Precipitate phases of a ferritic/martensitic 9% Cr steel for nuclear power reactors

Shen, Yin; Kim, Sung Hoon; Cho, Hai Dong; Han, Chang Hee; Ryu, Woo Seog

doi:10.1016/j.nucengdes.2008.12.018

Cited by 20 publications

(5 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such coarse precipitates as Laves phase (Fe 2 W or Fe 2 Mo) and Z phase ((Cr,Nb)N) should be delayed, although they could only form after a long service time (Sawada et al 2006). The formation of Laves phase and Z phase is a thermally automatic process which cannot be avoided (Shen et al 2009). However, this process can be delayed by reducing the content of tungsten, molybdenum and nitrogen.…”

Section: Discussionmentioning

confidence: 99%

Conventional Heat-Resistant Steels

Yan

Wang

Shan

et al. 2015

9-12Cr Heat-Resistant Steels

View full text Add to dashboard Cite

A change of the slope at about 660 °C on the dilatometry curve of 9Cr martensitic heat-resistant steel during heating process is explained by the large amount of carbonitride precipitation in the steel. The normalising temperature has little effect on mechanical properties of 10Cr steel at room temperature, while the tempering temperature has a greater effect. The toughness increases with increasing tempering temperature. Laves phase is one of the most significant precipitates in ferritic/martensitic heat-resistant steels. Co in the steel could accelerate the growth of Laves phase. Coalescence of the large Laves phase precipitates would lead to the brittle intergranular fracture. The nitride-strengthened martensitic heatresistant steel is precipitation strengthened only by nitrides. In the latter part of the chapter, the effect of nitride precipitation behaviour on the impact toughness is discussed. When the tempering temperature is increased, a large amount of nitrides form in the matrix. The impact energy is greatly increased. The ductilebrittle transition temperature also decreases when the tempering temperature is increased from 650 to 750 °C. The nitride precipitation while increasing tempering temperature is responsible for the improved impact toughness. Key Alloying Elements and Alloy-Design Philosophy of 9-12Cr SteelsThe chemical compositions of the typical 9-12 %Cr ferritic/martensitic heat-resistant steels have been widely reported in literature (Klueh and Nelson 2007;Huang et al. 2004a). The functions of some important alloying elements such as Cr, Mo, W, Co, Nb, Ta, V, Si and B are briefly explained here. Cr is a vital element to offer the high oxidation resistance and provide Cr 23 C 6 precipitates for the steels. It has been revealed that the optimum Cr content is 9 %, by which the longest creep life could be achieved (Masuyama 2001). However, in order to obtain better oxidation resistance, the Cr content was increased to 10-12 %, although this might decrease

show abstract

Section: Discussionmentioning

confidence: 99%

Conventional Heat-Resistant Steels

Yan

Wang

Shan

et al. 2015

9-12Cr Heat-Resistant Steels

View full text Add to dashboard Cite

show abstract

“…According to other authors [1][2][3][4][5][6] carbides M 23 C 6 type (M5Fe, Cr, Mo) are formed in the structure. Moreover,…”

Section: Structurementioning

confidence: 90%

“…An example of such a material is steel X10CrMoVNb 9-1 (P91) which is modified 9%Cr martensitic steel alloyed with molybdenum, niobium and vanadium. 5 The development of structural changes during long term service is a serious problem for this steel. These changes include coarsening of M 23 C 6 type carbides, precipitation of Mo- and Cr-rich Laves phase and decomposition of finely dispersed nitrides and carbide–nitrides.…”

Section: Introductionmentioning

confidence: 99%

Using of transpassive dissolution for detection of structural changes in 9Cr–1Mo creep resistant steel

Rapouch

Bystrianský

2014

Corrosion Engineering, Science and Technology

View full text Add to dashboard Cite

The development of structural changes during long term service is a serious problem of heat resistant steels due to formation of deleterious Cr-and Mo-rich phases in the structure. Since chromium and molybdenum are easily soluble by transpassive mechanisms, electrochemical polarisation in appropriate electrolyte could be used as method for detection of such phases. Transpassive behaviour of creep resistant steel 9Cr-1Mo (P91) in different states of heat treatment/long term aging was studied in this work. Materials were studied by means of electrochemical methods, OES analysis and SEM observation. Potentiodynamic curves of tempered and aged (650uC/10 000 h) samples in NaOH solution show a significant local peak in transpassivity/secondary passivity region. No peak was observed on polarisation curve of quenched sample. Formation of the local peak on polarisation curve is assumed to be caused by dissolution of Cr-and Mo-rich phases by a transpassive mechanism. This assumption was confirmed using potentiostatic etching, chemical analysis of electrolytes and microstructure observation.

show abstract

“…Numerous papers report the microstructural changes of the steels in this temperature range. [3,[9][10][11][12] On the contrary, little information is available on the microstructural changes at lower tempering temperatures 573 K to 873 K (300°C to 600°C) [5,8,13] which are presently not of commercial interest. Moreover, double-tempering treatments have been proposed for 9-12 Cr steels which involve a tempering stages at temperatures of 823 K to 893 K (550°C to 620°C).…”

Section: Introductionmentioning

confidence: 99%

Evolution of Minor Phases in a 9PctCr Steel: Effect of Tempering Temperature and Relation with Hydrogen Trapping

Hurtado-Noreña

Danón

Luppo

et al. 2015

Metall Mater Trans A

View full text Add to dashboard Cite

The evolution of minor phases in ASTM A335 P91 steel has been studied on specimens submitted to different thermal treatments including a tempering step. Particular emphasis has been put on the tempering temperature range 573 K to 873 K (300°C to 600°C), which has not been yet intensively studied. The techniques used in this investigation were X-ray diffraction with synchrotron light, scanning electron microscopy with field emission gun and transmission electron microscopy. In the low tempering temperature range [573 K to 673 K (300°C to 400°C)], retained austenite, Fe 3 C and MX precipitates are observed. In the high tempering temperature range [773 K to 1053 K (500°C to 780°C)], M 23 C 6 -type carbides, MX-type carbonitrides and M 2 X precipitates are observed. The effect of the microstructure on hydrogen trapping is analyzed. The distorted matrix around the M 2 X and MX particles provides the most important trap sites in the P91 steel.

show abstract

Precipitate phases of a ferritic/martensitic 9% Cr steel for nuclear power reactors

Cited by 20 publications

References 17 publications

Conventional Heat-Resistant Steels

Conventional Heat-Resistant Steels

Using of transpassive dissolution for detection of structural changes in 9Cr–1Mo creep resistant steel

Evolution of Minor Phases in a 9PctCr Steel: Effect of Tempering Temperature and Relation with Hydrogen Trapping

Contact Info

Product

Resources

About