Titanium and its alloys, particularly Ti6Al4V, are widely used, especially in the aerospace and medicine due to their relatively low density, high strength and good corrosion resistance. However, there are formidable challenges in casting, forming and machining titanium alloys, which result in final products, that are considerably more expensive. Nowadays, Additive Manufacturing (AM) is considered as one of the most promising technologies for metallic materials due to its ability to produce complex geometries with high density and accuracy in a short amount of time. AM is a process based on layer-by-layers method and represents a new way of making machine or structural elements. It allows us to make products with complex geometries from CAD base data, that cannot be made with traditional metallurgical processes. One of the most used technologies for metals alloys is selective laser melting (SLM). This is a powder-based AM process, which consists of melting and solidifying metallic powder layers by using high energy laser beam.
This master's thesis determines which conditions are the most favourable to be used during SLM process for Ti6Al4V alloy powder by using process maps and the effect of different process parameters on the mechanical properties, microstructure and corrosion resistance of SLM samples from Ti6Al4V alloy powder. By using three different laser powers and four different scanning speeds, the process maps of hardness and porosity were created. With these results, we determined the optimal parameters with the highest hardness and the lowest fraction of porosity for the SLM Ti6Al4V samples, suitable for further production. The samples for mechanical properties were made in two different directions at selected printing process parameters - different laser power and scanning speed. Three different shapes and dimensions of the samples were made. For corrosion tests (potentiodynamic measurements) samples were made in the form of low cylinders. For mechanical testing (tensile tests), flat samples were made. We also made samples in the form of cubes for metallographic analysis (light and scanning electron microscopy), where the microstructure and chemical composition in the material made by the SLM process is determined.
|
