金属型球铁磨球非平衡凝固特性与成分控制

Non-equilibrium Solidification Characteristics and Composition Control of the Metal Mould Nodular Iron Ball

通过分析不同成分球铁磨球零件性能和金相组织,对金属型磨球的非平衡凝固特性进行了较深入的研究。试验结果发现,过共晶球铁凝固时出现非平衡奥氏体;亚共晶球铁出现非平衡渗碳体相和晕圈铁素体;在柱状晶与等轴晶过渡区中存在着夹杂和偏聚物。为改善球铁磨球的显微组织及性能,球铁成分应控制在共晶或稍过共晶范围。

The non-equilibrium crystallizing processes of the metal mould nodular iron ball were investigated through analyzing the properties and microstructures of the nodular iron grinding ball. The results show that during non-equilibrium solidification the non-equilibrium austenite appears in hyper-eutectic nodular iron and the halo-ring ferrite, non-equilibrium cementite appear in hypo-eutectic nodular iron, and the inclusion and segregated solute distribute in the transition boundary of the column crystal and the equiaxial crystal. In order to improve the microstructure and the properties of the nodular iron ball, the chemical composition should be controlled in the point of eutectic or hyper-eutectic near the point of eutectic.