承载超声冲击提高TC4钛合金焊接接头的疲劳性能

Improvement of fatigue performance of TC4 Ti-alloy welded joints by loading ultrasonic peening

关键词:  焊接接头  疲劳性能  承载超声冲击

Key words:  welded joint  fatigue performance  loading ultrasonic peening

摘要:

利用自行研制的HJ-II型超声冲击处理装置对钛合金十字接头焊趾处进行了处理,并对接头的疲劳性能进行了研究.结果表明,在应力比R=0.5加载条件下,非承载超声冲击处理的TC4钛合金焊接接头较原始焊态的疲劳强度提高了约73.5%,寿命延长了12~17倍左右,承载超声冲击处理的TC4钛合金焊接接头较原始焊态的疲劳强度提高了148.1%,寿命延长了23~26倍左右.同时,从超声冲击前后应力集中系数的改变、焊接接头残余应力的改变、接头焊趾区表层塑性变形及硬度的变化等几个方面阐述了超声冲击提高焊接接头疲劳性能的机理,特别是承载超声冲击提高TC4钛合金焊接接头疲劳性能的原因.

Abstract:

In order to improve the fatigue performance of Ti alloy welded joints,the weld toe in cross-shaped joint was processed by the HJ-Ⅱ-type ultrasonic peening treat plant developed by authors.The test results indicate that when the stress ratio R is equal to 0.5 in loading condition,the conventional ultrasonic peening processing makes the fatigue strength of the cross-shaped joint of TC4 titanium alloy be enhanced by about 73.5%,the life be lengthened about 12-17 times,while loading ultrasonic peening processing makes the fatigue strength of the cross shaped joint of TC4 titanium alloy be enhanced by about 148.1%,and the life be lengthened about 23-26 times.Meanwhile,the mechanism for the fatigue performance of welded joints enhanced by the ultrasonic peening,especially the loading ultrasonic peening is expounded from the change of the stress concentration factor after the ultrasonic peening,the change of the residual stress of welded joints,the plastic deformation in the surface layer of the weld toe area and the change in hardness.