Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718
In this work, influence of ultrasonic nanocrystal surface modification (UNSM) on the degree of sensitization (DOS) in Inconel 718 has been studied and correlated with the resulting microstructure. The UNSM processed samples decreased their grain size from 11.9 µm to 7.75 µm, increa...
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doaj-12e94299049748d88aba641ae769e73c2020-11-25T03:32:57ZengMDPI AGMetals2075-47012020-02-0110220410.3390/met10020204met10020204Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718Ulises Martin0Jacob Ress1Juan Bosch2David M. Bastidas3National Center for Education and Research on Corrosion and Materials Performance, NCERCAMP-UA, Dept. Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, 302 E Buchtel Ave, Akron, OH 44325-3906, USANational Center for Education and Research on Corrosion and Materials Performance, NCERCAMP-UA, Dept. Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, 302 E Buchtel Ave, Akron, OH 44325-3906, USANational Center for Education and Research on Corrosion and Materials Performance, NCERCAMP-UA, Dept. Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, 302 E Buchtel Ave, Akron, OH 44325-3906, USANational Center for Education and Research on Corrosion and Materials Performance, NCERCAMP-UA, Dept. Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, 302 E Buchtel Ave, Akron, OH 44325-3906, USAIn this work, influence of ultrasonic nanocrystal surface modification (UNSM) on the degree of sensitization (DOS) in Inconel 718 has been studied and correlated with the resulting microstructure. The UNSM processed samples decreased their grain size from 11.9 µm to 7.75 µm, increasing the surface of grain boundaries, and thus enhancing the area where δ phase and niobium carbides precipitate. The effect of the UNSM process on the DOS of Inconel 718 was studied by the double loop electrochemical potentiokinetic reactivation (DL−EPR) test. The DL−EPR showed that for UNSM processed samples with no thermal treatment, the DOS increased up to 59.6%, while for UNSM treated samples that were post-annealed at 1000 °C for 10 min and water quenched the DOS decreased down to 40.9%. The increase of grain boundaries surface area and triple junctions after the UNSM process enables the formation of twice the amount of δ phase compared to the as-received Inconel 718 bulk sample. The area fraction of the grain boundary covered by δ phase was of 9.87% in the UNSM region while in the bulk the area fraction was 4.09%. In summary, it was found that after UNSM process, the annealing at 1000 °C for 10 min and water quenching promoted the transformation of γ″ to form δ phase on the grain boundaries, which reduces the intergranular corrosion susceptibility.https://www.mdpi.com/2075-4701/10/2/204double loop electrochemical potentiokinetic reactivation (dl−epr)sensitizationultrasonic nanocrystal surface modification (unsm)intergranular corrosioninconel 718 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Ulises Martin Jacob Ress Juan Bosch David M. Bastidas |
spellingShingle |
Ulises Martin Jacob Ress Juan Bosch David M. Bastidas Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718 Metals double loop electrochemical potentiokinetic reactivation (dl−epr) sensitization ultrasonic nanocrystal surface modification (unsm) intergranular corrosion inconel 718 |
author_facet |
Ulises Martin Jacob Ress Juan Bosch David M. Bastidas |
author_sort |
Ulises Martin |
title |
Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718 |
title_short |
Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718 |
title_full |
Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718 |
title_fullStr |
Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718 |
title_full_unstemmed |
Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718 |
title_sort |
evaluation of the dos by dl−epr of unsm processed inconel 718 |
publisher |
MDPI AG |
series |
Metals |
issn |
2075-4701 |
publishDate |
2020-02-01 |
description |
In this work, influence of ultrasonic nanocrystal surface modification (UNSM) on the degree of sensitization (DOS) in Inconel 718 has been studied and correlated with the resulting microstructure. The UNSM processed samples decreased their grain size from 11.9 µm to 7.75 µm, increasing the surface of grain boundaries, and thus enhancing the area where δ phase and niobium carbides precipitate. The effect of the UNSM process on the DOS of Inconel 718 was studied by the double loop electrochemical potentiokinetic reactivation (DL−EPR) test. The DL−EPR showed that for UNSM processed samples with no thermal treatment, the DOS increased up to 59.6%, while for UNSM treated samples that were post-annealed at 1000 °C for 10 min and water quenched the DOS decreased down to 40.9%. The increase of grain boundaries surface area and triple junctions after the UNSM process enables the formation of twice the amount of δ phase compared to the as-received Inconel 718 bulk sample. The area fraction of the grain boundary covered by δ phase was of 9.87% in the UNSM region while in the bulk the area fraction was 4.09%. In summary, it was found that after UNSM process, the annealing at 1000 °C for 10 min and water quenching promoted the transformation of γ″ to form δ phase on the grain boundaries, which reduces the intergranular corrosion susceptibility. |
topic |
double loop electrochemical potentiokinetic reactivation (dl−epr) sensitization ultrasonic nanocrystal surface modification (unsm) intergranular corrosion inconel 718 |
url |
https://www.mdpi.com/2075-4701/10/2/204 |
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