常见问题

🔬  1、 Types and characteristics of core protective gases

Helium (He)

Advantages: The highest ionization energy (24.6 eV), almost no reaction with metals, can effectively suppress plasma cloud formation, ensure direct laser energy to the workpiece, significantly improve penetration and welding speed; The porosity of the weld seam is low, making it particularly suitable for high-power welding (such as aluminum alloys and titanium alloys) 159.

Limitations: High cost (about 5-8 times that of argon gas), mostly used in high value-added fields such as aerospace and healthcare.

Argon gas (Ar)

Advantages: High density (1.784 g/L), good sinking coverage of the molten pool, low activity, and can prevent oxidation; The weld surface is smoother and cost-effective (with a market share of over 90%) 3710.

Limitations: Low ionization energy (15.8 eV), easy to ionize and form plasma shielding, reducing laser effective power and melting depth. Parameter compensation needs to be optimized to 25.

Nitrogen (N ₂)

Advantages: The lowest cost, moderate ionization energy (14.5 eV), and the ability to generate nitrides to strengthen the weld strength of 689 when welding stainless steel.

Limitations: Reacting with aluminum alloys and carbon steel to generate brittle nitrides, reducing toughness; Stainless steel welding may cause porosity, and strict control of the process is required.

⚙️  2、 The core role of protective gas

Suppress plasma shielding

High power lasers ionize metal vapor into plasma clouds, consuming laser energy. Helium accelerates electron recombination through its high ionization energy and light atomic properties, significantly reducing plasma obstruction to laser (penetration can be increased by 20% to 30%) 259.

Comparison: Due to its tendency to ionize, argon gas has a melting depth that is about 15% lower than helium gas.

Oxidation prevention and pollution control

Pool protection: Isolate harmful gases such as oxygen and nitrogen to avoid weld embrittlement and porosity (such as titanium alloy welding requiring full coverage with argon gas).

Lens protection: high-speed airflow blocks metal vapor and splashes, extending the lifespan of high-power equipment lenses (especially when power>6kW) 1410.

Optimize weld quality

Reduce splashing and porosity, improve sealing (such as achieving a gas tightness of 10 ⁻⁹ mbar · L/s for stainless steel welds under argon protection) 610.

Improve the fluidity of the melt pool and make the weld morphology uniform (nitrogen increases the strength of stainless steel welds by about 10% to 15%) 89.

📊  3、 Reference Table for Gas Selection Decision

Recommended material types, typical gas scenarios, and precautions

Stainless steel N ₂/Ar structural components and pipeline N ₂ can enhance strength, but anti porosity is required

Aluminum alloy/titanium alloy He/Ar automotive battery tray, aerospace components He priority, Ar needs to be matched with high-frequency modulation laser

Carbon steel Ar mechanical components and containers are prohibited from using N ₂ to prevent embrittlement

High reactive material (copper) He electron heat sink, conductive components with high power (>8kW) for better performance

🌬️  4、 Gas blowing method and process optimization

Side blowing on the side axis

Suitable for straight welding seams (butt joint, lap joint), with a wide protection range and excellent protection effect on the rigid solidification zone.

Parameter example: Airflow velocity of 15~20 L/min, inclined spray angle of 30 °~45 °.

Coaxial protection

Suitable for complex geometric welds (circular, polygonal), with coaxial airflow and laser to ensure even coverage of the molten pool.

Limitations: Weak protection for solidified areas, requiring matching with workpiece motion trajectory 6.

Key operating specifications

Airflow control: Insufficient protection due to low flow rate (<10 L/min); Excessive flow (>25 L/min) causes turbulent flow to be drawn into the air.

Start stop sequence: First turn on the gas → then start the laser → welding is completed → delay gas shutdown (oxidation prevention) 410.

💎  Summary and Suggestions for Super Meter Laser Welding Machine

Economic priority for argon gas: covering 90% of conventional scenarios (carbon steel, stainless steel), balancing cost and surface quality;

Helium is preferred for high-performance requirements: 19 is preferred for high reactive materials, deep fusion welding, and precision medical devices;

Stainless steel special nitrogen selection: strengthens weld strength, but requires process validation to prevent porosity.

In practical applications, it is necessary to comprehensively select based on material characteristics, welding power, and joint design, and balance cost and quality through parameter optimization (such as gas flow rate and blowing angle).