The effect of loading direction on the dwell fatigue properties of Ti-6Al-4V forged bar with highly oriented texture
The effect of loading direction on the dwell fatigue properties of Ti-6Al-4V forged bar with highly oriented texture
复制标题
加载方向对高取向织构Ti-6Al-4V锻棒驻留疲劳性能的影响
作者：
K. Mori;S. Hashimoto;T. Okui;Y. Shirai;M. Miyahara
本研究的目的是提高我们对宏观/微观织构对驻留疲劳性能影响的理解。采用具有高取向织构和细等轴组织的Ti-6Al-4V锻棒。使用沿棒材的纵向（L）方向和横向（T）方向采集的样品在室温下进行停留疲劳、循环疲劳和蠕变试验。详细研究了加载方向对驻留疲劳寿命和断裂表面形态的影响。 T方向的驻留疲劳寿命比L方向短。断裂表面形态随载荷波形、振幅和方向的变化而变化。在 0.2%PS 的 93 - 95% 范围内，在驻留疲劳中在 T 方向观察到特征大刻面。详细分析表明，大面由多个起始面和传播面组成。传播小平面和裂纹传播方向似乎对应于α(0001)<10-10>。此外，将应变率和寿命之间的关系与室温蠕变的关系进行了比较。 Monkman-Grant 关系的偏差对应于断裂表面形态的变化。
The purpose of this study was to improve our understanding of the effect of macro/micro texture on dwell fatigue properties. The Ti-6Al-4V forged bar with highly oriented texture and fine equiaxed microstructure was used. Dwell fatigue, cyclic fatigue and creep tests were conducted at room temperature by using specimens taken in the longitudinal (L) direction and the transverse (T) direction of the bar. The effects of loading direction on dwell fatigue life and fracture surface morphology were examined in detail. The dwell fatigue life in T direction was shorter than that in L direction. The fracture surface morphologies were characteristically varied by loading waveform, amplitude and directions. In the range of 93 - 95% of 0.2%PS, the characteristic large facets were observed in the T direction in dwell fatigue. Detailed analyses revealed that the large facet consists of multiple initiation facets and propagation facets. The propagation facet plane and crack propagation direction appeared to correspond to alpha (0001) <10-10>. Furthermore, the relationship between strain rate and life time was compared to that for room temperature creep. The deviation from the Monkman-Grant relationship corresponded to the change of the fracture surface morphology.