Abstract
To investigate the recrystallization behaviour of a 17 Cr ferritic stainless steel during hot rolling, wedge shaped specimens taken from continious casting slab were hot rolled at temperatures from 1 173 K to 1 453 K in single pass manner, and then hardness test and optical microscopic observation were conducted. The results are as follows.
At relatively lower heating temperatures near 1 173 K, deformation structure having many deformation bands forms especially in the vicinity of austenite phases that are isolatedly scattered in the initial ferrite grains. At higher rolling reduction, much deformation bands are introduced. At heating temperatures near 1 273 K, deformation structure changes into partial recrystallization structure with increasing rolling reduction. At relatively higher heating temperatures, recovery structure which contains many fine subboundaries is attained. Therefore the nose in recrystallization behavior exists at near 1 273 K.
In the recrystallization region, recrystallization is accelerated with increasing rolling reduction, and consequently hardness of hot rolled specimens decreases at higher rolling reduction. However in the recovery region accompanied with sub-boundaries hardness increases with increasing rolling reduction.
From the above results and discussion in mechanism of microstructural changes under restoration process it is concluded that recrystallization structure is statically formed after hot rolling and recovery structure is dynamically formed in hot rolling process.
