The formation of thick Ni-based coating on a steel substrate by coaxial laser cladding using the Nd:YAG 2 kW continuous laser was studied both from a theoretical and experimental point of view. The theoretical analysis concentrated on the transfer of laser irradiation and powder particles using a simple model of heat transfer to the substrate. This approach provides predictions of the laser power required for melting powder particles and substrate, respectively. For an appropriate experimental analysis of the main process parameters involved, a method based on a gradual change of a single processing parameter was examined. Correlations between the main processing parameters and geometrical characteristics of an individual laser track have been found and are discussed.

Analysis of coaxial laser cladding processing conditions

Joining steel with aluminum involving the fusion of one or both materials is possible by laser beam welding technique. This paper describes a method, called laser braze welding, which is a suitable process to realize this structure. The main problem with thermal joining of steel/aluminum assembly with processes such as TIG or MIG is the formation of fragile intermetallic phases, which are detrimental to the mechanical performances of such joints. Braze welding permits a localized fusion of the materials resulting in a limitation on the growth of fragile phases. This article presents the results of a statistical approach for an overlap assembly configuration using a filler wire composed of 85% Zn and 15% Al. Tensile tests carried on these assemblies demonstrate a good performance of the joints. The fracture mechanisms of the joints are analyzed by a detailed characterization of the seams.

Dissimilar material joining using laser (aluminum to steel using zinc-based filler wire)

Research and applications of viscoelastic vibration damping materials: A review

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 form shapes 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 solidific...

Laser surface cladding: The state of the art and challenges

Modeling of coaxial powder flow for the laser direct deposition process

A theoretical model for laser and powder particles interaction during laser cladding

One way of making car bodies lighter is to introduce some aluminium parts in place of steel. Steel and aluminium can be joined by laser braze welding. As in other types of thermal joining, inter-metallic phases may weaken the joint. In laser braze welding, these appear as a thin layer of brittle compounds at the steel/seam interface. Their formation is related to temperature. It has been shown that, if the layer is less than 10 μm thick, the joint is not compromised [Kreimeyer M., Sepold G. Laser steel joined aluminium-Hybrid structures, Proceedings of ICALEO'02, Jacksonville, USA; 2002]. Not only can temperature gradient be calculated by numerical simulation, but it is also possible to measure the surface temperature by thermography. We show here how thermography may be used to control temperature during laser braze welding.

B. Martin

Papers

A theoretical model for laser and powder particles interaction during laser cladding

Temperature control in laser brazing of a steel/aluminium assembly using thermographic measurements

Vibration reduction on city buses: Determination of optimal position of engine mounts

Heat transfer in semi-transparent materials during laser interaction

Numerical support for laser welding of zinc-coated sheets process development