Mechanism for the formation of Z-phase in 25Cr-20Ni-Nb-N austenitic stainless steel

Li, Yanmo; Liu, Yongchang; Liu, Chenxi; Li, Chong; Li, Huijun

doi:10.1016/j.matlet.2018.08.141

Cited by 30 publications

(8 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Inside the grains, the secondary dispersive Z-phase precipitations were observed in the steel (Figures 6 and 8). The Z-phase particles can precipitate independently by the in situ mechanism or as a result of the local conversion of MX precipitates into the Z-phase, probably by a mechanism similar to the formation of this phase in 9%-12%Cr martensitic steels [22,23]. The Z-particles precipitate near the grain boundaries and also on the dislocations.…”

Section: Test Results and Their Analysismentioning

confidence: 99%

“…Similarly, the precipitation of secondary Z-phase particles occurs in areas with high dislocation density, which results not only in the pile-up of dislocations, but also in the aggregation of precipitates (Figure 8). According to the Orowan law, the fine-dispersion Z-phase precipitates and their relatively high stability make the particles/aggregates effectively prevent the motion of dislocations and have an intensive pinning strengthening effect [10,11,23,24].…”

Section: Test Results and Their Analysismentioning

confidence: 99%

“…In case of creep properties of the HR3C steel, it is determined by the dispersion and stability of the dominant precipitates in this alloy, i.e., the Z-phase particles, as well as the M 23 C 6 carbides. The dispersive form of the Z-phase particles often precipitates at the dislocations [9][10][11]23,28], which enables their pinning, and their high thermodynamic stability [9,10] ensures the effective impeding of the free dislocation movement for a long time. Observed in the microstructure, the relatively fine M 23 C 6 precipitates at the grain boundaries probably also have an influence on the increase in the creep rate limiting through the slide on the boundaries of grains.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

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

et al. 2020

View full text Add to dashboard Cite

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.

show abstract

Section: Test Results and Their Analysismentioning

confidence: 99%

Section: Test Results and Their Analysismentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2020

View full text Add to dashboard Cite

show abstract

“…In HR3C steel and Sanicro 25, during aging process inside a grain, Z phase formation occurs; the formation of Z phase hardly strengthens austenitic steels and improves creep resistance due to high stability . According to the work performed by Li et al, the formation of a Z phase in HR3C austenitic stainless steel takes place through nucleation and growth and finally consumption of the preexisting NbX phase rather than as a result of in situ transformation. In contrast, Yan et al suggest development of a Z phase by the scenario similar to that observed in 9–12% Cr martensitic steels.…”

Section: Discussionmentioning

confidence: 99%

Effects of Long‐Term Ageing at High Temperatures on Oxide Scale Development and Evolution of Austenitic Steels Microstructure

Zieliński

Dudziak

Golański

et al. 2020

steel research int.

View full text Add to dashboard Cite

This study is conducted to investigate the effects of long‐term air oxidation on the microstructural stability of HR3C, HR6W, and Sanicro 25 stainless steel. The materials are exposed to air atmosphere for 1000 and 10 000 h at 650, 700, and 750 °C respectively. The postexposed materials indicate some microstructural changes: the HR3C stainless steel develops Fe–Cr‐rich oxide scale, whereas HR6W steel forms a brittle, low adherent oxide scale consisting different concentrations of Cr, Mn, Fe, and Ni. Finally, Sanicro 25 stainless steel promotes the formation of a homogeneous‐rich Cr oxide scale at high temperatures. The analyses are performed using scanning electron microscopy (SEM)/energy‐dispersive X‐ray spectrometry (EDS) and X‐ray mappings.

show abstract

“…Zurek et al presented a detailed report on the formation of precipitates of Sanicro 25 steel, including those in the form of a Z-(Nb,Cr)N phase, chromium nitride (Cr 2 N), a tungsten-rich phase, and a µ phase (F e7 W 6 ), at temperatures between 600 and 750 °C for up to 10,000 h [ 11 ]. Moreover, Li et al studied the nucleation and growth of secondary NbCrN in 25Cr–20Ni–Nb–N steel during long-term aging at 700 °C, revealing that NbN can provide a favorable site for the nucleation of NbCrN and that NbN can dissolve to supply Nb and N for NbCrN growth [ 16 , 17 , 18 , 19 ]. However, the phase transformation mechanism with respect to the applied alloys, temperature, and time is unclear.…”

Section: Introductionmentioning

confidence: 99%

Precipitate Evolution in 22Cr25NiWCuCo(Nb) Austenitic Heat-Resistant Stainless Steel during Heat Treatment at 1200 °C

Yang

Pan³

et al. 2021

Materials

View full text Add to dashboard Cite

In this study, 22Cr25NiWCuCo(Nb) heat-resistant steel specimens with high Cr and Ni contents were adopted to investigate the effect of Nb content on thermal and precipitation behavior. Differential scanning calorimetry profiles revealed that the melting point of the 22Cr25NiWCuCo(Nb) steel specimens decreased slightly with the Nb content. After heat treatment at 1200 °C for 2 h, the precipitates dissolved in a Nb-free steel matrix. In addition, the Z phase (CrNb(C, N)) and MX (Nb(C, N), (Cr, Fe)(C, N), and NbC) could be observed in the Nb-containing steel specimens. The amount and volume fraction of the precipitates increased with the Nb content, and the precipitates were distributed heterogeneously along the grain boundary and inside the grain. Even when the heat treatment duration was extended to 6 h, the austenitic grain size and precipitates became coarser; the volume fraction of the precipitates also increased at 1200 °C. The Z phase, rather than the MX phase, became the dominant precipitates at this temperature.

show abstract

Mechanism for the formation of Z-phase in 25Cr-20Ni-Nb-N austenitic stainless steel

Cited by 30 publications

References 17 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

Effects of Long‐Term Ageing at High Temperatures on Oxide Scale Development and Evolution of Austenitic Steels Microstructure

Precipitate Evolution in 22Cr25NiWCuCo(Nb) Austenitic Heat-Resistant Stainless Steel during Heat Treatment at 1200 °C

Contact Info

Product

Resources

About