Spreadability of Metal Powders for Laser-Powder Bed Fusion via Simple Image Processing Steps

Area of Science:

• Materials Science
• Additive Manufacturing
• Powder Metallurgy

Background:

• Laser Powder Bed Fusion (PBF-LB) is a key additive manufacturing technology.
• Powder characteristics significantly influence the quality of PBF-LB parts.
• Understanding powder spreadability is crucial for process optimization.

Purpose of the Study:

• To investigate the spreadability of spherical CoCrWMo powder for PBF-LB.
• To examine the dependence of spreadability on powder characteristics like size distribution, apparent density, and angle of repose.
• To quantify spreadability using image processing and MATLAB.

Main Methods:

• Preparation and characterization of CoCrWMo powder blends with varying particle size distributions.
• Performance of spreadability tests using PBF-LB equipment.
• Application of image processing algorithms and illumination invariant analysis for quantifying layer irregularities.

Main Results:

• An increased ratio of fine particles (below 10 µm) led to enhanced agglomeration and reduced powder flowability.
• Poor powder spreadability was observed with higher fine particle content.
• Quantification of irregularities on spread layers was achieved through image analysis.

Conclusions:

• Fine particle content critically affects CoCrWMo powder spreadability in PBF-LB.
• While spreadability is linked to powder properties, a direct correlation with 3D printed part porosity was not definitively established due to other influencing process parameters.
• Further research is needed to fully understand the interplay between powder characteristics, spreadability, and final part integrity in PBF-LB.