Fatigue crack propagation properties of Ti-6Al-4V in vacuum environments
Fatigue crack propagation properties of Ti-6Al-4V in vacuum environments
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DOI：
10.1016/j.ijfatigue.2012.02.012
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发表时间：
2013-05-01
影响因子：
6
通讯作者：
Nakamura, T.
中科院分区：
文献类型：
--
作者：
Oguma, H.;Nakamura, T.
为了确定真空环境对Ti-6Al-4V合金疲劳裂纹扩展的影响，在空气和真空中进行了K降低试验。随着真空度的降低，疲劳裂纹扩展速率变慢，门槛应力强度因子范围变大。这种趋势不能完全用裂纹闭合来解释。基于断口观察，仅在高真空和超高真空下在断口上观察到几微米尺寸的粗糙体的颗粒区域。高真空环境是颗粒区形成的必要条件之一，而吸附气体在断裂面上的表面覆盖率与这一现象有关。颗粒区的形成反映了真空和空气环境下裂纹扩展机制的不同。提出了一种新的颗粒区形成机制，这是真空中裂纹扩展速率降低的原因之一。(C)2012爱思唯尔有限公司保留所有权利。
To determine the effects of vacuum environment on fatigue crack propagations in a Ti-6Al-4V alloy, K-decreasing tests were conducted in air and vacuum. The fatigue crack propagation rate became slower and threshold stress intensity factor range became larger with decreasing vacuum pressure. The tendency cannot be fully explained by the crack closure. Based on fracture surface observations, granular region of a few micrometer size asperities was observed on the fracture surface only in high vacuum and ultra high vacuum. The high vacuum environment is one of the necessary conditions for the formation of the granular region, and the fraction of surface coverage of adsorbed gas on fracture surfaces relates to the phenomenon. The formation of the granular region represents the difference of the crack propagation mechanism between vacuum and air environments. A new mechanism for the formation of the granular region was proposed, and that is one of the phenomena which can explain the reduction of crack propagation rate in vacuum. (C) 2012 Elsevier Ltd. All rights reserved.