LPBF 공정으로 적층 제조된 Inconel 718 격자 구조체의미세조직, 상온 및 650℃ 기계적 특성

초록

Unit cell topology and mechanical properties at room temperature and 650℃ of additively manufactured IN718 lattice structures were investigated. 4-different lattice structures (BCC, FCC, BCCZ, FCCZ with 3mm unit-cell sizes; Z means strut designed along the build direction) were manufactured by laser powder bed fusion process. Solution treatment and standard aging (SA) were also conducted. The relative density values of lattice structures were measured at 14%~16% according to the design of the lattice structure. In standard-aged strut, γ?, γ??, δ, and carbide were observed. The characteristic of compressive stress-strain curves followed the general trend of typical lattice structures. However, although BCCZ has the highest relative density, FCCZ shows higher compressive strength in all conditions than BCCZ at RT (FCCZ:120.4MPa, BCCZ:73.6MP in SA) and 650℃ (FCCZ:111.3MPa, BCCZ:79.6MPa in SA). In addition, standard-aged specimens show an average of 20% higher compressive strength than as-built specimens. Correlations between structural and microstructural characteristics and deformation behavior were also discussed.