Banca de QUALIFICAÇÃO: HENRIQUE TOMÉ BARBOSA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : HENRIQUE TOMÉ BARBOSA
DATE: 04/05/2023
TIME: 08:00
LOCAL: Defesa Qualificação Henrique Quinta-feira, 4 de maio · 8:00 até 11:45am Informações de participação
TITLE:

Study of the microstructure of DP780 steel punched under room and cryogenic temperatures.

KEY WORDS:

AHSS, Dual-phase Steels, DP780, Cutting Edge, Cryogenic,
Lubri-refrigeration, EBSD, SEM.

PAGES: 60
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUMMARY:

Dual-phase steels (DP) are advanced high-strength steels (AHSS) used in
construction of automotive body parts due to their high strength, formability and
ability to absorb energy when deformed. They gained great importance since the
Paris Agreement (2016), as their use, in place of conventional steels, makes vehicles
lighter and less polluting.
To constitute these automotive parts, the dual-phase steels undergo stamping
processes, in which they are cut, pressed and folded, in order to compose the final
shape of the desired part. During these processes, the quality of the cutting edge of
these steels is a very important factor, as an edge with more and greater
heterogeneity and defects can lead to failure of the part even during its manufacture.
A more homogeneous cutting edge, with less voids and microcracks is necessary for
the good formability of these materials.
Addressing at making a cut that inflicts fewer defects on its edge, the cut of
DP780 steel was presented and performed under localized lubri-refrigeration by
liquid nitrogen vapor. This method aimed to cool the material at the cryogenic
temperature of -150oC and induce it to fracture brittlely, presenting low deformation
during expressive cracking.
The following work carried out a qualitative study of the microstructures of
DP780 steel cutting edges tested at cryogenic and ambient temperatures and
compared them, in order to verify their quality and homogeneity, as well as the
amount of deformation. The analysis of the microstructures was performed using the
Electron Backscatter Diffraction (EBSD) technique using a scanning electron
microscope (SEM).
It was observed that the localized lubri-refrigeration by liquid vapor is effective
for the induction of brittle fracture in the DP780 dual-phase steel, extending the
fractured region and decreasing the sheared area in the cut edges, diminishing
plastic deformation in the surface and internal microstructure of the edge.

COMMITTEE MEMBERS:
Presidente - 2266607 - FABIO JOSE PINHEIRO SOUSA
Interno - 2345599 - BISMARCK LUIZ SILVA
Externo ao Programa - 1938946 - NICOLAU APOENA CASTRO - UFRNExterno à Instituição - JETSON LEMOS FERREIRA