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Visar resultat 1 - 5 av 25 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Modelling phase separation in Fe-Cr alloys : A continuum approach

    Författare :Thomas Barkar; John Ågren; Nele Moelans; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Phase separation; spinodal decomposition; nucleation; diffusion; thermodynamics; kinetics; steel; ferritic;

    Sammanfattning : The formation of Cr-rich and Fe-rich domains upon ageing of an initially homogeneous Fe-Cr alloy at elevated temperatures (300-600 ºC) is commonly referred to as phase separation. The behaviour originates from a miscibility gap in the Fe-Cr phase diagram. LÄS MER

  3. 2. An Atom-Probe Tomography Study of Phase Separation in Fe-Cr Based Steels

    Författare :Jing Zhou; John Ågren; Peter Hedström; Hänninen Hannu; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fe-Cr alloys; Ferritic stainless steels; Spinodal decomposition; Phase separation; Atom probe tomography; Radial distribution function RDF ; Materials Science and Engineering; Teknisk materialvetenskap;

    Sammanfattning : Stainless steels are very important engineering materials in a variety of applications such as in the food industry and nuclear power plants due to their combination of good mechanical properties and high corrosion resistance. However, ferrite-containing stainless steels are sensitive to the so-called ‘475°C embrittlement’, which is induced by phase separation of the ferrite phase, where it decomposes into Fe-rich ferrite (α) and Cr-rich ferrite (α'). LÄS MER

  4. 3. Investigations on the Oxidation of Iron-chromium and Iron-vanadium Molten Alloys

    Författare :Haijuan Wang; Seshadri Seetharaman; Ashok Lahiri; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Oxidation; High-alloy steelmaking; Retention; CO2-O2; Fe-Cr melt; Fe-Cr-C melt; Fe-V melt; Vanadium containing slags; Kinetics; Thermodynamics properties.; Metallurgical process engineering; Metallurgisk processteknik; Materials science; Teknisk materialvetenskap;

    Sammanfattning : With the progress of high alloy steelmaking processes, it is essential to minimize the loss of valuable metals, like chromium and vanadium during the decarburization process, from both economic as well as environmental view points. One unique technique to realize this aim, used in the present work, is the decarburization of high alloy steel grades using oxygen with CO2 in order to reduce the partial pressure of oxygen. LÄS MER

  5. 4. Laser cladded steel - microstructures and mechanical properties of relevance for railway applications

    Författare :Simon Niederhauser; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fe-Cr alloy; Carbon Steel; Microstructure; Internal Stresses; HAZ; Laser Cladding; Co-Cr alloy; Cracking Behaviour; Mechanical Properties; Low Cycle Fatigue;

    Sammanfattning : Owing to increased requirements like increased axle load for railway wheels and rails, new material have to be employed. However, these requirements are mostly surface related, which makes it appropriate to change only the surface layer while keeping the bulk unchanged. LÄS MER

  7. 5. Thermodynamic and kinetic properties of Fe-Cr and TiC-ZrC alloys from Density Functional Theory

    Författare :Vsevolod Razumovskiy; Pavel Korzhavyi; Andrei Ruban; Malin Selleby; Sergei Dudarev; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ab initio; first principles; point defects; vacancy clusters; alloys; steels; iron; carbides; diffusion; phase diagram; density functional theory; elastic constants; elastic properties; thermodynamic modelling;

    Sammanfattning : The complete and accurate thermodynamic and kinetic description of any systemis crucialfor understanding and predicting its properties. A particular interest is in systemsthat are used for some practical applications and have to be constantly improved usingmodification of their composition and structure. LÄS MER