Microstructural Evolution and Oxidation Resistance of Fe-30Ni-15Cr Alloy for Internal Combustion Engine Valves Under Long-Term High-Temperature Exposure and Heat Treatment

Iron–nickel-based superalloy is an ideal substitute for the expensive Inconel 625 and Inconel 751 alloys. To elucidate the evolution of the microstructure and properties of Ni30 alloy under different thermal treatment conditions, a systematic study was conducted on the microstructural transformation...

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Main Authors: Yuguo Tu, Xueshan Xiao, Zhiyuan Zhu, Linzhen Zhou
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Metals
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Online Access:https://www.mdpi.com/2075-4701/15/1/61
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author Yuguo Tu
Xueshan Xiao
Zhiyuan Zhu
Linzhen Zhou
author_facet Yuguo Tu
Xueshan Xiao
Zhiyuan Zhu
Linzhen Zhou
author_sort Yuguo Tu
collection DOAJ
description Iron–nickel-based superalloy is an ideal substitute for the expensive Inconel 625 and Inconel 751 alloys. To elucidate the evolution of the microstructure and properties of Ni30 alloy under different thermal treatment conditions, a systematic study was conducted on the microstructural transformation of the alloy’s strengthening γ′ phase following solution treatment and aging, as well prolonged exposure at 750 °C, and the oxidation behavior of the Ni30 alloy was examined. During prolonged thermal exposure, grain growth occurs mainly in the initial stage, and after 200 h, the prolonged exposure time leads to a significant coarsening of γ′ precipitates, whose area fraction increases by more than 10 times compared to their unaged state. After 100 h of aging, the alloy reaches a peak tensile strength of 1270 MPa and a yield strength of 820 MPa; after 2000 h, the alloy maintains a relatively high strength with a slight decrease in ductility. The oxidation kinetic curve of Ni30 alloy follows the quasi-parabolic oxidation law at 750 °C, and its oxidation rate is consistently lower than 0.1 g·m<sup>−2</sup>·h<sup>−1</sup> throughout the whole oxidation process, which indicates that it has excellent oxidation resistance. The external oxide layer of Ni30 alloy shows a bilayered structure, and no obvious surface porosity or flaking of oxidation products were observed throughout the high-temperature oxidation test. This study not only contributes to the improvement of material properties, but also promotes innovation and development in the field of high-temperature engineering applications that will help to meet the increasingly stringent requirements of high-temperature working environments.
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spelling doaj-art-6bf7164263c0495ea8c13bbd02a71f552025-01-24T13:41:33ZengMDPI AGMetals2075-47012025-01-011516110.3390/met15010061Microstructural Evolution and Oxidation Resistance of Fe-30Ni-15Cr Alloy for Internal Combustion Engine Valves Under Long-Term High-Temperature Exposure and Heat TreatmentYuguo Tu0Xueshan Xiao1Zhiyuan Zhu2Linzhen Zhou3School of Materials Science and Engineering, Shanghai University, Shanghai 200444, ChinaSchool of Materials Science and Engineering, Shanghai University, Shanghai 200444, ChinaInstitute of Materials Henan Academy of Sciences, Zhengzhou 450046, ChinaSchool of Mechanical Engineering, Yancheng Institute of Technology, Yancheng 224501, ChinaIron–nickel-based superalloy is an ideal substitute for the expensive Inconel 625 and Inconel 751 alloys. To elucidate the evolution of the microstructure and properties of Ni30 alloy under different thermal treatment conditions, a systematic study was conducted on the microstructural transformation of the alloy’s strengthening γ′ phase following solution treatment and aging, as well prolonged exposure at 750 °C, and the oxidation behavior of the Ni30 alloy was examined. During prolonged thermal exposure, grain growth occurs mainly in the initial stage, and after 200 h, the prolonged exposure time leads to a significant coarsening of γ′ precipitates, whose area fraction increases by more than 10 times compared to their unaged state. After 100 h of aging, the alloy reaches a peak tensile strength of 1270 MPa and a yield strength of 820 MPa; after 2000 h, the alloy maintains a relatively high strength with a slight decrease in ductility. The oxidation kinetic curve of Ni30 alloy follows the quasi-parabolic oxidation law at 750 °C, and its oxidation rate is consistently lower than 0.1 g·m<sup>−2</sup>·h<sup>−1</sup> throughout the whole oxidation process, which indicates that it has excellent oxidation resistance. The external oxide layer of Ni30 alloy shows a bilayered structure, and no obvious surface porosity or flaking of oxidation products were observed throughout the high-temperature oxidation test. This study not only contributes to the improvement of material properties, but also promotes innovation and development in the field of high-temperature engineering applications that will help to meet the increasingly stringent requirements of high-temperature working environments.https://www.mdpi.com/2075-4701/15/1/61iron–nickel-based superalloyheat treatmentmicrostructural evolutionlong-term heat exposureoxidation resistance
spellingShingle Yuguo Tu
Xueshan Xiao
Zhiyuan Zhu
Linzhen Zhou
Microstructural Evolution and Oxidation Resistance of Fe-30Ni-15Cr Alloy for Internal Combustion Engine Valves Under Long-Term High-Temperature Exposure and Heat Treatment
Metals
iron–nickel-based superalloy
heat treatment
microstructural evolution
long-term heat exposure
oxidation resistance
title Microstructural Evolution and Oxidation Resistance of Fe-30Ni-15Cr Alloy for Internal Combustion Engine Valves Under Long-Term High-Temperature Exposure and Heat Treatment
title_full Microstructural Evolution and Oxidation Resistance of Fe-30Ni-15Cr Alloy for Internal Combustion Engine Valves Under Long-Term High-Temperature Exposure and Heat Treatment
title_fullStr Microstructural Evolution and Oxidation Resistance of Fe-30Ni-15Cr Alloy for Internal Combustion Engine Valves Under Long-Term High-Temperature Exposure and Heat Treatment
title_full_unstemmed Microstructural Evolution and Oxidation Resistance of Fe-30Ni-15Cr Alloy for Internal Combustion Engine Valves Under Long-Term High-Temperature Exposure and Heat Treatment
title_short Microstructural Evolution and Oxidation Resistance of Fe-30Ni-15Cr Alloy for Internal Combustion Engine Valves Under Long-Term High-Temperature Exposure and Heat Treatment
title_sort microstructural evolution and oxidation resistance of fe 30ni 15cr alloy for internal combustion engine valves under long term high temperature exposure and heat treatment
topic iron–nickel-based superalloy
heat treatment
microstructural evolution
long-term heat exposure
oxidation resistance
url https://www.mdpi.com/2075-4701/15/1/61
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