Sökning: "Cr-steels"

Visar resultat 1 - 5 av 6 avhandlingar innehållade ordet Cr-steels.

  1. 1. Development of a new generation of 12% Cr steels: Z-phase strengthened steels

    Författare :Masoud Rashidi; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; atom probe tomography; Z-phase; 9-12% Cr steels; martensitic steels; transmission electron microscopy; precipitation hardening; creep;

    Sammanfattning : Fossil-fuel fired steam power plants provide more than 60% of the electricity generated worldwide, and account for about one third of the global CO2 emissions. The thermal efficiency of the steam power plants is limited by the maximum allowed steam temperature and pressure, which in turn are determined by the long-term corrosion and creep resistance of economically viable materials. LÄS MER

  3. 2. Aspects of microstructural evolution in chromium steels in high temperature applications

    Författare :Åsa Gustafson; KTH; []
    Nyckelord :Cr-steels; nucleation; coarsening; model; DICTRA; precipitates; carbides; carbo-nitrides; MX; VN; M23C6; TiC; TEM; EFTEM; Curie-temperature;

    Sammanfattning : In this thesis 9-12 % Cr steels, used for high-temperaturecomponents in fossil-fired power plants are considered. Thecreep strength of thees steels depend on their microstructurethat consists of a matrix of tempered lath martensite withdensely distributed precipitates. LÄS MER

  4. 3. Creep modelling of particle strengthened steels

    Författare :Hans Magnusson; Rolf Sandström; Göran Engberg; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Particle strengthening; dislocation climb; ferritic steels; dislocation evolution; creep rate modelling; Materials science; Teknisk materialvetenskap;

    Sammanfattning : Materials to be used in thermal power plants have to resist creep deformation for time periods up to 30 years. The role of alloying elements for creep strength of 9-12% Cr steels is analysed. The creep strength in these steels relies on minor additions of alloying elements. LÄS MER

  5. 4. Development of a new generation of creep resistant 12% chromium steels: Microstructure of Z-phase strengthened steels

    Författare :Masoud Rashidi; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; phase transformation; CrNbN; impact toughness; Creep; CrTaN; Laves-phase; atom probe tomography; precipitation hardening; M2N; MX; transmission electron microscopy; coarsening;

    Sammanfattning : Fossil-fuel fired steam power plants provide more than 60% of the electricity generated worldwide, and account for about one third of the global CO2 emissions. Increasing the steam temperature and pressure leads to a higher thermal efficiency of the power plants and thus lower emissions. LÄS MER

  7. 5. Theoretical studies of boron and transition-metal carbonitride additions in steels

    Författare :Dan Fors; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Electronic structure; Dislocation network; Interfaces; Peierls-Nabarro model; Density functional theory; Steels; Coarsening; Diffusion; Misfit; Precipitates;

    Sammanfattning : Martensitic 9-12%Cr steel alloys are today widely used as critical components in fossil-fired steam power plants with steam temperatures up to 600°C, where sound oxidation resistance and excellent creep strength are required. Their strength and long-term creep resistance are closely connected to the presence and stability of Cr-rich M23C6 (M = Cr, Fe) carbides and densely distributed MX precipitates (M = transition metal, X = C or N), which effectively act as obstacles for dislocation migration. LÄS MER