Speciální mikrolegovaná ocel odolná proti požáru

Abstract

Fire resistant steel belongs among manifold structural steels widely demanded for its specific properties. Comparing to other structural steels, it´s typical of having better strength properties at elevated temperatures, i. e. minimum decrease in YS with increasing the temperature notably over the range of 300 – 600 °C. At temperatures up to 600 °C, the yield point of this type of steel falls to about 2/3 level of the YS measured at ambient temperature. Due to increased fire resistance parameters, the steel can practically be used in fireproof steel constructions where otherwise other passive protection systems have to be applied otherwise other (eg. rigid boards, spray and intumescent coatings, concerete encasement, sprinklers etc.). Generally, the development progress in this field contributes to acceleration and price reduction in building construction. This PhD thesis concerns the development programme of a new fire resistant steel in Třinecké železárny, a. s. Besides the application area, some complex information on improving the fire resistance are thoroughly explained. Further on, significant microstructural mechanisms resulting in fire resistance instability at higher temperatures are discussed. Finally, the new steel development progress from the selection of chemical composition to verification of all required properties according to production standards is then systematically elaborated in step-by-step order. Moreover, the new steel marketability analysis is also a part of this work.