Efeitos da microestrutura, direção de construção e formação de defeitos nas propriedades de flexão e desgaste do aço ferramenta H13 processado por fusão em leito de pó a laser

Abstract

Additive manufacturing (AM) has shown promise to produce complex parts. Molds and dies fit these characteristics and are therefore difficult to machine, resulting in significant material waste. To apply AM in the manufacture of these parts, it is essential to explore how the primary materials used in these tools behave after processing. This study investigated how H13 tool steel processed by laser powder bed fusion behaved during bending and wear tests, correlating this behavior with microstructure, build direction, and formed defects. The microstructure revealed a cellular morphology of martensite surrounded by retained austenite. The bending tests demonstrated a high sensitivity to intrinsic process defects and little sensitivity to the part's build direction (BD). The sample fabricated with 400J/mm³ showed the highest values of density and bending stress. In contrast, the sample produced with 600J/mm³ exhibited fewer defects and more extensive deformation before fracture. During wear tests, the printed samples displayed a Coefficient of Friction (COF) between 0.72 and 0.85, while the printed and heat-treated samples showed a reduced range of 0.72 < COF < 0.76. The specific wear rate (K) did not vary significantly with BD but was lower for the printed samples (1.2 x 10^-4 mm³/N·m) compared to the conventionally processed sample (2.2 x 10^-4 mm³/N·m). These behaviors were explained by considering the microstructural refinement, the fraction of retained austenite, the intrinsic tempering of the process, wear mechanisms (abrasion, adhesion, and delamination), and the presence of defects. The findings indicate the possibility of manufacturing H13 parts with complex geometries, maintaining excellent wear properties even before heat treatment.