Grain boundary microchemistry and metallurgical characterization of Eurofer'97 after simulated service conditions

Positron annihilation studies on 9Cr reduced activation ferritic/martensitic steels

“…Figure 2 shows the variation of Vickers microhardness with annealing temperature. As evidenced from the figure, the hardness is 220 HVN and is nearly constant up to about 1100 K annealing with an increase to > 400 HVN beyond 1100 K. This is understood based on the stability of microstructure at lower temperatures, while at higher temperatures above 1200 K, the formation of hard martensite phase is consistent with earlier reports on mechanical properties of EUROFER97 [3,5]. Figure 3 shows the positron lifetime and Doppler broadening line shape S-parameter variation as function of annealing temperature.…”

“…However, additional precipitation and coarsening of precipitates can arise during annealing in the temperature range of 700 to 1000 K. Further, as the dislocations are more mobile at these temperatures the martensite lath structures start rearranging [5,6]. This type of intra-grain MC formation is also reported in Ti bearing austenitic steels [9].…”

Present development status of EUROFER and ODS-EUROFER for application in blanket concepts

“…A large characterisation program is being performed including microstructural, mechanical properties, corrosion and compatibility experiments [6][7][8]10].…”

“…The slightly higher DBTT of F82H mod at −40 • C can be attributed to the larger grain size and oxygen content of this material [7]. Ageing between 500 and 600 • C up to 10,000 h does not significantly influence the tensile and impact properties, while at higher temperatures (700 • C, 2000 h) it decreases tensile strength and causes a shift in DBTT [7,[10][11][12].…”

Grain boundary misorientation and positron annihilation characteristics in steel Eurofer processed by equal channel angular pressing

“…4 Grain boundary misorientation map and corresponding misorientation distribution and inverse pole figure for Eurofer in a the astempered condition, and after ECAP processing b for 1 pass, c 2 passes, and d 4 passes concentration of second phases precipitated in Eurofer after ECAP processing, such as carbide and oxide particles, would lead to deformation mechanisms at high temperatures similar to those operating in a dispersion-strengthened material and giving rise to high-stress exponents [33]. It should be noted that non-ODS Eurofer irrespective of processing, i.e., rolled, extruded, or powder metallurgy processed, exhibits stress exponents as high as 21 at 450°C, which decreasing with increasing temperature [34]. These results were attributed to solid solution and precipitation strengthening mechanisms in the Eurofer due to the presence of W and M 23 C 6 , and MX precipitates.…”