硬质合金截齿刀在使用中的开裂及疲劳行为分析

THE CRACKING FAILURE AND CRACK FATIGUE PROPAGATION ANALYSIS OF WC-Co COMPOSITE BITS IN COOL CUTTER USED IN HARD COAL

借助于扫描电镜，全面分析了截齿硬质合金刀头在使用过程中的开裂及裂纹的疲劳扩展行为。结果表明，硬质合金刀头在使用过程中的开裂是由针焊开裂、热疲劳和冲击疲劳所造成的微裂纹引起的。裂纹扩展的疲劳行为主要源于硬质含金的高Co含量和大的WC颗粒造成的对裂纹扩展的阻碍、裂纹扩展路线的拐折造成的裂纹尖端应力强度因子的降低及刀头承受的交变冲击载荷的共同作用。

<Absract> The cracking failure and crack fatigue behavior of Co-WC Composite bits in coal cutter used for hard coal is analysized by means of SEM. The results show that the crack failure of composite bits was caused by brazying crack on composite bits surface,thermal fatigue and impact fatigue during operation of bits. The fatigue behavior of Crack propagation is the result of cooperation among the resistance of crack propagation caused by higher Co content and coarse WC grain size, the decrease in the Value of K1 at crack tip path by the bend of crock propagation course and the alternating impact load coal cutters subjected.