Grain Boundary Engineering for Additive Manufacturing

Variability in mechanical properties of additively manufactured (AM) metal parts is a concern. AM metal exhibits cracks, low toughness, low plasticity, and high residual stress. Understanding microstructure evolution during the AM process is a precondition for optimization of AM process parameters. Metallic alloys consist of grains. Boundaries between grains are formed through recrystallization during fabrication and heat treatment. Grain boundaries influence mechanical properties. The current research explores grain boundary engineering (GBE) to generate desired microstructures in metal parts. One method is traditional heat treatment. A second method designs grain size and grain boundaries by altering process print parameters and injecting nanoparticles in specific regions during the process. Both approaches are supported by Integrated Computational Material Engineering to guide the AM process, predict thermal behavior, alter parameters and produce the part. Further, modeling is needed to predict effect of inclusions and effect of defects on mechanical properties. The results of both approaches are compared and improvements to the process suggested. The technology offers a new way to create AM polycrystalline alloys.

Presenter – Dr. Rashid Miraj  of AlphaSTAR