Author:
Ghoussoub Joseph N.,Tang Yuanbo T.,Dick-Cleland William J. B.,Németh André A. N.,Gong Yilun,McCartney D. Graham,Cocks Alan C. F.,Reed Roger C.
Abstract
AbstractThe susceptibility of nickel-based superalloys to processing-induced crack formation during laser powder-bed additive manufacturing is studied. Twelve different alloys—some of existing (heritage) type but also other newly-designed ones—are considered. A strong inter-dependence of alloy composition and processability is demonstrated. Stereological procedures are developed to enable the two dominant defect types found—solidification cracks and solid-state ductility dip cracks—to be distinguished and quantified. Differential scanning calorimetry, creep stress relaxation tests at 1000 °C and measurements of tensile ductility at 800 °C are used to interpret the effects of alloy composition. A model for solid-state cracking is proposed, based on an incapacity to relax the thermal stress arising from constrained differential thermal contraction; its development is supported by experimental measurements using a constrained bar cooling test. A modified solidification cracking criterion is proposed based upon solidification range but including also a contribution from the stress relaxation effect. This work provides fundamental insights into the role of composition on the additive manufacturability of these materials.
Publisher
Springer Science and Business Media LLC
Subject
Metals and Alloys,Mechanics of Materials,Condensed Matter Physics
Cited by
27 articles.
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