Laser surface cladding: the state of the art and challenges

Laser cladding is a process whereby a new layer of material is deposited on a substrate by laser fusion of blown powders or pre-placed powder coatings. Multiple layers can be deposited to formshapes with complex geometry. This manufacturing process has been used for material surface property modification and for the repair and manufacture of three-dimensional components. Laser cladding has attracted extensive research over the past 30 years. Over 2000 research papers have been published in journals and international conferences. Research in laser cladding covers many scientific issues, including processing techniques, physical and chemical properties of deposited materials and clad-substrate interfaces, microstructure and phases, rapid solidification phenomena, modelling and simulation, and systems engineering and applications. This article, focusing on the rapid heating/cooling processes and material response, summarizes the state of the art on two fundamental scientific aspects: rapid solidification and the material characteristics. The article includes a review of the microstructural refinement, extended solid solution, metastable phases, amorphous structure, and directional solidification. In addition, the article discusses the progress and state of the art in laser cladding of commercial alloy powders, carbides and intermetallics, in-situ synthesized particulate reinforced metal matrix composite coatings, compositional gradient materials, and alloy development. Laser cladding is capable of producing materials with designed macro/microstructures and properties.