Mechanical Characterization at Nanoscale of Austenite, Ferrite, and Sigma Phases via Hardness Measurement and Fretting Wear Behavior of a Duplex Stainless Steel

This study aimed at the mechanical characterization, on a nanometric scale, of the constituents obtained for different fractions in duplex stainless-steel plates subjected to 850, 950, 1000, and 1150 °C heating treatments via hardness measurements and determining their influences on the fretting wea...

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Main Authors: Jomar José Knaip Ribeiro, Alba Regina Turin, Yamid E. Nuñez de la Rosa, Pedro Victorio Caetano Abrantes Quadros, Oriana Palma Calabokis, Carlos Maurício Lepienski, Silvio Francisco Brunatto, Paulo César Borges
Format: Article
Language:English
Published: MDPI AG 2023-04-01
Series:Metals
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Online Access:https://www.mdpi.com/2075-4701/13/5/864
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author Jomar José Knaip Ribeiro
Alba Regina Turin
Yamid E. Nuñez de la Rosa
Pedro Victorio Caetano Abrantes Quadros
Oriana Palma Calabokis
Carlos Maurício Lepienski
Silvio Francisco Brunatto
Paulo César Borges
author_facet Jomar José Knaip Ribeiro
Alba Regina Turin
Yamid E. Nuñez de la Rosa
Pedro Victorio Caetano Abrantes Quadros
Oriana Palma Calabokis
Carlos Maurício Lepienski
Silvio Francisco Brunatto
Paulo César Borges
author_sort Jomar José Knaip Ribeiro
collection DOAJ
description This study aimed at the mechanical characterization, on a nanometric scale, of the constituents obtained for different fractions in duplex stainless-steel plates subjected to 850, 950, 1000, and 1150 °C heating treatments via hardness measurements and determining their influences on the fretting wear behavior of the studied steel. The obtained ferrite (α)-, austenite (γ)-, and sigma (σ)-phase fractions were determined using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. The mechanical characterization was carried out using hardness measurement and fretting wear techniques via nanoindentation. For comparison purposes, the Vickers microhardness was also characterized to determine the effect of the σ phase, which eventually formed, on the obtained microstructure properties as a whole. Two distinct behaviors were observed, depending on the eventual formation of σ phase as a function of the treatment temperature: (i) specimens treated at 850 and 950 °C showed a hardening effect (HV<sub>0.5</sub> values of 333 ± 15 and 264 ± 13, respectively) due to σ-phase precipitation (hereafter termed ‘as-aged’), and (ii) specimens treated at 1000 and 1150 °C (with HV<sub>0.5</sub> values of 240 ± 13 and 249 ± 4, respectively) showed no σ-phase precipitation (hereafter termed ‘as-solubilized’). The increases in the microhardness values for the as-aged specimens were attributed to the hardness of the σ-phase precipitates (which showed nanohardness values varying in the 8.0–8.5 GPa range), which was approximately twice that of the austenite and ferrite grains (both phases showed nanohardness values in the 3.6–4.1 GPa range, on average). When formed (for fractions on the order of 8% and 3% at 850 and 950 °C, respectively), σ phase was mainly observed at the α/γ grain interfaces or boundaries. Fretting wear tests, using a diamond sphere with a radius of 10 μm as the counter body and a load of 20 mN, revealed the same wear mechanisms in the α/γ matrix for all studied conditions. However, as-solubilized specimens (heat-treated at 1000 and 1150 °C) displayed higher resistance to fretting micro-wear in the austenitic grains compared to the ferritic grains, indicating lower plastic deformation in the respective wear scars on the obtained tracks. In particular, as-aged specimens (heat-treated at 850 and 950 °C) exhibited lower coefficients of friction due to their higher surface resistances. The localized wear at σ-phase grains was much less pronounced than at ferrite and austenite grains. Overall, this study provides valuable insights into the mechanical behavior of microstructural changes in duplex steel at the nanometric scale.
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spelling doaj.art-be41281df2c845f78272a5f2d8f05a092023-11-18T02:26:55ZengMDPI AGMetals2075-47012023-04-0113586410.3390/met13050864Mechanical Characterization at Nanoscale of Austenite, Ferrite, and Sigma Phases via Hardness Measurement and Fretting Wear Behavior of a Duplex Stainless SteelJomar José Knaip Ribeiro0Alba Regina Turin1Yamid E. Nuñez de la Rosa2Pedro Victorio Caetano Abrantes Quadros3Oriana Palma Calabokis4Carlos Maurício Lepienski5Silvio Francisco Brunatto6Paulo César Borges7Department of Mechanical Engineering, Campus Ecoville, Federal Technological University of Paraná, Curitiba 81280-34, BrazilDepartment of Mechanical Engineering, Campus Ecoville, Federal Technological University of Paraná, Curitiba 81280-34, BrazilDepartment of Mechanical Engineering, Campus Ecoville, Federal Technological University of Paraná, Curitiba 81280-34, BrazilDepartment of Mechanical Engineering, Campus Ecoville, Federal Technological University of Paraná, Curitiba 81280-34, BrazilDepartment of Mechanical Engineering, Campus Ecoville, Federal Technological University of Paraná, Curitiba 81280-34, BrazilDepartment of Mechanical Engineering, Campus Ecoville, Federal Technological University of Paraná, Curitiba 81280-34, BrazilDepartment of Mechanical Engineering, Federal University of Paraná (UFPR), Curitiba 81531-990, BrazilDepartment of Mechanical Engineering, Campus Ecoville, Federal Technological University of Paraná, Curitiba 81280-34, BrazilThis study aimed at the mechanical characterization, on a nanometric scale, of the constituents obtained for different fractions in duplex stainless-steel plates subjected to 850, 950, 1000, and 1150 °C heating treatments via hardness measurements and determining their influences on the fretting wear behavior of the studied steel. The obtained ferrite (α)-, austenite (γ)-, and sigma (σ)-phase fractions were determined using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. The mechanical characterization was carried out using hardness measurement and fretting wear techniques via nanoindentation. For comparison purposes, the Vickers microhardness was also characterized to determine the effect of the σ phase, which eventually formed, on the obtained microstructure properties as a whole. Two distinct behaviors were observed, depending on the eventual formation of σ phase as a function of the treatment temperature: (i) specimens treated at 850 and 950 °C showed a hardening effect (HV<sub>0.5</sub> values of 333 ± 15 and 264 ± 13, respectively) due to σ-phase precipitation (hereafter termed ‘as-aged’), and (ii) specimens treated at 1000 and 1150 °C (with HV<sub>0.5</sub> values of 240 ± 13 and 249 ± 4, respectively) showed no σ-phase precipitation (hereafter termed ‘as-solubilized’). The increases in the microhardness values for the as-aged specimens were attributed to the hardness of the σ-phase precipitates (which showed nanohardness values varying in the 8.0–8.5 GPa range), which was approximately twice that of the austenite and ferrite grains (both phases showed nanohardness values in the 3.6–4.1 GPa range, on average). When formed (for fractions on the order of 8% and 3% at 850 and 950 °C, respectively), σ phase was mainly observed at the α/γ grain interfaces or boundaries. Fretting wear tests, using a diamond sphere with a radius of 10 μm as the counter body and a load of 20 mN, revealed the same wear mechanisms in the α/γ matrix for all studied conditions. However, as-solubilized specimens (heat-treated at 1000 and 1150 °C) displayed higher resistance to fretting micro-wear in the austenitic grains compared to the ferritic grains, indicating lower plastic deformation in the respective wear scars on the obtained tracks. In particular, as-aged specimens (heat-treated at 850 and 950 °C) exhibited lower coefficients of friction due to their higher surface resistances. The localized wear at σ-phase grains was much less pronounced than at ferrite and austenite grains. Overall, this study provides valuable insights into the mechanical behavior of microstructural changes in duplex steel at the nanometric scale.https://www.mdpi.com/2075-4701/13/5/864sigma phasefretting micro-wearduplex stainless steel
spellingShingle Jomar José Knaip Ribeiro
Alba Regina Turin
Yamid E. Nuñez de la Rosa
Pedro Victorio Caetano Abrantes Quadros
Oriana Palma Calabokis
Carlos Maurício Lepienski
Silvio Francisco Brunatto
Paulo César Borges
Mechanical Characterization at Nanoscale of Austenite, Ferrite, and Sigma Phases via Hardness Measurement and Fretting Wear Behavior of a Duplex Stainless Steel
Metals
sigma phase
fretting micro-wear
duplex stainless steel
title Mechanical Characterization at Nanoscale of Austenite, Ferrite, and Sigma Phases via Hardness Measurement and Fretting Wear Behavior of a Duplex Stainless Steel
title_full Mechanical Characterization at Nanoscale of Austenite, Ferrite, and Sigma Phases via Hardness Measurement and Fretting Wear Behavior of a Duplex Stainless Steel
title_fullStr Mechanical Characterization at Nanoscale of Austenite, Ferrite, and Sigma Phases via Hardness Measurement and Fretting Wear Behavior of a Duplex Stainless Steel
title_full_unstemmed Mechanical Characterization at Nanoscale of Austenite, Ferrite, and Sigma Phases via Hardness Measurement and Fretting Wear Behavior of a Duplex Stainless Steel
title_short Mechanical Characterization at Nanoscale of Austenite, Ferrite, and Sigma Phases via Hardness Measurement and Fretting Wear Behavior of a Duplex Stainless Steel
title_sort mechanical characterization at nanoscale of austenite ferrite and sigma phases via hardness measurement and fretting wear behavior of a duplex stainless steel
topic sigma phase
fretting micro-wear
duplex stainless steel
url https://www.mdpi.com/2075-4701/13/5/864
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