Effect of normalizing temperature on microstructural stability and mechanical properties of creep strength enhanced ferritic P91 steel

Pandey, Chandan; Giri, A.; Mahapatra, Manas Mohan

doi:10.1016/j.msea.2016.01.066

Cited by 133 publications

(34 citation statements)

References 14 publications

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“…Figure 2 presents SEM micrographs showing the typical microstructures of various samples after tempering at 760 • C for 2 h. As shown in Figure 2a,b, the normalized and tempered microstructure of Gr.91 steel showed lath martensite packets and austenite boundaries decorated by M 23 C 6 carbides. Stable fine MX carbides or carbonitrides were dispersed in the martensite matrix, which resisted coarsening at elevated temperature [23]. The prior austenite grain sizes (PAGSs) of the samples were determined by means of the line-intercept method and further confirmed by EBSD crystallographic analysis, as described in the following section.…”

Section: Resultsmentioning

confidence: 99%

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

Shiue

et al. 2018

Metals

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As-received Gr.91 steel tube was normalized at either 940 or 1060 • C for 1 h, followed by Ar-assisted cooling to room temperature, then tempered at 760 • C for 2 h. Those samples were designated as 940NT or 1060NT samples. An infrared heating system was used to simulate HAZ microstructures in the weld, which included over-tempering (OT) and partial transformation (PT) zones. The results of short-term creep tests showed that normalizing at higher temperature improved the creep resistance of the Gr.91 steel. By contrast, welding thermal cycles would shorten the creep life of the Gr.91 steel. Among the tested samples in each group, the PT samples had the shortest life to rupture, especially the 940NT-PT sample. The microstructures of the PT samples comprised of fine lath martensite and ferrite subgrains with carbides decorating the grain and subgrain boundaries. Excessive dislocation recovery, rapid coalescence of refined martensite laths, and growth of ferrite subgrains were responsible for the poorer creep resistance of the PT samples relative to those of the other samples.

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Section: Resultsmentioning

confidence: 99%

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

Shiue

et al. 2018

Metals

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“…The high interfacial energy of boundaries facilitates nucleation of M 23 C 6 precipitates, which are more effective in enhancing creep strength of heat resistant steel than that of other carbides because the size of M 23 C 6 phase is close to the thickness of subgrain boundaries. Therefore, it is difficult for subgrain boundaries to pass these M 23 C 6 carbides during long‐time service . There are a small number of MX particles, which are mostly located within the sub‐grains.…”

Section: Discussionmentioning

confidence: 99%

Effect of Normalizing Temperature on Microstructure and Mechanical Properties of 11Cr–3Co–2.3W Steel

Cui

Gao

Cheng-lin

et al. 2019

steel research int.

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Mechanical properties of 11Cr–3Co–2.3W steel are affected by various parameters, and normalizing temperature is an important parameter. OM, FESEM, EBSD, and TEM are carried out to study the microstructure evolution of 11Cr–3Co–2.3W steel normalized at different temperature ranging from 900 °C to 1150 °C and tempered at 780 °C. The tensile and impact properties are evaluated from the tempered specimens. The results show that an obvious grain coarsening occurs and the tempered strength of 11Cr–3Co–2.3W steel increases with increasing normalizing temperature. The specific strengthening mechanisms are discussed. The fracture morphology shows mainly dimples and cleavage facets, implying mixed‐mode of fracture mechanism when the normalizing temperature is up to 1050 °C. Normalizing at 1150 °C, the mixed‐mode of fracture mechanism is transformed to brittle fracture.

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“…It was reported [15][16][17][18][19] that not only the microstructure but also the carbides precipitated during tempering had an effect on properties. Some researchers [15][16][17] pointed out that large size particles precipitated along boundaries of PAG, martensitic packet, block and lath deteriorated the toughness.…”

Section: Effect Of Microstructure and Precipitates On Mechanical Propmentioning

confidence: 99%

Effect of Microstructure and Precipitates on Mechanical Properties of Cr–Mo–V Alloy Steel with Different Austenitizing Temperatures

Zheng

Wang

et al. 2018

ISIJ Int.

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The mechanical properties of as-quenched and tempered steels are affected by austenitizing temperature. The present work has investigated the effect of austenitizing temperature on martensitic microstructure, carbide precipitates and mechanical properties of 30NiCrMoV12 alloy steel for the axle of high-speed train. The martensitic microstructure and carbide precipitates were studied using OM, FE-SEM, TEM, EBSD and EDS. Thermodynamic calculation of equilibrium precipitation were carried out by Thermo-Calc software. The results showed that the prior austenite grains, martensitic packets, blocks and laths were coarsening with increasing austenitizing temperature. Besides, with increasing austenitizing temperature, after tempering the amount of large size carbides precipitated at martensitic lath boundaries decreased while the amount of small size carbides precipitated in matrix increased. Meanwhile, phase transformation from M 23 C 6 to M 7 C 3 during tempering was enhanced with increasing austenitizing temperature. Coarse grains and wide martensitic laths were beneficial to reducing the amount of strip-like M 23 C 6 carbides precipitated at martensitic lath boundaries due to the reduction of boundary area and thereby obtaining more fine precipitates in matrix. The strength and impact toughness could be improved to a certain extent by refining carbides in tempered steel with higher austenitizing temperature. However, the degree of favorable influence on impact toughness resulting from refining carbides was lower than the negative effect from coarse martensitic structures. Therefore, the toughness is deteriorated and the strength is improved with increasing austenitizing temperature.

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Effect of normalizing temperature on microstructural stability and mechanical properties of creep strength enhanced ferritic P91 steel

Cited by 133 publications

References 14 publications

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

Effect of Normalizing Temperature on Microstructure and Mechanical Properties of 11Cr–3Co–2.3W Steel

Effect of Microstructure and Precipitates on Mechanical Properties of Cr–Mo–V Alloy Steel with Different Austenitizing Temperatures

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