On the build orientation effect in as-printed and as-sintered bending properties of 17-4PH alloy fabricated by metal fused filament fabrication

Abstract

Purpose The purpose of this paper is to systematically investigate the influence of build orientation on the anisotropic as-printed and as-sintered bending properties of 17-4PH stainless steel fabricated by metal fused filament fabrication (MFFF). Design/methodology/approach The bending properties of 17-4PH alloy fabricated by low-cost additive manufacturing (MFFF) using three build orientations (the Flat, On-edge and Upright orientations) are examined at both as-printed and as-sintered states. Findings Unlike tensile testing where the Flat and On-edge orientations provide similar as-sintered tensile properties, the On-edge orientation produces a significantly higher bending strain with a lower bending strength than the Flat orientation. This arises from the printed layer sliding due to the Poisson's effect, which is only observed in the On-edge orientation together with the alternated layers of highly deformed and shifted voids. The bending properties show that the Upright orientation exhibits the lowest bending properties and limited plasticity due to the layer delamination. Originality/value This study is the first work to study the effect of build orientation on the flexural properties for MFFF. This work gives insight information into anisotropy in flexural mode for MFFF part design.

A Review on Material Extrusion Additive Manufacturing of Metal and How It Compares with Metal Injection Moulding

“…However, as reported by Damon et al [45] and Caminero et al [66], there is no significant difference in tensile properties between the flat and on-edge built orientations. As for tensile properties, flexural properties are also orientation dependent as reported by Suwanpreecha and Manonukul [110]. It is found that weak points between two layers can result in layer sliding during bending, leading to the difference in flexural strength and strain [110].…”

“…preecha and Manonukul [110]. It is found that weak points between two layers can result in layer sliding during bending, leading to the difference in flexural strength and strain [110]. The degree of overhang also influences the mechanical properties, as studied by Alkindi et al [65].…”

“…preecha and Manonukul [110]. It is found that weak points between two layers can result in layer sliding during bending, leading to the difference in flexural strength and strain [110].…”

“…The higher sintering temperature and longer sintering time provide the highest relative sintered density [149]. The effect of sintering conditions on the relative sintered density of 17-4PH [8,49,64,92,110], 316L [9,41,45,52,53,56,57,66,68,70,72,75,81,98,108] and Ti-6Al-4V [78,79] alloys fabricated by metal MEX, MIM [134,157,[159][160][161]163,164,170,171] and the corresponding MIM international standards [169,172] are graphically compared in Figures 19-21, respectively. Figure 19 shows that most relative sintered densities of MEX 17-4PH alloy, which are in the range of 97% to 99%, meet the minimum value of the MPIF standard 35 for MIM materials (>96.7%).…”

“…It is noted that the part sintered at 1380 °C for 5 h (black square symbol) should have the highest relative density; however, this value was reported in early work in this field [49], and, as such, the low relative sintered density may be the result of poor printing quality. [8,49,64,92,110,134,157,169].…”