半固态高铬铸铁球状先共晶奥氏体的形成

Formation of Spherical Pro-eutectic Austenite Grains in Semi-solid High Chromium Cast Iron

采用自行研制的倾斜取样板进行取样,并借助金相图像分析系统研究了半固态高铬铸铁先共晶奥氏体的衍变过程。结果表明,金属液在流动过程中被倾斜板过冷,奥氏体不断形核长大成枝晶状,枝晶又由于相互间的碰撞、摩擦等物理作用被熔断、折断、破碎而得到细化、球化。上述过程交替出现,初期以奥氏体形核长大为主,后期以枝晶奥氏体被熔断、折断、破碎而被细化、球化为主。

The evolution of pro-eutectic austenite in semi-solid high chromium cast iron was studied by self-made slope sampling plate through metallographical image analysis system. The dendritic austenite grains, which grew up from nucleus in the highly undercooled molten melt by the slop plate, were broken to the fine and spherical ones by a series of physical and metallurgic processes such as dendritic austenite grains conflicting, washing out each other. The previous austenite nucleation, growth, conflicting and washing out processes were taken place alternatively. But the austenite nucleation and growth process dominated during the initial molten melt flowing periods, and the conflictina and washina out orocess dominated durina the later flowina periods.