Design and Characterization of a Heat-Resistant Ferritic Steel Strengthened by MX Precipitates

Du, Yanyan; Li, Xin; Zhang, Xu; Chung, Yip Wah; Isheim, Dieter; Vaynman, Semyon

doi:10.1007/s11661-019-05525-1

Cited by 15 publications

(7 citation statements)

References 58 publications

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“…where d MX and d α are the interplanar spacing of the particle and ferritic matrix, respectively. If a carbonitride exhibits a plate-like shape along (001) α broad faces with square-like cross-section its misfit, δ, is ≤ 3% that provides coherency of these interfaces with interfacial energy of ~0.5 J m − 2 [26,[68][69][70]. VX carbonitrides having plate-like shape precipitate during tempering in this steel [6,34,36,50,51].…”

Section: Tablementioning

confidence: 93%

Effect of creep temperature on Z-phase formation in heat-resistant 9% Cr–3% Co martensitic steel

Fedoseeva

Nikitin

Dudova

et al. 2021

Materials Science and Engineering: A

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The Z-phase (CrVN) precipitation in a 9% Cr-3% Co martensitic steel during creep at 923 K and 948 K has been investigated with aim to establish the effect of temperature on the nucleation mechanism of these particles and their coarsening behavior. Ostwald ripening of VX carbonitrides strongly affects these processes. An increase in creep temperature significantly accelerates the transformation of the nanoscale MX carbonitrides into the Zphase particles causing the Z-phase nucleation in a shorter time. Two different mechanisms of the Z-phase precipitation have been observed. Firstly, for creep tests at 923 K and 948 K with creep rupture time longer than 2000 h, the formation of the stable Z-phase particles with a tetragonal lattice occurs through in-situ transformation of a cubic lattice of the MX carbonitrides leading to a continuous flux of Cr atoms from the ferritic matrix into these particles. The coarsening Z-phase occurs at the expense of dissolution of VX carbonitrides. Secondly, for creep test at 948 K with duration of 773 h, the strain-induced metastable Z-phase with the cubic lattice nucleates on the V-rich MX/ferrite interfaces with following transformation into the stable Z-phase with the tetragonal lattice under creep testing with longer duration. Concurrently, extensive coarsening Cr-rich VX carbonitrides occurs independently. As a result, coarsening Z-phase leads to insignificant dissolution of VX carbonitrides. The creep strength breakdown appearance is not related to the formation and/or coarsening of the Z-phase at both temperatures.

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Section: Tablementioning

confidence: 93%

Effect of creep temperature on Z-phase formation in heat-resistant 9% Cr–3% Co martensitic steel

Fedoseeva

Nikitin

Dudova

et al. 2021

Materials Science and Engineering: A

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“…With the increase of aging temperature and aging time, the precipitates on grain boundary begin to gather, the size of precipitates in grain becomes larger and the coherent relationship with matrix is lost. On the one hand, the crystal structure of the coarse intermetallic compound is different from that of the matrix, so it is easy to produce the uncoordinated deformation in the plastic deformation, resulting in the stress concentration at the interface between the intermetallic compound and the matrix, forming the crack source [40,41]. On the other hand, the mechanism of dislocation slip changes from shear to bypass.…”

Section: Effect Of Precipitates On Mechanical Propertiesmentioning

confidence: 99%

The Effect of Aging on Precipitates, Mechanical and Magnetic Properties of Fe-21Cr-15Ni-6Mn-Nb Low Magnetic Stainless Steel

Dong

et al. 2021

Metals

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The effect of aging on the precipitates, mechanical and magnetic properties of Fe-21Cr-15Ni-6Mn-Nb low magnetic stainless steel were investigated. The steel was aged at 550–750 °C for 2 h after solution heat treatment at 1100 °C for 1 h. During the aging treatment, the (Nb, V)(C, N) particles gradually precipitated in the grain, which were coherent or semi-coherent with the matrix. When the aging temperature was beyond 650 °C, the coarsening rate of (Nb, V)(C, N) particles increase rapidly and the coherent orientation between (Nb, V)(C, N) particles and the matrix was lost gradually. Meanwhile, coarse M23C6 was distributed at the grain boundary with chain shape, which was non-coherent with the matrix. The coarsening behavior of (Nb, V)(C, N) precipitates in the grain was analyzed, and the size of the particles precipitated after aging treatment at 650°C for different time was calculated and studied. After aging treatment at 650 °C for 2 h, the yield strength and tensile strength of the stainless steel was 705.6 MPa and 1002.3 MPa, the elongation and the relative magnetic permeability was 37.8% and 1.0035, respectively.

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“…[ 1,2 ] The 9–12% chromium ferritic/martensitic steels are ideal for constructing advanced USC power plants because of their enhanced thermophysical properties, high creep strength, and low cost. [ 3,4 ] The microstructure of 9–12% chromium martensitic steels is complex. The steels are composed of prior‐austenite grains, martensitic laths and blocks, and several precipitated phases.…”

Section: Introductionmentioning

confidence: 99%

“…

Fossil power plants operating at ultrasupercritical (USC) temperatures must be constructed with enhanced heat-resistant materials with creep strengths that can withstand temperatures above 600 C. [1,2] The 9-12% chromium ferritic/martensitic steels are ideal for constructing advanced USC power plants because of their enhanced thermophysical properties, high creep strength, and low cost. [3,4] The microstructure of 9-12% chromium martensitic steels is complex. The steels are composed of prior-austenite grains, martensitic laths and blocks, and several precipitated phases.

…”

mentioning

confidence: 99%

Plastic Flow Behavior of an Advanced 9Cr Martensitic Heat‐Resistant Steel at High Temperatures

Gao

Zhang

2021

steel research int.

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Advanced 9Cr–1.5Mo–1Co–VNbBN martensitic steel is used for thick castings under ultra‐supercritical conditions. The microstructure, including martensitic laths, dislocations, and precipitations, is observed before and after deformation by transmission electron microscope. Steady‐state flow behavior and deformation mechanisms are investigated by analyzing strain‐rate jump test data at 600–650 °C. Results show that the plastic flow behavior of 9Cr steel is well characterized by a stress power law whose apparent stress exponent n is between 20.5 and 27.0 for the three test temperatures. The apparent activation energy of 621 kJ mol is estimated for the plastic flow of this steel, and the stress exponent and apparent activation energy are particularly high. The analysis incorporates the effect of a threshold stress, which is associated with the pinning effect of particles on dislocations. The truly modified stress exponent n0 is 4.6 at all test temperatures after removing the threshold stress, which is close to that of dislocation‐climb deformation, indicating the deformation of this steel can be described as a lattice diffusion‐controlled dislocation‐climb mechanism. Transmission electron microscopy observation is conducted to characterize the interaction of dislocation–precipitate to provide structural evidence for specific deformation mechanisms.

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Design and Characterization of a Heat-Resistant Ferritic Steel Strengthened by MX Precipitates

Cited by 15 publications

References 58 publications

Effect of creep temperature on Z-phase formation in heat-resistant 9% Cr–3% Co martensitic steel

Effect of creep temperature on Z-phase formation in heat-resistant 9% Cr–3% Co martensitic steel

The Effect of Aging on Precipitates, Mechanical and Magnetic Properties of Fe-21Cr-15Ni-6Mn-Nb Low Magnetic Stainless Steel

Plastic Flow Behavior of an Advanced 9Cr Martensitic Heat‐Resistant Steel at High Temperatures

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