Toughness dependence of nano-bainite on phase fraction and morphology

Kumar, Avanish; Singh, Aparna

doi:10.1016/j.msea.2018.05.106

Cited by 59 publications

(14 citation statements)

References 20 publications

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“…Therefore, although the total volume fraction of retained austenite decreases, the stable film retained austenite is beneficial to improve the impact toughness [24][25][26][27]42]. The key role of more stable film retained austenite in improving the impact toughness can be contributed to retarding the formation of microcracks, effectively blunting the crack tip as well as causing more energy consumption during the crack propagation process mainly by the TRIP effect [43,44].…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Effect of Isothermal Transformation Times below Ms and Tempering on Strength and Toughness of Low-Temperature Bainite in 0.53 C Bainitic Steel

Liu

Naseem

et al. 2020

Materials

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This study aims to investigate the microstructures, strength, and impact toughness of low-temperature bainite obtained by isothermal transformation at temperature below Ms (Martensite Starting temperature) for different times and tempering process in 0.53 C wt% bainitic steel. By using the optical microscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), electron back scatter diffraction (EBSD), and mechanical property test, it was found that the microstructures after heat treatment consist of small amounts of martensite, fine bainite, and film retained austenite. After tempered at 250 °C for 2 h, the volume fraction of retained austenite (10.9%) in the sample treated by isothermal transformation at 220 °C for three hours is almost the same as that of the sample without tempering. In addition, the retained austenite fraction decreases with the increase of holding times and is reduced to 6.8% after holding for 15 h. The ultimate tensile strength (1827 MPa), yield strength (1496 MPa), total elongations (16.1%), and impact toughness (up to 58 J/cm2) were obtained by isothermal transformation at 220 °C for three hours and tempered at 250 °C. Whereas, the impact toughness of sample without tempering is 28 J/cm2. After holding for 15 h, the impact toughness raises to 56 J/cm2, while the ductility and strength decreases. These results indicate that the tempering process is helpful to improve the impact toughness of low-temperature bainite.

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Section: Mechanical Propertiesmentioning

confidence: 99%

Effect of Isothermal Transformation Times below Ms and Tempering on Strength and Toughness of Low-Temperature Bainite in 0.53 C Bainitic Steel

Liu

Naseem

et al. 2020

Materials

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“…The GB with fine dispersion distribution can refine the structure. The GB is of nearly spherical and isotropic shape, which can strengthen the oxide inclusions and improve the comprehensive mechanical properties of steel [26]. The inclusions consist of Al-O + MnS.…”

Section: The Rolling Microstructure Of Fh40mentioning

confidence: 99%

The effect of M (M = Ce, Zr, Ce–Zr) on rolling microstructure and mechanical properties of FH40

Meng

Wang

et al. 2020

High Temperature Materials and Processes

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Ce, Zr and Ce–Zr composite experimentl steel were prepared by vacuum induction furnace and 550 twin-roll reversible rolling mill. Optical microscope (OM), scanning electronic microscopy (SEM) and energy dispersive spectrometer (EDS) were used to observe the rolling microstructure of the experimental steel. The mechanical properties of the experimental steel were tested and analyzed. The effect of cerium zirconium oxide inclusions on nucleation, tensile and impact fracture mechanism of intragranular acicular ferrite (IAF) was investigated. The results show that the rolling microstructure of steel containing 0.0052% Ce and the steel under composite treatment containing 0.0053% Ce and 0.0055% Zr is refined. IAF generation can be induced by Al–Ce–O inclusion of the size of 4 µm or induced by Al–Ce–Zr–O + MnS inclusion of the size of 3 µm. The yield strength and tensile strength of the steel treated by Ce–Zr are 428 and 590 MPa, respectively, the elongation is 23.55%, the longitudinal impact energy at −60°C is 189 J, which are 31, 45, 46 J and 6.25%, respectively, higher than those of the matrix steel. The dimple of the experimental steel at the fracture surface is larger and deeper than that of the matrix steel. The small inclusions in uniform distribution contribute to the high tensile strength of the experimental steel.

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“…Previous investigations have shown that the characteristic features of different phases, including the amount, size, morphology and orientation, are important factors that influence the final mechanical properties of bainitic steels [22,23]. Both the carbon content as well as austempering temperature were important parameters influencing the kinetics of phase transformation [24,25].…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Kinetics of Bainite Transformation Behaviour in a High-Silicon Medium-Carbon Steel above and below the Ms Temperature

et al. 2022

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This work deals with the kinetic aspects of bainite formation during isothermal holding above and below the martensite start (Ms~275 °C) temperature using a low-alloy, high-silicon DIN 1.5025 steel in a range suitable for achieving ultrafine/nanostructured bainite. Dilatation measurements were conducted to study transformation behaviour and kinetics, while the microstructural features were examined using laser scanning confocal microscopy and electron backscatter diffraction (EBSD) techniques combined with hardness measurements. The results showed that for isothermal holding above the Ms temperature, the maximum bainitic transformation rate decreased with the decrease in isothermal holding temperature between 450 and 300 °C. On the other hand, for isothermal holding below the Ms temperature at 250 and 200 °C, the maximum rate of transformation was achieved corresponding to region I due to the partitioning of carbon and also possibly because of the ledged growth of isothermal martensite soon after the start of isothermal holding. In addition, a second peak was obvious at about 100 and 500 s, respectively, during holding at 250 and 200 °C due to the occurrence of bainitic transformation, marking the beginning of region II.

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Toughness dependence of nano-bainite on phase fraction and morphology

Cited by 59 publications

References 20 publications

Effect of Isothermal Transformation Times below Ms and Tempering on Strength and Toughness of Low-Temperature Bainite in 0.53 C Bainitic Steel

Effect of Isothermal Transformation Times below Ms and Tempering on Strength and Toughness of Low-Temperature Bainite in 0.53 C Bainitic Steel

The effect of M (M = Ce, Zr, Ce–Zr) on rolling microstructure and mechanical properties of FH40

Characteristics and Kinetics of Bainite Transformation Behaviour in a High-Silicon Medium-Carbon Steel above and below the Ms Temperature

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