微观组织参数及工艺条件对430不锈钢凝固显微结构的影响

Effect of microstructural parameters and casting conditions on the solidification microstructure of 430 stainless steel

在多元合金CAFE模型的基础上,分析了微观组织参数(形核密度、高斯分解参数、Gibbs-Thomson系数等)与430不锈钢凝固过程中晶粒形貌的复杂关系,以及过热度与冷却强度等工艺参数对凝固组织的影响.研究发现,晶粒尺寸和柱状晶向等轴晶转变不仅与体最大形核过冷度有关,也受体形核密度的影响.高斯分解参数和Gibbs-Thomson系数增大时,一次枝晶间距减小,等轴晶范围增大;但当它们增加至一定范围后,其对显微结构的影响逐渐变得不明显.过热度或冷却强度增大时,等轴晶范围减小,但一次枝晶间距的变化不明显.

The relation of the morphology of grains in 430 stainless steel with microstructural parameters, such as grain nucleation density, Gaussian decomposition parameters and Gibbs-Thomson coefficient, was studied based on the CAFE model. The effects of casting conditions, such as superheat and cooling intensity, on the solidification microstructure were also analyzed in this paper. It is found that the grain size and the columnar to equiaxed transition （ CET） are both affected by maximum bulk nucleation undercooling and maximum nucleation density. As the Gaussian decomposition parameters and Gibbs-Thomson coefficient increase in an appropriate range, the primary dendrite arm space decreases, but the central equiaxed area increases. Besides, the central equiaxed area decreases with increasing superheat and cooling intensity, while the primary dendrite arm space shows no obvious change.