Banca de DEFESA: BRUNO WILSON ANDRADE

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : BRUNO WILSON ANDRADE
DATE: 31/07/2024
TIME: 19:00
LOCAL: Videoconferência (meet.google.com/btn-twrv-vyi)
TITLE:

Evaluation and comparison of resistance to isothermal and cyclic
oxidation at 900 and 1000 °C of Inconel 625 nickel superalloy forged and produced by
additive manufacturing.

KEY WORDS:

cyclic oxidation, isothermal oxidation, oxide layer characterization, Inconel 625, additive manufacturing, direct energy deposition.

PAGES: 11
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia Física
SPECIALTY: Corrosão
SUMMARY:

Superalloys are widely used in high temperature applications and harsh environments. Inconel 625 is one of the most applied superalloys due to its high resistance to oxidation and mechanical properties. In this work, the microstructure and oxidation mechanism at 900 and 1000 °C of the Inconel 625 superalloy manufactured by the directed energy deposition (DED) and conventionally manufactured (CNV) additive manufacturing process were studied. The samples were cyclically oxidized for up to 100 cycles and isothermally oxidized at 900 °C for 200 hours and at 1000 °C for 100h. Each thermal cycle consisted of 60 minutes at the oxidation temperature and 10 minutes in which the samples were exposed to room temperature for cooling. To characterize the oxidized layers, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analyzes were carried out. The microstructure of the DED samples alternated between fine equiaxed grains and columnar grains, with Nb and Mo segregations located in the dendritic and interdendritic regions. At 900 °C the oxidation rate was similar for both materials, both in the cyclic and isothermal tests, but was clearly higher for the DED material at 1000 °C in both tests. Inconel 625 (CNV and DED) showed detachment at 900 and 1000 oC in cyclic tests. The oxide layer was identified as predominantly Cr2O3 under all conditions, providing good resistance to oxidation. In addition, oxides such as NbCrO4 as well as NiCr2O4 were identified for the CNV and DED samples. In isothermal tests, the delta phase Ni3(Nb,Mo) was observed for the CNV and DED alloys at the grain boundaries at 900 °C and at the metal/oxide interface for both temperatures as a result of chromium depletion. Finally, Inconel 625 produced by DED showed lower resistance to oxidation, being related to the microstructure, the segregation and the open porosity observed in the samples produced by DED.

BANKING MEMBERS:
Presidente - 1049564 - ARTUR MARIANO DE SOUSA MALAFAIA
Interna - 2029927 - ROSELI MARINS BALESTRA
Externo à Instituição - FÁBIO EDSON MARIANI