Effect of Build Orientation on the Fatigue Limit of CX Steel by Laser Powder Bed Fusion

The effect of part build orientation on the fatigue properties of additively manufactured parts has been demonstrated to be highly influenced by the type or composition of the raw material. In this study, an experimental campaign was carried out to investigate this effect in the case of CX maraging steel processed by laser powder bed fusion. For this purpose, specimens were manufactured with vertical, horizontal, and 45° inclined orientations. First, the dimensional accuracy, surface finishing, density, and hardness of specimens were characterized to determine the role of part build orientation. Then, the specimens were tested to determine the fatigue curve and limit. Finally, the fracture region was observed via scanning electron microscope. The results reveal that the effect of build orientation on the fatigue strength in the finite life domain is not statistically significant. Conversely, the build orientation affects the achievable surface finishing of parts after machining and, consequently, the fatigue limit of the material. The highest fatigue resistance is observed in specimens inclined at 45°, while vertical specimens showed the lowest limit.