SLM공정에 의해 제조된 316L 스테인레스 스틸 격자구조체의 압축 거동 평가

Lattice structures are multi-functional materials with various advantages such as high specific stiffness, high energy absorption capacity and good thermal management capability. Recently, the development of manufacturing technologies using metal powders has facilitated fabrication of complex products; consequently, interest in lattice structures has grown. In this work, two kinds of lattice structures, pyramidal and tetrahedral, were designed and fabricated via a selective laser melting (SLM) process using stainless steel 316L powder. Scanning electron microscope (SEM) and optical microscope (OM) results revealed that lattice structures with various unit cell sizes and angles of inclination can be manufactured using SLM without the need for additional support structures. However, many unmelted and partially melted particles were observed on the surface of the lattice structures, which caused dimensional errors related to the struts. This research examined the effects of topology and unit cell design parameters on the macroscopic compressive behavior of lattice structures. Compressive characteristics, including elastic modulus, initial peak stress, strain energy absorption and mean stress, were evaluated through uniaxial compression tests. Lattice structures with the same relative density exhibited excellent elastic modulus, initial peak stress, energy absorption and mean stress results at inclination angles of 45-50°. These characteristics showed a tendency to increase with increasing relative density at the same inclination angle. The experimental results suggested these design parameters are the main factors influencing the mechanical characteristics of lattice structures. (Received November 18, 2019; Accepted February 4, 2020)