Functionally graded mold inserts by laser-based flexible fabrication: processing modeling, structural analysis, and performance evaluation

Laser-based flexible fabrication (LBFF), a novel solid freeform fabrication (SFF) method-based on the principles of laser cladding (LC), was developed to produce functionally graded mold (FGM) inserts using shaped laser beams, quasi-coaxial nozzle for powder delivery, and functionally graded materials. As a case study of this innovative method, a hollow square mold insert was fabricated with additive layers of H13 steel, Ni/Cr alloy, and TiC using circular and rectangular beam (RB) profiles. Finite element analysis using ANSYS® was applied to determine temperature fields and thermal gradients associated with circular and rectangular beams. The microstructures and interfaces were examined using a scanning electron microscope (SEM), and related to the temperature gradients. Characterization results show a nearly full-density mold with excellent integrity, beneficial microstructures, strong interfaces, and high hardness. In addition, the mold insert was tested and compared to H13 steel molds in a thermal fatigue environment for ability to resist crack initiation, thermal strain, and oxidation.