Microstructural characterization of 5 to 9 pct Cr-2 pct W-V-Ta martensitic steels

Jayaram, R.; Klueh, R.L.

doi:10.1007/s11661-998-0077-2

Cited by 53 publications

(25 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…12) MX particles Ta or V-rich were also reported for normalized ORNL RA steels, tempered at 750°C. 7) These three types of morphologies, including in some cases the "wing" morphology, have been observed in 9CrMoVNb, 13) 9CrWCoVNb 14) and CrWNb 15) steels after tempering but, to our knowledge, the "wing" morphology involving Ta and V has not been reported in other alloys of composition similar to Eurofer97, such as F82H or JLF1. On the other hand, "duplex" precipitates, in which many TaC particles precipitate on a rectangular TiN particle were found for the F82H RA steel.…”

Section: Morphology and Compositionmentioning

confidence: 77%

“…More generally, the type of carbide precipitated after 1 h tempering at 750°C in CrWV and CrWTa steels has been observed to depend on the Cr content of the matrix, giving a transition from a major phase M 7 C 3 (trigonal structure, space group Pnma) for 5Cr steels to the M 23 C 6 phase for 9Cr steels. 7) The M 23 C 6 phase was Cr-rich with smaller amounts of W and V, the balance of the metallic component being iron. 7) Similar results for carbide composition measurements were found in experimental AEA-Culham 9 to 11CrWVTa steels after tempering at 675 or 750°C and ageing at 750°C for 500 h or at 500°C for 1 000 h, 18) and for the Eurofer97 RA alloy after tempering 11) and ageing.…”

Section: C 6 M 7 C 3 or M 6 C Carbidesmentioning

confidence: 98%

“…7) The M 23 C 6 phase was Cr-rich with smaller amounts of W and V, the balance of the metallic component being iron. 7) Similar results for carbide composition measurements were found in experimental AEA-Culham 9 to 11CrWVTa steels after tempering at 675 or 750°C and ageing at 750°C for 500 h or at 500°C for 1 000 h, 18) and for the Eurofer97 RA alloy after tempering 11) and ageing. 12) On the other hand, M 7 C 3 , M 23 C 6 , M 3 C, and M 6 C carbides have been observed in 2.25Cr steels.…”

Section: C 6 M 7 C 3 or M 6 C Carbidesmentioning

confidence: 98%

“…12) On the other hand, M 7 C 3 , M 23 C 6 , M 3 C, and M 6 C carbides have been observed in 2.25Cr steels. 7) Ta uptake by the M 23 C 6 phase is controversial. Carburization of ferrotantalum or prolonged annealing of powder compacts of Ta and cementite showed that Ta does not substitute for Fe in cementite, nor does it form a double carbide of any type of the general formula (Fe, Ta) x C y .…”

Section: C 6 M 7 C 3 or M 6 C Carbidesmentioning

confidence: 99%

See 3 more Smart Citations

Thermodynamic Modeling in Reduced Activation Steels

Danón

Servant

2005

ISIJ Int.

View full text Add to dashboard Cite

Reduced Activation (RA) martensitic steels of the 9/11CrWVTa type are promising candidates for fusion reactor applications as long as they exhibit good mechanical properties-similar to those of commercial martensitic steels of the 9/12CrMo(NbV) type-and satisfy design criteria related to the behavior under irradiation. A contribution on thermodynamic modeling in RA steels is presented. The current status of the development of a thermodynamic database in the framework of the CALPHAD approach is reported. Thermodynamic calculations concerning RA alloys are discussed which can be helpful to interpret experimental observations on phase relationships, phase compositions, transition temperatures, etc.

show abstract

Section: Morphology and Compositionmentioning

confidence: 77%

Section: C 6 M 7 C 3 or M 6 C Carbidesmentioning

confidence: 98%

Section: C 6 M 7 C 3 or M 6 C Carbidesmentioning

confidence: 98%

Section: C 6 M 7 C 3 or M 6 C Carbidesmentioning

confidence: 99%

See 2 more Smart Citations

Thermodynamic Modeling in Reduced Activation Steels

Danón

Servant

2005

ISIJ Int.

View full text Add to dashboard Cite

show abstract

“…It is reported that V(CN) particles on the extracted replicas from high Cr heat resistant steels of the normalized and tempered state contain about 15 % of Cr according to the TEM-EDS analysis. 13,14) Other researchers reported the TEM-EDS with an noticeable peak of Cr 15,16) and without any peak of Cr. 12,17) The above reports are on the normalized and tempered specimens, so that Cr carbides should be around the V(CN) particles of interest.…”

Section: Optical Microscopy and Precipitatesmentioning

confidence: 98%

Solubility Product of VN in Austenite of High Cr Heat Resistant Steel

et al. 2003

View full text Add to dashboard Cite

Dissolved V in austenite of 7%Cr-0.4%V-0.09%N steel (hereinafter, % means mass%) was measured and the solubility product of VN was determined as follows:where T is the absolute temperature in K. The solubility product obtained is 3 to 5 times larger than those in the literature and about one order larger than that for iron. The decrease in the activity coefficient of nitrogen due to the presence of Cr and V in the experimental steel is responsible for the increase in the solubility product of VN.KEY WORDS: precipitation; MX; thermodynamics; activity coefficient. log([% ][% ])V N 4.38 ϭ Ϫ 8 436 T stituent elements. The detectable limit for V in this study is about 0.42 ppm for the experimental steel. The solubility product of VN is calculated using the following equation assuming that chemical composition of VN is stoichiometric.[%V] [%N] Symbols, [%V] and [%N], denote the dissolved V and N in austenite, and V t , N t denote the total V and N, respectively. Symbol, [%N 0 ], denotes the dissolved N in Fe-V-N alloy which is calculated from the observed values of the dissolved V. The amount of the dissolved vanadium in the matrix, [%V], is assumed to be equal to the amount of the dissolved vanadium observed. Experimental Results and Discussion Thermal EquilibriumCharacteristic features of the present analyzing method are that the duration of heat treatment is relatively short, and that the V content of a filtered solution is directly measured. Therefore, firstly, whether the equilibrium in the precipitation of VN is satisfactorily guaranteed by 1 h heating or not becomes a problem. Therefore, the effects of heating rate and heating duration should be discussed. Figure 1 shows the Arrhenius plot of the dissolved V. Open marks correspond to rapid heating where a small coupon was put into a pre-heated furnace and temperature of the coupon was reached to an aiming temperature within 5 min at least. Closed marks correspond to slow heating where a coupon was set in a cold furnace and gradually heated up to an aiming temperature taking 3 h. All coupons were held for 1 h at a temperature in both cases. The figure shows that a linear relationship is found in a wide range of temperature by the rapid heating and the regression line may probably correspond to the equilibrium solubility limit of V in austenite. On the other hand, the amount of the precipitates by the slow heating is insufficient at low temperatures as compared with those of the rapid heating. Figure 2 shows the time dependence of the dissolved V of the rapidly heated specimens at 1 100°C. This figure shows that the enough precipitation has been roughly accomplished by the 1 h rapid heating. Therefore, from Figs. 1 and 2 it is found that the equilibrium of the precipitation of VN in austenite is practically realized by a technique of the rapid heating of a small coupon followed by the short time holding at a temperature. The authors have studied the precipitation behavior of TaC and NbC and concluded that the precipitation of MX in austenite is accomplished wit...

show abstract

High‐Temperature Phase Stability of 9Cr–W–Ta–V–C Based Reduced Activation Ferritic–Martensitic (RAFM) Steels: Effect of W and Ta Additions

Kirana

Raju

Mythili

et al. 2015

steel research int.

View full text Add to dashboard Cite

The high‐temperature phase stability of reduced activation ferritic–martensitic steels having various W and Ta contents has been investigated using calorimetry, microscopy, and thermodynamic simulations. Calorimetric studies revealed the following transformation sequence as a function of increasing temperature upon slow heating at 1 K min−1: α‐ferrite (ferromagnetic) + M23C6 + MX → α‐ferrite (paramagnetic) + M23C6 + MX → γ‐austenite + M23C6 + MX → γ + MX → γ → δ+ γ → γ + δ + L → δ + L → liquid. This is fully supported by equilibrium thermodynamic simulations. It is found that the complete dissolution of M23C6 carbide required significant overheating above Ac3 that is, α + M23C6 + MX → γ + MX transformation finish temperature. The measured values of lattice parameter, Curie temperature, liquidus, solidus, and carbide dissolution temperatures, as well as melting enthalpy, did not reveal a drastic variation with W content, from 0 to 0.2 wt%. However, the measured dissolution temperature of MX phase exhibited a mild increase with Ta content, for up to about 0.2 wt%. The extent of dissolution of M23C6 especially around Ac3 temperature is found to depend on heating rate. Higher heating rates and higher W content yielded inhomogeneous austenite and this is found to have significant influence on subsequent γ‐austenite → α′‐martensite formation during cooling. The critical cooling rate for γ → α′‐martensite formation is found to be 6 K min−1, for all the RAFM steels. Electron microscopy and thermodynamic simulations support the possibility of simultaneous presence of two types of MX type carbonitrides at service conditions.

show abstract

Microstructural characterization of 5 to 9 pct Cr-2 pct W-V-Ta martensitic steels

Cited by 53 publications

References 14 publications

Thermodynamic Modeling in Reduced Activation Steels

Thermodynamic Modeling in Reduced Activation Steels

Solubility Product of VN in Austenite of High Cr Heat Resistant Steel

High‐Temperature Phase Stability of 9Cr–W–Ta–V–C Based Reduced Activation Ferritic–Martensitic (RAFM) Steels: Effect of W and Ta Additions

Contact Info

Product

Resources

About