Laser Cutting Quality and Material Composition

Currently, laser cutting technology has gradually replaced traditional metalworking methods — especially for processing metals like carbon steel, stainless steel, copper, and aluminum — thanks to its low processing cost, fast production efficiency, precise cutting accuracy, and excellent processing quality.

With the widespread adoption of laser cutting technology, problems began to emerge in laser processing; for example, some issues were identified when cutting steel sheets of different compositions using the same process, the same power, the same temperature, and the same laser cutting machine. The surface quality of the cut samples showed noticeable differences.

How Material Composition Affects Laser Cutting Quality

Additives in steel directly affect laser cutting quality. The type and amount of additives present in steel can affect the material’s heat resistance, cutting speed, and cutting temperature. Some additives can disrupt the steel’s heat distribution and lower laser cutting quality. Other additives, however, can improve the steel’s cutting performance and increase laser cutting quality.

Metals with high carbon content mostly belong to the group of metals with a high melting point. Since they’re difficult to melt, cutting and piercing time is extended. On one hand, this widens the kerf and expands the heat-affected zone, causing unstable cutting quality;

On the other hand, a high content in the alloy composition increases the viscosity of the molten metal and increases the rate of spatter and dross, placing higher demands on adjusting laser power and air blowing pressure during processing.

When the assist gas is oxygen, an increase in the C and Cr content of the material worsens the cut surface and significantly increases surface roughness;

When the assist gas is air, the cutting effect will not be significantly affected at the same thickness and power.

Effect of Carbon Content

In high-carbon steels, edge hardening (heat-affected zone) during laser cutting can be more pronounced.

Chromium-Nickel Alloys

Chromium and nickel in stainless steels can require different gas and power settings for laser cutting.

Surface Reflection

Highly reflective metals like aluminum and copper can make cutting difficult, since they reflect part of the laser energy.

Which Alloying Element Affects Laser Cutting Quality, and How?

The effects of the following elements on laser cutting surface quality are given as examples:

Carbon (C): High carbon amounts improve cutting performance by increasing the steel’s hardness, but can also cause bubbles to form on the cut surface. Low carbon amounts increase the steel’s cuttability, but can also cause the cut surface to be rough. In general, for the best surface quality in laser cutting, a carbon ratio of 0.3-0.5% in the steel is recommended.
Manganese (Mn): Manganese improves cutting performance by increasing the steel’s hardness, but can also cause bubbles to form on the cut surface and reduce surface quality.
Nickel (Ni): Nickel increases cutting quality by improving the steel’s corrosion resistance, but can also disrupt heat distribution and lower surface quality.
Chromium (Cr): Chromium increases cutting quality by improving the steel’s corrosion resistance, but can also cause bubbles to form on the surface.
Molybdenum (Mo): Molybdenum improves cutting performance by increasing the steel’s hardness and durability, but can also disrupt heat distribution and lower surface quality.

The effects of these elements depend on the type of steel and the amount of the element present. When selecting steel materials and setting up processing for laser cutting, the effects of alloying elements on surface quality should be taken into account.