Evaluation of the mechanical properties of Inconel 718 components built by laser cladding

Abstract

Laser-cladding process is one of the most relevant new processes in the industry due to the particular properties of the processed parts. The main users of this process are aeronautical turbine parts manufacturers and engineering maintenance services. The main advantage of laser-cladding process is the possibility of obtaining high quality material deposition on complex parts. Thus, laser cladding can be applied in the repair of high added-value and safety critical parts. This ability is especially useful for high-cost parts that present wears or local damage due to operating conditions. Different types of parts can be processed, such as housings, blades or even complete turbine rotors. Once the parts are repaired by laser cladding, they can be reassembled on the engine, reducing lead times. Laser-cladding process can permit buildup of complex geometries on previously forged or machined parts, such as stubs or flanges. However, one of the main drawbacks of the laser-cladding process currently is lack of knowledge on the properties of the deposited material. Most of the available data relate to the microstructure and the final hardness values. Nevertheless, there are few data of the mechanical properties of the parts. Moreover, it is difficult to gather data related to the influence of the laser-cladding parameters and strategies on the mechanical behaviour of a part. This paper presents the mechanical properties of a series of samples builtup by laser cladding. Two different types of specimens are tested: first, hybrid parts, in which laser cladding deposits materials built up layer-by-layer onto a substrate and the resulting part is a combination of deposited material and the substrate and second, complete rapid manufactured test samples. The results of tensile tests on various parts show that the laser-cladding strategy has a significant influence on their stress–strain curves. In addition, the laser-cladding process can result in a high directionality of their mechanical properties. The direction depends on the particular strategy in use. The study demonstrates that these properties present high anisotropy, a factor that should be carefully considered when selecting the most appropriate laser-cladding strategy.