Study of the Influence of Post-processing of Ni-Cr-Mo-Nb-Al Alloy After Selective Laser Melting

In this work, the optimal technological mode for manufacturing using the selective laser melting (SLM) method and the influence of subsequent heat treatment on the properties (porosity, mechanical properties, microhardness) of samples made of Ni-Cr-Mo-Nb-Al (EK171) alloy. Solution annealing at 1100 °C without aging practically does not improve mechanical properties of SLMed samples. The relationship between the technological modes of powder fusion and the properties obtained is established. The influence of the main technological parameters (laser radiation power, scanning speed, direction and step) of the SLM process and the estimated parameter of the volumetric energy density of laser radiation on the density of the material is shown. The minimum residual porosity of the material of 0.02-0.025% is achieved at an energy density of 118.3 J/mm3. In previous works it was found that in the case of additional HIP processing, a difference in the residual porosity of the material of ~ 0.02% is observed. At the same time, the difference in the porosities of the samples subjected to HIP and not subjected to it is insignificant; and therefore, the use of the HIP technological operation is economically impractical when using a more economical two-stage heat treatment mode studied in this work. Significant improvement of mechanical properties is achieved by using double aging after solution annealing. Fourfold aging leads to a significant decrease in ductility. Due to a dynamic strain aging the serration on the curves stress–strain was observed. © ASM International 2025.