Carbide Precipitation in 2.25 Cr-1 Mo Bainitic Steel: Effect of Heating and Isothermal Tempering Conditions

Dépinoy, Sylvain; Toffolon-Masclet, Caroline; Urvoy, Stéphane; Roubaud, Justine; Marini, B.; Roch, François; Kozeschnik, Ernst; Gourgues-Lorenzon, Anne-Françoise

doi:10.1007/s11661-017-4045-6

Cited by 41 publications

(23 citation statements)

References 32 publications

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“…The peak related to cementite is seen after tempering for both specimens, since cementite phase is detectable by XRD, 5% or more cementite exists in tempered steels. These Fe 3 C carbides, dissolve upon tempering to form Cr 7 C 3 carbides at the same location [29]. As discussed earlier, in bainite, the bainitic ferrite contains 0.19 wt % of carbon.…”

Section: Cementite Precipitationmentioning

confidence: 86%

In Situ Study of Phase Transformations during Non-Isothermal Tempering of Bainitic and Martensitic Microstructures

Talebi

Ghasemi-Nanesa

Jahazi

et al. 2017

Metals

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Abstract:Phase transformations during non-isothermal tempering of bainitic or martensitic microstructures obtained after quenching of a medium-carbon low-alloy steel was studied. The microstructures correspond to different locations of an as-quenched large-sized forged ingot used as a die material in the automotive industry. High-resolution dilatometry experiments were conducted to simulate the heat treatment process, as well as to investigate different phenomena occurring during non-isothermal tempering. The microstructures were characterized using optical and scanning electron microscopy. Dilatometry analyses demonstrated that tempering behavior varied significantly from bainitic to martensitic microstructures. Retained austenite, which exists between bainitic ferrite sheaves, decomposes to lower bainite causing a remarkable volume increase. It was found that this decomposition finishes below 386 • C. By contrast, martensite tempering was accompanied with a volume decrease due to the decomposition of medium-carbon martensite to low carbon martensite and carbides.

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Section: Cementite Precipitationmentioning

confidence: 86%

In Situ Study of Phase Transformations during Non-Isothermal Tempering of Bainitic and Martensitic Microstructures

Talebi

Ghasemi-Nanesa

Jahazi

et al. 2017

Metals

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“…In addition to retained austenite decomposition, the type and size of carbides that precipitate during tempering affect mechanical properties and therefore need to be engineered during the tempering process [ 15 , 16 , 17 ]. Five types of carbides, M 3 C, M 2 C, M 7 C 3 , M 23 C 6 and M 6 C, have the potential to precipitate in medium carbon low alloy steels, based on tempering time and temperature [ 18 , 19 , 20 , 21 ]. Among them, M 23 C 6 is the equilibrium carbide, M 3 C is the stable carbide, M 2 C and M 7 C 3 are metastable carbides [ 18 , 19 , 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

Retained Austenite Decomposition and Carbide Precipitation during Isothermal Tempering of a Medium-Carbon Low-Alloy Bainitic Steel

2018

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The effect of isothermal tempering on retained austenite decomposition and carbide precipitation were investigated in a medium-carbon low-alloy bainitic steel. High-resolution dilatometry was used to perform isothermal tempering at 350 °C, 550 °C and 600 °C for different holding times up to 16 h. The decomposition of retained austenite, morphology and composition of carbides were investigated by analyzing the dilatometric curves and were confirmed through scanning and transmission electron microscopy observations. The decomposition behavior of retained austenite varied significantly as a function of the tempering temperature with a full decomposition observed at 600 °C. It was also found that by increasing the tempering temperature from 550 °C to 600 °C, carbides precipitate approximately twice as fast, and evolve from M3C type to Cr7C3 and Cr23C6 after 16 h of tempering at 600 °C.

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“…In literature, it is reported that the following carbides, characterized by different thermal stability, can precipitate depending on tempering time and temperature: M 3 C, M 2 C, M 7 C 3 , M 23 C 6 , and M 6 C [11]. Increasing tempering time leads to evolution of the unstable carbides towards the equilibrium ones, whose nature depends on the steel composition.…”

Section: Discussionmentioning

confidence: 99%

“…The modification of carbides morphology in fully bainitic steels depends on the carbides type. For example, as evidenced by Depinoy et al [11], for a 2.25Cr-1Mo steel four types of carbides can precipitate depending on tempering temperature and time: M 3 C, M 2 C, M 7 C 3 and M 23 C 6 . M 3 C is the least stable carbide and is characterized by lenticular-globular morphology, M 2 C and M 7 C 3 are characterized by a needle like and rhombus shaped morphology, M 23 C 6 is the equilibrium carbide and possesses a rod-like morphology.…”

Section: Introductionmentioning

confidence: 92%

Study of the Effect of Multiple Tempering on the Impact Toughness of Forged S690 Structural Steel

Pezzato

Gennari

Chukin

et al. 2020

Metals

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During the production of forged metal components, the sequence of heat treatments that are carried out, as well as hot working, remarkably influences mechanical properties of the product, in particular impact toughness. It is possible to tailor impact toughness by varying tempering temperature and soaking time after hardening treatment, widening the application range of structural steels. In this work, we consider the effects of a second tempering treatment on the microstructural properties and impact toughness of a structural steel EN 10025-6 S690 (DIN StE690, W. n: 1.8931). The steel was first forged and quenched in water after austenitization at 890 °C for 4 h. After quenching different tempering treatments were performed, at 590 °C in single or multiple steps. The effect of these treatments was evaluated both in microstructural terms, by means of optical microscopy, scanning and transmission electron microscopy and X-ray diffraction, and in terms of impact toughness. The mechanical behavior was correlated with the microstructure and a remarkable increase in impact toughness was found after the second tempering treatment due to carbide shape change.

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Carbide Precipitation in 2.25 Cr-1 Mo Bainitic Steel: Effect of Heating and Isothermal Tempering Conditions

Cited by 41 publications

References 32 publications

In Situ Study of Phase Transformations during Non-Isothermal Tempering of Bainitic and Martensitic Microstructures

In Situ Study of Phase Transformations during Non-Isothermal Tempering of Bainitic and Martensitic Microstructures

Retained Austenite Decomposition and Carbide Precipitation during Isothermal Tempering of a Medium-Carbon Low-Alloy Bainitic Steel

Study of the Effect of Multiple Tempering on the Impact Toughness of Forged S690 Structural Steel

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