高磷球墨铸铁曲轴快速不平衡正火工艺

Quick Imbalance Normalizing Process for High Phosphorus Nodular Iron Crankshaft

用化学成分分析、金相检测、力学性能试验等方法对发生早期脆断的QT600-3曲轴进行分析。结果表明,脆断的原因主要是球铁的含磷量过高,使基体中磷共晶数量增加且沿晶界呈网状分布,造成曲轴伸长率和韧性的下降。对高磷球铁曲轴采用快速不平衡正火工艺,可获得含有破碎铁素体的金相组织,并能够减少磷共晶数量,促进伸长率和韧性的提高,最终较好地解决高磷球铁曲轴的脆断问题。

The causes of early brittle fracture of QT600-3 nodular iron crankshaft were analyzed by chemical composition analysis,metallographic examination and mechanical performance test.The results show that excessive phosphorus in the nodular iron is the main cause of the brittle facture,which increases the number of phosphide eutectics that distributed reticularly along the grain boundary in the matrix,and thus decreases elongation and toughness of the crankshaft.By applying a quick imbalance normalizing process,the proposed method can produce microstructures with broken ferrite and reduced number of phosphide eutectics improving the elongation and toughness of the high phosphorus iron crankshaft,and effectively solve the brittle facture problem.