**13. Applications of laser welding**

The application of laser beam welding (LBW) in the industry is increasingly expanding, from microelectronics to shipbuilding can use this welding process. This user potential can be attributed to the following factors [3–7, 13, 17, 19–21]:


Some of these features make LBW the preferred option for some industries that have previously used the resistance welding process. The LBW process can also be combined with an electric arc welding process with a wire used in neutral shielding gas or the MIG welding process. These process combinations are designed to be placed on the surface to be welded. In addition, the special equipment used significantly reduces the tools needed to prepare the desired edge for welding. The existing filler wires with the appropriate chemical composition have provided the necessary conditions for the uniformity of the mechanical properties of the welding area. In addition, the combined processes can significantly increase the speed of work, are also effective in deep penetration and the overall sealing. Recent advances in laser diodes have provided a new opportunity to solve industry problems.

Powerful CO2 lasers (2-10 kW) are currently used in automobile structure welding, heat exchangers, etc. For years, ruby lasers less than 500 W have been used to weld small workpieces such as small, delicate parts of medical instruments, electronic packs, and even razors. High-power ruby lasers use optical fibers to transfer the beam. This was done simply by robots and made possible a wide range of 3D applications such as cutting and laser welding automobile structures.

The laser beam is focused on a small point and creates at that point, it causes the metal to melt and even evaporate. To focus the power of powerful CO2 lasers, water-cooled mirrors are used instead of lenses.

Fiber laser welding stands out as a robust technique when the joining of dissimilar materials is considered using the LBW in medical devices, electronics, automotive, and aerospace applications. It can simultaneously reduce manufacturing costs and offer design flexibility.

Theoretically, any material that can be joined by conventional methods, can be also welded by LBW. However, when welding dissimilar materials due to their different physical and chemical properties (e.g. melting point, boiling point, density, thermal conductivity, and coefficient of thermal expansion) various difficulties can occur, which makes the joint unacceptable. Moreover, good solid solubility is vital for the production of sound welds of dissimilar metals. This is only achieved when the materials have compatible melting points. If the vaporization temperature of a material is close to the melting point of the other one, the weldability is low, which results in low-quality joint and/or formation of brittle intermetallic phases.

Formerly, most dissimilar welds were performed by flashlamp pulsed Nd:YAG lasers. Lamp-pumped sources can produce multi-millisecond pulses, which have peak powers much higher than the average source power (with a low duty cycle). High peak power of the lamp-pumped Nd:YAG sources along with the pulse shaping capabilities results in an ideal option for welding dissimilar materials. Penetration depth is too deep during this technique, which may lead to defective joints. However, insufficient weld depths can be prevented by adjusting the initial and final powers based on the base metals and the joint geometry.

Researchers have developed various pulse shapes to improve weld quality and decrease cracks and porosity. These attempts have provided valuable solutions to join dissimilar materials in the absence of welding defects.

LBW is a versatile method that can be used for various types of metals (**Table 2**). Some of the metals commonly used in LBW are:


*Laser Welding DOI: http://dx.doi.org/10.5772/intechopen.102456*


#### **Table 2.**

*Recent reports on dissimilar LBW joints.*


Further advances have been made in this technology to expand its scope. It can now be used for many other types of metals and even dissimilar materials.
