VLIYANIE REZHIMOV NAGREVA I DEFORMATSII NA RAZNOZERNISTOST' I VELICHIMU AUSTENITNOG ZERNA STALI P18.

A study was made of the causes and conditions of occurrence of grain size inhomogeneity in steel R18 during rolling and subsequent heat treatment. It was found that the reason for grain size inhomogeneity in steel R18 during plastic deformation is an excessively high heating temperature during deformation of the steel. Plastic deformation of steel at temperatures of 1100 degree C or higher is accompanied by the formation in the steel of a blockless recrystallized austenite, which has a great tendency to grow during secondary recrystallization. In subsequent annealing or high-temperature tempering operations the grains may be crushed during recrystallization, but the grain size inhomogeneity remains. Steel R18 possesses a maximum grain size inhomogeneity, if plastic deformation is terminated at small area reductions (28-30%) and at temperatures of about 1100 degree C.