Influence of Hydrogen Environment on the Mechanical Properties of Cast and Electron Beam Melted Ti-6Al-4V

摘要

In order to save weight in a certain engine application the possibility of replacing the currently used material with cast Ti-6Al-4V is investigated here. The working environment for this particular engine part is pure hydrogen gas at high pressure. Therefore selected mechanical properties such as tensile and low cycle fatigue (LCF) in air and hydrogen atmosphere have been studied for cast Ti-6Al-4V. In addition to cast Ti-6Al-4V, the corresponding mechanical properties of a more recently developed additive manufacturing method,electron beam melting (EBM),is also investigated in hydrogen and compared with cast Ti6Al-4V. Cast Ti-6Al-4V showed lower yield strength and lower ultimate tensile strength in hydrogen compared with air. However.no significant change in the ductility was observed. The LCF was significantly reduced in the hydrogen atmosphere,mostly at high strain range (≈ 2%). The EBM Ti-6Al-4V in hydrogen showed higher yield sitrength,higher ultimate strength and higher ductility as well as improved fatigue life compared with cast Ti-6Al-4V under the same test conditions. Microstructural and fractographic characterization were also performed and the results are included.