直流电位差法测量316L管道疲劳裂纹扩展的研究
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摘要
本文首先介绍了用直流电位差法测量疲劳裂纹长度的基本原理、实现方法及所用的仪表。并采用直流电位法测量系统测试固溶处理的316L电气管道的疲劳裂纹扩展速率。试验结果表明:利用CT试样做降K试验时一定要保证后一阶段的裂纹扩展完全穿过前阶段造成的塑性区域。当裂纹长度的表征值a/W>0.55时,如果K>30 MPa/m疲劳开裂可能偏离试样的平面应变准则较大,所测量到的裂纹扩展速率会有较大误差。1030的降K实验结果和1033的升K实验结果是试样的真正的疲劳裂纹扩展速率。
In this paper, the basic principle, realization method and instrument of measuring fatigue crack length by DC potential method are introduced at first, and the fatigue crack propagation rate of 316 L electric pipeline of solution treatment was tested by measuring system of DC potential method. Results show that when K-decreasing test is carried out with the CT specimen, it must be ensure that the crack growth in the latter stage completely passes through the plastic zone caused by the former stage. When the representative value of the crack length is a/W>0.55, if the fatigue crack of K>30 MPa/m may deviate from the plane strain criterion of the specimen, the measured crack growth rate will have a great error. The real fatigue crack growth rate of the specimen is determined by the K-decreasing test results of 1030 and the K-increasing test results of 1033.
In this paper, the basic principle, realization method and instrument of measuring fatigue crack length by DC potential method are introduced at first, and the fatigue crack propagation rate of 316 L electric pipeline of solution treatment was tested by measuring system of DC potential method. Results show that when K-decreasing test is carried out with the CT specimen, it must be ensure that the crack growth in the latter stage completely passes through the plastic zone caused by the former stage. When the representative value of the crack length is a/W>0.55, if the fatigue crack of K>30 MPa/m may deviate from the plane strain criterion of the specimen, the measured crack growth rate will have a great error. The real fatigue crack growth rate of the specimen is determined by the K-decreasing test results of 1030 and the K-increasing test results of 1033.
引文
[1] 李家伟,陈积懋.无损检测手册[M].北京:机械工业出版社,2002:426-441.
[2] 王亮,丁传富.高温下直流电位法测量裂纹长度的应用[J].理化检验,2006.42(9):454-456.
[3] Amiri Rad A,Forouzan M R,Sadeghi Dolatabadi A.Three-dimensional fatigue crack growth modelling in a helical gear using extended finite element method[J].Fatigue &Fracture if Engineering Materials & Structures,2014,37(6):581-591.
[4] 石凯凯.循环与准静态裂纹扩展的理论和测试方法[D].成都:西南交通大学博士学位论文,2010.
[5] 刘彤,杨荣根,张晓慧,等.疲劳裂纹深度自动检测系统的研制与应用[J].机械强度,2004.24(S):288-290.
[2] 王亮,丁传富.高温下直流电位法测量裂纹长度的应用[J].理化检验,2006.42(9):454-456.
[3] Amiri Rad A,Forouzan M R,Sadeghi Dolatabadi A.Three-dimensional fatigue crack growth modelling in a helical gear using extended finite element method[J].Fatigue &Fracture if Engineering Materials & Structures,2014,37(6):581-591.
[4] 石凯凯.循环与准静态裂纹扩展的理论和测试方法[D].成都:西南交通大学博士学位论文,2010.
[5] 刘彤,杨荣根,张晓慧,等.疲劳裂纹深度自动检测系统的研制与应用[J].机械强度,2004.24(S):288-290.