Repository logo

Browsing by Subject "stal - metalografia"

Filter results by typing the first few letters
Now showing 1 - 1 of 1
  • thumbnail.journal.alt
    Item type:Doctoral Dissertation, Access status: Open Access ,
    Kinetyka przemian fazowych przy odpuszczaniu i jej wpływ na własności stali
    (Data obrony: 2007-05-14) Bała, Piotr
    Wydział Inżynierii Metali i Informatyki Przemysłowej
    In the paper a description of phase transformations during continuous heating and isothermal holding from quenched state (tempering), its influence on properties of steel has been presented and the influence of development of selected phase transformations during tempering (by pre-tempering) on final properties of steel has been defined. The following sequence of phase transformations during tempering of test tool steels has been found: precipitation of carbide $\varepsilon$, precipitation of cementite within the range of which the retained austenite transforms, after that, in case of steels characterized by secondary hardness effect, independently nucleating carbides of $MC$ type and the subsequent $M_{2}C$ Separated carbides of $MC$ type remain in the structure exhibiting poor inclination for coagulation, while carbides of $M_{2}C$ type transform „in situ” into $M_{6}C$ and $M_{23}C_{6}$ carbides.It has been shown that development (by pre-tempering) of selected phase transitions during tempering may have an effect on steel properties after actual tempering. An advantageous influence of pre-tempering within the range of carbides $\varepsilon$ precipitation has been stated. The influence of the progress of cementite precipitation and transition of retained austenite may not be generalized for its strong dependence from chemical composition of the steel. However it is possible, using CHT (continuous heating transformations from quenched state) and ITH (isothermal holding transformations from quenched state) diagrams, to control both transformations in order to change desired properties of steel.