Development of A New Class of Fe-3Cr-W(V)Ferritic Steels for Industrial Process Applications

Sikka, V.J.; Jawad, Maan H.

doi:10.2172/939630

Cited by 4 publications

(8 citation statements)

References 7 publications

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“…Separate master curves for different strain rates can arise from the evolution of range of plastic strain rates limited by the imposed applied strain rate. Normalisation of plastic strain rate with applied strain rate provided single 11 Variations in work hardening rate h as function of reciprocal of normalised plastic strain rate : e a = : e p at different temperatures and applied strain rates: solid line is according to equation (5) 12 Variations in true stress rate ds/dt as function of normalised plastic strain rate : e p = : e a at different temperatures and applied strain rates 13 Variations in normalised true stress rate (ds/dt)/ : e a as function of normalised plastic strain rate : e p = : e a at different temperatures and applied strain rates: solid line is according to equation (6) 10 Variations in work hardening rate h as function of normalised plastic strain rate : e p = : e a at different temperatures and applied strain rates: solid line is according to equation (5)…”

Section: Discussionmentioning

confidence: 99%

“…The selection of the steel for steam generator application is based on low thermal expansion coefficient, high resistance to stress corrosion cracking compared with austenitic steels and superior mechanical properties at elevated temperatures than the alternate 2?25Cr-1Mo steel. 12,13 The steel has also emerged as an important candidate material for wrapper applications in future sodium cooled fast reactors due to its high resistance to irradiation creep and void swelling, as compared with austenitic steels. 14,15 9Cr-1Mo steel displays three distinct temperature regimes for the variations in tensile strength, average work hardening rate and ductility with respect to temperature.…”

Section: Introductionmentioning

confidence: 99%

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Unified tensile work hardening behaviour of 9Cr–1Mo ferritic steel

Choudhary

Palaparti

Samuel

et al. 2013

Materials Science and Technology

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Tensile work hardening behaviour of 9Cr-1Mo ferritic steel has been examined in terms of the variations in instantaneous work hardening rate (h5ds/de p , where s is true stress and e p is true plastic strain) with stress and plastic strain rate : e p for a wide range of temperatures (300-873 K) and strain rates (6?33610 25 -6?33610 23 s 21 ). Both h-s and hs-s exhibited two stage work hardening behaviour and distinct three temperature regimes with signatures of dynamic strain aging at intermediate temperatures and dominance of dynamic recovery at high temperatures. The variations in h with : e p for 300-873 K exhibited unified work hardening in terms of separate master curves for different strain rates. At all the strain rates, h varied linearly with reciprocal of plastic strain rate 1=: e p independent of temperature. As a consequence, direct proportionality between rate of change in true stress and plastic strain rate is obtained.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Unified tensile work hardening behaviour of 9Cr–1Mo ferritic steel

Choudhary

Palaparti

Samuel

et al. 2013

Materials Science and Technology

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“…The 10 5 h creep rupture strength of modified 9Cr-1Mo steel has been found to be higher than 2 . 25Cr-1Mo and 9Cr-1Mo steels, and remains higher or equal to that of type 304 austenitic stainless steel up to 898 K. 1 Furthermore, the long term creep properties of modified 9Cr-1Mo steel has been observed to be superior than the conventional steels with Cr content up to 9%Cr i.e. plain 9Cr-1Mo steel and 12Cr-Mo-W-V steel.…”

Section: Introductionmentioning

confidence: 99%

“…9Cr-1Mo ferritic steel and its modified versions are important grades of ferritic-martensitic steels widely used in the petrochemical and electric power generating industries. 1,2 Modified 9Cr-1Mo steel has been chosen for all the components (tube, shell and tube sheet/plate) of steam generator (SG) of the Indian Prototype Fast Breeder Reactor (PFBR) 3 under construction at Kalpakkam, India. The selection of modified 9Cr-1Mo steel for PFBR steam generator applications is based on important considerations, such as high temperature mechanical properties including creep, low cycle fatigue (LCF) and creep-fatigue interaction, resistance to loss of carbon in liquid sodium and consequent reduction in strength, resistance to wastage in the case of small leaks leading to sodium-water reaction and resistance to stress corrosion cracking in sodium and water media.…”

Section: Introductionmentioning

confidence: 99%

Influence of post-weld heat treatment on tensile properties of modified 9Cr–1Mo ferritic steel base metal

Samuel¹,

Choudhary²,

Rao³

2007

Materials Science and Technology

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The paper presents the influence of post-weld heat treatment (PWHT) on tensile properties of modified 9Cr-1Mo ferritic steel base metal. Tensile tests at room and elevated temperatures (300-873 K) were performed on specimens in normalised and tempered condition as well as with additional PWHT (993 K for 1 h; 1013 K for 1 h and 1033 K for 1 h). The yield and ultimate tensile strengths decrease gradually up to intermediate temperatures followed by a rapid fall at high temperatures in all heat treatment conditions. At intermediate temperatures, the steel exhibited ductility minima, serrated flow, negative strain rate sensitivity on flow stress and peak in the average work hardening rate. The influence of additional PWHT is reflected in a systematic and gradual decrease in both the yield and tensile strength values with increasing PWHT temperature from 993 to 1033 K for 1 h. However, there has been no appreciable change in ductility values as well as the fracture mode in PWHT conditions compared with those observed in normalised and tempered condition. Comparison of strength values in PWHT conditions suggested that the strength values remained higher than the average values specified in the French Nuclear Design Code, RCC-MR.

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“…By the removal of grain boundary precipitates, commonly M 23 C 6 , there is a reduction in the number of chromium depleted zones, and failure by intergranular corrosion cracking can be reduced. 2,3 This paper investigates the effect of Hf as a potential addition to stainless steels to improve creep properties, and corrosion resistance. This is achieved through the use of precipitation and creep modelling, and experimental analysis of Hf containing steels.…”

Section: Introductionmentioning

confidence: 99%

Novel hafnium containing steels for power generation

Grice¹,

Faulkner²,

Yin³

2009

Ironmaking & Steelmaking

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There is clear evidence that creep damage in power plant steels is associated with grain boundary precipitates. These particles provide favourable nucleation sites for grain boundary cavities and microcracks. The formation of M 23 C 6 carbides as grain boundary precipitates can also lead to grain boundary chromium depleted zones which are susceptible to corrosive attack. Such precipitates are the causing loss of creep life in the later stages of creep because of their very high coarsening rate. Through Monte Carlo based grain boundary precipitation kinetics models, combined with continuum creep damage modelling it is predicted that improvements in creep behaviour of power plant steels can be achieved by increasing the proportion of MX type particles. Studies of a Hf containing steel have produced improvements in both creep and corrosion properties of 9%Cr steels. Hf has been ion implanted into thin foils of a 9 wt-%Cr ferritic steel to study its effect on precipitation. Two new types of precipitates are formed, Hf carbide, (an MX type precipitate) and a Cr-V rich nitride, with the formula M 2 N. The Hf carbide particles were identified using convergent beam diffraction techniques, and micro-analysis. The nanosized particles are present in much higher volume fractions when compared to VN volume fractions in conventional power plant ferritic steels. Furthermore it is confirmed that the Hf causes the removal of M 23 C 6 grain boundary precipitates. This has led to an increased concentration of Cr within the matrix, reduced chromium depleted zones at grain boundaries, and increased resistance to intergranular corrosion cracking.

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Development of A New Class of Fe-3Cr-W(V)Ferritic Steels for Industrial Process Applications

Abstract: All tests have failed. The longest term rupture time is 5606.8 h at 1150ºF/12 ksi.

Cited by 4 publications

References 7 publications

Unified tensile work hardening behaviour of 9Cr–1Mo ferritic steel

Unified tensile work hardening behaviour of 9Cr–1Mo ferritic steel

Influence of post-weld heat treatment on tensile properties of modified 9Cr–1Mo ferritic steel base metal

Novel hafnium containing steels for power generation

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