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Accelerating Cementite Precipitation during the Non-Isothermal Process by Applying Tensile Stress in GCr15 Bearing Steel

In this work, the non-isothermal process of GCr15 bearing steel after quenching and tempering (QT) under different tensile stress (0, 20, 40 MPa) was investigated by kinetic analysis and microstructural observation. The Kissinger method and differential isoconversional method were employed to assess...

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Autores principales: Wang, Feng, Qian, Dong-Sheng, Xiao, Peng, Deng, Song
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317003/
https://www.ncbi.nlm.nih.gov/pubmed/30487422
http://dx.doi.org/10.3390/ma11122403
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author Wang, Feng
Qian, Dong-Sheng
Xiao, Peng
Deng, Song
author_facet Wang, Feng
Qian, Dong-Sheng
Xiao, Peng
Deng, Song
author_sort Wang, Feng
collection PubMed
description In this work, the non-isothermal process of GCr15 bearing steel after quenching and tempering (QT) under different tensile stress (0, 20, 40 MPa) was investigated by kinetic analysis and microstructural observation. The Kissinger method and differential isoconversional method were employed to assess the kinetic parameters of the microstructural evolution during the non-isothermal process with and without applied stress. It is found that the activation energy of retained austenite decomposition slightly increases from 109.4 kJ/mol to 121.5 kJ/mol with the increase of tensile stress. However, the activation energy of cementite precipitation decreases from 179.4 kJ/mol to 94.7 kJ/mol, proving that tensile stress could reduce the energy barrier of cementite precipitation. In addition, the microstructural observation based on scanning and transmission electron microscopy (SEM and TEM) shows that more cementite has formed for the specimens with the applied tensile stress, whereas there is still a large number of ε carbides existing in the specimens without stress. The results of X-ray diffraction (XRD) also verify that carbon in martensite diffuses more and participates in the formation of cementite under the applied tensile stress, which thus are in good agreement with the kinetic analysis. The mechanisms for the differences in cementite precipitation behaviors may lie in the acceleration of carbon atoms migration and the reduction of the nucleation barrier by applying tensile stress.
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spelling pubmed-63170032019-01-08 Accelerating Cementite Precipitation during the Non-Isothermal Process by Applying Tensile Stress in GCr15 Bearing Steel Wang, Feng Qian, Dong-Sheng Xiao, Peng Deng, Song Materials (Basel) Article In this work, the non-isothermal process of GCr15 bearing steel after quenching and tempering (QT) under different tensile stress (0, 20, 40 MPa) was investigated by kinetic analysis and microstructural observation. The Kissinger method and differential isoconversional method were employed to assess the kinetic parameters of the microstructural evolution during the non-isothermal process with and without applied stress. It is found that the activation energy of retained austenite decomposition slightly increases from 109.4 kJ/mol to 121.5 kJ/mol with the increase of tensile stress. However, the activation energy of cementite precipitation decreases from 179.4 kJ/mol to 94.7 kJ/mol, proving that tensile stress could reduce the energy barrier of cementite precipitation. In addition, the microstructural observation based on scanning and transmission electron microscopy (SEM and TEM) shows that more cementite has formed for the specimens with the applied tensile stress, whereas there is still a large number of ε carbides existing in the specimens without stress. The results of X-ray diffraction (XRD) also verify that carbon in martensite diffuses more and participates in the formation of cementite under the applied tensile stress, which thus are in good agreement with the kinetic analysis. The mechanisms for the differences in cementite precipitation behaviors may lie in the acceleration of carbon atoms migration and the reduction of the nucleation barrier by applying tensile stress. MDPI 2018-11-28 /pmc/articles/PMC6317003/ /pubmed/30487422 http://dx.doi.org/10.3390/ma11122403 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Wang, Feng
Qian, Dong-Sheng
Xiao, Peng
Deng, Song
Accelerating Cementite Precipitation during the Non-Isothermal Process by Applying Tensile Stress in GCr15 Bearing Steel
title Accelerating Cementite Precipitation during the Non-Isothermal Process by Applying Tensile Stress in GCr15 Bearing Steel
title_full Accelerating Cementite Precipitation during the Non-Isothermal Process by Applying Tensile Stress in GCr15 Bearing Steel
title_fullStr Accelerating Cementite Precipitation during the Non-Isothermal Process by Applying Tensile Stress in GCr15 Bearing Steel
title_full_unstemmed Accelerating Cementite Precipitation during the Non-Isothermal Process by Applying Tensile Stress in GCr15 Bearing Steel
title_short Accelerating Cementite Precipitation during the Non-Isothermal Process by Applying Tensile Stress in GCr15 Bearing Steel
title_sort accelerating cementite precipitation during the non-isothermal process by applying tensile stress in gcr15 bearing steel
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317003/
https://www.ncbi.nlm.nih.gov/pubmed/30487422
http://dx.doi.org/10.3390/ma11122403
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