Sökning: "VN precipitates"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden VN precipitates.

  1. 1. 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

  3. 2. Precipitate stability in creep resistant 9-12% chromium steels

    Författare :Ardeshir Golpayegani; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; growth; precipitates; coarsening; atom probe field ion microscopy APFIM ; energy filtered TEM EFTEM ; 9-12% chromium steel;

    Sammanfattning : 9-12% chromium steels are used extensively in modern steam power plants at service temperatures up to 600°C. These materials are subjected to creep deformation during exposure which is the limiting factor in increasing the steam temperature and thus the thermal efficiency of the plants. LÄS MER

  4. 3. Precipitation Reactions at High Temperatures in 9-12% Chromium Steels

    Författare :Mats Hättestrand; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; thermo-dynamical simulations; creep resistant; 9-12% chromium steel; energy filtered TEM; precipitates; atom probe field ion microscopy; quantitative metallography;

    Sammanfattning : This thesis reports on quantitative investigations of microstructural changes, mainly precipitation reactions, occurring during heat treatment, ageing and creep of 9-12% chromium steels. Several alloys with varying composition have been investigated. LÄS MER

  5. 4. Multiscale Modeling of Interfaces

    Författare :Sven Johansson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; misfit; Peierls-Nabarro model; semicoherent interfaces; interfaces; cemented carbides; grain boundaries; microstructure; VN precipitates; density-functional theory;

    Sammanfattning : Understanding strength and stability of interfaces between dissimilar materials or phases is a highly active field of contemporary materials research. Knowledge of interface structure and energetics is important for modeling of complex materials both on a mechanical and thermodynamical level as well as for many functional properties. LÄS MER

  7. 5. 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