Randomization of Ferrite/austenite Orientation Relationship and Resultant Hardness Increment by Nitrogen Addition in Vanadium-microalloyed Low Carbon Steels Strengthened by Interphase Precipitation

Zhang, Yongjie; Shinbo, K.; Ohmura, Takahito; Suzuki, Takuya; Tsuzaki, Kaneaki; Miyamoto, Gorō

doi:10.2355/isijinternational.isijint-2017-537

Cited by 13 publications

(4 citation statements)

References 32 publications

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“…4e) shows the same tendency as that in number density, indicating that higher hardness of a can be obtained by more dispersed VC interphase precipitation. 56 It should be mentioned that these data also include some cases of GBF holding a near K-S OR, which means that the dispersion of interphase precipitation and resultant hardening effects are actually determined by a/c OR rather than by the morphology of a. The occurrence of interphase precipitation in planar sheets at the a/ c interface with a non-K-S OR suggests that, even when the a/c OR largely deviates from the rational K-S OR, the macroscopic a/c interface should be composed of some partially coherent crystal planes in local regions, the mobility of which is sufficiently low to enable the nucleation of alloy carbides at the interface, 57 whereas, in some special cases when the degree of coherency is not sufficiently low, irregular or even random dispersion of alloy carbides rather than planar sheets might also be formed.…”

Section: Effects Of A/c Orientation Relationship On the Dispersion Of Interphase Precipitationmentioning

confidence: 99%

Current Understanding of Microstructure and Properties of Micro-Alloyed Low Carbon Steels Strengthened by Interphase Precipitation of Nano-Sized Alloy Carbides: A Review

Zhang

Chandiran

Dong

et al. 2021

JOM

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The current understanding of the microstructural features and mechanical properties of micro-alloyed low carbon steels strengthened by interphase precipitation of nano-sized alloy carbides are critically reviewed in this paper. The experimental results obtained via advanced quantitative characterization have revealed that interphase precipitation is promoted at the ferrite/austenite interface with a relatively lower degree of coherency caused by the deviation from the exact Kurdjumov–Sachs orientation relationship. Its dispersion becomes refined by enlarging the driving force for its precipitation, as adjusted by changing the transformation condition and chemical composition. The occurrence of interphase precipitation can significantly increase the strength of steels due to its large precipitation strengthening, and maintain good ductility as a result of enhanced work-hardening and dynamic recovery in different stages of tensile deformation. Finally, the application of interphase precipitation to ferrite/martensite dual-phase steels, together with our outlook on the challenging points in future research, are briefly explained.

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Section: Effects Of A/c Orientation Relationship On the Dispersion Of Interphase Precipitationmentioning

confidence: 99%

Current Understanding of Microstructure and Properties of Micro-Alloyed Low Carbon Steels Strengthened by Interphase Precipitation of Nano-Sized Alloy Carbides: A Review

Zhang

Chandiran

Dong

et al. 2021

JOM

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“…In addition, K–S OR has 24 possibilities. Hence, though significant amount of α‐ferrite nucleation was considered having K–S OR with austenite, [ 35 ] the misorientation angle between FPAGB and δ‐ferrite could be considered random. However, since the FIADF and δ‐ferrite belong to the same ferrite grain, the orientation of FIADF and δ‐ferrite was almost the same.…”

Section: Resultsmentioning

confidence: 99%

Strain‐Associated Alpha‐Ferrite Phase Transformation in a Micro‐Laminated Low‐Density Steel

Liú

Shang

et al. 2022

steel research int.

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Aluminum-alloyed low-density steels have recently received significant attention because of the advantage in strength-todensity ratio [1] and superior corrosion resistance. [2][3][4] Aluminum is a strong ferrite-forming element and expands both α-ferrite and δ-ferrite phase region. Thus, the addition of aluminum in steel can result in δ-ferrite that always exists below solidification temperature, in spite of the addition of austenitic stabilizing elements. Under the action of deformation, the dualphase composed of δ-ferrite and austenite is expected to be elongated and forms micro-laminated microstructure. [5][6][7][8][9][10][11][12][13][14][15][16][17] Except prior δ-ferrite lamellae, through diversified alloy design, hot working process, and heat treatment process, the microstructure transformed from prior austenite can be designed as dual-phase or multiphase constituents, containing austenite, [5][6][7][8][9][10][12][13][14] α-ferrite, [5][6][7][8]12] martensite, [5][6][7][8][9][10][11][12][13] pearlite, [10] and bainite, [10] and the fraction range of each phase is also wide. Accordingly, the mechanical properties also vary among different phases. Hence, micro-laminated low-density steels have a broad application prospect, with extraordinary combinations of mechanical properties. [8,[10][11][12][13] Based on the microstructure, the deformation-induced evolution of the microstructure and the fracture mechanism are also complex. In general, δ-ferrite is a brittle phase, while the complex microstructure transformed from the original austenite has superior plasticity and resistance to crack growth. [17,18] Cracks propagate preferably into δ-ferrite or at the interface l ayer along the δ-ferrite {100} planes. [15,18] The embrittlement of δ-ferrite is because of higher aluminum content. [17][18][19] With the increase of aluminum content, the reduced mobility of dislocations [19,20] and the formation of ordered structure [17][18][19] result in lower ductility and toughness. Given that the retained austenite stability is critical for fracture resistance, [17] previous studies have focused on controlling the content and stability of retained austenite.However, studies on α-ferrite phase transformation on δ-ferrite and corresponding effect on mechanical properties are rare. Li et al. [14] reported that coarse δ-ferrite is harmful to mechanical properties. The grain refinement of ferrite is simultaneously beneficial to both strength and toughness.

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“…Precipitation strengthening is an effective approach to increase the strength of steels and has received significant attention. Since its discovery in the 1960s [ 1 ], interphase precipitation has been an important form of precipitation and of particular interest to researchers [ 2 , 3 , 4 ]. Studies have shown that a number of precipitate-forming elements can form interphase precipitation, such as carbonitrides of Ti, Nb, V, Mo, Cr, etc.…”

Section: Introductionmentioning

confidence: 99%

The Impact of Interphase Precipitation on the Mechanical Behavior of Fire-Resistant Steels at an Elevated Temperature

Cong

Fan

et al. 2020

Materials

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In this study, we address the challenge of obtaining high strength at ambient and elevated temperatures in fire-resistant Ti–Mo–V steel with ferrite microstructures through thermo-mechanical controlled processing (TMCP). Thermally stable interphase precipitation of (Ti, Mo, V)C was an important criterion for retaining strength at elevated temperatures. Electron microscopy indicated that interphase precipitation occurred during continuous cooling after controlled rolling, where the volume fraction of interphase precipitation was controlled by the laminar cooling temperature. The interphase precipitation of MC carbides with an NaCl-type crystal structure indicated a Baker–Nutting (B–N) orientation relationship with ferrite. When the steel was isothermally held at 600 °C for up to 3 h, interphase precipitation occurred during TMCP with high thermal stability. At the same time, some random precipitation took place during isothermal holding. The interphase precipitation increased the elastic modulus of the experimental steels at an elevated temperature. It is proposed that fire-resistant steel with thermally stable interphase precipitation is preferred, which enhances precipitation strengthening and dislocation strengthening at elevated temperatures.

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Randomization of Ferrite/austenite Orientation Relationship and Resultant Hardness Increment by Nitrogen Addition in Vanadium-microalloyed Low Carbon Steels Strengthened by Interphase Precipitation

Cited by 13 publications

References 32 publications

Current Understanding of Microstructure and Properties of Micro-Alloyed Low Carbon Steels Strengthened by Interphase Precipitation of Nano-Sized Alloy Carbides: A Review

Current Understanding of Microstructure and Properties of Micro-Alloyed Low Carbon Steels Strengthened by Interphase Precipitation of Nano-Sized Alloy Carbides: A Review

Strain‐Associated Alpha‐Ferrite Phase Transformation in a Micro‐Laminated Low‐Density Steel

The Impact of Interphase Precipitation on the Mechanical Behavior of Fire-Resistant Steels at an Elevated Temperature

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