Orthogonal experiments were designed to investigate and to compare failure modes of the Al2 O3/Ti ( C, N) ceramic tool in intermittent turning of hardened steel in different cutting speed.The results show that the main tool failure modes are chipping and flaking at low speed, and fatigue failure of impact is small.With the increasing of cutting speeds, the influence of fatigue failure is gradually increased.At high speed, the main failure modes are fracture caused by fatigue crack propagation.Due to the difference of in-terior stress level of cutting tool at different cutting speeds, fatigue characteristics are differently shown because of the variation of crack propagation rate and direction.At lower cutting speed, the fatigue characteristic is shown fatigue striations, while the characteristic is fatigue curve at high cutting speed.%采用Al2 O3／Ti （ C， N）陶瓷刀具进行淬硬钢的断续车削正交试验，对不同切削速度下刀具的失效形态进行了对比。结果表明，低速时，刀具的失效形态主要是崩刃和前刀面剥落，疲劳破损影响较小。随着切削速度的增加，疲劳破损对刀具的影响逐渐增大。高速时，疲劳裂纹扩展引起的破损成为刀具主要失效形式。在不同切削速度下，刀具内部的应力水平不同，导致裂纹扩展速率及裂纹方向有所差异，疲劳特征则表现出不同形式。低速时疲劳特征表现为疲劳条带，而高速时的疲劳特征通常为疲劳弧线。
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