采用光学显微镜、扫描电镜及能谱仪,通过断口形貌观察及显微组织检测,对GEST80钢模具失效件开裂的原因进行分析。结果表明,该塑料模具失效件开裂的原因,是因为模具材料在最终热处理过程中,加热温度过高及保温时间过长,材料组织产生严重过热现象,致使组织晶粒急剧长大。晶粒粗大带来晶间弱化,晶间强度显著降低,热处理淬火的组织应力超过材料的抗拉强度,造成模具失效件的淬火应力开裂。并对模具材料的各加工工序,提出了改进措施及优化方案,使组织晶粒得到细化,保证和延长模具产品的使用寿命。 Using optical microscope, scanning electron microscope and energy dispersive spectrometer, the fracture reason of GEST80 steel die failure was analyzed by fracture surface morphology observation and microstructure inspection. The result shows that the reason of the cracking of the plastic mold failure parts is because the mold material is overheated during the final heat treatment, the heating temperature is too high and the holding time is too long, causing the crystal grains to grow sharply. Coarse grains lead to grain intergranular weakening, intergranular strength is significantly reduced, heat treatment of the quenched tissue stress exceeds the tensile strength of the material, resulting in mold failure of the quenching stress cracking. And the processing of mold materials, put forward improvements and optimization programs to refine the grain of the organization to ensure and extend the life of mold products.