1. Introduction
Laser welding technology features low heat input, dense and aesthetically pleasing weld seams, high precision control, and easy automation integration, enabling its rapid adoption in the metal manufacturing industry. However, not all materials are suitable for laser welding. Factors such as thermal conductivity, optical absorption characteristics, melting point differences, alloying elements, and surface conditions can influence welding quality. Therefore, understanding the applicable material range and limitations of laser welding is crucial for equipment selection, process planning, and production quality control.
2. Applicable Material Range
Laser welding is suitable for multiple categories of metallic materials, among which ferrous materials represent the most mature application field. Materials such as carbon steel, low-alloy steel, and stainless steel exhibit good absorption of the laser beam, providing stable weld formation, controllable penetration depth, and sufficient mechanical strength. Nickel-based alloys also show stable microstructures during welding with low cracking tendency, and are widely used in aerospace components and battery tabs. These materials are considered the most laser-friendly.
Aluminum and aluminum alloys are also weldable, though with higher process difficulty compared to ferrous materials. Aluminum exhibits high reflectivity, high thermal conductivity, and low melting point, making the molten pool unstable and prone to porosity. Therefore, welding aluminum typically requires higher laser power, more precise focal position control, and optimized shielding gas selection to ensure process stability and weld density. Despite the challenges, aluminum alloys are frequently used in battery enclosures, consumer electronics housings, and aerospace structures.
Copper and copper alloys represent materials with even higher welding difficulty. Copper has extremely high reflectivity and thermal conductivity, resulting in low initial laser coupling efficiency and frequent defects such as lack of fusion, discontinuous welds, or solidification cracking. With the development of high-power fiber lasers, green lasers, and pulsed laser sources, copper welding performance has improved and is increasingly utilized in battery busbars, electrical connectors, terminals, and precision electronic components.
Laser welding is also suitable for precious metals such as gold, silver, and platinum. These materials are widely used in jewelry fabrication and electrical contact manufacturing. Although they have high thermal conductivity, their welding stability remains excellent. Pulsed lasers are commonly used for precision micro-welding, delivering exceptional weld consistency and surface quality.
3. Materials with Limitations
Laser welding is not suitable for all materials. High-carbon steels and cast iron, although belonging to the ferrous system, contain higher carbon content. During rapid heating and cooling, they tend to form hard and brittle microstructures, generating cracks or porosity. Such materials require preheating, controlled cooling, or reduced energy density to minimize welding defects.
Zinc, magnesium, and certain magnesium–aluminum alloys exhibit process limitations as well. These materials have low melting points and high vapor pressures, which tend to produce porosity, spatter, and unstable molten pools, resulting in poor weld appearance and density. Although process optimization can improve performance, industrial applications remain relatively limited.
Materials with surface coatings such as silver, nickel, or gold present additional challenges. The coating layer alters laser energy absorption, leading to insufficient coupling or inconsistent melting. Moreover, multi-layer coatings may delaminate under heat due to poor interfacial adhesion. Surface sanding or the use of pulsed or green lasers is often required to improve absorption.
For non-metallic materials, conventional metal laser welding systems are not suitable for plastics, rubber, or composites. Plastic welding requires specific transmission welding processes and material pairings, typically applying dedicated laser plastic welding systems rather than conventional metal laser sources.
4. Dissimilar Metal Welding
Laser welding is also used for joining dissimilar metals. However, metallurgical compatibility, thermal expansion mismatch, and melting point differences impose significant constraints. Stainless steel and carbon steel are easier to weld together, while aluminum–stainless steel, copper–stainless steel, and aluminum–copper pairs are prone to forming brittle intermetallic compounds, reducing joint strength. Industrial practice often adopts laser brazing, wobble scanning, filler wire addition, or optimized beam paths to improve joint performance. The feasibility depends more on process strategy than on the base materials themselves.
5. Process Limitations and Influencing Factors
Material suitability for laser welding is determined by multiple influencing factors, including laser wavelength, surface absorption characteristics, alloying elements, thermal conductivity, reflectivity, surface contamination, oxide layers, travel speed, focal position, and shielding gas. Different materials have distinct processing windows, requiring careful equipment selection and parameter adjustment based on material characteristics.
6. Conclusion
In summary, laser welding machines exhibit broad applicability in metal processing. Ferrous and nickel-based materials are the most suitable, while aluminum and copper alloys are weldable but require advanced process control. Certain high-carbon materials, coated metals, and lightweight alloys show application limitations, and plastics or non-metallic materials require specialized laser systems rather than conventional metal welding sources. With the advancement of high-power fiber lasers, green/blue laser sources, and ultrafast lasers, the applicable material range continues to expand, and current welding bottlenecks are expected to be overcome in more industrial sectors.