Creep-resistant steels

Abe, Fujio; Kern, Torsten-Ulf; Viswanathan, R.

doi:10.1533/9781845694012

Cited by 251 publications

(399 citation statements)

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“…These cavities grow under the influence of stress which can lead to failure. Generally, strategies are adopted to prevent creep damage to form, or slow down its growth [1,2]. An alternative method in the form of self healing has been proposed by Laha and coworkers [3] and Shinya [4], where selective precipitation of supersaturated solute at creep cavities hinders the creep cavity growth in stainless steels.…”

Section: Introductionmentioning

confidence: 99%

Finite element modelling of creep cavity filling by solute diffusion

Versteylen

Szymanski

Sluiter

et al. 2018

Philosophical Magazine

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Section: Introductionmentioning

confidence: 99%

Finite element modelling of creep cavity filling by solute diffusion

Versteylen

Szymanski

Sluiter

et al. 2018

Philosophical Magazine

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“…[2][3][4][5][6] They offer the best combination of high creep strength, high resistance against thermal fatigue, high steam oxidation resistance and good manufacturability at relatively low costs. 7 The steel grade PK942 (X11CrNiMo12) is a martensitic creep-resistant steel that is generally used for turbine blades and fittings.…”

Section: Introductionmentioning

confidence: 99%

De-oxidation of PK942 steel with Ti and Zr

Koležnik¹,

Burja²,

Batič³

et al. 2017

Mater. Tehnol.

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The effects of titanium and zirconium additions on the non-metallic inclusions and microstructure of PK942 (X11CrNiMo12) steel were investigated. Laboratory steel charges with additions of Ti, Zr and a combination of both elements were melted. The inclusions' size, quantity, distribution and composition were analysed using optical and scanning electron microscopy (SEM). Other than the difference in d-ferrite quantity, there are no significant differences in the microstructure. The Ti and Zr additions had a significant effect on the non-metallic inclusions, and while the addition of Ti did have an effect on the composition of inclusions, the addition of Zr also had a great effect on the size distribution and the number of non-metallic inclusions. The result of the Zr addition was a large reduction in the total non-metallic inclusion surface area. The additions of both titanium and zirconium had similar effects to the addition of Zr. Thermodynamic reactions were considered to explain the modification of the non-metallic inclusions. Keywords: non-metallic inclusions, clean steel, de-oxidation with Ti, de-oxidation with Zr, creep resistant steel S pomo~jo opti~ne ter elektronske mikroskopije se je preiskal vpliv dezoksidacije jekla PK942 (X11CrNiMo12) s cirkonijem, titanom ter kombinacijo obeh. Poudarek raziskave je bil na spremembi velikosti, razporeditve ter sestave nekovinskih vklju~kov v jeklu PK942. Razen v majhni razliki dele`a d-ferita, ni bilo bistvenega vpliva na osnovno mikrostrukturo jekla. Ve~ji vpliv pa se je pokazal na velikost, {tevilo ter kemi~no sestavo nekovinskih vklju~kov. Analiza nekovinskih vklju~kov je pokazala, da Ti vpliva predvsem na kemi~no sestavo, med tem ko ima Zr zelo velik vpliv tudi na velikostno porazdelitev ter {tevilo nekovinskih vklju~kov, rezultat~esar je manj{i skupni povr{inski dele`nekovinskih vklju~kov. Dodatek kombinacije Zr in Ti ima podoben vpliv kot dodatek Zr, vendar v manj{em obsegu. Pri razlagi modifikacije vklju~kov so se upo{tevale osnovne termodinami~ne reakcije oksidacije.

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“…Este comportamiento en creep es propio de los aceros de alta resistencia, donde la etapa de creep secundario está ausente y por lo tanto, inmediatamente después de la etapa de creep primario comienza la etapa de creep terciario [17]. Así, en la evaluación de su resistencia en estos tipos de aceros, se considera la velocidad mínima de deformación, en lugar de la velocidad en el estado estacionario el cual nunca llega a realizarse.…”

Section: Resultados Y Discusiónunclassified

Influencia del tiempo de revenido a 780°C sobre la resistencia al creep del acero ASTM A335 P91

2018

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It has been investigated the effect of tempering time at 780°C on the creep strength of ASTM A335 grade P91 steel. The tempering temperature corresponded to the industrial tempering temperature and the times evaluated were chosen in such a way to accumulate, between the tempering prior as received (40 min) and the treatment carried out in the laboratory, times of 3; 4; 5; 5,5; 5,7; 6 and 7 hours, so that in practice a double tempering was applied. Subsequently, the samples were creep tested at 600 ºC and 190 MPa up to rupture. The results show that a tempering time to 780 ºC has a very significant impact on the creep strength of the P91 steel. Up to 3 hours of tempering, the P91 steel retains its creep strength, with a minimum creep rate of 7x10 -9 s -1 . This creep strength falls off sharply to the 5 hours of tempering (1.5x10 -7 s -1 ), and retrieved to the 5.5 hours (3 x10 -8 s -1 ). This creep behavior is probably related to the evolution of the MX particles during tempering. The average size of the particles of the second phase in the samples tempered to 780 °C during different times and subjected to creep to 600 °C, would indirectly indicate a state of dissolution and reprecipitation of MX particles, which occurs during the tempering. Creep rupture occurs by the nucleation, Se investigó el efecto del tiempo de revenido a la temperatura de 780 °C sobre la resistencia al creep del acero ASTM A335 grado P91. La temperatura de revenido correspondió a la temperatura de revenido industrial y los tiempos evaluados se eligieron de tal manera de acumular, entre el revenido previo del material de suministro (40 minutos) y el tratamiento realizado en el laboratorio, tiempos de 3; 4; 5; 5,5; 5,7; 6 y 7 horas, por lo que en la práctica se aplicó un doble revenido. Posteriormente, las muestras fueron ensayadas a 600 ºC y 190 MPa hasta rotura. Los resultados muestran que el tiempo de revenido a 780 ºC, tiene un efecto muy importante en la resistencia al creep del acero P91. Hasta 3 horas de revenido, el acero P91 mostró una buena resistencia al creep con una velocidad mínima de creep de 7x10 -9 s -1 . Una marcada caída en la resistencia al creep se observó para un tiempo de revenido de 5 horas (1.5x10 -7 s -1 ), con una posterior recuperación a las 5.5 horas (3x10 -8 s -1 ). Este comportamiento al creep probablemente esté relacionado a la evolución de las partículas MX durante el revenido. El tamaño promedio de las partículas de segunda fase en las probetas revenidas a 780º C con diferentes tiempos y sometidas a creep a 600º C, indicarían de manera indirecta un estado de disolución y re-precipitación de las partículas MX que ocurre durante el revenido. La rotura por creep ocurre por la nucleación, crecimiento y coalescencia de cavidades en regiones próximas a los límites de grano de austenita previa, resultando en una fisura y propagación de la fisura hasta su rotura. Palabras clave: Acero 9% Cr, Comportamiento a creep, Resistencia a creep, Precipitación.

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Creep-resistant steels

Cited by 251 publications

References 0 publications

Finite element modelling of creep cavity filling by solute diffusion

Finite element modelling of creep cavity filling by solute diffusion

De-oxidation of PK942 steel with Ti and Zr

Influencia del tiempo de revenido a 780°C sobre la resistencia al creep del acero ASTM A335 P91

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