Advances in Physical Metallurgy and Processing of Steels. Microstructural Evolutions with Precipitation of Carbides in Steels.

Ohmori, Yasuya

doi:10.2355/isijinternational.41.554

Cited by 37 publications

(16 citation statements)

References 52 publications

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“…However, the interface planes can be easily determined with the present method. Interestingly, we found for the first time a new type of habit planes that exist in lamellar pearlite, although the other one in example 1 has been frequently reported in the literature (Ohmori, 2001;Zhou & Shiflet, 1992). This clearly shows the merit of our new method.…”

Section: Methodssupporting

confidence: 62%

Indirect two-trace method to determine a faceted low-energy interface between two crystallographically correlated crystals

et al. 2007

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An indirect two‐trace method to determine interfaces between two crystals with a uniquely defined interface plane is proposed. It involves preparation of only one sample surface, instead of the two perpendicular sample surfaces required by the traditional two‐trace method. By making use of two independent interface trace vectors from one uniquely defined interface and the orientations of their adjacent crystals, the interface plane normal and thus the interface plane in the two correlated crystal systems can be determined through numerical calculations concerning coordinate system change. The new method is widely applicable to identify any uniquely defined and reproducible interfaces between crystallographically correlated crystals, even slip systems, provided that they are microscopically visible and crystallographically of the same nature. It can simplify the experimental procedure, increase the determination accuracy and broaden the scope of interface studies.

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Section: Methodssupporting

confidence: 62%

Indirect two-trace method to determine a faceted low-energy interface between two crystallographically correlated crystals

et al. 2007

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“…An explanation may be based on an in situ observation on a Fe-9 pct Ni-0.4 pct C alloy at 623 K (350°C) by Ohmori et al [18] (Figure 6 in Reference 18). Sharp relief effects after 10 minutes revealed the presence of several thin plates of ferrite but some of them were covered by layers revealed by a less distinct relief called rumpling.…”

Section: B Cooperative Growth In Upper Bainitementioning

confidence: 99%

Second Stage of Upper Bainite in a 0.3 Mass Pct C Steel

Yin

Hillert

Borgenstam

2017

Metall Mater Trans A

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Upper bainite forms in at least two stages, the formation of parallel plates of ferrite and the transformation of the interspaces to a mixture of cementite and ferrite. The first stage was examined in a preceding metallographic study of the formation of ferrite in hypoeutectoid steels and the second stage, which is initiated by the occurrence of cementite in the interspaces, is the subject of the present study. The alloy from the preceding study will also be used here. The band of austenite in the interspaces between parallel plates is generally transformed by a degenerate eutectoid transformation when this band is thin. When it is thicker, it will transform by a more cooperative growth mechanism and result in a eutectoid colony, often with cementite platelets. A series of sketches are presented which illustrate in detail how the second stage of upper bainite progresses according to the present observations. The cooperative manner did not increase as the temperature was lowered because the tendency to form plates of ferrite was still increasing at lower temperatures, making the interspaces too narrow for the cooperative reaction to dominate over the formation of fine plates of ferrite.

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“…The continuous cooling causes the bainitic transformation in different temperature ranges to form two morphologies of bainite, i.e., upper bainite (UB) and lower bainite (LB). The UB is formed at relatively high temperature just below bainitic start temperature, while LB, which has a lamellar structure of lath bainitic ferrite (BF) and thin film retained austenite (TFRA), forms at rather low temperature just above martensitic start temperature [27][28][29][30]. Simultaneously, the formation of bainite during the continuous cooling is not complete due to limited transformation time.…”

Section: Influence Of Microstructure On Mechanical Propertiesmentioning

confidence: 99%

“…Depending on the bainite transformation temperature, there exist two distinct forms of bainite, i.e., upper bainite and lower bainite. The upper bainite, which is obtained in the high temperature range (~400-500 • C for the rail steels), consists of coarser laths of bainitic ferrite and carbides than lower bainite formed in the lower temperature range (300-400 • C) [26][27][28][29][30][31]. This results in poorer mechanical properties in the upper bainite [32,33] than in the lower bainite, which offers better mechanical properties, namely strength, hardness and toughness [33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Influence of Microstructure on Mechanical Properties of Bainitic Steels in Railway Applications

Hajizad

Kumar

et al. 2019

Metals

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Wheel–rail contact creates high stresses in both rails and wheels, which can lead to different damage, such as plastic deformation, wear and rolling contact fatigue (RCF). It is important to use high-quality steels that are resistant to these damages. Mechanical properties and failure of steels are determined by various microstructural features, such as grain size, phase fraction, as well as spatial distribution and morphology of these phases in the microstructure. To quantify the mechanical behavior of bainitic rail steels, uniaxial tensile experiments and hardness measurements were performed. In order to characterize the influence of microstructure on the mechanical behavior, various microscopy techniques, such as light optical microscopy (LOM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), were used. Three bainitic grades industrially known as B360, B1400 plus and Cr-Bainitic together with commonly used R350HT pearlitic grade were studied. Influence of isothermal bainitic heat treatment on the microstructure and mechanical properties of the bainitic grades was investigated and compared with B360, B1400 plus, Cr-Bainitic and R350HT in as-received (AR) condition from the industry. The results show that the carbide-free bainitic steel (B360) after an isothermal heat treatment offers the best mechanical performance among these steels due to a very fine, carbide-free bainitic microstructure consisting of bainitic ferrite and retained austenite laths.

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Advances in Physical Metallurgy and Processing of Steels. Microstructural Evolutions with Precipitation of Carbides in Steels.

Cited by 37 publications

References 52 publications

Indirect two-trace method to determine a faceted low-energy interface between two crystallographically correlated crystals

Indirect two-trace method to determine a faceted low-energy interface between two crystallographically correlated crystals

Second Stage of Upper Bainite in a 0.3 Mass Pct C Steel

Influence of Microstructure on Mechanical Properties of Bainitic Steels in Railway Applications

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