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高压富气输送管道要求发展管道钢的裂纹尖端张开角的测试方法。采用准静态的撕裂过程和长裂纹扩展长度试件,进行了X70管道钢的裂纹扩展试验,用摄像机跟踪拍摄裂纹扩展全过程,从获得的照片上直接测量出裂纹扩展全过程的CTOA值,分析了裂纹扩展中的断裂力学行为。试验结果表明,试件的韧带厚度越小,越容易获得稳定的扩展过程,且稳态裂纹扩展的CTOA值随试件韧带厚度的增加而增大,太厚的试件不易得到稳态扩展过程。韧带厚度为4 mm、8 mm试件的稳态的裂纹扩展阶段分别为7.6°、11.3°,裂纹扩展长度与韧带厚度比在4~25、4~10之间。
High Pressure Gas Transmission Pipeline Requirements Development of Test Method for Opening Angle of Cracked Tip of Pipe Steel. The quasi-static tearing process and long crack extension length specimens were used to test the crack growth of X70 pipeline steel. The whole process of crack propagation was tracked with a camera. The CTOA value of the crack propagation was directly measured from the obtained photographs. The fracture mechanics behavior in crack propagation is analyzed. The experimental results show that the smaller the thickness of the ligament, the easier it is to obtain a stable expansion process. The steady-state crack growth CTOA value increases with the increase of the ligament thickness of the specimen, and the thicker specimen is not easy to obtain the steady state expansion process . The thickness of the ligament was 4 mm, and the steady-state crack propagation phases of the 8 mm specimens were 7.6 ° and 11.3 °, respectively. The crack propagation length and the ligament thickness ratio were between 4 and 25 and 4 to 10, respectively.