Banca de QUALIFICAÇÃO: ANDEILSON BERNARDO BEZERRA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : ANDEILSON BERNARDO BEZERRA
DATE: 15/12/2021
TIME: 09:00
LOCAL: videoconferência: https://meet.google.com/teo-qtfy-xex
TITLE:

Effect of the cryogenic punching applied to advanced high-strength steels (AHSS)

KEY WORDS:

AHSS, punching, cryogenic, edge stretching

PAGES: 84
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUBÁREA: Processos de Fabricação
SPECIALTY: Processos de Fabricação, Seleção Econômica
SUMMARY:

Thin sheets of Advanced High Strength Steels (AHSS) have been widely applied in the manufacturing structural parts for automotive bodies. AHSS combines a ferritic matrix with high ductility; and a second high hardness constituent (which may be martensite, bainite, or a combination of both) dispersed in the matrix. This microstructural characteristic allows the processing of AHSS by forming and stamping. However, defects such as cracks, nucleated from the cut edges, can occur due to the presence of this second constituent. An alternative to minimize crack nucleation is to carry out the stamping process at cryogenic temperatures. The hypothesis is that, if the process is carried out at low temperatures, there may be a change in the plastic deformation mechanism from shear to deformation by mechanical twinning and cleavage. Therefore, the main objective of this work is to evaluate the influence of cryogenic temperatures on punching operations in thin AHSS sheets. Thus, a punching tooling was designed and manufactured to allow experiments on a shaper machine, which allows adjustment of the cutting velocity. Optical and scanning electron micrographs were carried out aiming to evaluate the samples to identify the main deformation mechanisms. Initial tests were carried out with interstitial-free (IF) steel, with a thickness of 0.65 mm, showing the process's feasibility at cryogenic temperatures and a change in the plastic deformation mechanism. The most significant changes observed by scanning electron microscopy (SEM) were the reduction of plastic deformation regions and the increase in the shear zone on the cut surface of the samples at a temperature of -100 °C when compared with samples tested at a temperature of 20 °C.

BANKING MEMBERS:
Presidente - 1792669 - ADILSON JOSÉ DE OLIVEIRA
Interno - 1545410 - ANDERSON CLAYTON ALVES DE MELO
Externo ao Programa - 1938946 - NICOLAU APOENA CASTRO
Externo ao Programa - 1792681 - ULISSES BORGES SOUTO