Microstructural stability of modified 9Cr–1Mo steel during long term exposures at elevated temperatures

Paul, V. Thomas; Saroja, S.; Vijayalakshmi, M.

doi:10.1016/j.jnucmat.2008.06.033

Cited by 138 publications

(17 citation statements)

References 22 publications

(23 reference statements)

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“…13), which may result from coarsening of M 23 C 6 carbides and Laves phase, but also from the probable presence of Z-phase precipitates in the microstructure, which results in a reduction in the effect of precipitation and solution strengthening. The similar impact of long-term thermal ageing on changes in mechanical properties in 9%Cr steel was also observed in [8,[12][13][14][15]24]. The effect of the time of ageing at 600 and 650…”

Section: Microstructure and Properties Of P92 Steel After Long-term Tsupporting

confidence: 73%

“…The main reason for the decrease in impact energy of the examined steel should be sought in precipitation and growth of the particles of Laves phase precipitated at the grain/lath boundaries, which is also implied by other researchers [12,15,24]. The decrease in ductility of the examined steel was also affected by the increase in an amount of M 23 C 6 carbides precipitated at the grain boundaries, which form the socalled "network of precipitates" in places, but also the degradation of tempered martensite lath microstructure (Figs.…”

Section: Microstructure and Properties Of P92 Steel After Long-term Tmentioning

confidence: 56%

“…7, 8). According to data [24,25], Laves phase as well as M 23 C 6 carbides precipitated at the grain boundaries have a negative impact on the ductility of the examined steel, weakening the cohesion of grain boundaries. According to tests [25], Laves phase precipitates with average diameter higher than 130 nm contribute to a change in the cracking mechanism of high-temperature creep resisting steel from ductile to brittle (transcrystalline cleavable fracture) and are the main reason for the sudden reduction in creep strength of 9%Cr steel.…”

Section: Microstructure and Properties Of P92 Steel After Long-term Tmentioning

confidence: 99%

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Assessment of microstructure stability and mechanical properties of X10CrWMoVNb9-2 (P92) steel after long-term thermal ageing for high-temperature applications

Zieliński¹,

Golański²,

Sroka³

2016

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This paper presents changes in mechanical properties and microstructure of the material of components of a power station boiler made of X10CrWMoVNb9-2 (P92) steel after long--term thermal ageing. Mechanical properties and microstructure were examined on material in initial heat treatment condition and after long-term thermal ageing up to 100,000 h at 600 and 650• C. The microstructure was observed using a scanning and transmission electron microscope. The examinations of steel microstructure and mechanical properties in initial heat treatment condition have confirmed that the requirements for this steel are met. Longterm thermal ageing at a temperature similar to the operating one as well as mechanical properties and microstructure examinations allowed to assess the effect of long-term impact of temperature on the properties and microstructure of P92 steel. The presented method can be used for evaluation and qualification of microstructural changes in power station boiler components operating under creep conditions. K e y w o r d s : P92 steel, microstructure, mechanical properties, long-term thermal ageing

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Section: Microstructure and Properties Of P92 Steel After Long-term Tsupporting

confidence: 73%

Section: Microstructure and Properties Of P92 Steel After Long-term Tmentioning

confidence: 56%

Section: Microstructure and Properties Of P92 Steel After Long-term Tmentioning

confidence: 99%

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Assessment of microstructure stability and mechanical properties of X10CrWMoVNb9-2 (P92) steel after long-term thermal ageing for high-temperature applications

Zieliński¹,

Golański²,

Sroka³

2016

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“…Dyson considered that the Larson-Miller parameter, Robinson's rule and omega parameter were the subsets of CDM, while the θ projection method had important common characteristics. T91 (9Cr-1Mo-V-Nb) steel, a typical 9-12 %Cr ferritic/martensitic heatresistant steel, has complicated microstructure evolution during long-term service (Hasegawa et al 2001;Thomas Paul et al 2008). In Sect.…”

Section: Modelling Of Creep Curve By Continuum Damage Mechanicsmentioning

confidence: 99%

Introduction to Heat-Resistant Steels

Yan

Wang

Shan

et al. 2015

9-12Cr Heat-Resistant Steels

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This chapter introduces the various topics included in the book, in subsequent chapters. As the research book assumes that the reader has graduatelevel materials science knowledge, this is not discussed in the introduction chapter here. Instead, the introduction focuses on different types of steels, including conventional heat-resistant steels, silicon-bearing high chromium heat-resistant steels and nitride-strengthened reduced activation heat-resistant steels. Topics relevant to service conditions and behaviour of steels follow, in thermal ageing, microstructural stability and creep. Finally, the hot deformation processing of steels is discussed. The chapter can be read independently of the rest of the book, but, with its wide referencing, it is also useful in assisting in reading the in-depth chapters that follow and being referred back to. Directly referring to later chapters and sections helps with the latter.

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“…6.3.1) after thermal exposure? In addition to carbide and MX, change of another precipitate, Laves phase, should not be neglected (Kadoya et al 2002;Lee et al 2006;Cui et al 2001;Thomas et al 2008). With increasing exposure time, the number, volume fraction and size of Laves phase precipitates increase.…”

Section: Effect Of Thermal Exposurementioning

confidence: 99%

Thermal Ageing of Heat-Resistant Steels

Yan

Wang

Shan

et al. 2015

9-12Cr Heat-Resistant Steels

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The microstructural evolution during short-term thermal exposure of 9/12Cr heat-resistant steels is described, as well as mechanical properties after exposure. The tempered martensitic lath structure, as well as the precipitation of carbide and MX-type carbonitrides in the steel matrix is stable. On thermal exposure, with increase of cobalt and tungsten contents, cobalt could promote the segregation of tungsten along the martensite lath to form Laves phase, and large size and high density of Laves phase precipitates along the grain boundaries could lead to the brittle intergranular fracture of the steels. In addition, the longterm thermal ageing effect on China Low Activation Martensitic (CLAM) steel is discussed. The microstructural evolution, including the growth of M 23 C 6 carbides and the formation of Laves phase precipitates as well as the evolved subgrains, leads to changes in the mechanical properties. The upper shelf energy of the thermally aged CLAM steel decreases with the extension of ageing time, while the yield strength changes slightly. After long-term thermal ageing, the MX-type precipitates remain stable. The growth of M 23 C 6 and the formation of Laves phase are confirmed. The Laves phase was the main factor leading to the increase in the ductile-brittle transition temperature. Microstructure Heat Treatment, Martensitic Lath and SubgrainStructure, M 23 C 6A normalising treatment can give the desired martensitic microstructure for the China Low Activation Martensitic (CLAM) steel (Table 6.1) and provide good solubilisation for carbide into the matrix with a homogeneous microstructure. The treatment of air cooling from 980 °C leads to martensitic transformation with lath sections between 0.14 μm and 0.42 μm. The subsequent tempering softens the steel and promotes the formation of M 23 C 6 and fine MX precipitates. Dislocations

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Microstructural stability of modified 9Cr–1Mo steel during long term exposures at elevated temperatures

Cited by 138 publications

References 22 publications

Assessment of microstructure stability and mechanical properties of X10CrWMoVNb9-2 (P92) steel after long-term thermal ageing for high-temperature applications

Assessment of microstructure stability and mechanical properties of X10CrWMoVNb9-2 (P92) steel after long-term thermal ageing for high-temperature applications

Introduction to Heat-Resistant Steels

Thermal Ageing of Heat-Resistant Steels

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