Vliv rychlosti ochlazování na fázové transformace C-Mn kolejnicové oceli

Abstract

Based on the evaluation of laboratory dilatometric tests with deformation, which were performed on the plastometer Gleeble 3800 with using optical noncontact scanning dilatometer and based on evaluated metallographic analyses and hardness tests of dilatometric tested samples, the DCCT diagram of rail steel R260 were constructed. On the Reversing rolling mill at Třinecke železarny a.s. was measured the surface temperature of the head of rail during their accelerated or free cooling after finish rolling. These rails were also subjected to metallographic analyses and hardness tests. The measured cooling curves of these rails were inserted to the DCCT diagram. From obtain results ensue that unwanted martensitic phase is generated in the structure at a cooling rate 5 °C•s-1 or higher and selected accelerated manner of cooling the head of rails from steel R260 is safety from point of reaching needed structure.