Technology
Vacuum laser welding vs protective gas welding
Laser welding under protective gas (argon)
In many conventional processes, an inert gas (often argon) is used to protect the molten pool from oxidation.
However, this process has several limitations:
Higher energy consumption:
Argon absorbs part of the energy and disrupts heat transfer. To achieve the same penetration, laser power must be increased.
Formation of metallurgical defects:
Despite protection, gas bubbles can be trapped in the molten pool → appearance of porosity. In some cases, reactions with argon can also create inclusions.
Sometimes heterogeneous weld bead:
Gas flow can destabilize the welding cavity (keyhole) and cause continuity defects in the weld bead.
Impact on mechanical performance
- ✗ The residual presence of porosity or microcracks locally weakens the welded section.
- ✗ These defects act as crack initiators, reducing static mechanical strength (tension, bending).
- ✗ In fatigue (cyclic loading), the effect is even more pronounced: micro-porosity is sufficient to trigger premature cracking.
- ✗ Result: the weld may have lower strength than the base material, with significant performance dispersion.
Vacuum laser welding
Conversely, welding performed in a vacuum chamber completely removes air and gases around the joint:
Less energy required → all laser energy is transmitted to the workpiece.
No porosity: complete absence of trapped gases in liquid metal.
No oxidation: ideal for aluminum, titanium or stainless steel.
Perfectly homogeneous and more regular weld bead.
Impact on mechanical performance
- Absence of trapped gases → no porosity → no weak zones.
- Absence of oxidation → cleaner and more homogeneous metal-to-metal bonding.
- Solidification is more regular, limiting residual stresses.
- High and stable mechanical strength, often close to or equivalent to that of the base material.
- Excellent fatigue resistance, as no crack initiators are present.
- Better long-term reliability.
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