【摘要】 分析了采用板条马氏体大变形轧制工艺制备超细晶钢板时的显微组织演变过程及其晶粒细化机制。结果表明,该工艺包含3个具有不同晶粒细化机制的工艺过程:①轧前预淬火+回火使原始奥氏体晶粒分裂为均匀细小的板条马氏体,板条晶内部含有大量吸附着碳原子的位错;②大变形轧制细化、破碎板条马氏体,并进一步增加了组织中的位错密度;③在轧后再结晶退火时,基体中的高密度位错提供了超常的驱动力,使再结晶晶核尺寸小于1μm,400℃和500℃退火后钢板的晶粒尺寸分别为52nm和316nm。更多还原

【Abstract】 The microstructure evolution and grain-refining mechanism of the process, severe rolling of lath martensite, was studied. The result shows that the mechanism is composed of three steps: ① subdivision of austenite grains into homogeneous and tiny martensite laths with plenty of dislocations with C atoms absorbed during quenching and tempering before severe rolling; ② thinning and damage of martensite laths and increase of dislocation density in laths during severe rolling; ③ recrystallization driven by ultra-high density of dislocations in matrix, making the nucleus size less than 1 μm. The grain size of steel sheet annealed at 400 ℃ and 500 ℃ was 52 nm and 316 nm respectively.更多还原