Pasquale Cavaliere - Laser Cladding of Metals

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Laser cladding (LC) for additive manufacturing is a very interesting process for both the production industry and research. Today, LC challenges process engineers and material scientists with many adjustable processes and material parameters, metallurgy, and defects. The development of laser cladding with its unique advantages will continue to advance with additive manufacturing of complex functional and volumetric parts. Additive manufacturing through laser cladding is a nonlinear process depending on many variables. Many models have been developed in order to predict the optimal cladding properties as a function of the fundamental processing parameters governing the deposition. The online continuous process monitoring is fundamental for the final quality of the laser cladded structures. Although laser cladding process is currently well controlled from a manufacturing strategy point of view and allows producing healthy components with a low or nonexistent porosity level, the microstructure of the parts obtained by these techniques is far from being understood and controlled. In metals, the grain size and orientation are essential factors for the control of the properties, especially the mechanical properties. The type of solidification (columnar or equiaxed) and grain size depend on the local solidification conditions, while the grain orientation is strongly conditioned by epitaxy phenomena based on the current orientation of the substrate microstructure. It is therefore very important to be able to model the behavior of the metal during its solidification and to be able to predict what type of solidification will occur. The goal is to correlate the main parameters of this additive manufacturing process with the microstructure generated by them and relate them to the mechanical properties obtained from samples.

The introductory chapters of the book illustrate the potential of Laser Cladding Technology as an optimal additive manufacturing tool. Laser cladding has evolved into a potent three-dimensional additive manufacturing technology by stacking the deposited material layers. Currently, a wide variety of materials can be processed. The ability to functionalize surfaces as well as 3D-printed objects leads to further integration of structural, optomechanical, and thermal properties into these parts. One approach is the combination and encapsulation of optical elements like quartz lenses or laser crystals with custom alloys, thus creating multi-material components. Additive manufacturing with laser cladding also offers the opportunity to integrate cooling solutions, which reduce mechanical stresses and improve optical properties of the assemblies. These complex structures lead to increasingly complex processes with narrow process and parameter windows within which defects can occur. Several materials can be employed for the production of laser cladding coatings in order to achieve high hardness for wear resistance, thermal and corrosion barriers, and fatigue life improvement.

The books chapters are devoted to illustrate the model employed for production of the optimal microstructure of laser cladded components. The main aim is to correlate the main parameters of this additive manufacturing process with the microstructure generated by them and relate them to the mechanical properties obtained from samples.

Many examples on laser-cladded superalloys, titanium alloys, and steel are provided. The specific relationship among composition, processing parameters, corrosion, and mechanical properties in laser cladding technology are described.

My special acknowledgments to the passion and cooperation of all the authors and reviewers who made possible the realization of this book and the reduction of the publication time with their hard work and prompt responses. My special thanks to the professionalism of the editorial office manager and assistants.