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将亚共晶高铬铸铁铸态试样和半固态试样加热至液固温度区间保温,研究了保温过程中初生奥氏体形态和尺寸的演变过程。结果表明,两种试样保温过程中奥氏体晶粒都经历了粗化并趋于球化的发展过程,其粗化是由于溶质原子迁移和晶粒合并所导致。原始奥氏体形态决定其球化速度,含颗粒状奥氏体的半固态试样中奥氏体经历了简短的长大而球化过程。含枝晶状奥氏体的铸态试样中奥氏体先形成网状结构,然后经过复杂的熔断、长大过程,奥氏体球化速度极其缓慢。
The sub-eutectic high chromium cast iron as-cast sample and semi-solid sample were heated to the liquid-solid temperature range for insulation. The evolution of the morphology and size of primary austenite in the process of heat preservation was studied. The results show that the austenite grains in both samples undergo a coarsening process and tend to spheroidize during the heat preservation process. The roughening is caused by the migration of solute atoms and the coalescence of grains. The initial austenite morphology determines the rate of spheroidization. The austenite undergoes a brief growth and spheroidization in a semi-solid sample containing granular austenite. Austenite in the as-cast sample containing dendritic austenite forms a network structure first, and then undergoes a complicated process of fusing and growth, resulting in extremely slow austenite spheroidization.