Optimum alloy compositions in reduced-activation martensitic 9Cr steels for fusion reactor

Precipitation of Fe2W laves phase and modeling of its direct influence on the strength of a 12Cr-2W steel

“…According to Lacy and Gensamer's experimental work, [26] the strength increment SS due to the substitutional alloying elements in bcc iron can be simply expressed as [1] where k is the strengthening coefficient measured by Lacy and Gensamer. [26] For W and Mo, k takes the values of 11,000 and 9600, respectively, and n is 0.75 for all the elements investigated.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Fe 2 W Laves phase is an important intermetallic component, which can significantly influence microstructures and microstructural stability as well as mechanical properties. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Conventionally, Fe 2 W Laves phase is often considered detrimental for steels since it reduces their toughness. [2][3][4][5][6] Kunimitsu et al [2] observed a decrease in toughness after Fe 2 W Laves phase precipitated in a 9Cr-2W steel.…”

Phenomenological calculation of the Fe-Pd-based L10-ordered phase in the Fe-Pd-Ni ternary system

“…[3] They ascribed the origin of the strengthening mechanism to fine precipitation of an Fe-Pd-based L1 0 ordered phase, which has a particular crystallographic orientation relationship with respect to a bcc matrix, namely, {001} matrix //{001} L10 and Ͻ100Ͼ matrix //Ͻ110Ͼ L10 . [4,5] In addition, it was found that the effect of the addition of Pd was more pronounced at higher temperatures. A critical problem of this new heat-resistant steel with Pd, however, is the fact that Pd is quite expensive.…”

Thermodynamic Modeling in Reduced Activation Steels

“…However, it has been established that Laves phases could have a detrimental effect on mechanical properties of high chromium steels, especially as toughness is concerned. 2,8,26) The experimental evidence has shown that Laves phases precipitate in RA steels and that the W content of the steel is one of the main factors that controls precipitation at fixed temperature. Thus, AEA-Culham experimental steels containing less than 1 wt% W did not exhibit precipitation of Laves phases after ageing at 250-550°C for up to 10 000 h, 8) or at 750°C for 500 h, 18) while this phase was detected for a 3 wt% W composition after ageing at 550°C 8) for 10 000 h or at 675°C for 500 h. 27) As for the Eurofer97 steel (ϳ1 wt% W), ageing at 500°C for 5 000 h or at 600°C for 1 000 h did not result in Laves phase precipitation.…”

“…In addition to requirements regarding chemical composition, mechanical and radiation damage properties must be taken into account for RA steels in view of the severe service conditions envisaged for them, these conditions including neutron irradiation up to 70 dpa (DEMO reactor), an operating temperature range of 250-550°C and a lifetime of 20 000 h. 1) Ferritic and martensitic RA steels have been investigated in European, USA, Japanese and international collaborative fusion materials programs. [2][3][4][5][6] The basic compositions of these steels, taken from Refs. 2), 7)-9), are summarized in Table 1.…”