Microstructure evolution in HR3C austenitic steel during long-term creep at 650°C

Zhang, Zhen; Hu, Zhang; Tu, Haoyun; Schmauder, Siegfried; Wu, Gaoxiang

doi:10.1016/j.msea.2016.10.077

Cited by 93 publications

(36 citation statements)

References 35 publications

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“…The twin boundaries in the austenite steel could improve the plasticity and ductility by interrupting the continuity of the austenite grain boundaries and relaxing the stress at the austenite grain boundaries [4,6]. According to [15], two types of twin substructures, coherent twins and incoherent twins are observed in HR3C steel. The coherent twins have straight sub-grain boundaries across the entire austenite, while incoherent twins are inside the austenite grain as shown in Figure 1, arrows two and three, respectively.…”

Section: Test Results and Their Analysismentioning

confidence: 99%

“…The coarsening of M23C6 carbides at the grain boundaries is very harmful to the properties of the materials-increase in embrittlement and loss of the strengthening effect of particles [6,11]. The precipitation and growth of M23C6 carbides, Cr-rich particles, at the grain However, M 23 C 6 carbides are characterised by low thermodynamic stability [10,15,19,20], and this contributes to an increase in both their amount and size at the boundaries, which results in the loss of this favourable impact. This rapid growth and coarsening of M 23 C 6 carbides greatly widened the grain boundaries ( Figure 7).…”

Section: Test Results and Their Analysismentioning

confidence: 99%

“…Yan [21] suggests that the formation of depletion zone near the grain boundaries may affect a decrease in the local strength and promotes inhomogeneous deformation. However, M23C6 carbides are characterised by low thermodynamic stability [10,15,19,20], and this contributes to an increase in both their amount and size at the boundaries, which results in the loss of this favourable impact. This rapid growth and coarsening of M23C6 carbides greatly widened the grain boundaries ( Figure 7).…”

Section: Test Results and Their Analysismentioning

confidence: 99%

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The Effect of Service on Microstructure and Mechanical Properties of HR3C Heat-Resistant Austenitic Stainless Steel

et al. 2020

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The physical metallurgical tests were performed on the test samples made of HR3C steel, taken from a section of a pipeline in the as-received condition and after approximately 26,000 h of service at 550 °C. In the as-received condition, the test material had austenitic microstructure with numerous large primary Z-phase precipitates inside the grains. The service of the test steel mainly contributed to the precipitation processes inside the grains and at the grain boundaries. After service, the following precipitates were identified in the microstructure of the test steel: Z-phase (NbCrN) and M23C6 carbides. The Z-phase precipitates were observed inside the grains, whereas M23C6 carbides - at the boundaries where they formed the so-called continuous grid. The service of the test steel contributed to the growth of the strength properties, determined both at room and elevated temperature (550, 600 °C), compared to the as-received condition. Moreover, the creep properties of HR3C steel after service were higher than those of the material in the as-received condition. The increase in the strength properties and creep resistance was connected with the growth of strengthening of the test steel by the precipitation of Z-phase and M23C6 carbides.

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Section: Test Results and Their Analysismentioning

confidence: 99%

Section: Test Results and Their Analysismentioning

confidence: 99%

Section: Test Results and Their Analysismentioning

confidence: 99%

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The Effect of Service on Microstructure and Mechanical Properties of HR3C Heat-Resistant Austenitic Stainless Steel

et al. 2020

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“…where a is the lattice parameter, G is the distance of the (h k l) spot from the (0 0 0 Several authors [21,23,28] describe NbC nanoparticles as coherent or semi-coherent.…”

Section: Shown Inmentioning

confidence: 99%

On the origin of extraordinary cyclic strengthening of the austenitic stainless steel Sanicro 25 during fatigue at 700 °C

et al. 2017

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The origin of the extraordinary strengthening of the highly-alloyed austenitic stainless steel Sanicro 25 during cyclic loading at 700°C was investigated by use of advanced scanning transmission electron microscopy (STEM). Along with substantial change of dislocation structure, nucleation of two distinct populations of nanoparticles was revealed. Fully coherent Cu-rich nanoparticles were observed homogeneously dispersed with high density along with nanometer-sized incoherent NbC carbides precipitating on dislocations during cyclic loading. Probe-corrected HAADF STEM imaging was used to characterize the atomic structure of nanoparticles. Compositional analysis was conducted using both EELS and high spatial resolution EDS. High temperature exposure induced precipitation of a high density of coherent Cu-rich nanoparticles while strain-induced nucleation of incoherent NbC nanoparticles leads to retardation of dislocation movement. The pinning effects https://ntrs.nasa.gov/search.jsp?R=20190000303 2019-02-10T17:10:39+00:00Z and associated obstacles to dislocation motion prevent recovery and formation of the localized lowenergy cellular structures. As a consequence, the alloy exhibits remarkable cyclic hardening at elevated temperature.

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“…Compared with the average size of the precipitates before creep test, the severe coarsening of M 23 C 6 carbides and slight coarsening of MX carbonitrides can be noticed. The extensive coarsening behavior of M 23 C 6 carbides can be explained by the fact that the carbon atoms diffuse much faster at grain boundaries than that inside the grain during the creep process, which favors the nucleation and growth of M 23 C 6 carbides [21]. The low growth rate of MX was also reported in the literature [22,23].…”

Section: Creep Propertiesmentioning

confidence: 58%

Improvement of High-Temperature Mechanical Properties of Low-Carbon RAFM Steel by MX Precipitates

Chen

Liu

Xiao

et al. 2018

Acta Metall. Sin. (Engl. Lett.)

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To investigate the influence of tantalum content on high-temperature mechanical properties of low-carbon reduced activation ferritic/martensitic (RAFM) steels, RAFM steels containing different tantalum contents (0 and 0.073%) were fabricated, and the tensile tests at room temperature and high temperature were performed, as well as the creep tests were conducted at 550°C with the applied stress of 180 and 220 MPa. It was found that 0.073% tantalum addition results in the increase in amount of stable carbonitrides (MX), and the creep rupture time of the steel under 180 MPa is obviously increased. In addition, the increase in MX caused by tantalum addition also leads to the improvement of high-temperature tensile strength. The improvement of high-temperature mechanical properties of RAFM steels is primarily related to the evolution of precipitates.Acta Metallurgica Sinica (English Letters) (2018) 31:706-712 https://doi.org/10.1007/s40195-018-0703-y( 0123456789().,-volV) (0123456789().,-volV)

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Microstructure evolution in HR3C austenitic steel during long-term creep at 650°C

Cited by 93 publications

References 35 publications

The Effect of Service on Microstructure and Mechanical Properties of HR3C Heat-Resistant Austenitic Stainless Steel

The Effect of Service on Microstructure and Mechanical Properties of HR3C Heat-Resistant Austenitic Stainless Steel

On the origin of extraordinary cyclic strengthening of the austenitic stainless steel Sanicro 25 during fatigue at 700 °C

Improvement of High-Temperature Mechanical Properties of Low-Carbon RAFM Steel by MX Precipitates

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