Page 12 - MSAM-2-1

Materials Science in Additive Manufacturing AM-produced CoCrFeMnNi properties

of chosen values revealed only the latter two regions of is a steep thermal gradient that develops due to the high
energy density domain as explained above. As shown in energy input and causes the higher cooling rate. As a
Figure 4A, laser scanning at slower than 400 mm/s resulted result, the molten material does not have enough driving
in severe porosity. Notice the top surfaces of the samples are force and time to spread to become flattened. This leads
not flat. This is a result of high energy density input used to a big wavy surface at the top of samples . Figure 4B
[49]
to produce samples in Figure 4. High energy input causes summarizes the quantitative characterization by means
two phenomena that take place in a molten pool. First, of measured density of cubic samples and visual analysis
the liquid viscosity is too low to keep up the integrity of of percent porosity as observed on their cross section. An
the melt pool . Melt pool agitates violently which results overall trend can be observed, that is, higher scanning
[47]
in a non-uniform top surface . Second phenomenon speeds (within the investigation range) are beneficial for
[48]
A

B

Figure 4. Effect of scanning speed on density and porosity of selective laser melting-produced CoCrFeMnNi. (A) Optical micrographs showing cross
sections of printed cubes for process optimization, and (B) density of the cubes measured according to ASTM B962 and porosity measured through image
processing.

Volume 2 Issue 1 (2023) 6 https://doi.org/10.36922/msam.42