Energy density-controlled tensile performance of ZGH401 superalloy via selective laser melting

To investigate the effects of different energy densities on the mechanical properties of a ZGH401 alloy processed by selective laser melting (SLM), specimens were fabricated using an orthogonal experimental design under different laser powers and scanning speeds. In as-deposited ZGH401, pores resulting from insufficient energy density and thermal cracks induced by excessive energy density are both present. Therefore, this study aims to obtain a defect-free microstructure by optimizing the additive manufacturing process for ZGH401. The validated process parameters are 200 W and 800 mm/s. The microstructure of the ZGH401 specimens was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Results indicate that in the as-deposited ZGH401, precipitates within dendrites and honeycomb grains consist of niobium-dominated carbides and Laves phases formed by niobium and silicon enrichment. As energy density increased, defects in the as-deposited ZGH401 gradually decreased. ZGH401 exhibited outstanding tensile properties. Furthermore, at room temperature (25 °C), the fracture surface displayed typical cup–cone fracture characteristics indicative of cleavage fracture, achieving a strength of 1048 MPa and elongation of 37%. Under high-temperature conditions (900 °C), the fracture surface exhibits a regular stepped morphology, indicating brittle intergranular fracture, with a strength of 468 MPa and elongation of 7%. This study provides a theoretical foundation for microstructural process optimization and performance characterization in additive manufacturing, offering data support for achieving high-performance additive-manufactured superalloys.