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
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2024-08-13Autor
Oliveira, Adriel Pugliesi de
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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.
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