Tribology and Materials | Volume 3 | Issue 3 | 2024 | 118-130
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https://doi.org/10.46793/tribomat.2024.013
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Influence of single- and multi-stage austempering treatments on microstructure and mechanical properties of AISI 4140 steel
Mohammad Badaruddin
1,
Purnomo Diarko2,
Dwi Asmi3,
Herry Wardono1
1 Faculty of Engineering, University of Lampung, Bandar Lampung, Indonesia
2 Politeknik Tunas Garuda, Panaragan Jaya, Indonesia
3 Faculty of Mathematics and Natural Sciences, University of Lampung, Bandar Lampung, Indonesia
Abstract: The present study examined the impact of single- and
multi-stage austempering treatments on microstructural changes and the
mechanical properties of AISI 4140 steel. All specimens underwent an
annealing treatment before undergoing austempering treatments. The
single-stage austempering treatment employed three distinct
temperatures: 312, 362 and 412 °C. The multi-austempering employed three
steps of austempering treatment, commencing at 312 °C and progressing in
increments of 50 °C for an hour each, up to a maximum temperature of 412
°C. The mechanical properties were determined using hardness, impact and
tensile testing. Furthermore, the microstructure alterations and phases
identified in heat-treated specimens were characterised using scanning
electron microscopy (SEM), electron dispersive spectroscopy (EDS) and
X-ray diffraction (XRD) patterns. The mechanical properties of AISI 4140
steel subjected to single-stage and multi-stage austempering treatments
exhibited a considerable enhancement compared to the annealed steel. The
microstructure of annealed steel is predominantly coarse ferrite and
pearlite. The austempering treatment forms a bainitic structure,
retained austenite structures and a small number of martensitic
structures within the steel's microstructure. In other words, the
mechanical properties of AISI 4140 steel concerning austempering
treatments are correlated with the microstructural changes resulting
from different austempering temperatures.
Keywords: AISI 4140 steel, annealing treatment, multi-stage austempering, bainitic ferrite, martensitic structure, retained austenite.
Received: 23-07-2024, Revised: 07-08-2024, Accepted: 13-08-2024
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license, which allows users to distribute, remix, adapt,
and build upon the material in any medium or format for non-commercial purposes only, and only so long as attribution is given to the creator.
2 Politeknik Tunas Garuda, Panaragan Jaya, Indonesia
3 Faculty of Mathematics and Natural Sciences, University of Lampung, Bandar Lampung, Indonesia
Abstract: The present study examined the impact of single- and multi-stage austempering treatments on microstructural changes and the mechanical properties of AISI 4140 steel. All specimens underwent an annealing treatment before undergoing austempering treatments. The single-stage austempering treatment employed three distinct temperatures: 312, 362 and 412 °C. The multi-austempering employed three steps of austempering treatment, commencing at 312 °C and progressing in increments of 50 °C for an hour each, up to a maximum temperature of 412 °C. The mechanical properties were determined using hardness, impact and tensile testing. Furthermore, the microstructure alterations and phases identified in heat-treated specimens were characterised using scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS) and X-ray diffraction (XRD) patterns. The mechanical properties of AISI 4140 steel subjected to single-stage and multi-stage austempering treatments exhibited a considerable enhancement compared to the annealed steel. The microstructure of annealed steel is predominantly coarse ferrite and pearlite. The austempering treatment forms a bainitic structure, retained austenite structures and a small number of martensitic structures within the steel's microstructure. In other words, the mechanical properties of AISI 4140 steel concerning austempering treatments are correlated with the microstructural changes resulting from different austempering temperatures.
Keywords: AISI 4140 steel, annealing treatment, multi-stage austempering, bainitic ferrite, martensitic structure, retained austenite.
Received: 23-07-2024, Revised: 07-08-2024, Accepted: 13-08-2024
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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license, which allows users to distribute, remix, adapt, and build upon the material in any medium or format for non-commercial purposes only, and only so long as attribution is given to the creator.