laser cut mild steel

Hi all

How does laser cutting create a hard skin on ordinary en3 mild steel?

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But it's not supposed to heat treatable steel ???????

I think it is due to the use of CO2 or Nitrogen in the cutting process to blow the molten metal away, some of the carbon from the CO2 gets into the metal and raises it's carbon content a bit like case hardening. The Nitrogen has a similar effect to Nitriding.

Thanks Jason, that makes sense.

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An alternative to laser cutting is water jet cutting which does not have the problem caused by heating the metal.

Materials are cut using a jet of pressurised water as high as 60,000 pounds per square inch (psi).

To increase cutting ability, abrasives such as garnets and aluminum oxide are often added. The overall process mimics erosion in nature, just at a much higher speed and concentration. Water jets are capable of cutting many industrial materials including stainless steel, titanium, aluminium, tool steel, ceramics, granite, and armour plate.

Paul

The laser will heat the metal around the cut to above its transformation point and this will create a Heat-affected Zone. The HAZ for laser cutting is quite small and localised near the cutting point. For CO2 lasers Oxygen is mainly used for cutting mild steel but Nitrogen can also be used for high pressure cutting. Nitrogen mainly used for high pressure cutting Aluminium and Stainless Steel. At least that's how we do it.