一前言在航空发动机或其他高温零件中不可避免地存在着键槽、销孔、榫槽、螺纹、尖角等尺寸形状的变化,也不可避免地存在各种裂纹、疏松、非金属夹杂等内部微观缺陷,以及压痕、划伤、磨坑等表面宏观缺陷。这种缺口、缺陷的存在,会引起零件应力分布不均匀,产生应力集中。用“应力集中系数”K_t衡量应力集中的程度。不同材料对同样缺口,其应力集中敏感度是不同的。如某材料其σ_b=170公斤/毫米~2,它用于机器上的螺栓,允许设计应力为40公斤/毫米~2。而30CrMnSi钢,其σ_b只有110公斤/毫米~2,却能允许使用到90～ I. INTRODUCTION In the aeroengine or other high temperature parts inevitably there are key groove, pin hole, tongue and groove, thread, sharp corner and other dimensional changes, but also inevitably there are all kinds of cracks, loose, non-metallic inclusions and other internal microscopic Defects, as well as indentation, scratches, grinding pit surface macro defects. This gap, the existence of defects, can cause uneven stress distribution of parts, resulting in stress concentration. With “stress concentration factor ” K_t measure the degree of stress concentration. Different materials on the same gap, the stress concentration sensitivity is different. Such as a material σ_b = 170 kg / mm ~ 2, it is used for bolts on the machine, allowing the design stress of 40 kg / mm ~ 2. The 30CrMnSi steel, σ_b only 110 kg / mm ~ 2, but can allow the use of 90 ~