Oxidation of ferritic and ferritic–martensitic steels in flowing and static supercritical water

Steam oxidation of aluminide coatings under high pressure and for long exposures

“…In this case, heat resistant ferritic-martensitic steels are commonly used for superheater tubes and pipes in ultrasupercritical boilers [6,7]. They offer a better heat transfer behaviour and lower thermal expansion coefficients [6,8,9] than austenitic stainless steels or the more expensive nickel base alloys Among this steel range, the T/P92 heat resistant steels (ASME grade 92) have been recognized as key structural components for ultrasupercritical power plants [10]. Despite its good properties, the P92 ferritic-martensitic steel has to be employed up to 650°C to maintain its mechanical resistance [6].…”

High Temperature Oxidation Behavior of Fe-Cr Steel in Air at 1000-1200 K

“…Meanwhile, the reason for gap formation at the inner/outer oxides interface seems to be the same as oxide cracking and spallation which commonly takes place at the oxide/alloy and oxide/coating interface. Several studies have pointed out that oxide cracking and spallation can occur due to thermal stress arising from a different in thermal expansion between oxide and the underlying materials [3,[5][6][7][8]11,19], grow stress [3,7,8,18] and the formation of other nonadhesive oxide/spinel [7]. During heating and cooling, the thermal stress can enhance the oxide crackingand spalling.…”

“…It can acts as short circuit part of oxygen. Accordingly, oxygen can diffuse easily to the alloy surface [1,7,18,19]. Meanwhile, the reason for gap formation at the inner/outer oxides interface seems to be the same as oxide cracking and spallation which commonly takes place at the oxide/alloy and oxide/coating interface.…”

“…The irregular and porous morphologies can be observed in the outer part of oxide scale after high temperature oxidation. The pores in the oxide layer are mostly formed due to vacancy coalescent which can act as transport paths for oxygen diffusion [1,7,18,19], leading to a high oxidation rate and the formation of thick oxide layer. In order to obtain more detail information on the microstructural development of the oxide scale on Fe-Cr steel after high temperature oxidation test at 1000-1200 K for 72 ks, the cross sectional observation was carried out by SEM and the elemental distribution across the oxidized sample was analyzed by EDX.…”

Effect of PCGTAW on the Inconel 690 alloy with respect to microsegregation attainment in comparison with the base metal processed with autogenous welding

“…This alloy was first used in nickel alloys showing good strength in comparison with stainless steel with regard to the corrosion resistance. 9,10 It is used in new areas like steam-generator tubing and other hightemperature corrosive environments. Alloy 600 is not completely resistant to different types of corrosion, depending on the environment, in which it is used, 11 the structural property 12 and the atmosphere, to which it is exposed.…”