Practical power range of commonly used materials in laser welding

In the process of laser welding, there are significant differences in the demand for laser power among different materials, and mastering these differences is crucial for the rational design of welding processes. The following lists typical power requirements divided by material type and thickness:

Carbon Steel and Low-Alloy Steel
Carbon steel and low-alloy steel are typically easy to weld using laser technology due to their moderate absorptivity and favorable thermal properties. For thin sections, such as those between 0.5 mm and 1 mm, laser power in the range of 200 to 800 watts is sufficient, operating in conduction mode. For automotive applications, such as body-in-white lap welding, power levels between 3 and 8 kilowatts are standard. For thicker sections, between 5 mm and 15 mm, multi-kilowatt systems ranging from 5 to 20 kilowatts are necessary to ensure good penetration and weld quality.

Stainless Steel
Laser welding of stainless steel is particularly effective because of its low thermal conductivity, which allows heat to remain localized, creating narrow, deep welds with minimal heat-affected zones. For sections up to 3 mm thick, power requirements typically range from 500 watts to 3 kilowatts. When welding thicker sections, particularly in aerospace and industrial applications, power needs increase, often requiring 5 kilowatts or more for sections thicker than 5 mm.

Aluminum Alloys
Aluminum alloys require higher power levels due to their high reflectivity and thermal conductivity. For thin sheets, especially in electronics and packaging, power levels of 1 to 3 kilowatts are commonly used. However, for thicker sections such as those found in automotive structural components, power needs typically rise to 4 to 8 kilowatts. For heavy aerospace components, power levels exceeding 10 kilowatts may be necessary to achieve sufficient penetration and proper weld formation.

Titanium Alloys
Titanium alloys share similar power requirements with stainless steel, but the welding process requires strict atmospheric shielding to prevent contamination. For thin foils, power levels starting at 500 watts are sufficient, whereas aerospace components, typically thicker than 3 mm, require several kilowatts of power for effective welding.

Copper and Copper Alloys
Copper and its alloys pose a significant challenge in laser welding due to their high reflectivity and thermal conductivity, requiring much higher power compared to steel for the same thickness. For thin foils, laser power can start at around 1 kilowatt, but for medium-thickness bus bars, power requirements may reach 10 kilowatts or higher. The use of green laser sources, which offer better absorption in copper, has been beneficial, particularly for applications in electronics and battery manufacturing.

Nickel-Based Superalloys
Nickel-based superalloys, commonly used in aerospace turbine components, present challenges due to their narrow welding process window. These alloys typically require moderate power levels, similar to stainless steel, but with extremely precise control. Power selection must carefully balance full fusion with control over the thermal cycle to prevent hot cracking, making the process window particularly narrow, especially in thicker sections.

The power requirements for welding different materials are directly linked to their thermophysical properties, such as absorptivity, thermal conductivity, and weldability. Carbon steels and stainless steels offer relatively flexible welding parameters, whereas aluminum and copper alloys demand significantly higher power levels due to their reflective and conductive properties. Titanium and nickel-based superalloys require precise control of power and environmental conditions, but they don’t need excessively high power levels compared to aluminum or copper. Therefore, the challenge in laser welding is not just selecting the right power level, but understanding how power interacts with material characteristics to ensure effective welds.