Precipitation behavior of B2 and κ-carbide during aging and its effect on mechanical properties in Al-containing high strength steel

Zhang, Bao-Guang; Zhang, Xiaoming; Liu, Haitao

doi:10.1016/j.matchar.2021.111291

Cited by 19 publications

(4 citation statements)

References 59 publications

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“…Figure 2f shows the elemental distribution of the κ‐carbide and its nearby structures in Figure 2d. Similar to the results of Zhang et al, [ 19 ] the concentration of Al and C elements in the κ‐carbide is higher than that of the austenite matrix. In contrast, their contents in the ferrite near the κ‐carbide are lower.…”

Section: Resultssupporting

confidence: 89%

Superior High‐Temperature Properties of Low‐Density Steel Enabled by a Tunable Hierarchical Microstructure

Zhao

et al. 2022

Adv Eng Mater

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The tensile properties, microstructure characteristics, and fracture mechanisms at 500 °C of Fe–Mn–Al–C–Mo–V steel processed by hot rolling (HR) and warm rolling (WR) are investigated. The HR steel obtained by rolling 1150 °C, consisting mainly of equiaxed austenite and banded ferrite, exhibits a tensile strength of 695 MPa, accompanied by an elongation of ≈45.5%. In contrast, the WR steel processed by rolling at 750 °C shows a hierarchical microstructure that consists mainly of lamellar ferrite/austenite + fine carbides, rendering a significantly increased tensile strength to 1040 MPa and an excellent elongation to ≈20.0%. This is mainly attributed to the remarkable refinement of ferrite and austenite in the WR steel, strengthening finely dispersed carbides, and obtaining numerous low‐angle grain boundaries in the matrix. The tensile fracture morphology is a ductile failure in both types of steel. The fracture of HR steel is attributed to the cracks enabled by the austenite localized slip deformation in the austenite and the fracture of the precipitates; the failure of the WR steel is mainly ascribed to the cracking along the lamellar structure due to the κ‐carbides pinning lamellar ferrite phase boundary leading to high strain localization.

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Section: Resultssupporting

confidence: 89%

Superior High‐Temperature Properties of Low‐Density Steel Enabled by a Tunable Hierarchical Microstructure

Zhao

et al. 2022

Adv Eng Mater

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“…The strip-like and rod-like B2s are located at the core of the primary or secondary dendrite because of the uncompleted transformation of the primary δ-ferrite to austenite during subsequent solidification. The formation of primary δ-ferrite in Fe-Mn-Al-C-Ni steels has been confirmed by Hwang [13] and Zhang et al [43]. After that, the heat transfer coefficient on the strip surface decreases when the strip leaves the kiss point of the two rolls, so the preferential growth of free crystals ahead of the dendritic solidification front will grow by means of equiaxed grain to form the center layer [39].…”

Section: Microstructure Difference Between Present Steel and Conventi...mentioning

confidence: 76%

Microstructure Characteristics, Mechanical Properties and Strain Hardening Behavior of B2 Intermetallic Compound-Strengthening Fe-16Mn-9Al-0.8C-3Ni Steel Fabricated by Twin-Roll Strip Casting, Cold Rolling and Annealing

et al. 2023

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In this study, the Fe-16Mn-9Al-0.8C-3Ni (wt.%) lightweight steel was fabricated by novel twin-roll strip casting technology. The microstructure, tensile properties and strain-hardening behavior of the present steel have been investigated and compared to those of conventionally processed steels with similar chemical compositions. After annealing, a unique gradient microstructure of intermetallic compound (B2)-austenite was obtained along the thickness direction, consisting of granular B2 (average: 430 nm) and fine austenite (average: 1.82 μm) at the surface layer, blocky B2 (average: 1.03 μm) and medium austenite (average: 3.98 μm) at the quarter layer and polygonal B2 (average: 1.94 μm) and coarse austenite (average: 6.13 μm) at the center layer. The cooperative action of B2 pinning dislocation, plane slip and back stress led to stronger strain hardening, among which the strong back stress effect originated from the multistage discontinuous austenite deformation and the mechanical incompatibility between austenite and B2 is believed to be the most important reason, thereby achieving an excellent balance of strength (ultimate tensile strength: 1147 MPa) and ductility (total elongation: 43.2%). This work not only developed a new processing way to fabricate Ni-containing Fe-Mn-Al-C lightweight steel with outstanding mechanical properties, but also provided a potential solution for manufacturing some other metallic materials accompanied by brittle B2 intermetallic.

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“…According to the above discussion of KAM value, it is found that the post-heat treatment increases the dislocation density inside the bainite ferrite (GB and LB), thereby contributing to the improvement of the yield strength. In addition, studies have shown that the precipitated carbide particles play an important role in improving the strength of high-strength steel due to the pinning of dislocations by carbide particles [39,40]. According to Orowan strengthening mechanism, iron-carbon particles can strongly interact with surrounding sub-grain boundaries and dislocations to improve the yield strength, the strengthening effect can be estimated according to Equation (1) [39,41]: where G = 81.6 GPa and b = 0.248 nm are the shear modulus and the Burgers Vector of the bainite ferrite, respectively [42].…”

Section: Discussionmentioning

confidence: 99%

“…In addition, studies have shown that the precipitated carbide particles play an important role in improving the strength of high-strength steel due to the pinning of dislocations by carbide particles [39,40]. According to Orowan strengthening mechanism, iron-carbon particles can strongly interact with surrounding sub-grain boundaries and dislocations to improve the yield strength, the strengthening effect can be estimated according to Equation (1) [39,41]: where G = 81.6 GPa and b = 0.248 nm are the shear modulus and the Burgers Vector of the bainite ferrite, respectively [42]. f = 0.74% is the content of iron-carbon particles for post-heat CGHAZ.…”

Section: Discussionmentioning

confidence: 99%

Effect of post-heat treatment on microstructure and properties of EH47 steel CGHAZ

Yang

et al. 2023

Materials Science and Technology

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To clarify the effect of post-heat treatment on the microstructure and mechanical properties of the coarse-grained heat-affected zone (CGHAZ) for EH47 steel, simulated CGHAZ specimens were subjected to post-heat treatment at 250°C for 1.0 h. The results showed that the microstructure of CGHAZ was composed of granular bainite (GB) and lath bainite (LB), and a large number of iron-carbon particles (∼81 nm) were precipitated after post-heat treatment. The relationship between dislocations, low-angle grain boundaries and iron-carbon particles was revealed by KAM values. The iron-carbon particles hindered the movement of sub-grain boundaries and dislocations, thereby increased the yield strength (∼120 MPa). The precipitation of iron-carbon particles caused the cracking of bainite ferrite and reducing the fracture toughness of CGHAZ.

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Precipitation behavior of B2 and κ-carbide during aging and its effect on mechanical properties in Al-containing high strength steel

Cited by 19 publications

References 59 publications

Superior High‐Temperature Properties of Low‐Density Steel Enabled by a Tunable Hierarchical Microstructure

Superior High‐Temperature Properties of Low‐Density Steel Enabled by a Tunable Hierarchical Microstructure

Microstructure Characteristics, Mechanical Properties and Strain Hardening Behavior of B2 Intermetallic Compound-Strengthening Fe-16Mn-9Al-0.8C-3Ni Steel Fabricated by Twin-Roll Strip Casting, Cold Rolling and Annealing

Effect of post-heat treatment on microstructure and properties of EH47 steel CGHAZ

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