Selective laser melting of a novel 13Ni400 maraging steel: Material characterization and process optimization

Abstract

Selective laser melting (SLM) has attracted recent attention in building parts with improved functionality and properties. Accordingly, the present work attempts to fabricate a novel 13Ni400 maraging steel parts with maximum theoretical density by SLM. A Box Behnken Design response surface methodology (RSM) approach is used to evaluate the influence of critical process parameters (laser power, laser scan speed, layer thickness, and hatch spacing) on the relative density, micro hardness, surface roughness, and tensile strength. Both the powder and the fabricated parts were characterized for the structural and microstructural features using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influences of energy density and other process variables are explored through careful parametric studies and 3-D surface plots. Analysis of variance (ANOVA) is carried out, which reveals that the laser power and layer thickness are the most dominant process parameters impacting the performance of the SLM process. A revolutionary preference ranking organization technique for enrichment evaluation (PROMETHEE) is adopted to convert the multiple responses into an equivalent net outranking flow and rank the alternatives. The PROMETHEE-based outcomes are further improved by using a cuckoo search (CS) algorithm. A confirmatory test is conducted on the optimum build conditions obtained by the hybrid methodology (combination of PROMETHEE and Cuckoo Search) to validate the proposed work. It is seen that the value of net outranking flow is enriched by ∼5 %. This work is proficient in producing defect-free parts, with maximum densification and with improved mechanical properties for a newly developed 13Ni-400 maraging steel.