High-Precision Determination of Fundamental Properties of Creep-Fatigue Crack Propagation

蠕变疲劳裂纹扩展基本特性的高精度测定

基本信息

批准号：
04452116
负责人：
OHJI Kiyotsugu
金额：
$ 4.22万
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：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04452116/
关键词：
Creep-Fatigue Crack Propagation Creep Crack Propagation Fatigue Crack Propagation Fatigue Threshold Crack Closure Fracture Mechanics Life Prediction Laser-Based Interferometric Strain Displacement Gage

项目摘要

The safety assessment of high temperature equipment and strucures is indispensable for their effective use. In the present study prediction method of high temperature creep and fatigue crack propagation lives and fundamental crack propagation behavior were investigated for the assessment. The main conclusions obtained are summarized in the followings.1.Using the laser-based interferometric strain/displacement gage system, crack closure in fatigue crack propagation tests was successfully measured at high temperatures. By using platinum plate for reflecting laser beam and filter for eliminating back-ground noise, the measurement was made up to 700'C.2.The behaviors of crack propagation and crack closure were investigated under stress rations of R = -0., 0.1 and 0.5, at 450', 550', 650' and 700'C for type 304 stainless steel. The dependence of the crack propagation rate on R was reconsiled by DELTA K_<eff> which accounted for the effect of crack closure.3.The effect of specimen geometry on the fatigue crack growth in type 304 stainless steel was studied at room and high temperatures. It was found that the near-threshold fatigue crack propagation behavior depended on specimen thickness.4.Creep crack propagation in used 2 1/4 Cr 1Mo steel was studied. Creep crack propagation rate in the heat affected zone was higher than that in the base material. The crack propagation rate correlated well with the modified J integral.5.The engineering approach was applied to predicting the creep crack propagation behavior. The predicted crack propagation in C(T) specimens agreed well with experimental one. The approach was then applied to the crack propagation of an inner longitudinal crack and an inner circumferential crack in pipes for the safety assessment of the pipe.

高温设备和结构的安全评估对于它们的有效使用是必不可少的。在本研究中，研究了高温蠕变和疲劳裂纹繁殖生命和基本裂纹传播行为的预测方法进行评估。 1.通过激光的干涉应变/位移量规系统总结了所获得的主要结论，在高温下成功测量了疲劳裂纹传播测试中的裂纹闭合。通过使用铂板来反射激光束和滤波器以消除后地面噪声，将测量最高为700'C.2。裂纹繁殖和裂纹闭合的行为在R = -0，0.1和0.5，在450'，550'，550'，650'，650'，650'和700'C的压力级别下进行，用于304型304型钢丝。裂纹传播率对R的依赖性由Delta k_ <eff>重新考虑，这是构成裂纹闭合作用的3.样品几何形状对房间和高温下304型不锈钢型疲劳裂纹生长的影响。发现接近阈值的疲劳裂纹繁殖行为取决于样品厚度。4。研究了用过的2 1/4 Cr 1MO钢中的裂纹传播。热影响区的蠕变裂纹传播速率高于基本材料中的传播率。裂纹传播率与修改后的J积分很好地相关。5。工程方法应用于预测蠕变裂纹的传播行为。 C（t）标本中预测的裂纹传播与实验性构成很好的一致。然后将该方法应用于内部纵向裂纹的裂纹传播，并在管道中的内圆形裂缝进行管道评估。