GEST80钢塑料模具裂纹原因分析

Analysis on crack reason of GEST80 steel plastic mold

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。

The causes of cracking failure of a mould made of GEST 80 steel were analyzed through fracture morphology observation and microstructure test by using metallographic microscope,scanning electron microscope and energy spectrometer. The results show that the failure is caused by too high heating temperature and too long holding time in the final heat treatment process,which leads to serious overheating and grains growing up quickly. The coarse grains weaken grain boundary and remarkably decrease intergranular strength of the steel. It is the transformation stress during hardening that exceeds the tensile strength of the material,and results in the die to crack in the quenching. Therefore,the improvement measures and optimized schemes for the quenching processing of the die are put forward,which refine the microstructure and prolong the service life of the dies.