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

Abstract

An in-house developed continuous wave CO 2 laser-based rapid manufacturing was deployed to fabricate porous structures of Inconel-625 using a new cross-thinwall 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 VHN 0.98N . 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.

Directed Energy Deposition (DED) Process: State of the Art

“…5 [42,[57][58][59][60][94][95][96][97]. The power of the laser, the scan speed of the laser and the feed rate (mass flow rate) of powders are major parameters affecting the bead formation, joining between successive layers, the porosity, the microstructure, and the residual stress [42,60,98]. Several researchers proposed a laser energy per unit length (LEL, Π) and a powder feed per unit length (PFL, Γ) to reflect the influence of the correlation between the three parameters, as shown in Eqs.…”

“…Several researchers proposed a laser energy per unit length (LEL, Π) and a powder feed per unit length (PFL, Γ) to reflect the influence of the correlation between the three parameters, as shown in Eqs. ( 1) and ( 2) [42,60,98]. The beam diameter and the profile of the laser beam affect the minimum size of the feature and the formation of the molten pool [60,94].…”

A bottom-up approach to experimentally investigate the deposition of austenitic stainless steel in laser direct metal deposition system

“…The main process parameters of laser deposition are the laser power, scanning speed and powder feed rate, and their values are selected from the available studies [16,[21][22][23]. A critical review of metal deposition using DED presented by DebRoy et al [24] is helpful in making selection of laser inputs for austenitic stainless steel material.…”

Laser-assisted directed energy deposition of nickel super alloys: A review

“…The compressive yield strength of the material decreases from 423 AE 8 MPa to 226 AE 6.8 MPa when porosity is increased from 2.63% to 11.57%. 69 There has been research efforts in the direction of fabricating composite structures and functionally graded components of IN625 by LAM-DED. Composites are fabricated by adding TiC 79,80 and TiB 2 81 to IN625 using LAM-DED.…”