Effect of Process Parameters on Texture in Quasi-Isotropic IN718 Processed by Laser Powder Bed Fusion

Abstract

This study attempts to elucidate the quasi-isotropic behavior observed in laser-based powder bed fusion of Inconel 718 (IN718) alloy. This effort emphasizes the effect of laser process parameters on crystal orientation and subsequent mechanical behavior. The plate-type IN718 rectangular coupons were deposited using a laser powder bed fusion technique with a volumetric energy density of 66.29 J/mm3 and a scanning strategy of 67 deg rotational between each consecutive layer. These coupons were solution-treated, and subsequently, precipitation-hardened. Quasi-isotropic mechanical properties were observed in the coupons through tensile experiments performed along 0 deg and 90 deg to the building direction. Electron backscattered diffraction studies have indicated the development of an <001> orientation in the as-built and precipitation-hardened coupons. But, the solution-treated coupons deviated from the ideal <001> orientation. However, X-ray diffraction studies revealed the presence of a weak cube texture for all thermally-treated conditions. The scanning strategy and volumetric energy density led to the development of the weak cube texture in the as-built sample, which is thus implicated in the quasi-isotropic mechanical properties in the printed coupons.