Development of a New Manufacturing Route by Direct Laser Metal Deposition With NiCrSiFeB Alloys to Replace Cobalt in Aeronautical Components

Nickel-based NiCrSiFeB alloy (Ni-Cr-Si-B self-fluxing family) are excellent candidates for replacing Cobalt-based alloys in aeronautical components such as sealing rings, valve seats, sliding bearing seats, etc. In this type of components, commonly manufactured by centrifugal casting and conventional processes, high temperature wear and stiffness under complex thermo-mechanical stresses cause lack of sealing and an increase in the wear rate. Metal additive manufacturing by direct laser metal deposition with powder (p-LMD) is presented as a potential manufacturing route for the complex processing of this type of alloys. This research work deals with the development of a new manufacturing route using p-LMD that ranges from the proper selection of the chemical composition for the starting powders, the development of the LMD process parameters to tackle the challenges associated to the wide solidification range and crack susceptibility of Ni-Cr-Si-B alloys, its monitoring and control, as well as the post-processing required to achieve the manufacture of aeronautical components. In this work, the porosity analysis, as-built microstructure, hardness at room temperature and at high temperature, and the strengthening mechanisms have been studied in cylinders manufactured with different chemical composition grades and LMD process parameter sets (slow, normal and fast deposition speed).