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由于刀具的使用期限不很长,通常认为很少发生疲劳断裂。但是长期断续切削时刀具的疲劳断裂并不能排除,在重复冲击载荷作用下可引起疲劳。变形高速钢圆盘铣刀(φ160×7.3)失效的主要原因是切削齿剥落。其断口特征是多次冲击载荷作用下因疲劳过程才出现的断口,从中可看出疲劳裂纹扩展前沿的痕迹——平行带式的沟痕。断口的电子显微分析表明,铣刀使用过程中存在疲劳断裂,其表现是裂纹解理前沿呈明显的方向性,断裂处出现一系列平行平面并分布有碳化物斑。一次冲击断裂的断口没有发现这种情况。
Due to the short life of the tool, it is generally considered less prone to fatigue fracture. However, the long-term intermittent cutting tool fatigue fracture and can not be ruled out, in the repeated impact load can cause fatigue. Deformation high-speed steel disc cutter (φ160 × 7.3) failure is the main reason for cutting tooth spalling. The fracture feature is the fracture caused by the fatigue process under multiple impact loads. It can be seen from the fore-edge of the fatigue crack propagation that the parallel belt-type groove marks. Electron microscopic analysis of the fracture shows that there is fatigue fracture during the milling process, which shows that the cleavage front has obvious directionality, a series of parallel planes appear at the fracture and are distributed with carbide spots. An impact fracture fracture did not find this situation.