Superior tensile properties of Hastelloy X enabled by additive manufacturing

This study reports the superior tensile properties of laser powder bed fused (L-PBF) Hastelloy X compared to wrought, exhibiting enhanced yield strength and improved ductility. By analyzing the tensile response of a variety of microstructures ranging from fully dendritic to fully solutionized, the as-solidified fine inter-dendritic region network was determined to be responsible for this superiority. Characterized by high chemical gradients, the inter-dendritic regions limited motion of dislocations, blocked the formation of long deformation bands, and promoted the uniform distribution of plastic strain. Further, a deformation mechanism not well known for Hastelloy X, i.e. deformation twinning, was observed and analyzed. IMPACT STATEMENT Superior tensile properties of as-fabricated, additively manufactured Hastelloy X relative to the wrought counterpart is reported. Room temperature deformation twinning is also observed in both as-fabricated and heat-treated conditions.