galvanising, blueing/blackening, clear coat. Raw mild steel will rust if left uncoated, so a protective finish is almost always required.

When to Choose Mild Steel

Choose mild steel when cost is a primary concern, the part will be painted or coated, structural strength is needed, or the application is indoors or protected from moisture. It is the default choice for brackets, frames, enclosures, guards, and general fabrication work.

Limitations

Mild steel rusts readily without a protective coating, making it unsuitable for exposed outdoor or marine environments unless galvanised or painted. It is significantly heavier than aluminium (roughly three times the density). Not suitable for food-contact or hygienic applications without appropriate coatings.

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Quick Info

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