Threads

The purpose was to evaluate part properties of additively manufactured 18Ni-300 maraging steel in a unified set-up when the printing orientation and the heat treatment were independently changed. Though the hardness, shrinkage, and drilling thrust force showed isotropic behavior to a certain extent, anisotropy was observed in the flatness, surface roughness, dross, and thread profiles. Solution treatment increases the surface roughness and reduces the flatness, surface hardness, drilling thrust force, and thread quality to some extent. Aging treatment significantly increases the surface hardness and yet still allows good-quality threads to be cut. The study aids designers in establishing and corroborating design for additive manufacturing.

Implementing additive manufacturing in an industry, particularly for critical applications of lightweight aluminum (AlSi10Mg), requires part properties that are both accurate and precise to conform to the intent of a robust design. In this experimental study, the objective was to evaluate anisotropy in part properties (i.e., flatness, surface roughness, surface porosity, surface hardness, pre-hole shrinkage, drilling thrust force, and thread-stripping force) when the part orientation (i.e., print inclination and recoater angle) was independently changed. This study developed and investigated an innovative procedure for determining anisotropy in part properties. The part properties were evaluated by designing specific features on a tailor-made flat plate. The replicas of the aluminum plate were additively manufactured at varying orientations using two commercial EOS parameter sets for the laser-based powder bed fusion technique. Conventional measurement equipment was used to analyze all the part properties, except the thread-stripping force, which was measured using a custom-made setup. All the part properties indicated a considerable degree of anisotropy, excluding the drilling thrust force. The printing parameters dictate the significance of the anisotropy. The anisotropy in flatness and pre-hole shrinkage decreases with an increased substrate temperature and a decrease in energy input and thermal gradient. The presence of surface overlapping contours in the scan strategy and an increased energy input can reduce anisotropy in surface roughness and hardness. No significant anisotropy was detected when the recoater angle was changed. This study helps designers establish and substantiate design for additive manufacturing that is within the limits of appropriate anisotropy for a robust design.

Abstract Languages with multiple paradigms or other special-purpose features often are implemented in ways that make true concurrency difficult in the virtual machine or runtime system. Several popular languages feature a global interpreter lock that limits them to ...