Cr12钢水胀型模具底座在使用过程中发生批量断裂，采用宏观检验、化学成分分析、金相检验、断口分析、硬度测试等方法对该批模具底座断裂的原因进行了分析。结果表明：该批模具底座断裂为沿晶脆性断裂；断裂的主要原因为模具材料碳含量超标，且锻造不充分导致共晶碳化物粗大且呈严重网状聚集分布，造成应力集中，在内应力和外力的共同作用下模具底座产生裂纹并迅速扩展而断裂。

The Cr12 steel water swelling mold bases fractured in bulk during use, and the fracture reasons of the mold bases were analyzed by macroscopic inspection, chemical composition analysis, metallographic examination, fracture analysis and hardness test. The results show that the fracture of the mold bases was brittle fracture. The main reasons for the fracture were that the carbon content of the mold material was excessive and the forging was not enough, which resulted in coarse eutectic carbides and serious reticular aggregation distribution, and eventually led to stress concentration of the material. Under the co-action of internal stress and external force, cracks generated in the mold bases, and then spread rapidly and led to fracture.