Selective Laser Melting of Inconel 718 under High Power and High Scanning Speed Conditions

Abstract

Selective laser melting (SLM) process has advantages in building free shape and simplification of manufacturing process. Since Ni-base superalloys have lower ductility at lower temperature, it is difficult to produce the parts by means of other process like forging. Therefore, SLM process has already applied to produce Ni-base superalloy parts. However, SLM process needs a long process time comparing to casting and machining. One of the means to solve this problem is an application of the high scanning speed condition under high power laser output. In this research, the optimum fabrication condition of Inconel 718 superalloy by SLM process under high power and high scanning speed condition was investigated. As a result, the optimum fabrication condition was obtained using the process map. However, the relative density of the as-built specimen fabricated under high power and high scanning speed condition is lower than that of the as-built specimen fabricated under the condition of 300 W and 600 mm/s. This may be mainly due to the occurrence of gas-pores by key-hole like phenomenon in melt pool and the increase of spattering at high power and high scanning speed condition.

Influences of Process Parameters on the Microstructure and Mechanical Properties of CoCrFeNiTi Based High-Entropy Alloy in a Laser Powder Bed Fusion Process

“…The high-density (≥99.7%) area, the so-called process window (red and orange area), was at a laser power of 300-400 W and a scan speed of 600-800 mm/s. This result was similar to that of Inconel 718 obtained previously [47]. The relationship between fabrication condition and defects was reported using a process map in terms of laser power and scan speed [47,48,[51][52][53].…”

“…A large pore existed in the microstructure of the specimen fabricated at E = 333 J/mm 3 (c). The effect of energy density on the density of specimens was investigated previously [44,[46][47][48], and a similar tendency reported.…”

“…The (volumetric) energy density, E, which is one of the important process parameters, affects the microstructure remarkably, for instance, grain size and grain growth. The increase in energy density results in grain growth direction aligned with build direction [41][42][43][44][45] and decreased porosity [44,[46][47][48]. However, the energy density poorly predicts the melt pool behavior, as reported as a limitation of energy density as a process parameter, according to Bertoli et al [49,50].…”

“…However, the energy density poorly predicts the melt pool behavior, as reported as a limitation of energy density as a process parameter, according to Bertoli et al [49,50]. Therefore, practically, laser power and scan speed, which are the main process parameters, are applied to fabricate sound parts and are determined using a process map [47,48,[51][52][53]. The authors reported on the creation of process maps in various alloys [47,48].…”

“…Therefore, practically, laser power and scan speed, which are the main process parameters, are applied to fabricate sound parts and are determined using a process map [47,48,[51][52][53]. The authors reported on the creation of process maps in various alloys [47,48].…”