TC17钛合金圆形开孔平板试样的疲劳性能存在差异,采用扫描电镜和能谱分析、金相检验、残余应力测试、粗糙度检测等方法对差异原因进行分析。结果表明:对于K_t=2.52且疲劳寿命较短的板状圆孔疲劳试样,其疲劳裂纹起源于孔边倒圆角加工损伤或孔内壁加工损伤处,寿命较长试样的疲劳裂纹均起源于孔内壁亚表面;对于K_t=2.1且疲劳寿命较短的板状圆孔疲劳试样,其疲劳裂纹起源于孔内壁加工损伤或孔边倒圆角损伤处,而寿命较长试样的疲劳裂纹多起源于表面加工缺陷或孔内壁亚表面处;试样加工损伤、孔内壁较大残余压应力以及残余应力较分散等因素造成了试样的疲劳性能存在较大差异。

The fatigue properties of TC17 titanium alloy circular perforated plate specimens were different. The reason for the differences was analyzed by scanning electron microscopy and energy spectrum analysis, metallographic examination, residual stress test and roughness test. The results show that for the plate-shaped circular hole fatigue specimen with K_t=2.52 and short life, the fatigue crack originated from the processing damage at the rounding of the hole edge or the processing damage of the inner wall of the hole, and the fatigue cracks of the longer life specimen originated from the inner wall of the hole. For the plate-shaped hole fatigue specimen with K_t=2.1 and short life, the fatigue crack originated from the machining damage of the inner wall of the hole or the rounding damage of the hole edge, while the fatigue cracks of the long-life specimen mostly originated from the surface machining defects or the subsurface of the inner wall of the hole. The fatigue properties of the samples were greatly different due to the processing damage of the samples, the large residual compressive stress on the inner wall of the hole and the dispersion of the residual stress.