论文部分内容阅读
为研究超声深滚处理技术(Ultrasonic Deep Rolling,UDR)对零件表面损伤的抗疲劳修复与强化作用,制备了Ti-6Al-4V缺口疲劳试件,采用UDR技术对缺口疲劳试件进行了深滚强化处理。通过疲劳试验对比了深滚处理前后的缺口试件的抗疲劳性能。采用体视显微镜对疲劳断口和深滚处理后缺口附近的塑性变形进行了观察分析,根据名义应力法和局部应力应变法对缺口件的疲劳寿命进行了计算,并与试验结果进行了比较。结果表明:试验结果与计算结果较接近;与未经超声深滚处理的试件相比,经超声深滚处理后缺口试件的疲劳强度由276 MPa提高到523 MPa。断口分析表明:经超声深滚处理后疲劳裂纹源下移到缺口根部以下0.68 mm处,说明超声深滚在缺口根部引入的残余压应力是提高缺口试件疲劳强度的主要原因。
In order to study the anti-fatigue repair and strengthening effect of Ultrasonic Deep Rolling (UDR) on the surface damage of parts, a Ti-6Al-4V notch fatigue specimen was prepared. The notch fatigue test specimen was deeply rolled using UDR technique Strengthen processing. The fatigue tests of notched specimens before and after deep-roll treatment were compared by fatigue tests. The stereoscopic microscope was used to observe and analyze the plastic deformation near the notch after fatigue fracture and deep rolling. The fatigue life of the notch was calculated according to the nominal stress method and the local stress-strain method, and the results were compared with the experimental results. The results show that the experimental results are in good agreement with the calculated ones. Compared with the deep-rolled specimens, the fatigue strength of the notched specimens after ultrasonic deep-rolling is increased from 276 MPa to 523 MPa. The fracture analysis shows that the source of fatigue cracks moves down to 0.68 mm below the notch root after the deep ultrasonic roll processing, which shows that the residual compressive stress introduced by deep ultrasonic roll in the notch root is the main reason to improve the fatigue strength of notch specimens.