WC-Co硬质合金热机械腐蚀疲劳性能的研究

Study on Thermo-mechanical-corrosion Fatigue Behaviourof Cemented Carbides

采用自行设计的实验装置对两种WC-Co硬质合金在压压循环载荷和循环加热冷却同时作用下的热机械腐蚀疲劳行为进行了研究,研究了冷却介质pH值和Co含量对硬质合金热机械腐蚀疲劳性能的影响,同时采用SEM对断口形貌进行了分析。实验结果表明:疲劳断裂的宏观形貌主要是切断型的断裂,疲劳裂纹稳定扩展区上存在很多摩擦碎屑,在稳定扩展区并没有发现疲劳条纹的存在,瞬断区的断裂形貌与静态断裂特征一致。在本文所提供的热机械腐蚀疲劳实验条件下,并未发现冷却介质pH值对两种WC-Co系列的硬质合金的热机械腐蚀疲劳性能的影响,低Co含量的硬质合金YGH30具有比高Co含量硬质合金YGH60更优异的热机械腐蚀疲劳性能。

A set of experimental apparatus was invented to investigate the thermo-mechanical- corrosion fatigue behaviour of two WC-Co cemented carbides under the simtdtaneous effect of compression-compression cyclic load and cyclic beating and cooling, The influence of Co content and pH value on the thermo-mechanical-corrosion fatigue behaviour was studied. Fractographic analysis was carried out by SEM. The results show that the macroscopic fracture morphology exhibits a shear type. A lot of friction debris is seen in the stable crack growth region while no fatigue stripes are found. The unstable crack growth region exhibits a static fracture appearance. In the present work,no significant influence of pH of the cooling medium on the thermo-mechanical- corrosion fatigue hehaviour is found for both cemented carbides. And the lower Co content cemented carbide YGH30 shows a better thermo-mechanlcal-corrosion fatigue behavior than the higher Co content cemented carbide YGH60.