Mild steel or stainless steel for laser cutting: which to choose

Two steel families, two different uses

In sheet metal fabrication, “mild steel” (called ferro in Italian workshops) means carbon steel — also known as structural or low-carbon steel — while “stainless” means stainless steels, which contain chromium and nickel. Both laser-cut very well and weigh practically the same, but they behave differently over time and have very different costs. The choice almost always depends on where the part will be used and how it will be protected.

Mild steel: cheap and strong, but needs protecting

Mild steel is the most widely used material in metalwork and mechanical components. Its strengths are:

• low cost: for the same weight it costs much less than stainless steel;
• high thicknesses: it’s available up to 10 mm, compared with 5-6 mm for stainless;
• excellent workability: it’s easy to cut, bend and weld.

Its main limitation is corrosion: unprotected mild steel rusts. That’s why mild steel parts are normally painted (powder or liquid), galvanised or otherwise treated. If the part is going to be painted anyway, perhaps for aesthetic reasons, mild steel is almost always the most cost-effective choice.

Stainless steel: resists corrosion without treatment

Stainless steel spontaneously forms a thin protective layer of chromium oxide on its surface, which makes it corrosion-resistant without the need for painting. It’s the natural choice when the part:

• remains visible and must keep a clean metallic look over time;
• is in contact with food, water or cleaning products;
• is intended for outdoor or humid environments;
• must be easy to wash and sanitise.

The two most common stainless alloys are AISI 304, suitable for most uses, and AISI 316, which thanks to molybdenum better resists chlorides, salt and chemicals. You’ll find a dedicated guide on the site comparing the two in detail.

Stainless finishes: 2B, SB and BA

Stainless steel comes in different surface finishes, which change the look of the finished part:

Finish	Appearance	Typical use
2B	Smooth and matt, light grey	Technical components, non-visible parts, industrial use
SB (brushed)	Uniform, directional brushing	Furniture, visible panels, cladding
BA (bright)	Shiny, almost mirror-like	Decorative elements, premium finishes

The finish doesn’t change the alloy’s mechanical strength or corrosion resistance: it’s an aesthetic choice. Brushed and bright finishes are, however, more delicate and may require a protective film during processing to avoid scratches.

Comparison table

Property	Mild steel	AISI 304 stainless	AISI 316 stainless
Material cost	Low	Medium-high	High
Corrosion resistance	None without protection	Good	Excellent
Maximum available thickness	10 mm	6 mm	5 mm (4 mm brushed)
Protective treatment	Required	Not required	Not required
Available finishes	Raw, to be painted	2B, SB, BA	2B, SB, BA
Indicative weight	about 8 kg/m² per mm of thickness	about 8 kg/m² per mm of thickness	about 8 kg/m² per mm of thickness

How to choose: quick checklist

1. Will the part be painted or otherwise protected? If so, mild steel is almost always the cheapest choice.
2. Will the part stay visible without paint, or be in contact with food or water? Choose stainless steel.
3. Is the environment marine, saline or chemically aggressive? Go for AISI 316.
4. Do you need a thickness above 6 mm? It’s currently only available in mild steel.
5. Does appearance matter? Choose the stainless finish based on the desired effect: 2B for technical parts, brushed or bright for visible ones.

If in doubt, you can upload the file to the calculator and compare the price of the same part in different materials: by changing only the material you’ll see straight away how much it affects the quote.