Effect of Multi-Step Austempering Treatment on the Microstructure and Mechanical Properties of a High Silicon Carbide-Free Bainitic Steel with Bimodal Bainite Distribution

The effect of multi-step austempering treatments on the microstructure and mechanical properties of a novel medium carbon high silicon carbide-free bainitic steel was studied. Five different isothermal treatment processes were selected, including single-step isothermal treatments above martensite start temperature (at 350 °C and 370 °C, respectively), and three kinds of two-step routes (370 °C + 300 °C, 370 °C + 250 °C, and 350 °C + 250 °C). In comparison with single-step austempering treatment adopting a two-step process, a microstructure with a bimodal-size distribution of bainitic ferrite and without martensite was obtained. Bainitic transformation was studied using dilatometry both for single-step and two-step routes and the specimens were completely characterised by electron microscopy (SEM and TEM), X-ray diffraction (XRD) and standard tensile tests. The mechanical response of the samples subjected to two-step routes was superior to those treated at a single temperature.

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Isothermal Transformation, Microstructure and Mechanical Properties of Ausformed Low-Carbon Carbide-Free Bainitic Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.329 ◽

2018 ◽

Vol 941 ◽

pp. 329-333 ◽

Cited By ~ 1

Author(s):

Jiang Ying Meng ◽

Lei Jie Zhao ◽

Fan Huang ◽

Fu Cheng Zhang ◽

Li He Qian

Keyword(s):

Mechanical Properties ◽

Retained Austenite ◽

Volume Fraction ◽

Bainitic Ferrite ◽

Isothermal Transformation ◽

Bainitic Transformation ◽

Isothermal Treatment ◽

Bainitic Steel ◽

Low Carbon ◽

Microstructure And Mechanical Properties

In the present study, the effects of ausforming on the bainitic transformation, microstructure and mechanical properties of a low-carbon rich-silicon carbide-free bainitic steel have been investigated. Results show that prior ausforming shortens both the incubation period and finishing time of bainitic transformation during isothermal treatment at a temperature slightly above the Mspoint. The thicknesses of bainitic ferrite laths are reduced appreciably by ausforming; however, ausforming increases the amount of large blocks of retained austenite/martenisite and decreases the volume fraction of retained austenite. And accordingly, ausforming gives rise to significant increases in both yield and tensile strengths, but causes noticeable decreases in ductility and impact toughness.

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Microstructure and mechanical properties of a high-carbon bainitic steel containing Si/Al by different heat treatment processes

Materials Express ◽

10.1166/mex.2020.1846 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1932-1940

Author(s):

Sufyan Naseem ◽

Enzuo Liu ◽

Xuefei Huang ◽

Weigang Huang

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Electron Microscope ◽

Retained Austenite ◽

Bainitic Ferrite ◽

Bainitic Steel ◽

Boundary Misorientation ◽

Treatment Processes ◽

Microstructure And Mechanical Properties ◽

The Impact

The present study aims to investigate the microstructure and mechanical properties of 0.79 C wt% bainitic steel containing Si and Al by three heat treatment processes: austempering and tempering (B-T), two-step austempering (2S-A) and the austempering-quenching-partitioning (AQP). The optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and electron backscatter diffraction (EBSD) were employed to analyze the microstructure of samples. The results demonstrate that the sample subjected to the AQP process exhibited a multiphase microstructure with martensite, filmy retained austenite (RA) and fine bainitic laths. The AQP sample evidenced a high tensile strength of 1705 MPa, yield strength of 1254 MPa, a better total elongation of 16.6%, product of strength and elongation (PSE) of 28 GPa% and the impact toughness of 33 J among all heat treatment processes. The higher strength and toughness could be ascribed to the fine bainitic ferrite as well as an appropriate amount of filmy retained austenite. A fraction of martensite that was formed during the quenching step at 110 °C possibly divided the untransformed austenite into small areas, which could refine the microstructure. EBSD analysis showed that the AQP sample exhibited a higher proportion (64%) of boundary misorientation angle greater than 15° than that of the 2S-A. These high angle boundaries can improve the toughness of steel.

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Effect of austempering treatment on the microstructure and mechanical properties of 0.4C–1.5Si-1.5Mn TRIP-aided bainitic ferrite steel

Materials Science and Engineering A ◽

10.1016/j.msea.2021.141479 ◽

2021 ◽

pp. 141479

Author(s):

Yutao Zhou ◽

Tomohiko Hojo ◽

Motomichi Koyama ◽

Eiji Akiyama

Keyword(s):

Mechanical Properties ◽

Bainitic Ferrite ◽

Microstructure And Mechanical Properties ◽

Ferrite Steel

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Microstructure and Mechanical Properties of Mullite-Silicon Carbide Composites

Journal of the American Ceramic Society ◽

10.1111/j.1151-2916.1989.tb06269.x ◽

1989 ◽

Vol 72 (6) ◽

pp. 1049-1054 ◽

Cited By ~ 22

Author(s):

M. Isabel Osendi ◽

Barry A. Bender ◽

David Lewis

Keyword(s):

Mechanical Properties ◽

Silicon Carbide ◽

Microstructure And Mechanical Properties

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Study on Microstructure and Mechanical Properties of Al7068 Reinforced with Silicon Carbide and Fly Ash by Powder Metallurgy

International Journal for Modern Trends in Science and Technology - RTT2020 ◽

10.46501/ijmtst0709009 ◽

2021 ◽

Vol 7 (09) ◽

pp. 47-53

Author(s):

Md Mehtab Alam and B.S Motgi

Keyword(s):

Mechanical Properties ◽

Silicon Carbide ◽

Fly Ash ◽

Powder Metallurgy ◽

Aluminum Matrix ◽

Hydraulic Press ◽

Powder Form ◽

X Ray ◽

Microstructure And Mechanical Properties ◽

Scanning Electron

The paper deals with detailed study on microstructure and mechanical properties of aluminum 7068 reinforced with fly ash and silicon carbide by powder metallurgy, aluminum 7068, silicon carbide and fly ash were taken in powder form of required size and mixed together in varying proportion according to specification and compacted with pressure of 400MPa using hydraulic press to make samples and then samples were sintered at 600°c for 2 hours, the samples were tested for density, compressive strength, hardness and microstructure was analyzed using scanning electron microscope, energy dispersive x-ray study was carried out in order to confirm presence of silicon carbide and fly ash in aluminum matrix.

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