## 1 Introduction
Recently, bound metal deposition (BMD), a new extrusion-based MAM technology based on material extrusion processes, in which material is selectively dispensed through a nozzle, has been offered by Desktop Metal. This technique can enable low-volume production and economical metal parts. Various materials can be fabricated using the BMD, such as stainless steel, copper, and titanium. The raw material is in the form of a rod comprising a mix of metal powder, wax, and binder. The metal and ceramic rods contained in extruders are fed and fused to form a metal part and ceramic support media, respectively, in the print process. Next, the binder is dissolved in the debinding process and is then densified in the sintering process. After metal particles fuse as a 3D object, the ceramic interface can be removed to obtain the final part. The AM parts fabricated using the BMD can be divided into three portions, i.e., infill structure, side wall, and top/bottom wall, as shown in Figure 1.  
Figure 1: The components of an AM part with the BMD technique. Most AM technologies can print a part with an infill density to reduce the consumption of raw materials and make the part with a lightweight feature. An AM part with an infill pattern inside can be treated as a lattice structure consisting of a number of unit cells. Lattice structures have been widely used as infill structures of AM parts because their mechanical properties can be efficiently designed by adjusting their unit cells. The mechanical properties of lattice structures with various patterns have been studied by many researchers [15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25]. For example, isotropic in-plane elastic properties of lattice structures with triangular unit cells were confirmed by an analytical study by [15] and an experimental study by [16]. Methods to determine the effective properties of lattice structures have also been investigated; in a study by [17], the effective in-plane properties were derived by an analytical method. [PERSON] et al. [18] proposed the exact forms of effective elastic properties of lattice structures with different patterns using exact curve fitting. In the same lattice structures studied, [PERSON] et al. [19] presented the derivation of closed-form effective elastic properties of the lattice structures using a generic symbolic finite element program. Effective in-plane material properties of 2D hexagonal lattices with and without considering the shear deformation of their struts were presented by [22]. The numerical and experimental investigations of in-plane and bending material behaviors of 2D lattice structures with various unit-cell patterns were proposed by [24; 25], respectively. In AM technologies using the BMD, a lattice structure with a triangular pattern was generally used as the infill pattern of AM parts. The mechanical properties of the AM parts can be optimized by modifying some significant print parameters related to the infill structure to achieve a light weight and sufficient strength for their applications, e.g., layer, density, and orientation. Print parameters influencing the mechanical properties of MAM parts fabricated using the BMD include infill density, side wall thickness, top/bottom wall thickness, and pattern orientations. Among the print parameters, infill density is directly related to the raw material used and the performance of AM parts, as well as time and cost in the manufacturing process. Consequently, the relationship between mechanical properties and infill density plays a significant role in assessing the specific performance of different infill parts. To date, few studies have reported the mechanical properties of metal parts fabricated using BMD [26; 27; 28]; in addition, no works emphasizing the influence of infill density on the mechanical properties are yet available. [PERSON] and [PERSON] [26] experimentally investigated the mechanical properties of additively manufactured specimens of 17-4 PH processed by BMD using a tensile test.