作者：张海伟1, 高怡斐1,2, 任欣3, 李顺3
作者单位：1. 钢铁研究总院分析测试研究所，北京 100081;
2. 钢研纳克检测技术股份有限公司，北京 100081;
3. 钢研纳克成都检测认证有限公司，四川 成都 610200
关键词：裂纹扩展;门槛值;裂纹闭合;钛合金;CPCA方法;压缩载荷
摘要：
针对不同尺寸紧凑拉伸试样门槛值实验中存在裂纹扩展速率提前下降的现象，选取R=0.1应力比，对试样宽度尺寸为25，50，75 mm的3组试样，分别进行ASTM E647规定的降载方法（load reduction, LR）与压缩预制裂纹恒载法(compression pre-cracking constant amplitude, CPCA)的钛合金门槛值实验，分析比较不同方法数据差异。实验结果证明传统降载方法由于裂纹闭合会导致较大尺寸试样裂纹扩展速率提前下降，获得较为保守的门槛值，存在尺寸效应；而压缩预制裂纹恒载法由于裂纹尖端应力场的不同，可以获得不受尖端裂纹闭合的门槛值数据，不存在尺寸效应，压缩预制裂纹恒载法可以作为测试裂纹扩展门槛值的方法。
Crack propagation threshold test of Ti-Alloy based on compression pre-cracking method
ZHANG Haiwei1, GAO Yifei1,2, REN Xin3, LI Shun3
1. National Analysis Center for Iron and Steel, Central Iron and Steel Research Institute, Beijing 100081, China;
2. NCS Testing Technology Co., Ltd., Beijing 100081, China;
3. NCS Chengdu Testing Certification Co., Ltd., Chengdu 610200, China
Abstract: In view of the phenomenon that the crack growth rate of different sizes of compact tensile specimens decreases in advance, the load reduction method specified in ASTM E647 and the compression pre-cracking constant amplitude method are carried out for three groups of specimens with the width of 25 mm, 50 mm and 75 mm respectively with R = 0.1 stress ratio. The results show that the crack growth rate of the larger specimen will decrease in advance due to the crack closure of the traditional load reduction method, and a more conservative threshold value is obtained, and there is size effect. However, due to the difference of the stress field at the crack tip, the CPCA method can obtain the crack closure free from the tip crack. The results show that there is no size effect on the threshold data, which verifies that the CPCA method can be used to test the crack growth threshold.
Keywords: crack growth;threshold;crack closure;titanium alloy;CPCA method;compression loading
2021, 47(6):27-32 收稿日期: 2020-09-05;收到修改稿日期: 2020-10-21
基金项目:
作者简介: 张海伟(1995-),男,山东潍坊市人,硕士研究生,专业方向为金属材料力学性能表征研究
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