Removing Alpha Case from Laser Powder Bed Fusion Components by Cavitation Abrasive Surface Finishing

Area of Science:

• Materials Science
• Manufacturing Engineering
• Surface Engineering

Background:

• Laser powder bed fusion (L-PBF) is a key additive manufacturing technique for metal components.
• L-PBF parts often require post-processing due to rough surfaces and oxide layers from heat treatments.
• Improving surface finish and removing oxide layers are critical for L-PBF component performance.

Purpose of the Study:

• To evaluate the effectiveness of Cavitation Abrasive Surface Finishing (CASF) for post-processing L-PBF Ti6Al4V components.
• To assess CASF's impact on surface roughness, residual stress, and oxide layer removal.
• To investigate the influence of treatment conditions and surface orientation on CASF performance.

Main Methods:

• Ti6Al4V components fabricated using L-PBF were subjected to CASF.
• Surface texture (roughness), residual stress, and material removal were measured.
• CASF treatment parameters and surface orientations were varied.

Main Results:

• CASF reduced average surface roughness from approximately 15 µm to below 5 µm.
• Compressive residual stresses up to 600 MPa were induced by CASF.
• Effective removal of the alpha case oxide layer was observed on direct line-of-sight surfaces.
• Uniform treatment of deep valleys and surfaces at high oblique angles (≥60°) remained challenging.

Conclusions:

• CASF is a potentially effective alternative to chemical treatments for post-processing L-PBF titanium and other metal components.
• CASF significantly improves surface finish and induces beneficial compressive residual stresses.
• Further research is needed to optimize CASF process parameters and evaluate fatigue performance.