9Cr-1Mo-V-Nb steel

Kimura, Kazuhiro

doi:10.1007/10837344_27

Cited by 5 publications

(3 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For low-alloy steels, the damage evolution equations are usually calibrated against the tertiary stage of the creep curve. For advanced steels, the essential part of the tertiary creep is associated with softening processes (e.g., coarsening of subgrain structure) as documented in Polcik et al (1999), Kimura (2006), and Kostenko and Naumenko (2008). For 9% Cr steels, the voids on former austenite grain boundaries and/or carbides can be observed after prolonged test durations and essentially higher values of the creep strain if compared to the low alloy steels, for example Rauch et al (2004) and Maile and Scheck (2008).…”

Section: Damage Processes and Long-term Strengthmentioning

confidence: 99%

A Combined Model for Hardening, Softening, and Damage Processes in Advanced Heat Resistant Steels at Elevated Temperature

Naumenko

Altenbach

Kutschke

2010

International Journal of Damage Mechanics

View full text Add to dashboard Cite

Phenomenological constitutive equations that describe inelastic behavior of advanced steels at elevated temperature are developed. To characterize hardening, recovery, and softening processes, a composite model with creep-hard and creep-soft constituents is applied. The volume fraction of the creep-hard constituent is assumed to decrease toward a saturation value. This approach reproduces well the primary creep as a result of stress redistribution between constituents and tertiary creep as a result of softening. To describe the whole tertiary creep stage, a damage variable in the sense of continuum damage mechanics is introduced. The material parameters and the response functions in the model are calibrated against experimental creep curves for X20CrMoV12-1 steel. For the verification, simulations of the inelastic response are performed and the results compared with experimental data including creep under stress change conditions and stressstrain response under constant strain rate. Furthermore, the lifetime predictions are analyzed and compared with the published creep rupture strength data. The results show that the consideration of both softening and damage processes is necessary to characterize the long-term strength in a wide stress range. Finally, the model is generalized to the multi-axial stress state.

show abstract

Section: Damage Processes and Long-term Strengthmentioning

confidence: 99%

A Combined Model for Hardening, Softening, and Damage Processes in Advanced Heat Resistant Steels at Elevated Temperature

Naumenko

Altenbach

Kutschke

2010

International Journal of Damage Mechanics

View full text Add to dashboard Cite

show abstract

“…The new RAFM steels have also demonstrated significantly improved short-term thermal creep resistance at high temperatures. Figure 3 summarizes some short-term (500 to ~50 000 h) thermal creep rupture strength results at 650 °C for four TMT heats of 9%Cr ferritic/martensitic steel compared to the behaviour for conventional 9%Cr steels (F82H RAFM and modified 9Cr-1Mo alloy Grade 91) [14,16,39,47,[72][73][74]. The detailed composition and heat treatment conditions for the new steels are provided in the original references, but in general involved increased N and lower C and tailored additions of V, Ta along with warm rolling at 600-700 °C and/or multi-stage austenitization and tempering to promote MX and M 2 X precipitates (M = V or Ta and X = N or C).…”

Section: Development Status For Next-generation 8-9%cr Rafmsmentioning

confidence: 99%

Development of next generation tempered and ODS reduced activation ferritic/martensitic steels for fusion energy applications

et al. 2017

View full text Add to dashboard Cite

Reduced activation ferritic/martensitic steels are currently the most technologically mature option for the structural material of proposed fusion energy reactors. Advanced nextgeneration higher performance steels offer the opportunity for improvements in fusion reactor operational lifetime and reliability, superior neutron radiation damage resistance, higher thermodynamic efficiency, and reduced construction costs. The two main strategies for developing improved steels for fusion energy applications are based on (1) an evolutionary pathway using computational thermodynamics modelling and modified thermomechanical treatments (TMT) to produce higher performance reduced activation ferritic/martensitic (RAFM) steels and (2) a higher risk, potentially higher payoff approach based on powder metallurgy techniques to produce very high strength oxide dispersion strengthened (ODS) steels capable of operation to very high temperatures and with potentially very high resistance to fusion neutron-induced property degradation. The current development status of these nextgeneration high performance steels is summarized, and research and development challenges for the successful development of these materials are outlined. Material properties including temperature-dependent uniaxial yield strengths, tensile elongations, high-temperature thermal creep, Charpy impact ductile to brittle transient temperature (DBTT) and fracture toughness behaviour, and neutron irradiation-induced low-temperature hardening and embrittlement and intermediate-temperature volumetric void swelling (including effects associated with fusionrelevant helium and hydrogen generation) are described for research heats of the new steels.

show abstract

“…In general, the intercritical thermal cycle in the ICHAZ has promoted multiple microstructural evolutions occurring simultaneously, including partial austenitization, precipitate dissolution or coarsening, and matrix tempering [ 10 , 11 , 12 ], which have led to very complicated microstructures [ 13 ]. A typical intercritical microstructure features a mixture of untempered martensite, transformed from austenite formed during heating, and overtempered martensite (OTM) originating from the base metal (BM) [ 14 , 15 ]. This weak microstructure in the ICHAZ, which results in faster creep strength degradation, acts as a metallurgical notch across welds.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Mechanical Properties of Intercritically Treated Grade 91 Steel

et al. 2020

View full text Add to dashboard Cite

Premature creep failures at the intercritical heat affected zone (ICHAZ) of creep-resistant steel weldments have been frequently reported. However, the creep degradation mechanism of different microstructure constituents in ICHAZ is complicated and needs further clarification. In this work, Grade 91 steel was intercritically heat-treated at a temperature (860 °C) between the critical temperatures AC1 and AC3, and a correlation between microstructure and mechanical properties of the heat-treated specimen was built. The effects of austenitization and tempering resulting from the intercritical treatment (IT) differentiated the local strain energies between the two microstructure constituents: newly transformed martensite (NTM) and over-tempered martensite (OTM). The formation of NTM grains led to a hardness increase from 247 HV0.5 in the base metal to 332 HV0.5 in the IT specimen. The ultimate tensile strength (UTS) increased from 739 MPa in the base metal to 1054 MPa in the IT specimen. Extensive growth of the OTM grains and rapid recovery of NTM grains took place simultaneously in the IT specimen during a typical tempering at 760 °C. These microstructure degradations led to a lowered hardness of 178 HV0.5, a reduced UTS of 596 MPa, and a poor creep resistance with a minimum creep strain rate of 0.49 %/h at 650 °C in an IT + tempering (ITT) specimen.

show abstract

9Cr-1Mo-V-Nb steel

Cited by 5 publications

References 23 publications

A Combined Model for Hardening, Softening, and Damage Processes in Advanced Heat Resistant Steels at Elevated Temperature

A Combined Model for Hardening, Softening, and Damage Processes in Advanced Heat Resistant Steels at Elevated Temperature

Development of next generation tempered and ODS reduced activation ferritic/martensitic steels for fusion energy applications

Microstructure and Mechanical Properties of Intercritically Treated Grade 91 Steel

Contact Info

Product

Resources

About