Studies on laser rapid manufacturing of cross-thin-walled porous structures of Inconel 625

Abstract

An in-house developed continuous wave CO2 laser-based rapid manufacturing was deployed to fabricate porous structures of Inconel-625 using a new cross-thin-wall fabrication strategy. Studies on the mechanical and metallurgical properties of these porous structures were carried out with laser energy per unit traverse length in the range of 150–300 kJ/m, powder fed per unit traverse length in the range of 16.67–36.67 g/m and transverse traverse index in the range of 0.7–1.3. The processing parametric dependence showed that the powder fed per unit traverse length was a predominating parameter in determining the porosity of the structures, followed by transverse traverse index and laser energy per unit traverse length. The compression testing of fabricated porous structures showed that the material had anisotropy up to 20% for 0.2% yield strength. It was found that the yield strength of the fabricated structures followed the power law and decreased from 423 ± 8 MPa for 2.63 ± 0.14% porosity to 226 ± 6.8 MPa for 11.57 ± 0.52% porosity. Scanning electron microscopy showed that shape of the pores was triangular due to the cross-thin-wall fabrication strategy and the observed values of microhardness were in the range 256–370 VHN0.98N. These studies are expected to augment our knowledge on the fabrication of porous structures with independent control on porosity and yield strength, which are important prerequisites for some of the prosthetic and engineering components in niche areas of applications.