Surface coating, repair, and rapid design changes of high-value components and tools are demanding challenges of modern manufacturing technology. In this field, advanced laser-based techniques are of outstanding importance for the related applications in mould and tool, aircraft and aerospace, as well as automotive industry. Many laser cladding solutions have been transferred into industrial series production within the last years. The motivations for the raising interest are given by the typical features of the technology: on the base of closed CAD/CAM chains, a quick and comprehensive treatment even of complex shaped and highly stressed components is possible. The heat input into the workpiece is less compared to TIG or PTA welding, although a metallurgical bonding to the substrate is guaranteed. Furthermore, the precise material deposition even at small partial areas is an advantageous characteristic. The coating materials include metal alloys (Co, Ni, Cu basis, Titanium, and steel), hard metals (e.g., WC/Co, TiC, and VC with metallic binders), and oxide ceramics (Al 2 O 3 /TiO 2 ). Typical base materials are steel, cast iron, and lightweight metal alloys based on Aluminum, Titanium, and Magnesium. The accuracy of the produced 3D structures in the range of 0.1 mm is the highest possible in the group of welding techniques. On the other hand, the available system technology (lasers, powder feeders and nozzles, CAD/CAM systems) permits a very easy and successful integration of the laser technology into manufacturing systems. Examples of application are the surface protection of lightweight automotive motor components, repair and quick modifications of metal forming tools as well as the complete restoration of damaged blades and disks of aero engines and gas turbines.

Hybrid laser welding technologies can be defined as the combination of a high quality laser heat source with an additional secondary heat source. Based on such a definition, known hybrid techniques are classified by the type of the heat sources used as well as their arrangement relative to each other. The classification is followed by a discussion of different theoretical aspects occuring during a hybrid laser beam welding process concerning the plasma characteristics and the resultant temperature distribution of the superposed heat sources. Finally, some practical examples demonstrate how the potential of hybrid technologies can be used to extend the application spectrum of the laser beam welding process.

The fabrication of hierarchical periodic microstructures on metals by means of direct laser interference patterning was investigated. A nanosecond pulsed Nd:YAG laser at 355 nm wavelength was used to produce the microstructures with grating periods ranging from 1 micron to 10 micron on stainless steel, titanium, and aluminum. The results indicate that the geometrical characteristics of the interference patterns as well as the thermal properties of the substrates determine the quality of the fabricated structures. In particular, the best structures were obtained when the material at the interference minima position remained in the solid state and the temperature at the interference maxima is below the vaporization temperature. Thermal simulations by finite element method were carried out modeling photothermal interactions of the interference pattern with the metallic substrates to evaluate laser induced thermal effects, such as temperature distribution and temperature gradients and, thus, enabling to explain the obtained results

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