A100钢外螺纹椭圆超声滚压强化试验研究

Study on Strengthening of External Threads in A100 Steel by Elliptical Ultrasonic Rolling

A100钢有较高的疲劳抗力和显著的减重效果。在航空工业中,飞机起落架主要承力件正逐步采用A100钢,且主要承力件多采用螺纹联接。为了提高螺纹疲劳寿命,提出了超声振动滚压强化工艺方法,设计了外螺纹超声滚压强化装置,进行了螺纹超声滚压强化前后性能对比试验。利用X射线分析仪、维式硬度计、粗糙度仪和疲劳试验机,分别测量了螺纹超声滚压强化前后的残余应力、维氏硬度、表面粗糙度以及疲劳寿命。结果表明,超声滚压强化后牙底残余应力提高了70%,显微硬度提高了14%,粗糙度降低了51%,600MPa应力条件下寿命提高了5倍。

A100 steel has the characteristics of high fatigue resistance and significantly low weight. In the aviation industry, A100 steel is used for aircraft landing gear gradually, and its main bearing parts are joined by screw thread. Ultrasonic vibration rolling strengthening technological process has been proposed to improve the fatigue life, and ultrasonic rolling device has been designed to strengthen external thread, and process parameters have been optimized. Residual stress near to the root of the threads has been measured by X-ray stress analyzer, surface roughness has been measured by rough- meter, micro-hardness has been measured by Vickers, and fatigue life has been measured by fatigue machine. The results show that the maximum axial stress increases by 70%, micro-hardness increases by 14%, and the roughness is reduced by 51%, and fatigue life of the threads strengthened by forming tap is five times longer than those of cutting threads under thestress of 600MPa.