湿喷丸强化对TC4疲劳性能的影响机制

Fatigue fracture mechanism of Ti-6Al-4V strengthened by wet peening treatment

摘要:

利用湿喷丸技术对TC4钛合金进行表面改性处理,显著提高了材料疲劳寿命。对疲劳断口微观组织观察发现,湿喷丸强化处理使试样疲劳裂纹萌生位置由表面转移至试样内部约1 mm深度区域。通过对湿喷丸改性层微观组织分析可知,改性层内的细晶强化和位错强化是导致裂纹萌生位置发生改变的主要因素。湿喷丸引入的残余压应力对裂纹扩展起到有效的阻碍作用。细晶强化、位错强化和残余压应力共同作用提高TC4钛合金的抗疲劳性能。

Abstract:

A modified surface layer was fabricated on Ti-6Al-4V alloy by means of wet peening treatment. The fatigue life of specimen which suffered wet peening treatment was obviously increased. Compared with the fracture of un-peened sample, the fatigue crack initial site was transferred from surface to the interior region beneath the surface (about 1 mm depth). The co-action of grain refinement strengthening and dislocation strengthening dominated the transferred fatigue crack initial site. The compressive residual stress effectively delayed the crack propagation. The grain refinement strengthening, the dislocation strengthening as well as the compressive residual stress were the main factors of increased fatigue life.