摘要
利用实验室自制的调温、调频、调载冲击实验机对3种组织成分的WC-Co硬质合金进行了不同实验条件下的冲击疲劳试验,研究了组织成分及实验条件对硬质合金冲击疲劳寿命的影响;通过扫描电子显微镜(SEM)及透射电镜(TEM)重点分析了疲劳过程中硬质合金微观组织的变化。结果表明:硬质合金的冲击疲劳寿命随试验温度和冲击能量的升高而下降,且随着冲击能量和试验温度的提高其疲劳敏感性增大。WC-Co合金的冲击疲劳断裂主要是以WC/WC界面和粘结相开裂为主,裂纹沿WC/WC和WC/Co界面及在Co相中扩展。随冲击次数的增加WC中位错数量增多并相互缠结,同时Co相发生面心立方-堆垛层错-密排六方的马氏体转变。
Impact fatigue tests for three types of cemented carbide with different composition and microstructure were carded out under various experimental conditions using self-made test machine with controllable temperature, frequency and load. The effects of microstructure and experimental conditions on the service life of the cemented carbide in the case of suffering impact were analyzed. The evolution of the microstructure in the cemented carbide after impact fatigue was characterized by scanning electron microscope （SEM） and transmission electron microscope （TEM）. The results show that the service life of the cemented carbide decreases with the increasing of impact load and temperature, whereas the sensitivity of fatigue increases. The cracking of the WC-Co cemented carbide is mostly along with WC/WC interface and binder phase, the cracks propagate are along with WC/WC and WC/Co interface and in Co phase. In the WC phase a large number of dislocations occur and twist when impact number increases. Co transforms from face-centered cubic phase to stacking fault to close-packed hexagonal martensite during the impact fatigue process.
出处
《硬质合金》
CAS
2015年第1期9-18,共10页
Cemented Carbides
基金
五矿湖南有色基金项目(YSZN2013CL01)
国家科技支撑计划项目(2011BAE09B03)
关键词
硬质合金
冲击疲劳
裂纹扩展
断裂
cemented carbide
impact fatigue
crack propagation
fracture
