Increasing the structural strength of steel 09G2S with ferritic-martensitic structure

Tushinskii, L. I.; Mironov, E. N.; Tikhomirova, L. B.; Ananin, V. A.

doi:10.1007/bf00700358

Cited by 4 publications

(4 citation statements)

References 6 publications

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“…The revealed transformations of the steel structure will significantly affect the strength and plastic characteristics of the metal, determining the service life of the product. The evaluation of the strengthening mechanisms allows the patterns connecting the The main contributions to the deformation resistance are as follows [30][31][32][33]: σ 0 = 35 MPa-friction stress of the dislocations in the crystal lattice of α-iron; σ ss -strengthening of a ferritebased solid solution by atoms of alloying elements; σ p -strengthening due to the pearlite; σ h -strengthening by the dislocations "herringbone" that cut the slipping dislocations; σ or -strengthening of the material by incoherent particles when bypassing them with dislocations according to the Orowan mechanism; σ l -strengthening by the internal longrange stress fields; and σ s -substructural strengthening.…”

Section: Resultsmentioning

confidence: 99%

Strengthening Mechanisms of Rail Steel under Compression

Ivanov,

Porfiriev,

Gromov

et al. 2023

Metals

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The evolution of the structure–phase states and the dislocation substructure of rail steel under uniaxial compression to the degree of 50% was studied by transmission electron microscopy. The obtained data formed the basis for a quantitative analysis of the mechanisms of rail steel strengthening at degrees of deformation by compressions of 15, 30, and 50%. Contributions to the strengthening caused by the friction of the matrix lattice, dislocation substructure, presence of carbide particles, internal stress fields, solid solution and substructural strengthening, and pearlite component of the steel structure were estimated. Using the adaptivity principle, which assumes the independent action of each of the strengthening mechanisms, the dependence of the rail steel strength on the degree of plastic deformation by compression was estimated. A comparative analysis of the stress–strain curves σ(ε) obtained experimentally and calculated theoretically was performed.

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Section: Resultsmentioning

confidence: 99%

Strengthening Mechanisms of Rail Steel under Compression

Ivanov,

Porfiriev,

Gromov

et al. 2023

Metals

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“…Quite often, the plates of cementite in perlite are curved and separated by ferritic bridges (Figure 3). Thus, it is believed that ferrite is solid in perlite, and cementite is an intermittent phase consisting of separate plates [24,25]. The contrast along the cementite plate is heterogeneous, which indicates the disorientation of one part of the plate relative to the other.…”

Section: Resultsmentioning

confidence: 99%

Evolution of Cementite Substructure of Rails from Hypereutectoid Steel during Operation

Gromov,

Ivanov,

Porfiriev

et al. 2023

Metals

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Transmission electron microscopy methods were used to analyze the cementite substructure in the head of special-purpose long rails of the DT400IK category, made of hypereutectoid steel, after long-term operation on an experimental track on the Russian Railways ring (the tonnage was 187 million tons). It is noted that the study of various aspects of cementite—its structure, morphology, chemical composition, crystal lattice defects—is relevant. The steel structure is represented by three morphological components at a distance of 10 mm from the sample surface: lamellar perlite, fractured and fragmented perlite. The volume fraction of lamellar perlite in the material is 65%. It is shown that after operation, the cementite plates are bent and separated by ferrite bridges. In the plates of ferrite and cementite, a dislocation substructure is formed, which is of a chaotically distributed and network type in ferrite and of an ordered type in cementite. An increased density of dislocations at the ferrite–cementite interfaces compared to the volume of ferrite plates was noted. Two possible mechanisms of deformation transformation of lamellar perlite grains are indicated: fracture of cementite plates and carbon pulling out from the lattice of the carbide phase. It is indicated that in the dissolution of cementite plates, the interfacial boundaries of “α-phase-cementite” play an important role. The removal of carbon from cementite plates occurs most intensively near defects in ferrite and cementite. The formed nanosized particles of tertiary cementite are unevenly distributed in the ferrite plates; most of them are observed at the locations of ferrite subgrains and interfacial boundaries. This results in non-uniform diffraction contrast in dark-field images of cementite plates. Nanosized particles of cementite can be taken out into the interlamellar space of pearlite colonies in the process of dislocation slip, or they are formed as a result of deformation decomposition, which is less likely. The fragmentation of ferrite and cementite plates is revealed and azimuthal components of total misorientation angles are estimated. The mechanisms of mass transfer of carbon atoms over interstitial sites, deformation vacancies, dislocation tubes, grain boundaries and fragments are considered. According to all the established patterns of the cementite substructure transformation, a comparison with the results for rails made of hypoeutectoid steel was performed.

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“…In steels of various purposes, in the process of tempering, a heterogeneous mechanism of separation of the second phase is generally realized with the formation of particles at the boundaries and at the joints of grains, at subboundaries and dislocations. Apart from that, formation of laminar two-phase structures that occur during pearlitic transformation is possible [38].…”

Section: Internal Stresses In Two-phase Structuresmentioning

confidence: 99%

“…And since the amplitude of bending-torsion of the crystal lattice χ [7] is inversely proportional to the width of bend contour, then the value of χ in the cementite plate is almost 4 times higher than in the ferrite plate: χ (α-phase) = 420 cm -1 ; χ (Fe3C) = 1750 cm -1 . Considering that the shear moduli of crystal lattices of ferrite and cementite phases are close [38], it turns out that the amplitude of internal stresses in cementite plates is several times higher than in the ferrite interlayer. The reason for this behavior is less plastic stress relaxation inside the cementite plates than in the α-phase interlayers.…”

Section: Internal Stresses In Two-phase Structuresmentioning

confidence: 99%

Internal Stresses and their Sources in BCC and FCC Steels

Конева

Попова

Никоненко

2020

SSP

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The present work summarizes and presents separate results obtained by the authors when investigating mesoscopic and microscopic internal stresses formed under the conditions of thermal and mechanical treatment of martensitic, pearlitic and austenitic steels. Internal stresses were investigated using the method based on the analysis of bend extinction contours. The results obtained on industrial steels were presented. The sources were described and examples of internal stresses induced by these sources were given. The nature of bending-torsion of the crystal lattice depending on the averaging volume was determined. It has been shown that in martensitic steels along with the increase in the averaging volume (carbide particle → separate martensitic lath → martensite packet→ martensitic plate → grain) the amplitude of bending-torsion of the crystal lattice decreases. The nature of distortions also changes. At large amplitudes and low volumes of averaging they are completely or partly elastic, at large volumes of averaging they are completely plastic. Thereby, distortions are fully driven by the excess dislocation density.

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Increasing the structural strength of steel 09G2S with ferritic-martensitic structure

Cited by 4 publications

References 6 publications

Strengthening Mechanisms of Rail Steel under Compression

Strengthening Mechanisms of Rail Steel under Compression

Evolution of Cementite Substructure of Rails from Hypereutectoid Steel during Operation

Internal Stresses and their Sources in BCC and FCC Steels

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