为研究钻、铰工艺对紧固孔件疲劳寿命的影响, 分别对LY12CZ硬铝合金疲劳试样采用钻、铰两种工艺加工出孔并进行了疲劳试验, 对钻、铰工艺下孔壁的表面形貌和粗糙度、切向残余应力以及试样的疲劳断口特征进行了测定和分析。结果表明: 钻削后孔壁的表面较粗糙, 其表面粗糙度为12.92 μm, 而铰削后孔壁表面非常光滑, 其表面粗糙度为1.57 μm; 钻削孔壁表层的应力为残余拉应力, 幅值为165 MPa, 而铰削孔壁表层的应力为残余压应力, 幅值为78 MPa; 相比于钻孔试样, 铰孔试样的疲劳条带间距较窄, 裂纹扩展速率较低, 其疲劳寿命是钻孔试样寿命的1.81倍。

In order to investigate the effects of drilling and reaming on the fatigue life of LY12CZ aluminum alloy specimen, a fastener hole was machined by drilling and reaming process, respectively, and fatigue tests were carried out. And the surface morphology, roughness and tangential residual stress of the hole wall were measured and analyzed as well as the fatigue fracture characteristics. The results show that the surface of hole wall after drilling was rough and its average surface roughness was 12.92 μm, while the surface of hole wall after reaming was much smooth and its average surface roughness was 1.57 μm. Moreover, the stress in the surface of hole wall after drilling was tensile residual stress and its magnitude reached to 310 MPa, while it was compressive residual stress after reaming and its magnitude reached to 78 MPa. Compared with the drilled specimen, the reamed specimen had narrower fatigue slip striation, and lower fatigue crack growth rate. The average fatigue life of the reamed specimen was 1.81 times as long as the drilling specimen.