Effect of stress on microstructural evolution and mechanical properties of 12Cr3W3Co steel during aging and short-term creep

Precipitates change of ferritic‐martensitic 11 % chromium steel under short‐term creep

“…However, Laves phase has so far not been detected in the ferritic-martensitic 11 % chromium steel with the normalized and tempered condition. Laves phase was reported to form during high-temperature creep tests in ferritic-martensitic 9 %-12 % chromium steels [12,[14][15][16]. Laves phase identified in the present study is considered to be formed in the steel during the creep test.…”

“…Even if ferritic-martensitic 9 %-12 % chromium steels were subjected to long-term creep tests, M 6 X precipitates were still not easy to form in the steels. As some examples of this description, M 6 X precipitates were not detected in the tempered (at 750 8C, 775 8C and 650 8C-675 8C) P91, P92, and 12CrMoVNb martensitic steels after creep for 16650 h, 17000 h and up to 94000 h at 600 8C, respectively [15,29,30]. In a few cases, M 6 X precipitates were reported to be present in ferritic-martensitic 9 %-12 % chromium steels with a final heat treatment condition and M 6 X precipitates free after long-term creep at relatively low temperatures.…”

“…It has been confirmed that M 23 C 6 and MX precipitates in ferritic-martensitic 9 %-12 % chromium steels could slightly coarsen during creep exposures [12,13]. Laves phase was present in ferritic-martensitic 9 %-12 % chromium steels after creep exposures at 550 8C-600 8C for times ranging from 1100 h to 139971 h [12,[14][15][16]. And small amounts of M 6 C precipitates were detected in ferritic-martensitic 12 % chromium steels after creep exposures at 475 8C and 550 8C for 39287 h and 24024 h, respectively [17].…”

Identification of Precipitate Phases in an 11%Cr Ferritic/martensitic Steel after Short-term Creep

“…Laves phase has been reported to form in 9-12%Cr martensitic steels during high-temperature creep tests. [28][29][30][31] Laves phase was also detected in the 11%Cr steel after the creep. Figure 7(a) is the TEM micrograph of carbon replica prepared from the crept 11%Cr FM steel, showing an irregularly block-like precipitate P4 with a metallic element composition of about 40Fe, 35W, 17Cr, 6Ta, and 2Co (in at.%).…”

Influence of normalizing and tempering temperatures on the creep properties of P92 steel

“…Reduction in dislocation density, increase in lath width, and change in orientation of martensitic laths manifest in dislocation substructure evolution. Under the action of creep stress, the dislocations at the grain boundary can be knit-in (a combination of opposite sign dislocations) resulting in a stress-free region/new boundary [24][25][26][27][28]. According to Blum et al [29] under the action of creep stress, dislocations in the same grain can interact in two ways: (a) Burger's vectors b1 and b2 subtract and b3 vanishes (annihilation of dislocations) or (b) Burger's vectors b1 and b2 add to become b3 (formation of new dislocation).…”