The Role of Oxygen in Laser Cutting Machines and Its Application in the Sheet Metal Industry

Chemical Principle of Oxygen in Fiber Laser Cutting

During fiber laser cutting, the auxiliary gas oxygen serves as a "combustion aid." The core principle involves utilizing the exothermic oxidation reaction between metal and oxygen to enhance the cutting effect. When a high-energy laser beam is focused on the metal surface, it instantaneously heats the local material to melting or even ignition. At this point, high-purity oxygen (typically >99.5% purity) sprayed onto the incandescent metal triggers a vigorous chemical reaction, generating metal oxides and releasing significant thermal energy. Taking iron as an example, under laser ignition, iron reacts with oxygen to form iron oxide (e.g., FeO, etc.). This exothermic reaction provides an additional "chemical energy source" to the cutting process. Studies indicate that the thermal power released by this oxidative combustion of iron can be comparable to the laser's own power, making the entire cutting process essentially a stimulated combustion of iron in oxygen. Therefore, compared to purely laser-melting metal, oxygen-assisted cutting achieves superposition of laser energy and chemical combustion energy, significantly improving heating and cutting efficiency for metals.

Oxygen combustion-aided cutting not only provides stronger heating but also helps blow away molten slag. While oxygen consumes metal during the reaction, the high-speed airflow and reaction products expel the molten metal oxides from the kerf, preventing the cut from re-solidifying. This synergistic effect of "mechanical blowing + chemical reaction" makes the cutting process more efficient. Since the oxidation reaction provides additional heat, when cutting medium-thick carbon steel plates, using oxygen assistance can reduce the requirement for laser power, even enabling smaller-power lasers to cut thicker materials. For example, conventionally, a 4kW fiber laser can cut nearly 20mm thick mild steel plates with oxygen assistance, which is the result of oxygen's exothermic combustion aid.

However, oxygen's chemical action also brings side effects. The reaction between metal and oxygen leaves an oxide layer (commonly known as scale or oxide slag) on the cut surface, causing the cut edge to appear dark gray or black. This oxide layer often adheres to the cut surface, degrading surface quality compared to inert gas cutting. Furthermore, the intense exothermic reaction of oxygen is detrimental to cutting thin sheets and fine sharp corners—excessive combustion can cause burning, leading to melting and collapse at sharp corners, preventing sharp edges. In summary, the chemical mechanism of oxygen in laser cutting can be summarized as: "Laser provides ignition, oxygen supports combustion." This mechanism grants stronger cutting capability but necessitates managing the resulting oxidation effects.

Comparative Analysis of Oxygen, Nitrogen, and Air in Cutting Different Metal Materials

Common auxiliary gases for laser cutting include oxygen (O₂), nitrogen (N₂), and compressed air. They exhibit differences in speed, cut quality, and cost when cutting different metal materials. The choice of gas depends on material properties and cutting priorities (efficiency, quality, or cost). Below is a comparison for carbon steel, stainless steel, and aluminum alloys:

• Carbon Steel (Mild Steel, Common Steel Plate):

  • Oxygen: The most common choice for cutting carbon steel because oxygen rapidly oxidizes iron exothermically, significantly increasing cutting speed. For medium-thick mild steel, oxygen-assisted cutting speed is typically about 30% faster than nitrogen. Oxygen cutting requires relatively lower pressure (approx. 0.3~0.8 MPa) and smaller gas flow rates, resulting in far lower gas consumption per unit time than nitrogen. Therefore, oxygen cutting has low gas costs and good overall economy. The iron oxide formed during cutting is also easily blown away by high-temperature vapor, allowing relatively smooth sections on thin sheets. However, due to oxidation, the cut surface retains an oxide layer, appearing dark, requiring subsequent grinding or descaling. If the cut requires welding or painting, the oxide layer must be thoroughly cleaned to avoid affecting weld quality (oxide scale peeling later causing weld defects). Overall, oxygen is suitable for thick carbon steel cuts where efficiency is prioritized and surface oxidation is acceptable.
  • Nitrogen: As an inert gas, nitrogen does not participate in any chemical reactions when cutting carbon steel; it only blows away molten metal with high-pressure airflow. Thus, nitrogen-cut carbon steel edges have no oxide adhesion, showing a silvery-white metallic luster with high edge quality, suitable for direct welding or coating. However, nitrogen provides no additional heat; cutting carbon steel relies entirely on laser power, making cuts slower than oxygen (especially for thicker plates). Only for very thin carbon steel sheets (e.g., <3mm) with sufficient laser power can nitrogen achieve speeds comparable to or even faster than oxygen, as maximum laser power can be used without burning. Generally, nitrogen cutting for carbon steel is primarily chosen to avoid oxidation and improve quality, e.g., for high subsequent surface quality requirements or parts needing no secondary processing. Its disadvantage is the need for high pressure (typically 1-2 MPa) and large flow rates, leading to significantly higher gas consumption per unit time for thick plates and the highest gas usage cost. Therefore, nitrogen is prioritized only for carbon steel processing requiring high-quality edges and willingness to bear higher gas costs.
  • Air: Compressed air consists of ~78% nitrogen and ~21% oxygen, with extremely low cost and convenient supply (only requiring an air compressor). Air cutting carbon steel represents a compromise between oxygen and nitrogen: On one hand, the oxygen content in air is much lower than pure oxygen, offering limited combustion assistance; on the other hand, the high nitrogen content provides some protective effect. Thus, for thin carbon steel sheets, air cutting effects can approach nitrogen cutting quality while maintaining low costs similar to oxygen, making it an economical and efficient choice. Practical tests show that with ~1.2 MPa compressed air, a 3000 W fiber laser can cut carbon steel sheets below 2mm with smooth, slag-free sections and significantly increased speed. However, air cutting also has obvious drawbacks: Due to oxygen content, the cut surface still exhibits slight yellowing, darkening, or burrs, requiring additional deburring and surface cleaning. Therefore, air can be used as a compromise gas for carbon steel processing where edge quality requirements are not high, sheets are thin, and low cost is pursued. But for high-quality, oxidation-free applications, air is inferior to nitrogen. In summary, oxygen is generally used for thick carbon steel for speed; for thin sheets, nitrogen is chosen for quality or air for cost depending on the situation.

• Stainless Steel:

  • Oxygen: Stainless steel (mainly containing iron, chromium, nickel, etc.) laser cutting typically does not use oxygen as the auxiliary gas (at least when finished part quality is required). While oxygen can also undergo heating and oxidation reactions with stainless steel to improve cutting capability, the major drawback is that the chromium oxide layer formed on the cut edge after oxidation is very hard and destroys the stainless steel's rust resistance. This causes the edge to discolor, blacken, and lose its stainless properties; if not subsequently processed or coated, it becomes prone to corrosion. Additionally, the high alloy content of stainless steel makes oxygen combustion less efficient and rapid than in carbon steel, potentially reducing cut quality (increased slag adhesion). Therefore, oxygen is only used temporarily for pre-piercing thick stainless steel (because oxygen combustion aids rapid piercing) before switching back to nitrogen for the cutting stage to ensure quality. Overall, oxygen is unsuitable for routine stainless steel cutting, as the quality loss outweighs the speed benefit.
  • Nitrogen: Nitrogen is the standard auxiliary gas for stainless steel laser cutting. The inert nitrogen environment prevents high-temperature metal from reacting with atmospheric oxygen. The cutting process only involves blowing away molten metal, forming no oxide layer. Thus, stainless steel cut with nitrogen has bright, clean, non-discolored edges, directly maintaining the material's original corrosion resistance. This is crucial for stainless steel products, as oxidation contamination or oxide layers damage surface aesthetics and the rust-protective film. The disadvantage of nitrogen cutting stainless steel is slower speed for thick plates, requiring reliance on high laser power for penetration. Simultaneously, nitrogen consumption is high and costly; thick plates require ultra-high purity nitrogen (>99.999%) and pressures above 2 MPa to avoid kerf dross. This makes thick stainless steel cutting extremely expensive. However, with the advent of high-power fiber lasers, nitrogen cutting capability for stainless steel has significantly improved, offering satisfactory speed and unparalleled quality for medium thicknesses. Therefore, in precision manufacturing, food/medical equipment, and other industries with stringent stainless steel edge quality requirements, nitrogen is the essential choice, with cost being secondary.
  • Air: Compressed air is a suboptimal solution for stainless steel cutting. Because it contains ~21% oxygen, cutting stainless steel inevitably generates a thin layer of chromium oxide/nitride on the cut, causing slight yellow or brown oxidation tinting. Although this tint is far less severe than the thick black oxide scale from pure oxygen cutting, it may be acceptable for applications insensitive to surface color (e.g., internal structural parts, parts to be painted later). The advantage of air cutting stainless steel lies in low cost and no need for bottled gas storage/transportation, but cut quality and stability are difficult to match nitrogen. Generally, air can be used for blanking thin stainless sheets or applications with medium quality requirements. Reports indicate that a 3000W laser with 1.2 MPa air can cut stainless steel within 10mm with acceptable section quality. However, for stainless steel products requiring high surface quality and corrosion resistance (e.g., decorative panels, uncoated components), nitrogen is still prioritized to ensure oxidation-free, clean cuts.

• Aluminum Alloy:
  Aluminum and its alloys present challenges for laser cutting compared to ferrous materials due to high reflectivity and the tendency to form a dense aluminum oxide (Al₂O₃) film. Pure oxygen is typically not used as an auxiliary gas for cutting aluminum alloys. On one hand, aluminum's affinity for oxygen does not release sufficient heat like iron, offering limited help in improving cutting efficiency. On the other hand, the aluminum oxide (Al₂O₃) formed on the surface after oxidation has an extremely high melting point and is very difficult to melt and blow away, instead easily forming refractory oxide slag that affects kerf quality. Therefore, oxygen is generally prohibited for aluminum alloy laser cutting to avoid stubborn black slag on the edges. Aluminum is usually cut using Nitrogen or Air as auxiliary gas: Nitrogen avoids oxidation, directly blowing away molten aluminum to achieve a silver-white, oxidation-free cut, suitable for aluminum parts with high appearance and quality requirements. Air, due to its oxygen content, causes slight oxidation darkening of the edge, but its low cost makes it acceptable for thinner aluminum parts requiring painting. It's important to note that aluminum alloys have high thermal conductivity; sufficient laser power combined with high-pressure auxiliary gas is needed to cut thick plates. In some cases, examples exist of using nitrogen to cut aluminum or copper alloys. Nitrogen is more inert, avoiding potential reactions with specific materials (e.g., titanium forming brittle nitrides with nitrogen). But nitrogen is more expensive and generally considered only for processing requiring extremely high quality or specific non-ferrous metals (copper, titanium, etc.).

Cutting Speed and Quality Comparison: In summary, the performance of different auxiliary gases on various materials can be summarized as follows: Oxygen offers the highest cutting speed (especially for combustible metals like carbon steel), but causes cut oxidation and surface discoloration, requiring relatively thorough post-processing costs. Nitrogen provides the best cut quality (oxidation-free, high smoothness), suitable for demanding materials like stainless steel, but has a relatively slower cutting speed and the highest gas cost. Air lies between them, with the lowest cost and wide applicability, offering decent efficiency for thin materials, but generally average cut quality with some oxidation and burrs, requiring trade-offs based on processing requirements. In actual production, material thickness and properties often determine the choice of auxiliary gas. For example, thick carbon steel plates mostly use oxygen for efficiency; stainless steel plates almost exclusively use nitrogen; while some medium-thin sheets may use air cutting for cost reasons.

Application Cases of Oxygen in the Sheet Metal Industry and Advantages in Carbon Steel Cutting

In the sheet metal processing industry, oxygen-assisted laser cutting plays an extremely important role, especially demonstrating significant advantages in carbon steel plate cutting. A considerable proportion of sheet metal manufacturing involves blanking mild steel and common steel plates, such as structural parts for engineering machinery, steel enclosures/cabinets, construction steel components, and various mechanical parts. These applications often involve steel plates ranging from a few millimeters to twenty millimeters in thickness, pursuing high cutting speeds and reasonable processing costs. Oxygen shines as an auxiliary gas in such processing for the following main reasons:

• Low Gas Cost, Convenient Supply: Oxygen sources are widespread and inexpensive, whereas obtaining and storing high-purity nitrogen is much more costly. Therefore, for large sheet metal workshops primarily processing carbon steel, using oxygen as the unified cutting gas can significantly reduce operating costs. Simultaneously, since only a single oxygen supply is needed, without frequent switching between different gases, production management is simpler, and equipment utilization is higher. Many sheet metal manufacturers report that using oxygen on carbon steel cutting lines significantly reduces time spent changing gases and adjusting processes, improving overall line efficiency. Especially when the processed parts are of a single material (all steel), one oxygen supply system can meet all cutting needs economically and efficiently.
• Strong Thick Plate Cutting Capability, High Speed: The most prominent advantage of oxygen-assisted cutting is its excellent performance on medium-thick carbon steel plates. Traditionally, steel plates thicker than 10mm were difficult to cut with lasers (requiring higher power and slower speed). However, with the aid of oxygen's combustion, even smaller-power lasers can quickly cut through thick steel plates. For example, some manufacturers have successfully cut 12mm carbon steel plates using a 1kW fiber laser with oxygen, attributable to the combustion significantly increasing effective cutting energy. Using nitrogen for similar thicknesses would be nearly impossible or require multiple times the power. For thick steel plates above 20mm, oxygen laser cutting even becomes an alternative to traditional flame cutting—lasers provide a precise, high-energy heat source, oxygen provides combustion heat, making the cutting process stable and far more precise than flame cutting. In practical cases, some engineering machinery manufacturers have replaced plasma or flame cutting with fiber laser + oxygen cutting for steel plates, resulting not only in narrower kerfs, smaller heat-affected zones, and less part deformation but also faster production cycles. Oxygen's speed advantage for carbon steel also applies to thin sheets: For carbon steel above 3mm, oxygen cutting speed is significantly faster than nitrogen. This means in large-volume steel blanking, oxygen cutting can shorten production cycles and improve delivery efficiency.
• Cut Quality Meets Subsequent Process Requirements: Although oxygen cutting produces oxide scale, this is not an unacceptable defect in many sheet metal applications. Firstly, carbon steel parts usually undergo subsequent processes like welding, painting, or rust prevention, which often involve sandblasting, pickling, or grinding beforehand, thereby eliminating the cutting oxide layer. Thus, the impact of oxide scale on final product quality is limited. Secondly, the slag produced by oxygen cutting carbon steel is less sticky and easy to clean; generally, chipping or polishing can remove residues, flattening the cut. Additionally, the oxide layer formed by oxygen cutting can temporarily act as a protective layer for the gap between weld seams if welding/painting doesn't occur immediately (though it needs removal before final processing). Many sheet metal structural parts have relatively low requirements for the cut edge; as long as there are no obvious burrs or large uneven surfaces, oxygen cutting fully meets the requirement. For example, connection plates for building steel structures are often blanked using oxygen laser cutting; the edge has a layer of black iron oxide scale, but this does not hinder its weldability—grinding the weld zone suffices. In applications like heavy machinery chassis parts, the slight burnt edge from oxygen cutting is usually hardened or treated before painting, posing no adverse effect on final coating adhesion. Evidently, for sheet metal parts primarily made of carbon steel requiring subsequent welding and painting, the quality obtained from oxygen cutting is practical and acceptable, striking a balance between efficiency and quality.

Overall, oxygen-assisted laser cutting holds irreplaceable practical value in carbon steel processing within the sheet metal industry: It balances high cutting speed with low operating costs and can handle cutting tasks for thick plates. In recent years, with the vigorous development of China's sheet metal industry, high-power fiber lasers combined with oxygen have become the standard process for many steel plate processing enterprises. Many typical application cases show that using oxygen to cut carbon steel compared to nitrogen can save significant gas costs and labor costs per year. For instance, some enterprises report saving over 100,000 RMB annually on auxiliary gas expenses after replacing some nitrogen cutting processes with oxygen. Another sheet metal factory, for its 8mm thick carbon steel products, switched from nitrogen cutting to oxygen cutting; although an additional sandblasting/descaling step was added, overall production capacity increased by over 20%. This demonstrates that in the field of steel plate processing emphasizing cost control and production capacity, the advantages of oxygen laser cutting are very prominent, making it one of the mainstream solutions for carbon steel laser cutting.

Applicability, Limitations, and Future Technological Outlook of Oxygen Cutting

Despite oxygen's indispensable role in laser cutting, with the development of metal processing technology, we also need to rationally view the applicability and limitations of oxygen-assisted cutting and look ahead to possible future technological evolution directions.

1. Applicability Analysis: From a material compatibility perspective, oxygen laser cutting is mainly suitable for high-speed cutting of medium-thick plates of iron-based metals (carbon steel, low-alloy steel, etc.). For these materials, oxygen's combustion-aiding effect can be fully utilized, significantly enhancing cutting efficiency, and oxidation effects can be compensated for in subsequent processes. In production scenarios focused on efficiency, primarily processing steel (e.g., steel cabinet, automotive chassis parts, engineering machinery component production), oxygen cutting is widely adopted due to its efficiency and cost advantages. Furthermore, when laser power is limited (e.g., medium/small-power lasers), oxygen assistance can broaden the range of cuttable thicknesses, allowing thick steel plates that were previously uncuttable to be cut smoothly, making oxygen an essential aid. Overall, when processing tasks involve primarily carbon steel, thicker plates, high volume, and allow for some oxidation in quality, oxygen cutting is the most cost-effective choice.
2. Limitations Analysis: The limitations of oxygen laser cutting are equally evident. Firstly, it is not suitable for precision processing of non-ferrous metals and high-alloy materials. Using oxygen for aluminum, copper, etc., offers no benefit and quickly forms oxides that interfere with cutting, degrading quality; using oxygen for stainless steel destroys the material's rust-resistant surface, being counterproductive. Secondly, the issue of poorer cut quality with oxygen cannot be ignored in applications requiring high precision. The oxide layer increases surface roughness and reduces smoothness, unable to meet the high-quality, impurity-free requirements for cut surfaces in fields like medical devices and precision instruments. In such cases, only inert gases like nitrogen can achieve oxidation-free, bright cuts. Thirdly, oxygen cutting is not friendly to thin sheets, small parts, and intricate patterns. Excessive oxidation can erode fine features, and the combustion reaction is difficult to control precisely, leading to reduced dimensional accuracy of small features, making it unsuitable for contour cutting of precision parts. Additionally, from a processing safety perspective, a pure oxygen environment is highly flammable; equipment pipelines need protection from oil/grease to avoid combustion/explosion risks, a hazard requiring attention when using oxygen. Finally, oxygen cutting produces relatively more oxide fumes containing metal oxide particles, impacting the environment and operator health, necessitating stronger dust collection systems. These factors limit the scope of oxygen cutting: It is more suitable for scenarios prioritizing "efficiency first, quality second" rather than "quality first" precision manufacturing.
3. Industry Trends & Alternative Processes: As laser cutting technology and market demands evolve, the position of oxygen cutting in the sheet metal industry is also changing dynamically. A major trend is the widespread application of high-power fiber lasers (e.g., 10kW and even 20kW class laser cutters are gradually becoming common in the industry). High power means that even using inert gases like nitrogen, cutting speed and thickness capability have achieved qualitative leaps. For example, some advanced processes enable a 6kW laser using nitrogen to cut medium-thickness carbon steel at speeds approaching those previously achieved only with oxygen. This partially erodes oxygen's traditional speed advantage. When laser power is abundant, more enterprises tend to uniformly use nitrogen as the auxiliary gas to obtain stable, oxidation-free cuts, thereby eliminating subsequent processes like pickling and rust prevention. As observed by industrial gas suppliers: "The current market trend is to use one multi-purpose gas (nitrogen) to cover all material cutting whenever possible. Of course, in some specific situations (e.g., companies only cutting steel plates 2-3mm and above in thickness), oxygen is still the essential choice." This indicates that as equipment capabilities improve, the application scope of oxygen cutting may contract, becoming more concentrated in its strongest area: thick steel plate processing. Another noteworthy trend is the emergence of mixed gas technology and process optimization. To balance the advantages of both oxygen and nitrogen, some equipment manufacturers have introduced oxygen-nitrogen mixed auxiliary gas solutions. For example, Bystronic's MixGas technology achieves near-nitrogen cut quality on medium-thick carbon steel while maintaining high cutting speeds (almost no oxide or burrs) through a specific ratio of oxygen + nitrogen. This mixed cutting essentially introduces trace oxygen into an inert environment to promote melting and slag expulsion while controlling oxidation effects at a very low level, opening a compromise route. Although mixed gas currently has higher costs and complex control, it represents one future development direction—optimizing gas composition to achieve high speed and high quality. Simultaneously, regarding process parameters, new methods have emerged in recent years to improve oxygen cut quality. For instance, the "Oxygen Bright Surface Cutting Process" adjusts focal position (negative defocus) and jet methods to achieve bright sections close to nitrogen cutting on medium-thickness carbon steel with oxygen. This technology reduces oxide layer thickness and surface roughness by altering melt pool dynamics, greatly enhancing oxygen cut surface quality. Similarly, some laser manufacturers have developed pulsed piercing + constant oxygen pressure cutting modes to accelerate piercing on thick plates, reducing heat impact and preventing overburning. Furthermore, manufacturers have introduced dual-layer coaxial nozzles in cutting head design, surrounding oxygen with an outer layer of inert gas to confine oxidation to the cutting interior and protect the surface from excessive oxidation. Such new technologies continuously expand the application boundaries of oxygen cutting and enhance its competitiveness.
4. Future Outlook: From the perspective of global sheet metal processing trends, oxygen laser cutting will continue to play a significant role for a considerable time, but its application areas may become more segmented and specialized. For carbon steel mass processing pursuing ultimate efficiency and low cost, oxygen cutting remains indispensable. However, for manufacturing emphasizing high quality and part precision, oxygen may yield to nitrogen or even new auxiliary processes. Technologically, future laser cutting may develop in the following directions:
   • Higher Power and Intelligence: Ultra-high-power lasers combined with adaptive beam control will continuously enhance nitrogen's thick plate cutting capability, weakening oxygen's unique advantage. But intelligent systems might also make oxygen cutting more controllable (e.g., automatically avoiding overburning, real-time oxide removal).
   • New Auxiliary Media: Besides oxygen-nitrogen mixtures, mixtures incorporating small amounts of hydrogen, carbon dioxide, etc., might appear to achieve better results on specific materials. Even new energy coupling methods like plasma-assisted laser cutting may develop, replacing traditional pure oxygen combustion.
   • Environmental and Cost Considerations: Due to environmental and safety concerns, zero-cost gas sources like compressed air may become more favored. Once air cutting quality improvement technologies mature, it could largely replace oxygen and nitrogen in medium-thin sheet applications, significantly reducing carbon emissions and operating costs. Recently, many manufacturers have promoted "air cutting processes," achieving success in some 3-5mm plate applications. In the future, with advancements in supporting technologies like air purification and pressure stabilization, air is expected to become one of the universal auxiliary gases for laser cutting.

In conclusion, although oxygen's role in laser cutting is based on century-old oxy-fuel cutting technology, it remains relevant in the new era of laser processing. It provides a high-speed, high-efficiency solution for the sheet metal industry, particularly excelling in carbon steel cutting. With technological development, we will continuously seek better balances between efficiency and quality. It is foreseeable that oxygen-assisted cutting will coexist long-term with nitrogen, air, and other solutions, each leveraging their strengths to provide diverse process choices for sheet metal processing. We need to apply oxygen cutting strategically based on specific materials, thicknesses, and quality requirements, maximizing its strengths and mitigating weaknesses. Looking ahead, with continuous process improvement and innovation, oxygen cutting has the potential to revitalize within its niche areas. Together with other advanced technologies, it will drive sheet metal processing towards a more efficient, intelligent, and green future.

References:

1. Metal-Interface Technical Report, Oxygen or Nitrogen Gas for Laser Cutting in 6 points! [5, 16, 21]
2. DPLaser Blog, Oxygen vs. Nitrogen Laser Cutting - How to Choose? [24, 25]
3. Glory Laser Technology Article, Effect of Different Gases on Laser Cutting Results [6, 10]
4. Wuhan Newrad Gas, Application of Laser Mixed Gas in Laser Cutting [1, 11]
5. Sina Blog Reprint, Difference Between Using Air and Oxygen in Laser Cutting Carbon Steel [12, 8]
6. Jialin Laser Industry News, Advantages and Disadvantages of Common Auxiliary Gases [17, 26]
7. Atlas Copco Compressor Encyclopedia, Laser Cutting Process and Auxiliary Gases [3]
8. John Powell et al., Laser-oxygen cutting of mild steel: oxidation reaction thermodynamics [2]

[1, 9, 11] Laser Mixed Gas Application Guide in Laser Cutting
https://www.qit88.com/knowledge/jghhqzjgqq_1.html

2. Energy characteristics of laser-oxygen cutting of steel by CO2-laser radiation
   https://quantum-electronics.ru/wp-content/uploads/2012/en/14810.pdf

3. Laser Cutting Process and Auxiliary Gases: Why Nitrogen is Used in Laser Cutting
   https://www.atlascopco.com.cn/zh-cn/compressors/wiki/compressed-air-articles/what-is-laser-cutting

[4, 5, 7, 16, 21] Oxygen or Nitrogen Gas for Laser Cutting in 6 points | Metal Interface
https://www.metal-interface.com/articles-news/t/technical-report-laser-cutting/oxygen-or-nitrogen-gas-laser-cutting-6-points

[6, 10] What Gas is Used in Laser Cutting Machines? Different Gases Have Significantly Different Effects on Laser Cutting Results
https://www.glorylaser.cn/went/jjguangqiegejiyongshimeqitiqiegebutongqitduijiguangqiegexiaoguodeyingxiangdabutong.html

[8, 12] What is the Difference Between Using Air and Oxygen for Laser Cutting Carbon Steel? Nanjing Bohang Electronics - Sina Blog
https://blog.sina.com.cn/s/blog_17bd9fb7e0102zh/h.html

[13, 14, 15, 24, 25] Oxygen vs. Nitrogen Laser Cutting-How to Choose?
https://dplaser.com/oxygen-vs-nitrogen-laser-cutting-how-to-choose/

[17, 26] Role of Common Auxiliary Gases in Metal Laser Cutting Machines - Jialin Laser
https://www.jiabangkj.com//industry/1640.html

18. (PDF) Laser-oxygen cutting of mild steel: The thermodynamics of the oxidation reaction
    https://www.researchgate.net/publication/230950560_Laser-oxygen_cutting_of_mild_stel_The_thermodynamics_of_the_oxidation_reaction

19. Break Convention, Save 1.1 Million RMB Per Year Cutting Carbon Steel with This Method - Maxphotonics
    http://www.maxphotonics.com/ClNews/74.html

20. How to Overcome Challenges in Processing Medium-Thick Carbon Steel Plates? Hans Laser High-Power Cutting Head Reveals Secrets
    https://www.hansfocus.com/corporate-dynamics/507765

21. Bystronic MixGas Hybrid Cutting - Industrial Application Channel "Laser World"
    https://www.laserfocusworld.com.cn/DelAP.asp?id=8637

22. New Process for Quality Improvement and Efficiency Increase: High-Speed Oxygen Negative Defocus Cutting for Carbon Steel - News Aggregation Channel "Laser..."
    https://www.laserfocusworld.com.cn/DelN.asp?id=6299

Page 1 | Page 2 | Page 3 | Page 4 | Page 5 | Page 6