Sökning: "sigma-phase"

Visar resultat 1 - 5 av 11 avhandlingar innehållade ordet sigma-phase.

  1. 1. Influence of multiple welding cycles on microstructure and corrosion resistance of a super duplex stainless steel

    Författare :Vahid Hosseini; Leif Karlsson; Högskolan Väst; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Super duplex stainless steel; autogenous TIG welding; multiple welding thermal cycles; sensitization; nitrogen loss; sigma phase; ferrite content; production technology; Production Technology; Produktionsteknik; Manufacturing and materials engineering; Produktions- och materialteknik;

    Sammanfattning : Super duplex stainless steel (SDSS) has found a wide use in demanding applications such as offshore, chemical and petrochemical industries thanks to its excellent combination of mechanical properties and corrosion resistance. Welding of SDSS, however, is associated with the risk of precipitation of secondary phases and formation of excessive amounts of ferrite in the weld metal and heat affected zone. LÄS MER

  3. 2. Fracture toughness properties of duplex stainless steels

    Författare :Henrik Sieurin; Rolf Sandström; Jan-Olof Nilsson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; duplex stainless steel; fracture toughness; austenite reformation; sigma phase; material optimisation; Materials science; Teknisk materialvetenskap;

    Sammanfattning : Good toughness properties in base and weld material enable the use of duplex stainless steels (DSS) in critical applications. DSS offer high strength compared to common austenitic stainless steels. LÄS MER

  4. 3. Evolution of Microstructure in Two Austenitic Alloys at High Temperatures

    Författare :Jenny M Erneman; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; N ; Thermo-Calc; Nb C; gamma prime; DICTRA; APFIM; quantitative metallography; AISI 347; Alloy 800; energy filtered TEM; sigma phase;

    Sammanfattning : A niobium stabilised AISI 347 austenitic stainless steel was investigated after static ageing and creep deformation at temperatures between 500°C and 800°C for times up to 88 000 h. Coarse and fine NbX precipitates and also s-phase precipitates were formed in the temperature range 500-700°C. LÄS MER

  5. 4. Precipitation reactions in a stabilised austenitic stainless steel

    Författare :Jenny Källqvist; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEM; niobium stabilised; modelling; ageing; creep; SEM; niobium carbo-nitrides; sigma-phase; microstructure;

    Sammanfattning : .... LÄS MER

  7. 5. Transformation phenomena in a super duplex stainless steel

    Författare :Anders Wilson; KTH; []
    Nyckelord :Duplex stainless steel; Microstructure; Phase transformations; Precipitates; Sigma phase; Kinetics; Thermodynamic calculation; Continuous cooling transformation diagram; Time temperature transformation diagram; Computer model.;

    Sammanfattning : Duplex stainless steels consist of about equal fractions offerrite and austenite and are attractive due to their highcorrosion resistance against pitting corrosion and stresscorrosion cracking. The pitting corrosion resistance can bedescribed by the PREN value which is defined asPREN=%Cr+3.3*%Mo+16*%N. LÄS MER