Short answer: Yılmaz Sac Profil cuts carbon steel on its 20 kW fiber laser up to 20 mm with nitrogen-based mixed gas (a nitrogen-rich mix with a small share of oxygen) and up to 30 mm with oxygen. A mixed-gas cut edge has minimal oxidation: without the distinct oxide layer that oxygen cutting leaves, it gives far more consistent results in priming, painting, powder coating and hot-dip galvanizing. Plate above 30 mm is cut by plasma or oxy-fuel.
Cutting carbon steel with nitrogen-based gas needs far more laser power than oxygen cutting, which is why many plants limit it to thin and medium gauges and cut thick plate with oxygen. This article explains what the mixed gas is, how it changes the cut edge, why it needs so much power, why the edge matters before painting and galvanizing, and which gas to choose for which job.
What is nitrogen-based mixed gas?
In fiber laser cutting the beam melts the material in a narrow zone and assist gas from the nozzle blows the melt out of the kerf. The choice of gas sets the physics of the cut and the chemistry of the edge. Oxygen reacts with the iron and adds energy to the cut; nitrogen is inert and simply clears the melt at high pressure.
Nitrogen-based mixed gas (mix gas in shop-floor terms) is an assist gas that is mostly nitrogen with a small share of oxygen. The cut is mainly a fusion cut driven by nitrogen, and the small oxygen share speeds it up. The result is a clean cut face with far less oxidation than an oxygen cut. In our plant carbon steel is cut with this mix up to 20 mm; stainless steel and aluminium are cut with nitrogen for edge quality and corrosion resistance.
How does the edge differ from an oxygen-cut edge?
In oxygen cutting the burning of the iron adds energy to the cut, so thick carbon steel can be cut with relatively modest power. The price is a distinct oxide layer on the cut face. That layer is a separate surface which may need removing before painting, powder coating or galvanizing, and before some welding.
With nitrogen-based mixed gas, oxidation is kept to a minimum. Cut faces are cleaner, and corners, small holes and fine details come out sharper and truer to size. The table compares the three gases for carbon steel, stainless steel and aluminium; the thickness figures refer to the 20 kW fiber laser in our plant.
| Property | Oxygen (O₂) | Nitrogen mixed gas (N₂ + some O₂) | Nitrogen (N₂) |
|---|---|---|---|
| Material | Carbon steel | Carbon steel | Stainless steel (304/316) and aluminium |
| Cutting mechanism | Reactive cut; oxygen reacts with the iron and adds energy | Mainly fusion cutting; the small oxygen share speeds the cut | Fusion cutting; the gas is inert and clears the melt |
| Cut edge | Distinct oxide layer | Minimal oxidation; clean cut face | Clean, bright edge |
| Corners, small holes, fine detail | Reaction heat limits fine detail | Sharp and true to size | Sharp and true to size |
| Before priming, painting, galvanizing | Oxide layer may need removing | Far more consistent results on the cut edge | Edge quality and corrosion resistance preserved |
| Laser power needed | Relatively low | Far higher | High |
| Thickness in our plant | Up to 30 mm | Up to 20 mm | Depends on material; confirmed at quotation |
| Cost | Most economical | Costs more than oxygen cutting | High gas consumption |
Why does nitrogen-based cutting need so much laser power?
In oxygen cutting the iron-oxygen reaction supplies a large part of the cutting energy. In nitrogen-based cutting that contribution largely disappears, and almost all the energy needed to melt the material has to come from the beam. As thickness rises, the volume of metal to be melted and ejected per unit of cut length grows, so the power needed climbs steeply with thickness.
That is why many plants limit nitrogen-based cutting of carbon steel to thin and medium gauges. On our 20 kW fiber laser we reach 20 mm with mixed gas; carbon steel from 20 to 30 mm is cut with oxygen, and plate above 30 mm goes to our plasma and oxy-fuel cutting lines. High power also raises cutting speed on thin and medium gauges, and because machine time feeds directly into part cost, it lowers unit cost on series work.
| Thickness | Method | Note |
|---|---|---|
| Up to 20 mm | Fiber laser: nitrogen mixed gas or oxygen | Mixed gas keeps oxidation to a minimum; the gas follows the edge requirement |
| 20–30 mm | Fiber laser: oxygen | Oxide layer on the edge; may need removing before painting or galvanizing |
| Above 30 mm | Plasma or oxy-fuel cutting | For thick plate and heavy fabrication parts |
Why does the cut edge matter for painting, powder coating and galvanizing?
A coating adheres to whatever surface it is applied to. On an oxygen-cut edge that surface is not the steel itself but the oxide layer formed during cutting. That is why oxygen-cut edges are often ground or blasted before painting or coating, and as part counts and cut lengths grow, this edge preparation becomes a cost and time item of its own in fabrication.
A mixed-gas cut edge carries no heavy oxide layer. Priming, painting, powder coating, coating and hot-dip galvanizing give far more consistent results on the cut edges, and the need for edge-specific cleaning drops. The surface preparation required is still set by the paint or coating system's specification; state your edge requirement in the quote request and we choose the cutting gas accordingly.
Which jobs call for oxygen, and which for mixed gas?
The choice of gas depends on thickness, on what happens to the part after cutting and on cost priorities. The table summarises typical cases; different parts in the same order can be cut with different gases.
You do not need to specify the gas in a quote request; it is enough to say what happens to the part after cutting. Will it be painted, galvanized, welded, or used on a visible surface? When the edge requirement is clear, the right gas is chosen and unnecessary cost is avoided. The cost drivers are covered in detail in how laser cutting is priced.
| Situation | Recommended cut | Why |
|---|---|---|
| Part to be painted, powder coated or galvanized (up to 20 mm) | Nitrogen mixed gas | No heavy oxide layer on the cut edge; more consistent coating result |
| Visible edges, small holes and fine detail (up to 20 mm) | Nitrogen mixed gas | Sharper corners, detail true to size |
| Edge to be machined or bevelled for welding afterwards | Oxygen | The edge is reworked anyway, so oxygen is more economical |
| Unpainted, hidden structural part; cost first | Oxygen | Most economical cut |
| Carbon steel plate 20–30 mm | Oxygen | Our mixed-gas limit is 20 mm; oxygen cuts up to 30 mm at laser quality |
| Plate above 30 mm | Plasma or oxy-fuel cutting | Beyond laser capacity; more economical on thick plate |
| Stainless steel and aluminium | Nitrogen | Edge quality and corrosion resistance |
What happens after cutting: bending, welding and delivery?
Laser-cut parts are bent in the same plant on a 1,000-ton press brake: our longest bend is 8 m in one piece, without a joint, and our thickest plate is 25 mm. These are separate maxima; on heavy plate the bendable length depends on thickness and grade and is confirmed at quotation. Box sections and tubes are cut on a dedicated tube and profile laser unit, and welding and assembly can follow in the same plant. We work to ±0.1 mm on laser-cut parts.
Parts ship across Türkiye and to Europe, the Middle East and North America by truck or container. EN 10204 3.1 mill certificates and certificates of origin are provided on request; delivery terms (EXW, FOB or CIF) are agreed at quotation. See fiber laser cutting and laser cutting services for capacity details.
What should you send for a quote?
Drawing (DXF or DWG preferred; a PDF drawing or dimensioned sketch also works), material and thickness (for example S235JR 12 mm), quantity and any recurring requirement, edge requirement (painted, powder coated, galvanized, welded or visible; an EN ISO 9013 quality class where needed), secondary operations (bending, welding, assembly) and delivery address.
Send your files through the quote form or to contact@yilmazsacprofil.com; we reply with the cutting gas, price and lead time.
Frequently asked questions
How thick can carbon steel be laser cut with nitrogen-based mixed gas?
On Yılmaz Sac Profil's 20 kW fiber laser, carbon steel is cut up to 20 mm with a nitrogen-rich mixed gas containing a small share of oxygen. Thicker carbon steel is cut with oxygen up to 30 mm, and plate above 30 mm by plasma or oxy-fuel.
How does mixed-gas cutting differ from oxygen cutting?
Oxygen reacts with the iron, adds energy to the cut and leaves a distinct oxide layer on the edge. Mixed-gas cutting is mainly a fusion cut: oxidation is kept to a minimum, the cut face is cleaner and corners and holes come out sharper. In return it needs far more laser power and costs more than oxygen cutting.
Can mixed-gas cut parts be painted and galvanized?
Yes; that is the main reason to use it. With no heavy oxide layer on the edge, priming, painting, powder coating and hot-dip galvanizing give far more consistent results on the cut edges. Surface preparation is still set by the paint or coating specification.
Why is carbon steel above 20 mm cut with oxygen?
In nitrogen-based cutting almost all the melting energy has to come from the beam, so the power needed climbs steeply with thickness. At 20 kW we reach 20 mm with mixed gas. With oxygen, the iron-oxygen reaction adds energy, so laser-quality cuts are possible up to 30 mm.
Does mixed-gas cutting cost more?
Yes, it costs more than oxygen cutting: it uses more laser power and more gas. Where the part will be painted, galvanized or used on a visible surface, it can still lower total fabrication cost because it reduces edge cleaning. The cost drivers are covered in how laser cutting is priced.
Which gas is used for stainless steel and aluminium?
Stainless steel (304/316) and aluminium are cut with nitrogen for edge quality and corrosion resistance. The thickness that can be cut depends on the material and is confirmed at quotation.