Fatigue properties of parts fabricated by laser powder bed fusion, a kind of additive manufacturing, are inferior to those of conventional materials. Defects and inclusions are the causes of low fatigue properties, but their effect is not clarified. Inconel 718 specimens were fabricated by laser powder bed fusion. Cross-sectional observation and fatigue tests were performed. Gas porosity, cracks, and inclusions were observed in cross-section. TiN inclusions were observed in the fatigue fracture origins for specimens with hot isostatic pressing. To enhance the fatigue properties of Inconel 718 fabricated by laser powder bed fusion, it was suggested to remove entirely TiN inclusions within the powder.

This Paper was Originally Published in Japanese in J. Jpn. Soc. Powder Powder Metallurgy 67 (2020) 419–423.