|ZRNÍK Jozef||COMTES FHT a.s.|
|Spoluautoři KRAUS LIbor, DOBATKIN Sergey|
By application of thermomechanical controlled rolling and accelerated cooling, the ferrite grain refinement is limited to levels of ~ 5 μm in steels. The strain assisted or strain induced transformation could be considered for the refining process. The present work, likewise, deals with grain refinement of medium carbon steel AISI 1045 containing 0.45 wt pct carbon. The structure refinement was conducted in two steps. Preliminary grain refinement has been achieved due to multistep open die forging process, which provided total strain of 3-4 across the forged billet. Uniform and fine recrystallized ferrite structure μm ermomechanical process. The further grain refinement was accomplished during warm Equal Channel Angular Pressing (ECAP) at 400°C of preliminary thermomechanically processed specimens. The steel was subjected to four pressing passes. Employment of this processing route resulted in extensively elongated ferrite grains, which were sufficiently refined to size below 1 μm. order dynamically recrystallized ferrite grains enclosed by subgrains of low angle boundaries were formed within the former elongated ferrite grains. The aim of the investigation was to find an optimized relationship between mechanical properties and microstructure developed in steel.