Abstract
Titanium aluminide (TiAl) alloy is attracting attention in the automobile and aviation industries as a promising lightweight heat-resistant alloy material. Parts used in high-temperature environments must have ductility and toughness at room temperature in addition to high strength at high temperatures, however, some alloys, such as TiAl alloys, are known to be difficult materials for casting and machining. Recently, manufacturing processes using additive manufacturing (AM) have been studied to solve these problems. In the present research, the effect of energy density during the AM process on surface roughness and on the strength of the built parts was studied by changing build parameters. As the energy density increased, the porosity and surface roughness decreased. Additionally, higher energy density tended to increase the fraction of lamellar structure. It was found, however, that an increase in lamellar structure does not necessarily lead to any improvement in tensile or creep strength at 750°C. We found that a constant energy density of 15 J/mm3 showed better tensile and creep properties than those of the standard parameter. Our results suggest that it is important to optimize the parameters according to the required properties of the parts.
This Paper was Originally Published in Japanese in J. JILM 72 (2022) 308–313. Abstract is slightly modified. The captions of Table 2, 3, 5 and 6 are slightly modified. The captions of Fig. 1, 2, 3, 4, 7 and 10 are slightly modified.
Higher energy densities reduced surface roughness and defects, while there was no clear relationship between energy density and high temperature strengths.
Fullsize Image
