Mapping of material properties of 3D-printed tungsten

Sammanfattning

Tungsten has properties that make it attractive for engineering applications such as aerospace andnuclear energy. Its high melting point makes traditional manufacturing difficult, which motivatesstudying the mechanical properties of additive manufactured tungsten.The aim of this bachelor thesis is to investigate microstructure and material properties of tungstenproduced by electron beam powder bed fusion and, in most samples, heat treated by hot isostaticpressing at different settings. The studied properties were micro-/nanohardness, Young’smodulus, porosity, density, microcracks and grain structure.Microhardness was measured using micro-Vickers and showed values around 399–405 HV, lowerhardness was observed at higher HIP pressures when HIP time was kept constant, and lower hardnessat longer HIP times when pressure is constant. For Young’s modulus, longer time resultedin lower elasticity at constant pressure and porosity was lowest at the highest pressures. Quantitativecrack analysis was not feasible since few cracks appeared, though some were present inevery sample. Porosity analysis resulted in a degree of porosity between 0.69-3.00 ‰.The results showed that HIP treatment resulted in an increase of nanohardness, but for Young’smodulus and microcracks its effect was inconclusive due to experimental uncertainties. Futurework should reduce these uncertainties by improving measurement control and expanding thesample set to more clearly determine how HIP influences the studied mechanical properties.