PSI - Issue 54

Ivana Zetková et al. / Procedia Structural Integrity 54 (2024) 256–263 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 1. Placement and connection of the samples on the building platform.

Table 2. Process parameters specification.

Parameter set

SP

SW10

MLT

T

SP120

Strategy specification

Stripe width [mm] Stripe overlap [mm]

10

10

10

10

10

0,08

0,2

0,08

0,08

0,08

Gap width [mm]

0,08

-

-

-

-

Layer thickness [µm]

40

40

40

50

40

Input energy

Field Laser power [W]

285 960 0,11

285 960 0,11

285 960 0,11

305

285 960 0,11

Scanning speed [mm/s] Hatch distance [mm]

1010 0,11 54,91

Volume energy density [J/mm3]

67,47

67,47

67,47

67,47

Gap Laser power [W]

100 400

- - - -

- - - -

- - - -

- - - -

Scanning speed [mm/s] Hatch distance [mm]

0,1

Volume energy density [J/mm3]

62,5

Additional information

Building preheating [°C]

40

40

40

40

120 820

Solution annealing on the temperature [°C]

820

820

820

940

Minimum layer print time [s]

-

-

52

-

The second set of samples (SW10) used a chessboard printing strategy recommended by the device manufacturer to minimize residual stresses. This process prints in 10 mm wide strips that overlap by 0.08 mm. Within each layer, the chessboard pattern contains two areas, called gaps and fields, which are printed with different process parameters in an automatically defined order to ensure uniform cooling of the part. In the next layer, the areas are switched so that they overlap. This strategy increases printing time, but according to the manufacturer, it should also reduce residual internal stress due to the way energy is delivered to the individual layers. However, Figure 2 shows that this strategy does not appear to be useful for reducing residual stresses in the selected type of sample. The results of samples printed with SW10 parameters (short dashed dark blue line) practically overlap with the results of SP (red line). The third set (MLT) uses standard process parameters, but with the minimum layer printing time set to a value equal to the time required to print one layer using the SW10 parameters. The purpose of this set is to verify the influence of printing time on the monitored stress values and to assess whether it is more influenced by printing speed