摘要
采用标准C(T)试样测定热等静压Ti-6Al-4V钛合金在应力比R=0.1、0.4和0.7的条件下疲劳裂纹扩展速率,获得相应条件下的疲劳裂纹扩展数据,绘制了对应的裂纹扩展速率与应力场强度因子(da/dN-ΔK)关系曲线,并结合疲劳裂纹扩展路径和断口形貌分析探究应力比R对热等静压Ti-6Al-4V钛合金裂纹扩展速率的影响。结果表明,随着应力比R的增大,裂纹扩展门槛值ΔKtn减小。相同ΔK下,裂纹扩展速率da/dN随应力比R一同增大,致使da/dN-ΔK关系曲线向左上移动;裂纹能够穿过等轴晶α相和纤薄的α片层结构呈直线型扩展,遇到较厚的α片层结构时,裂纹偏转并沿原始α片层方向继续扩展,最终发生断裂;断口由预裂区、稳态扩展区和快速断裂区构成,分别对应于疲劳裂纹扩展的三个阶段。
The fatigue crack growth rate of hot isostatic pressing Ti-6Al-4V titanium alloy under different stress ratios ( R =0.1, 0.4 and 0.7) was studied by standard C(T) specimens, and the fatigue crack propagation data under corresponding conditions were obtained. Corresponding crack growth rate and stress field strength factor (d a /d N -Δ K ) are plotted, and the effects of stress ratio R on the fatigue crack growth of Ti-6Al-4V titanium alloy rate was investigated by combining the fatigue crack growth path and fracture morphology analysis. The results show that as the stress ratio R increases, the crack growth threshold Δ K th decreases. Under the same Δ K condition, the crack growth rate d a /d N increases with the stress ratio R , causing the d a /d N -Δ K relationship curve to move to the upper left. The crack can extend linearly through the equiaxed α-phase and the thin α-layer structure. When a thick α-layer structure is encountered, the crack deflects and continues to expand along the original α-layer, eventually breaks. The fracture is composed of pre-crack zone, steady-state extension zone, and rapid fracture zone, respectively, corresponding to three stages of fatigue crack growth.
作者
梁超
刘文彬
王铁军
车洪艳
王磊
LIANG Chao;LIU Wenbin;WANG Tiejun;CHE Hongyan;WANG Lei(Central Iron & Steel Research Institute,Beijing 100081, China;Advanced Technology & Materials Co., Ltd (AT&M),Beijing 100081, China;Shanghai Aircraft Manufacturing Co., Ltd,Shanghai 201324, China)
出处
《有色金属工程》
CAS
北大核心
2019年第9期17-23,共7页
Nonferrous Metals Engineering
基金
河北省涿州市创新基金项目(2018090103)~~
关键词
钛合金
应力比
疲劳裂纹扩展速率
疲劳断口形貌
titanium alloy
stress ratio
fatigue crack growth rate
fatigue fracture morphology