开缝衬套挤压工艺影响TA15孔疲劳增益研究

采用对比疲劳试验方法,研究了相对挤压量、终铰参量、衬套开缝放置角度等工艺参数和特征对开缝衬套挤压TA15钛合金连接孔疲劳增益的影响。结果表明,开缝衬套挤压技术可有效提高TA15钛合金孔结构疲劳强度,延长其疲劳寿命；相对挤压量越大,孔挤压疲劳增益越大,但是TA15钛合金对挤压量非常敏感,微小的相对挤压量波动会导致显著的疲劳增益波动；在完全去除开缝衬套在孔壁遗留的材料凸脊前提下,0.190 mm和0.065 mm两种单边终铰参量对TA15孔结构挤压疲劳增益有明显影响,0.190 mm单边铰削量时挤压疲劳增益更大,而非终铰参量越小越好；在s_max=400 MPa,R=0.1疲劳载荷条件下,衬套开缝与试样最窄截面平行放置,仍能够获得明显的疲劳增益,但相对于与试样与最窄截面呈90°放置,疲劳增益会略有下降,建议在实际孔挤压操作中,衬套开缝尽量避开最窄截面放置。

Effect of Split Sleeve Cold Expansion Process On the TA15 Hole Fatigue Gain

The effects of process parameters and characteristics such as relative extrusion amount, final reaming value and sleeve split placement on the fatigue gain of the split sleeve cold expansion TA15 titanium alloy hole structure were studied by the comparative fatigue test method. The results show that the split sleeve cold expansion technology can effectively improve the fatigue strength of the hole structure of TA15 alloy and prolong its fatigue life. The larger the relative extrusion amount, the greater the fatigue gain of the hole cold expansion, but the TA15 alloy is very sensitive to the extrusion amount, small relative fluctuations in the amount of extrusion can cause significant fatigue gain fluctuations. Under the premise of completely removing the material ridges left by the sleeve split in the hole wall, the 0.190 mm and 0.065 mm reaming amount are pressed influence the cold expansion fatigue gain significantly, the fatigue gain is greater at 0.190 mm single-sided reaming. Under the maximum fatigue load of 400 MPa, the placement of sleeve split has a significant impact on fatigue life, the sleeve split needs to be placed away from dangerous sections in actual split sleeve cold expansion operations.