Fatigue Crack Growth Mechanisms in HCP Single Crystals

HCP 单晶的疲劳裂纹扩展机制

基本信息

批准号：
11650715
负责人：
TAKASHIMA Kazuki
金额：
$ 2.43万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650715/
关键词：
Titanium Single Crystal Fatigue Crystallographic Orientation Crack Growth Rate Crack Growth Mechanism Slip System Twinning HCP金属疲労き裂伝播分子動力学

项目摘要

There have been few studies on fatigue crack growth mechanisms in HCP crystals. This may be partly due to the fact that the slip systems of HCP crystals have often not yet been identified precisely. In addition, mechanical twinning may occur in HCP crystals to accommodate deformation, since the number of slip systems in HCP metals is limited. This may also make it difficult to clarify fatigue crack growth mechanisms in HCP metals. Among HCP crystals, a-titanium and its alloys have been applied to aerospace structures and engine components because of their excellent specific strength and corrosion resistance. Therefore, it is important to address fundamental mechanisms in such materials. In this investigation, the fatigue crack growth behavior of a-titanium single crystals has been investigated in laboratory air at room temperature. Two types of CT specimens E and F with different notch orientations were prepared. In the E- and the F-specimens, the notch plane was (0001), and the notch directions were [1010] and [2110], respectively. The crack propagates roughly parallel to the basal plane in both the E- and the F-specimens, and the traces which correspond to {1012} twin systems are found near the crack plane. Ridges parallel to <1010>, and traces and bands due to {1012} twinning are observed on the fatigue surfaces. These results suggest that the crack growth might occur plausibly by the activation of micro-twins.

关于HCP晶体中疲劳裂纹生长机制的研究很少。这可能部分是由于HCP晶体的滑移系统通常尚未确切确切地识别。此外，由于HCP金属中的滑移系统数量有限，因此在HCP晶体中可能会发生机械孪生以适应变形。这也可能使很难阐明HCP金属中的疲劳裂纹生长机制。在HCP晶体中，由于具有出色的特异性强度和耐腐蚀性，因此A-Titanium及其合金已被应用于航空航天结构和发动机组件。因此，重要的是要解决此类材料中的基本机制。在这项研究中，已经在室温下在实验室空气中研究了A型单硝基单晶的疲劳裂纹生长行为。制备了两种具有不同缺口方向的CT样品E和F。在E-和f特性的情况下，Notch平面为（0001），而Notch方向分别为[1010]和[2110]。裂纹在E-和F特性中大致平行于基底平面，并且在裂纹平面附近发现与{1012}双系统相对应的迹线。在疲劳表面上观察到平行于<1010>的脊，并且由于{1012}孪生而引起的痕迹和带。这些结果表明，裂纹生长可能通过微训练的激活而可能发生。