aroundhere-
The Inconel 718 powder will be laser sintered in an inert atmosphere, but as Kenat noted the microstructure of the DLMS part will not be as good as forged (AMS 5662) or wrought (AMS 5664) bar. At best you might get something similar to an investment cast material (AMS 5383). The mechanical properties shown in the data sheet you linked seem overly optimistic since they are at the upper end of what MMPDS-01 lists for forged and wrought bar. For your reference I've attached the relevant pages from MMPDS-01 showing min mechanical properties for AMS 5383, AMS 5662 and AMS 5664.
As to whether a laser sintered material would be a suitable replacement for forged/wrought material in your particular application, first you should review the requirements contained in your engineering documentation and/or your customer's PO. It is never a good idea to make a material substitution for a demanding application like this without getting approval from everyone involved.
Your concerns about defects in the laser sintered material are valid. For example, since the material is built-up in discrete horizontal layers the surface a DLMS part has numerous tiny steps where the laser is started/stopped. These abrupt fusion boundaries might pose a stress problem, but they can be eliminated by making the part over-sized and removing the outer surface layers. The material data sheet you linked seems to acknowledge this problem, since it had a footnote stating that the properties listed only applied in one direction relative to build-up.
If internal material defects like voids or incomplete fusion are a concern, you can employ the same NDI techniques used with fusion welds to check for them. Or you could even have the parts HIP'd to consolidate these internal defects.
Having said all this, the reality for your particular case is that it is probably much more cost effective and expedient to simply make the parts the same way you have been (wire EDM from wrought bar) except using an outside vendor.
Best of luck to you.
Terry
