Sökning: "John Ågren"

Visar resultat 6 - 10 av 26 avhandlingar innehållade orden John Ågren.

1. 6. 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. 7. Studies of oxide reduction and nitrogen uptake in sintering of chromium-alloyed steel powder

   Författare :Ola Bergman; John Ågren; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; powder metallurgy; chromium; pre-alloying; surface oxides; sintering; Materials science; Teknisk materialvetenskap;

   Sammanfattning : The powder metallurgy (PM) process route is very competitive for mass production of structural steel components with complex shape, due to efficient material utilisation, low energy consumption, and short overall production time. The most commonly used alloying elements are the processing friendly metals Cu, Ni and Mo. LÄS MER

4. 8. Phase equilibria and thermodynamic properties of high-alloy tool steels : theoretical and experimental approach

   Författare :Johan Bratberg; John Ågren; Bengt Hallstedt; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; thermodynamic modelling; thermodynamic calculations; tool steels; high-speed steels; CALPHAD; Other materials science; Övrig teknisk materialvetenskap;

   Sammanfattning : The recent development of tool steels and high-speed steels has led to a significant increase in alloy additions, such as Co, Cr, Mo, N, V, and W. Knowledge about the phase relations in these multicomponent alloys, that is, the relative stability between different carbides or the solubility of different elements in the carbides and in the matrix phase, is essential for understanding the behaviour of these alloys in heat treatments. LÄS MER

5. 9. Structure and mechanical properties of dual phase steels : An experimental and theoretical analysis

   Författare :Ylva Granbom; John Ågren; Ir Bruno C. De Cooman; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Dual phase steels; continuous annealing; dilatometry; microstructure; mechanical properties; process parameters; dislocation model; plastic deformation; Metallurgical process and manufacturing engineering; Metallurgisk process- och produktionsteknik; Mikrostrukturutveckling i avancerade höghållfasta stål;

   Sammanfattning : The key to the understanding of the mechanical behavior of dual phase (DP) steels is to a large extent to be found in the microstructure. The microstructure is in its turn a result of the chemical composition and the process parameters during its production. LÄS MER

7. 10. On high temperature oxidation resistance : Towards the materials genome of high temperature alloys

   Författare :Samuel Hallström; John Ågren; Roger Reed; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materials Science and Engineering; Teknisk materialvetenskap;

   Sammanfattning : The efficiency of a heat engine increases with increasing service temperature. This leads to a demand for material that can withstand aggressive environments and sometimes also high load at higher and higher temperature. That is the rationale for the work of this thesis. LÄS MER