[16P-T6-04] A Novel Route for Predicting the Cracking of Inoculant-Added AA7075 Processed via Laser Powder Bed Fusion
キーワード：AA7075, Solidification cracking model, Additive Manufacturing, Laser powder bed fusion, Backfilling mechanism
Solidification cracks induced by columnar grains in precipitation-hardenable aluminum alloys, such as Al–Zn–Cu–Mg, pose limitations on the feasibility of laser-based additive manufacturing. Recent efforts have successfully mitigated cracking by introducing equiaxed grains through the addition of inoculants to aluminum alloy powder. Despite this progress, the mechanisms by which equiaxed grains avert cracking remain unexplored in terms of both microstructure and process parameters. Consequently, the control over the cracking behavior of aluminum alloys during the laser powder bed fusion (LPBF) process has been constrained due to a lack of theoretical comprehension. In this investigation, we propose a solidification cracking model based on the parametric LPBF outcomes of ZrH2 particle-added AA7075, wherein equiaxed grains were generated in response to energy density variations. According to the proposed model, cracks in the previously formed layer were remedied through liquid backfilling during remelting under specific solidification conditions. The collaborative influences of both repeatable melting (layer-by-layer) and equiaxed grain formation on cracking behavior were elucidated. As a result, the presented model offers an innovative approach to preventing cracking in laser-based metal additive manufacturing processes.