Role of grain boundary engineering in the SCC behavior of ferritic–martensitic alloy HT-9

Tensile and stress corrosion cracking behavior of ferritic–martensitic steels in supercritical water

“…The microstructure of all three steels consisted of tempered martensite laths forming subgrains in a ferrite matrix, with (V, Nb)-carbonitrides precipitated mainly on dislocations within the subgrains, and M 23 C 6 precipitated on the prior austenite grain (PAG) boundaries and on subgrain boundaries [7]. The major difference in the three F-M steels tested in this study is their PAG size as reported in previous papers; 9, 13.5, and 50 lm for T91 [7], HCM12A [8], and HT-9 [9], respectively.…”

IGSCC of grain boundary engineered 316L and 690 in supercritical water

“…This was attributed to the lower diffusivity of the low-R boundaries compared to the RHABs which made the grain boundary diffusivity as a whole closer to the bulk diffusivity. The only study to date on IGSCC of GBE alloys in SCW was done by Gupta et al [25] on ferritic-martensitic alloy HT-9. In this study the observed mitigation of IGSCC was attributed to a reduction in precipitate coarsening at the CSLBs and LABs due to the lower diffusivities along these boundaries.…”

Deposition, characterization and performance evaluation of ceramic coatings on metallic substrates for supercritical water-cooled reactors

“…ZrO 2 coatings without open pores and crack-free were formed successfully on Zr-2.5Nb substrates using a plasma electrolytic oxidation method. The coated Zr-2.5Nb samples showed somewhat better corrosion resistance than the bare substrates when tested in static autoclaves but showed more-or-less identical weight changes when tests in a flowing system.…”

“…One of the most promising advanced reactor concepts is the supercritical water-cooled reactor (SCWR). Operating above the thermodynamic critical point of water (374°C, 22.1 MPa), SCWRs offer many advantages compared to current light water reactors (LWRs), such as the use of a single phase coolant with high enthalpy, the elimination of expensive components such as steam generators, dryers, and a low coolant mass inventory resulting in smaller components with much higher thermal efficiency (i.e., up to 50% thermal efficiency vs. about 33% thermal efficiency for LWRs) as well as better fuel usage [2]. The SCWR design fulfils the criteria of economics, safety and sustainability considered in the Generation IV International Forum.…”