With the gradual increase in the application of pipeline steel,the propagation research of crack prevention has attracted much attention as the research focus of pipeline steel structure performance.In this test,the fatigue method was used to prefabricate the crack notch,and the oscillographic impact test was used to test the effect of the prefabricated crack notch and the conventional V-shaped notch on the toughness of X70 pipeline steel at different temperatures.The results show that compared with the conventional V-notch impact test,the toughness and brittle transition temperature of the prefabricated crack notch is increased by about 44℃,which is closer to the minimum service temperature specified in GB/T 20801.2-2020 Pressure Piping Code—Industrial Piping—Part 2:Materials,it provides a scientific reference for the determination of temperature value.Through the analysis of the characteristic parameters and macro-microscopic fracture morphology during the prefabricated crack propagation process,the results show that the crack propagation reveals a certain regularity with the decrease of temperature,which provides a certain reference basis for predicting the fracture mechanism of oscillographic impact test.
High grade pipeline steelsPrefabricated crack notchOscilloscope impact testCrack propagation
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