Sökning: "John Ågren"

Visar resultat 21 - 25 av 26 avhandlingar innehållade orden John Ågren.

  1. 21. Welds in the lean duplex stainless steel LDX 2101 : effect of microstructure and weld oxides on corrosion properties

    Författare :Elin M. Westin; John Ågren; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Duplex stainless steel; welding; weld metal; HAZ; nitrogen; manganese; austenite formation; phase balance; precipitates; pitting resistance; heat input; solidification; element loss; evaporation; deposition; weld oxides; discoloration; mechanical properties; thermo-mechanical simulation; Geeble; GTA; laser; LOM; SEM; EDS; TEM; Leco; EPMA; ferroxyl test; XPS; post weld cleaning; pickling; Materials science; Teknisk materialvetenskap;

    Sammanfattning : Duplex stainless steels are a very attractive alternative to austenitic grades due to their higher strength and good corrosion performance. The austenitic grades can often be welded autogenously, while the duplex grades normally require addition of filler metal. LÄS MER

  3. 22. Thermodynamic and Kinetic Investigation of the Fe-Cr-Ni System Driven by Engineering Applications

    Författare :Wei Xiong; Malin Selleby; John Ågren; Byeong-Joo Lee; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; phase transformation; magnetism; spinodal decomposition; stainless steel; low temperature CALPHAD; phase field; ab initio; atom probe tomography; calorimetry; SRA - E-vetenskap SeRC ; SRA - E-Science SeRC ; SRA - Energy; SRA - Energi;

    Sammanfattning : This work is a thermodynamic and kinetic study of the Fe-Cr-Ni system as the core of stainless steels. The Fe-Cr, Fe-Ni and Cr-Ni systems were studied intensively using both computational and experimental techniques, including CALPHAD (CALculation of PHAse Diagrams), phase field simulation, ab initio modeling, calorimetry, and atom probe tomography. LÄS MER

  4. 23. Phase Separation in Stainless Steels Studied by Small-angle Neutron Scattering

    Författare :Xin Xu; Peter Hedström; Joakim Odqvist; John Ågren; Cristelle Pareige; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fe-Cr alloys; stainless steels; spinodal decomposition; phase separation; small-angle neutron scattering; mechanical properties; Teknisk materialvetenskap; Materials Science and Engineering;

    Sammanfattning : Fe-Cr based steels, i.e. stainless steels, possessing a combination of excellent corrosion resistance and good mechanical properties, have indispensable applications ranging from low-end cooking utensils, to sophisticated components for nuclear power plants. LÄS MER

  5. 24. Martensitic Transformations in Steels : A 3D Phase-field Study

    Författare :Hemantha Kumar Yeddu; John Ågren; Annika Borgenstam; Yunzhi Wang; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Phase-field method; Martensitic transformations; Plastic de formation; Multi-length scale modeling; Microstructure; Stress states; Steels;

    Sammanfattning : Martensite is considered to be the backbone of the high strength of many commercial steels. Martensite is formed by a rapid diffusionless phase transformation, which has been the subject of extensive research studies for more than a century. LÄS MER

  7. 25. 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