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High cycle thermal fatigue crack growth and high temperature crack growth law

高周热疲劳裂纹扩展及高温裂纹扩展规律

基本信息

批准号：
02452100
负责人：
OGURA Keiji
金额：
$ 4.42万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-02452100/
关键词：
Thermal striping Thermal stress Crack growth Crack closure Leser speckle Surface crack Austenitic stainless steel オーステナイト系ステンレス鋼熱応力表面き裂有限要素法サ-マルストライピング SUS304L鋼 SUS304鋼

项目摘要

In order to simulrate the thermal striping situation in the sodium-cooled components of fast breader reactors, an apparatus was developed in which a high frequency of 1Hz in thermal stress cycling was applied to the test sample by a combination of direct current heating and cyclic shower. Crack growth tests were conducted for austenitic stainless steep plate samples of 10mm in thickness with a small semi-circular precrack of 0.4mm in diameter under the three levels (low, intermediate and high) of thermal stress cycling. The surface temperature of the sample was 540*80ﾟC in the intermediate level in the thermal stress cycling. The crack was accelerated in the first stage of growth, but it was decelerated for further growth after for any level of thermal stress cycling. The crack finally stopped growing under the low level of thermal stress cycling at a crack length of 0.6mm in a thickness direction. A leser speckle displacement gage was developed and used to monitor the crack opening and closure of the growing crack under thermal stress cycling. The thermal stress was estimated by the finite element analysis by using the temperature distribution obtained experimentally. The stress intensity factor was also estimated on the basis of this thermal stress. The correlation between the crack growth under thermal stress cycling and that under conventional stress cycling at constant temperatures was discussed. Both the data were found to be adjusted by the effective range of the stress intensity factor.

为了模拟快堆钠冷部件的热剥离情况，研制了一套装置，采用直流加热和循环喷淋相结合的方法，对试验样品施加1Hz的高频热应力循环。对带有直径为0.4mm的半圆形预裂纹的10mm厚奥氏体不锈钢厚板试样进行了低、中、高三个水平热应力循环下的裂纹扩展试验。在热应力循环中，样品的表面温度为540 × 80 ℃，处于中间水平。在热应力循环的第一阶段，裂纹的扩展速度加快，但在任何水平的热应力循环后，裂纹的进一步扩展速度减慢。在低水平的热应力循环下，裂纹在厚度方向上的裂纹长度为0.6mm时停止扩展。研制了一种激光散斑位移计，用于监测热应力循环下扩展裂纹的张开和闭合。利用实验得到的温度分布，通过有限元分析估算了热应力。在此基础上，对应力强度因子进行了估算。讨论了恒温热应力循环下裂纹扩展与常规应力循环下裂纹扩展的相关性。这两个数据被认为是调整的应力强度因子的有效范围。