*3.1. Granulomorphometry and Samples' Production*

The results of the granulo- and morphometric analysis of the powder showed that spherical particle shape, high fluidity, a microcrystalline structure, equiaxial morphology, and a small number of satellites characterize both of the steels (Figure 4, Table 3).

**Figure 4.** Granulometry and morphology (scanning electron microscopy) of the steel powders: (**a**) measurement results of PR 20kH13 (AISI 420); (**b**) measurement results of PR 12kH18N9T (AISI 321); (**c**) SEM-image of PR 20kH13 (AISI 420) particles, 2.98k×; (**d**) SEM-image of PR 12kH18N9T (AISI 321) particles, 510×.


**Table 3.** Shape parameters of the powders according to EN ISO 9276-6; 7; 8.

Tracks were made from PR 20kH13 (AISI 420) and PR 12kH18N9T (AISI 321) steels at laser power in the range from 40 to 120 W, and scanning speeds from 50 to 150 mm·s<sup>−</sup>1; the thickness of the powder layer applied to the substrate varied from 20 to 50 μm; the length of the track (melt pool) was 15 mm for all experiments. The height of the track above the substrate, the depth of the penetration zone of the underlying layer, the width of a single track, the width of the penetration zone, and the substrate's wetting angle in the zone of exposure laser radiation were analyzed for each experiment. The following laser powder bed fusion factors were selected for the manufacture of samples with the aim of further research because of the conducted analysis (Table 2):

